1. NAVIGATION 5
OPERATIONAL USE
OF
ECDIS
INSTRUCTOR
CAPT. D. TUMANENG, M. M. E.

2. GOOD MORNING / AFTERNOON
LADIES AND GENTLEMEN
I AM CAPT. DANIEL D. TUMANENG A LICENSED
and EXPERIENCED MASTER MARINER
(Unlimited) ON WORLDWIDE (Bulk, Ro-Ro,
Crude Oil Tanker) and FAR EAST ROUTE (Pure
Container) INCLUDING OFFSHORE.
I AM YOUR NEW INSTRUCTOR IN NAVIGATION
5: OPERATIONAL USE OF ECDIS.

3. THIS IS OUR 12th WEEK IN MIDTERM
OUR INITIAL TOPIC AS PER SCHOOL’s
INSTRUCTOR’s GUIDE (IG) IS ABOUT
DIFFERENTIAL GLOBAL POSITIONING SYSTEM
(DGPS).

4. • Differential Global Positioning System (DGPS)
is an enhancement to
Global Positioning System
that provides improved
location accuracy, from
the 15-meter nominal
GPS accuracy to about
10 cm in case of the
best implementations.

5. • Enhancement means to raise in a higher
degree or intensify. e.g. The dynamic circuit
network is really an enhancement rather
than a replacement.
• to increase in quality or value, to change to a
product which is intended to make it better in
some way. e.g. New functions, faster or more
compatible with other system

6. A satellite navigation or satnav system is a system of
satellites that provide autonomous geo-spatial positioning
with global coverage. It allows small electronic receivers to
determine their location (longitude, latitude, and altitude) to
high precision (within a few metres) using time signals
transmitted along a line of sight by radio from satellites. The
signals also allow the electronic receivers to calculate the
current local time to high precision, which allows time
synchronisation.
A satellite navigation system with global
coverage may be termed a global navigation satellite
system or GNSS.

10. As of April 2013, only the United States
NAVSTAR Global Positioning System
(GPS) and the Russian GLONASS are
global operational GNSSs.
China is in the process of expanding its
regional Beidou navigation system into the
global Compass navigation system by 2020. The
European Union's Galileo positioning system is a
GNSS in initial deployment phase, scheduled to be
fully operational by 2020 at the earliest. France,
India, and Japan are in the process of developing
regional navigation systems.

11. Fundamentals
The GPS system concept is based on time. The
satellites carry atomic clocks which are synchronized and very
stable;
any drift from true time maintained on the ground is
corrected daily. Likewise, the satellite locations are monitored
precisely. User receivers have clocks as well. However, they
are not synchronized with true time, and are less stable.
GPS satellites transmit data continuously which
contains their current time and position. A GPS receiver
listens to multiple satellites and solves equations to
determine the exact position of the receiver and its deviation
from true time.
At a minimum, four satellites must be in view of the
receiver in order to compute four unknown quantities (three
position coordinates and clock deviation from satellite time).

12. DGPS uses a network of fixed, ground-
based reference stations to broadcast the
difference between the positions indicated by
the satellite systems and the known fixed
positions.
These stations broadcast the difference
between the measured satellite pseudoranges
and actual (internally computed)
pseudoranges, and receiver stations may
correct their pseudoranges by the same
amount.

13. • Q: How can Pseudorange Measurements be
Generated from Code Tracking?
• A: Every GNSS receiver processes the received
signals to obtain an estimate of the propagation
time of the signal from the satellites to the
receiver. These propagation times are then
expressed in meters to solve for the user
position using trilateration.
• Because the resulting distances are not only
related to the distance between the receiver
antenna and the satellites, i.e. the range, but also
to an imperfect alignment of the receiver’s time
scale to the GPS time scale, they are called
“pseudoranges”.

14. The digital correction signal
is typically broadcast locally
over ground-based transmitters
of shorter range.
The term refers to a general technique of augmentation
(the amount by which something is increased). The United States
Coast Guard (USCG) and Canadian Coast Guard (CCG)
each run such systems in the U.S. and Canada on the
longwave radio frequencies between 285 kHz and 325
kHz near major waterways and harbors.
The USCG's DGPS system has been named NDGPS
(National DGPS) and is now jointly administered by the
Coast Guard and the U.S. Department of
Transportation’s Federal Highway Administration.

15. It consists of broadcast sites located
throughout the inland and coastal portions of
the United States including Alaska, Hawaii and
Puerto Rico.
A similar system that transmits
corrections from orbiting satellites instead of
ground-based transmitters is called a Wide-
Area DGPS (WADGPS) or Satellite Based
Augmentation System.

16. HISTORY
When GPS was first being put into service, the
US military was concerned about the possibility of
enemy forces using the globally available GPS signals
to guide their own weapon systems.
Originally, the government thought the "coarse
acquisition" (C/A) signal would only give about 100
meter accuracy, but with improved receiver designs,
the actual accuracy was 20 to 30 meters.
Starting in March 1990, to avoid providing such
unexpected accuracy, the C/A signal transmitted on
the L1 frequency (1575.42 MHz) was deliberately
degraded by offsetting its clock signal by a random
amount, equivalent to about 100 meters of distance.

17. I
“COARSE ACQUISITION“ Initially, the highest quality signal was
reserved for military use, and the signal available for civilian use was
intentionally degraded (Selective Availability). This changed with
President Bill Clinton ordering Selective Availability to be turned off at
midnight May 1, 2000, improving the precision of civilian GPS from
100 to 20 meters (328 to 66 ft).
The executive order signed in 1996 to turn off Selective Availability in
2000 was proposed by the U.S. Secretary of Defense, William Perry,
because of the widespread growth of differential GPS services to
improve civilian accuracy and eliminate the U.S. military advantage.

18. This technique, known as "Selective
Availability", or SA for short, seriously
degraded the usefulness of the GPS signal
for non-military users.
More accurate guidance was possible
for users of dual frequency GPS receivers
that also received the L2 frequency (1227.6
MHz), but the L2 transmission, intended for
military use, was encrypted and was only
available to authorised users with the
encryption keys.

19. This presented a problem for civilian users who
relied upon ground-based radio navigation systems
such as LORAN, VHF Omnidirectional Range (VOR)
and Non-directional Beacon (NDB) systems costing
millions of dollars each year to maintain. The advent
of a global navigation satellite system (GNSS) could
provide greatly improved accuracy and performance
at a fraction of the cost.
The military received multiple requests from
the Federal Aviation Administration (FAA), United
States Coast Guard (USCG) and United States
Department of Transportation (DOT) to set S/A aside
to enable civilian use of GNSS, but remained steadfast
in its objection on grounds of security.

20. Through the early to mid 1980s, a number of
agencies developed a solution to the SA "problem". Since
the SA signal was changed slowly, the effect of its offset
on positioning was relatively fixed – that is, if the offset
was "100 meters to the east", that offset would be true
over a relatively wide area.
This suggested that broadcasting this offset to local
GPS receivers could eliminate the effects of SA, resulting
in measurements closer to GPS's theoretical performance,
around 15 meters.
Additionally, another major source of errors in a
GPS fix is due to transmission delays in the ionosphere,
which could also be measured and corrected for in the
broadcast. This offered an improvement to about 5
meters accuracy, more than enough for most civilian
needs.

21. The US Coast Guard was one of the more aggressive
proponents of the DGPS system, experimenting with the system
on an ever-wider basis through the late 1980s and early 1990s.
These signals are broadcast on marine longwave (a range of radio
waves with frequency below 300 kilohertz) frequencies, which could be
received on existing radiotelephones and fed into suitably
equipped GPS receivers.
Almost all major GPS vendors offered units with DGPS
inputs, not only for the USCG signals, but also aviation units on
either VHF or commercial AM radio bands.
They started sending out "production quality" DGPS
signals on a limited basis in 1996, and rapidly expanded the
network to cover most US ports of call, as well as the Saint
Lawrence Seaway in partnership with the Canadian Coast Guard.
Plans were put into place to expand the system across the US, but
this would not be easy.

22. • LEGEND
• kHz “Kilohertz” a unit of measurement of
frequency, also known as cycles per second. One
kilohertz is equal to 1,000 hertz or 1,000 cycles
per second.
• GHz “Gigahertz” is a unit of alternating current
(AC) or electromagnetic (EM) wave frequency
equal to one thousand million hertz
(1,000,000,000 Hz).
• MHz “Megahertz” is equal to 1,000,000
kilohertz. It can also be described as 1,000,000
cycles per second. MHz is use to measure wave
frequencies, as well as the speed of
microprocessors.

23. Operation
A reference station calculates differential
corrections for its own location and time. Users
may be up to 200 nautical miles (370 km) from
the station, however, and some of the
compensated errors vary with space: specifically,
Satellite Ephemeris Errors and those introduced
by Ionospheric and Tropospheric
distortions.
For this reason, the accuracy of DGPS
decreases with distance from the reference
station. The problem can be aggravated if the
user and the station lack "inter visibility"—when
they are unable to see the same satellites.

24. • Ephemeris and Clock Errors
While the ephemeris data is transmitted
every 30 seconds, the information itself may be up
to two hours old. Variability in solar radiation
pressure has an indirect effect on GPS accuracy due
to its effect on ephemeris errors.
If a fast time to first fix (TTFF) is needed, it is
possible to upload a valid ephemeris to a receiver,
and in addition to setting the time, a position fix
can be obtained in under ten seconds. It is feasible
to put such ephemeris data on the web so it can be
loaded into mobile GPS devices.

25. • Overview
User equivalent range errors (UERE)
are shown in the table. There is also
a numerical error with an estimated
value, , of about 1 meter. The
standard deviations, , for the coarse
/acquisition (C/A) and precise
codes are also shown in the table.
These standard deviations are
computed by taking the square
root of the sum of the squares
of the individual components
(i.e., “RSS” for Root Sum Squares).

26. To get the standard deviation of receiver position estimate,
these range errors must be multiplied by the appropriate
dilution of precision terms and then RSS'ed with the
numerical error. Electronics errors are one of several
accuracy-degrading effects outlined in the table above. When
taken together, autonomous civilian GPS horizontal position
fixes are typically accurate to about 15 meters (50 ft). These
effects also reduce the more precise P(Y) code's accuracy.

27. However, the advancement of technology
means that today, civilian GPS fixes under
a clear view of the sky are on average
accurate to about 5 meters (16 ft)
horizontally. The term user equivalent range
error (UERE) refers to the error of a
component in the distance from receiver
to a satellite. These UERE errors are given
as ± errors thereby implying that they are
unbiased or zero mean errors. These UERE
errors are therefore used in computing
standard deviations. The standard deviation
Of the error in receiver position, , is computed by multiplying
PDOP (Position Dilution Of Precision) by , the standard deviation of
the user equivalent range errors. is computed by taking the square
root of the sum of the squares of the individual component standard
deviations.

28. PDOP is computed as a function of receiver and satellite
positions. A detailed description of how to calculate PDOP is
given in the section, geometric dilution of precision computation
(GDOP). for the C/A code is given by:
The standard deviation of the error in estimated receiver
position again for the C/A code is given by: The error
diagram on the left shows the inter relationship of indicated
receiver position, true receiver position, and the intersection of
the four sphere surfaces.

29. Signal Arrival Time Measurement
The position calculated by a GPS receiver requires the current time,
the position of the satellite and the measured delay of the received
signal. The position accuracy is primarily dependent on the satellite
position and signal delay. To measure the delay, the receiver compares
the bit sequence received from the satellite with an internally
generated version.
By comparing the rising and trailing edges of the bit transitions,
modern electronics can measure signal offset to within about one
percent of a bit pulse width, , or approximately
10 nanoseconds for the C/A code. Since GPS signals propagate at the
speed of light, this represents an error of about 3 meters.
This component of position accuracy can be improved by a factor of 10
using the higher-chiprate P(Y) signal. Assuming the same one percent
of bit pulse width accuracy, the high-frequency P(Y) signal results in
an accuracy of or about 30 centimeters

30. ACCURACY
The United States Federal Radionavigation
Plan and the IALA Recommendation on the
Performance and Monitoring of DGNSS
Services in the Band 283.5–325 kHz cite the
United States Department of
Transportation's 1993 estimated error
growth of 0.67 m per 100 km from the
broadcast site but measurements of
accuracy across the Atlantic, in Portugal,
suggest a degradation of just 0.22 m per 100
km.

31. VARIATIONS
DGPS can refer to any type of Ground
Based Augmentation System (GBAS). There are
many operational systems in use throughout
the world, according to the US Coast Guard, 47
countries operate systems similar to the US
NDGPS (Nationwide Differential Global
Positioning System).

32. European DGPS Network
The European DGPS network has been mainly developed
by the Finnish and Swedish maritime administrations in order to
improve safety in the archipelago between the two countries.
In the UK and Ireland, the system was implemented as a maritime
navigation aid to fill the gap left by the demise of the Decca
Navigator System in 2000.
With a network of 12 transmitters sited around the
coastline and three control stations, it was set up in 1998 by the
countries' respective General Lighthouse Authorities
(GLA) — Trinity House covering England, Wales and the Channel
Islands, the Northern Lighthouse Board covering Scotland and the
Isle of Man and the Commissioners of Irish Lights, covering the
whole of Ireland.
Transmitting on the 300 kHz band, the system underwent
testing and two additional transmitters were added before the
system was declared operational in 2002.

33. United States NDGPS
The United States Department of Transportation, in
conjunction with the Federal Highway Administration, the Federal
Railroad Administration and the National Geodetic Survey
appointed the Coast Guard as the maintaining agency for the U.S.
Nationwide DGPS network (NDGPS).
The system is an expansion of the previous Maritime
Differential GPS (MDGPS), which the Coast Guard began in the late
1980s and completed in March 1999. MDGPS only covered coastal
waters, the Great Lakes, and the Mississippi River inland
waterways, while NDGPS expands this to include complete
coverage of the continental United States.
The centralized Command and Control unit is the USCG
Navigation Center , based in Alexandria, VA.
There are currently 85 NDGPS sites in the US network,
administered by the U.S. Department of Homeland

34. Canadian DGPS
The Canadian system is similar to the
US system and is primarily for maritime
usage covering the Atlantic and Pacific coast
as well as the Great Lakes and Saint
Lawrence Seaway.

35. Australia
Australia runs three DGPS systems: one is
mainly for marine navigation, broadcasting its signal
on the longwave band; another is used for land
surveys and land navigation, and has corrections
broadcast on the Commercial FM radio band.
While the third at Sydney airport is currently
undergoing testing for precision landing of aircraft
(2011), as a backup to the Instrument Landing System
at least until 2015. It is called the Ground Based
Augmentation System.
Corrections to aircraft position are broadcast
via the aviation VHF band.

36. POST PROCESSING
Post-processing is used in Differential GPS to obtain precise
positions of unknown points by relating them to known points such
as survey markers.
The GPS measurements are usually stored in computer
memory in the GPS receivers, and are subsequently transferred to a
computer running the GPS post-processing software.
The software computes baselines using simultaneous
measurement data from two or more GPS receivers.
The baselines represent a three-dimensional line drawn
between the two points occupied by each pair of GPS antennas.
The post-processed measurements allow more precise
positioning, because most GPS errors affect each receiver nearly
equally, and therefore can be cancelled out in the calculations.

37. Differential GPS measurements can also be computed in real-
time by some GPS receivers if they receive a correction signal using a
separate radio receiver, for example in Real Time Kinematic (RTK)
surveying or navigation.
• REAL TIME KINEMATIC (RTK) satellite navigation is a technique used in
land survey based on the use of carrier phase measurements of the GPS,
GLONASS and/or Galileo signals where a single reference station provides
the real-time corrections of even to a centimeter level of accuracy. When
referring to GPS in particular, the system is also commonly referred to as
Carrier-Phase Enhancement, CPGPS.
• This GPS technique uses the radio signal (carrier) to refine it location
initially calculated using DGPS. The receivers are able to reach this level of
accuracy by performing an initialization, that requires data from at least
five common satellites to initialize on-the-fly (in motion) tracking at least
four common satellites after initializing.

38. • The improvement of GPS positioning doesn't require
simultaneous measurements of two or more receivers in
any case, but can also be done by special use of a single
device.
• In the 1990s when even handheld receivers were quite
expensive, some methods of Quasi-Differential [QDGPS]
were developed, using the receiver by quick turns of
positions or loops of 3-10 survey points.
• QD - The analysis of errors computed using the Global
Positioning System is important for understanding how
GPS works, and for knowing what magnitude errors
should be expected. The Global Positioning System
makes corrections for receiver clock errors and other
effects but there are still residual errors which are not
corrected.

39. A Short Overview of Differential GPS
Differential GPS
The Global Positioning
System delivers about
6 m horizontal error
and 10 m in three
dimensions to a dual
frequency user. This
was much worse for
the civilian user before
the intentional degradation
of the signal was removed.
It likely will improve in the
future.

40. • Differential GPS works by
having a reference system
at a known location measure
the errors in the signals and
send corrections to users in
the "local" area. • These
corrections will not be universal,
but will be useful over a significant
area. The corrections are normally
sent every few seconds.
• The user is generally some mobile
platform such as a ship, car, truck
or even an aircraft.

41. For the majority of civilian users single
frequency receivers are used. The public ranging
modulation is currently only on the L1 signal. The only
ranging signal on L2 is encrypted.
The exceptions are survey and scientific systems
that use expensive receivers with methods to work
around the L2 encryption. The single frequency user
must deal with the error produced as the signals go
through the ionosphere.
The second frequency was put on the GPS
satellites to allow real time removal of the ionospheric
error. It does this to an accuracy better than 1 cm.

42. The use of differential GPS produces a position
solution much more accurate than the that of the
standalone user, either civilian or military. It does this
even for the single frequency receivers.
In fact all common DGPS systems work only
with the L1 frequency signal, even if the receiver can
track both L1 and L2 frequencies.
It is common today to have ships navigating on
DGPS with 1 to 2 meter position accuracy.
This note will address the broad topics that
lead to the GPS errors, how DGPS corrects for them,
the different DGPS techniques and philosophies.

43. Errors in GPS Range Measurements.
Differential GPS works by measuring
the errors in GPS signals at a reference
station(s) and sending the corrections to
users.
The errors in the signal at then antenna
should be almost the same for another
receiver close by.
The definition of "close" depends on
the specific error.

44. FIGURE 1: Pseudorange computation based on reception time. On the left
side, the satellites are transmitting messages syn¬chronously. On the right
side, the four subframes are received asynchronously, due to the different
propagation times. X, Y, Z, W are the code periods in every channel at the
observation time. The time differences δi are computed on the basis of the
distance of the current samples from the beginning of the subframe, which is
stored in the channel counters.

46. A diagram of the
errors in a GPS range
measurement is shown
in Figure 2. The true
range, on the top line,
is the value needed
for navigation. It is
between 20,000 and
40,000 km. The other
large value on that line,
the receiver clock error,
is estimated each time
a solution is performed.

47. It can be thousands of kilometers in some
receivers. The estimation of the receiver clock
error is usually is done each time a new solution
is done in a navigation receiver commonly every
second. The "other" item on the top line is
expanded below. It is only a few 10s of meters at
most.
The Selective Availability (SA), when it was
turned on, had a standard deviation of about 30
meters. It was usually the dominant error for the
civilian GPS user. It is zero now. However, when it
was on, it was totally removed by DGPS systems.

48. The ionosphere error varies greatly with
time of day, location, and the solar cycle. It also is
a function of elevation angle. Low elevation angle
lines of sight have a longer path length within
the ionosphere than vertical paths.
At night for high elevation angles the
ionospheric error can be as low as 1 meter. In late
afternoon, in the tropics, at solar maximum, a 20
degree elevation angle observation could have a
50 m ionospheric error.
Ionosphere errors in the tropics at the
10 to 30 m level are common.

49. The atmospheric error is about 2.5 m for a
vertical line of sight. It varies in a very
predictable way and is well modeled in most
receivers. Only at angles below 5 degrees do
complex bending effects come into play. Only
very precise scientific work needs to go beyond
the standard modeling for this error.
The ionosphere is the dominant error for
single frequency user. The last three errors are
the dominant error sources for a dual frequency
user. They are also important for the single
frequency user.

50. In order to navigate, not only are good ranges
needed, but also the location of the end point of the
range. That is, the positions of the satellites are required.
Providing this information is the job of the US Air
Force, which runs the GPS system. They use a series of
monitor stations to acquire data in real time and estimate
the position, velocity, and satellite clock error of each
satellite every 15 minutes.
They use these solutions to make a prediction of
the satellite parameters for the following day. These
predictions are then parameterized and loaded into the
satellite onboard memory.
This data is sent to the user on the GPS signal. It is
called the Broadcast Ephemeris (BCE). On average this
prediction will be 12 hours old.

51. The largest error will be the satellite clock error. If
all the satellite clocks are not synchronized, navigation is
degraded. Setting all the GPS satellite clocks to a form of
Universal Time Coordinated (UTC) accomplishes this. (The
time differs from UTC by some integer number of seconds.
For this reason it is called GPS Time.) Even though
extremely good atomic clocks are
on each satellite, there is a wander in the clocks. This is a
random process and cannot be modeled.
There may also be some residual systematic error
in the predicted clock state. All these errors, which are
marked with a diagonal bar in Figure 2, are the same for
close receivers.
These are the errors that are removed in DGPS systems.

52. There are two remaining errors that are specific
to individual receivers. The multipath error is caused by
reflections of the GPS signals from metal objects near
the antenna. DGPS reference stations go to great
lengths to minimize this error though good antenna
locations.
The DGPS user may not have this option. The last
error is the thermal noise inside the receiver. This is a
function of the individual receiver design. It is lower in
more expensive receivers.
However each year the receiver noise level on new
receivers decreases some. It is like the increase in speed
on computers, but not quite as dramatic a change.
Today the receiver noise varies from 2 m to 10
cm for civilian receivers.

53. Today the ionosphere and Orbit-and-Clock
errors are usually the dominant errors for the
civilian navigator. DGPS essentially removes these.
The orbit error is only slightly different for
users within a 1000 km or so of the reference
station. That cannot be said of the ionosphere
error. Its change with distance from the reference
station is discussed later under ionospheric
divergence.
The remaining issues in designing or choosing
a DGPS system are how to get the errors to th user,
and what solution technique to use.

54. Correction Parameterization and Distribution
There are two approaches to parameterizing
the errors measured by the reference station(s). In
the most common approach, the range error is
measured for each satellite and these satellite by
satellite errors sent to the user.
This is a point approach. It is valid at the
reference receiver. Its validity will decrease with
distance from that site. In the second approach
multiple stations are used to estimate the errors
over an extended area.
This is called Wide Area DGPS (WADGPS). The
Federal Aviation Administrations (FAA) Wide Area
Augmentation System (WAAS) is this type of
system.

55. There are also commercial systems of this type.
The corrections are parameterized in a way that allows
the user to compute corrections based on his location.
Two users separated by a 100 km or so will get different
corrections from the same WADGPS parameter set.
In both these cases the information volume is
quite small. A few hundred bytes contain one set of
corrections for all the satellites in an area. The
corrections are sent at different rates by different
systems.
Six second updates are common. The more
accurate systems use one second updates. This is still a
very low data rate. Note that distribution of the
corrections is just a communication problem.

56. Standard DGPS systems normally distribute the
corrections to the user over a radio link. The
US Coast Guard has an existing system of directional radio
beacons in the 275 to 325 kHz band.
It chose to modulate the DGPS corrections from its
reference stations on these signals. If it
were not for ionospheric divergence (see below) the only
limitation on the use of the US Coast
Guard DGPS signals would the range at which these radio
beacons can be received.
A map showing the USCG West Coast sites, the
broadcast frequencies, and their official coverage
areas is shown in Figure 3.

57. The original USCG
system covered the
West Coast, the East
Coast, the Gulf Coast,
the Great Lakes, and
the Mississippi River.
As seen on the map,
new inland sites
are now being added
to the system.

58. The FAA uses a geostationary satellite to broadcast
the WAAS corrections. The satellite has a transponder
and just retransmits a signal originating on the ground.
This same approach is used by at least one commercial
service that provides WADGPS.
Some other commercial services put the data on a
sub-carrier on FM radio broadcasts. For science and
surveying applications, a special radio link is often set up.
This is usually done when a dedicated reference
site is installed for a particular survey or science study or
campaign.
There are also experimental systems that deliver
the corrections over the Internet.

59. The format of the correction information
varies. There are now two public formats, the
RTCM-104 and the WAAS. The RTCM or Radio
TeleCommunications, Marine, is a standards
organization.
The format was generated by its special
committee number 104. The WAAS was
designed by a similar industry/government
organization, the RTCA.
In addition many manufactures of high end
equipment have a proprietary format. The
manufacturers formats are often aimed at the more
precise DGPS method called Kinematics.

60. The RTCM format was adopted by the US Coast
Guard. This has lead to its wide acceptance. Essentially
all receivers that do DGPS positioning accept RTCM-104
as one of their input formats.
The FAAs WAAS format has been standardized
more recently. However, because the signal is available
thought out North America on a free basis, it is being
incorporated into many receivers.
(The WAAS is currently in a test and evaluation
phase.) The WAAS format is mandated for use in aircraft,
but boat, car and handheld GPS receivers are available
that use it.
This format has more error checking than the
RTCM format because it is designed for a "safety
of life" function.

61. In most cases, a separate receiver is used to
receive the DGPS corrections. These are then feed
to the GPS receiver over a RS232 serial line. With
this architure, the corrections could come from any
of several sources.
In some instances multiple sources are on
ships and a simple switch is used to change
between sources.
In other cases standard sources (such as the
US Coast Guard) are received at some convenient
location and relayed by other means, such as
cell telephone or VHF/UHF radio links, to the user.

62. Ionospheric Divergence
The normal limitation on the utility of DGPS
corrections is the difference in the ionospheric
error seen by the reference station and the user.
This ionospheric error is determined by the
ionospheric conditions where the line of sight
passes through 300 to 400 km altitude.
For a vertical ray, this is overhead. For a low
elevation ray it can be 1500 km away (about 15
degrees of earth central angle).

63. The ionosphere is much more variable than
the atmosphere. It most dramatic variation is from
day to night. It essentially goes away late at night. It
rebuilds quickly at dawn and then intensifies
thought the day. Its decay after sunset is gradual.
Maps of the peak electron density of the
ionosphere are shown in Figures 4 and 5. These
values are proportional to the ionospheric error.
The plots are for 1800 UT, when sunrise is in
the Pacific and sunset over the zero of longitude
line. Sunrise at 300 km occurs before it does on the
ground.

64. The data in Figure 4 is for
Solar maximum. This
occurred in 2000-2001
for the current Solar cycle.
The solar cycle is about 11
years long. Therefore the
next minimum should
occur in 2006.

65. The two humps during the day are caused
by the magnetic field of the earth. The peaks
are about 12 degrees north and south of the
geomagnetic equator, which is shown as a line
on these plots.
The precise location of these "equatorial
anomalies" can vary from day to day. These
figures are analogous to climate models, not
weather data.

66. The spatial gradients on the sides of these
peaks will be where the largest spatial
divergences in DGPS signals occur.
There are also large gradients a dawn.
Note that satellites to the south at 20 degrees
elevation angle seen from the extreme
southern US will be seen though this gradient
on some days.
Sites nearer the equator will experience
this more often and at higher elevation angles.

67. Solution Method
There are two common methods of finding a
location with differential GPS. The most common
method for navigation applications is to use
corrected ranges. This is the same solution method
used by the standalone user, but with some
systematic errors removed.
The survey community has used the carrier
phase as its basic measurement from the beginning
of GPS surveying. This was then applied to cases
where the unknown location was in motion.
This was called Kinematics.

68. In practice kinematics can only be done with dual
frequency data. Even though both frequencies are used, it
is sensitive to ionospheric divergence. The user usually
needs to be within 30 km of the reference site during the
day.
In the beginning, kinematics was only done on a
post-processing basis. However with the increase in
computation capabilities, it became possible to do the
kinematic solution inside the GPS receiver. This is called
Real Time Kinematics, or RTK.
Many high end dual frequency receivers now can
do RTK. It is still limited to ranges of 30 to 100 km of the
reference sites. Also the system often needs to be
initialized at 30 km or less.

69. The original version of the RTCM format
did not allow for the corrections necessary for
RTK.
However, revision 2 has new message
formats designed for this.
Many RTK implementations allow both the
RTCM and manufacturer proprietary DGPS
formats.

70. New Developments
The package of changes that was accepted
when the Selective Availability was turned off
includes two other items important to civilian DGPS
users. First the publicly available ranging signal will
be placed on both the GPS frequencies beginning
with launches in 2003.
The earlier spacecraft only had this signal on
the L1 frequency. This will make it possible for low
end receivers now to automatically correct for the
ionospheric error.
Using the L2 signal in DGPS will require some
changes to the RTCM format, but this is expected.

71. Beginning in about 2007, satellites
launched will have a third civilian frequency,
called L5. This will allow kinematic solutions to
be initialized and utilized at much longer ranges.
The precise ranges will have to be
determined post launch. It is likely that WAAS
will not utilize the new signal on L2, but it is
likely to use the L5 signal.
This is due to a low, but measurable,
probability of interference on L2 with some
radars and mobile communications services in
Europe.

72. There are many science experiments done
each year using GPS. Some, for example from
NASAs Goddard Space Flight Center, have done
kinematics out to a thousand kilometers.
Experiments have been conducted on using a
network of reference stations to generate standard
GPS corrections. Receivers are becoming immune
to multipath, at least for the top of the line
receivers.
The noise level in receivers is also coming
down. Where all this will lead is unclear, but the
results can only be beneficial to the GPS
community.

73. The BeiDou Navigation Satellite System (BDS
Is a Chinese satellite navigation system. It consists
of two separate satellite constellations – a limited test
system that has been operating since 2000, and a full-
scale global navigation system that is currently under
construction.
The first BeiDou system, officially called the BeiDou
Satellite Navigation Experimental System (simplified
Chinese:
traditional Chinese and also known as BeiDou-1, consists
of three satellites and offers limited coverage and
applications.
It has been offering navigation services, mainly for
customers in China and neighboring regions, since 2000.

74. The second generation of the system,
officially called the BeiDou Satellite Navigation
System (BDS) and also known as COMPASS or
BeiDou-2, will be a global satellite navigation
system consisting of 35 satellites, and is under
construction as of January 2013.
It became operational in China in December
2011, with 10 satellites in use, and began offering
services to customers in the Asia-Pacific region in
December 2012.
It is planned to begin serving global
customers upon its completion in 2020.

75. Nomenclature
The BeiDou Navigation System is named after the
Big Dipper constellation, which is known in Chinese as
Běidǒu. The name literally means "Northern Dipper", the
name given by ancient Chinese astronomers to the
seven brightest stars of the Ursa Major constellation.
Historically, this set of stars was used in navigation
to locate the North Star Polaris. As such, the name
BeiDou also serves as a metaphor for the purpose of the
satellite navigation system.

76. HISTORY
Conception and initial development
The original idea of a Chinese satellite navigation system was
conceived by Chen Fangyun and his colleagues in the 1980s.
According to the China National Space Administration, the
development of the system would be carried out in three steps:
1. 2000–2003: experimental BeiDou navigation system
consisting of 3 satellites
2. by 2012: regional BeiDou navigation system covering China
and neighboring regions
3. by 2020: global BeiDou navigation system
The first satellite, BeiDou-1A, was launched on 30 October
2000, followed by BeiDou-1B on 20 December 2000.
The third satellite, BeiDou-1C (a backup satellite), was put into
orbit on 25 May 2003.

77. The successful launch of BeiDou-1C also meant the
establishment of the BeiDou-1 navigation system. On 2
November 2006, China announced that from 2008 BeiDou
would offer an open service with an accuracy of 10 meters,
timing of 0.2 microseconds, and speed of 0.2 meters/second.
In February 2007, the fourth and last satellite of the
BeiDou-1 system, BeiDou-1D (sometimes called BeiDou-2A,
serving as a backup satellite), was sent up into space. It was
reported that the satellite had suffered from a control system
malfunction but was then fully restored.
In April 2007, the first satellite of BeiDou-2, namely
Compass-M1 (to validate frequencies for the BeiDou-2
constellation) was successfully put into its working orbit.

78. The second BeiDou-2 constellation satellite Compass-
G2 was launched on 15 April 2009. On 15 January 2010, the
official website of the BeiDou Navigation Satellite System
went online, and the system's third satellite (Compass-G1)
was carried into its orbit by a Long March 3C rocket on 17
January 2010.
On 2 June 2010, the fourth satellite was launched
successfully into orbit. The fifth orbiter was launched into
space from Xichang Satellite Launch Center by an LM-3I
carrier rocket on 1 August 2010.
Three months later, on 1 November 2010, the sixth
satellite was sent into orbit by LM-3C. Another satellite, the
Beidou-2/Compass IGSO-5 (fifth inclined geosynchonous
orbit) satellite, was launched from the Xichang Satellite
Launch Center by a Long March-3A on 1 December 2011
(UTC).

79. Chinese involvement in Galileo system
In September 2003, China intended to join the European
Galileo positioning system project and was to invest €230 million
(USD296 million, GBP160 million) in Galileo over the next few years. At
the time, it was believed that China's "BeiDou" navigation system
would then only be used by its armed forces. In October 2004, China
officially joined the Galileo project by signing the Agreement on the
Cooperation in the Galileo Program between the "Galileo Joint
Undertaking" (GJU) and the "National Remote Sensing Centre of China"
(NRSCC).
Based on the Sino-European Cooperation Agreement on
Galileo program, China Galileo Industries (CGI) , the prime contractor of
the China’s involvement in Galileo programs, was founded in December
2004. By April 2006, eleven cooperation projects within the Galileo
framework had been signed between China and EU.
However, the Hong Kong-based South China Morning Post
reported in January 2008 that China was unsatisfied with its role in the
Galileo project and was to compete with Galileo in the Asian market.

80. Experimental system (BeiDou-1)
Description
BeiDou-1 is an experimental regional
navigation system, which consist of four
satellites (three working satellites and one
backup satellite).
The satellites themselves were based on
the Chinese DFH-3 geostationary
communications satellite and had a launch
weight of 1,000 kilograms (2,200 pounds) each.

81. Unlike the American GPS, Russian
GLONASS, and European Galileo systems, which
use medium Earth orbit satellites, BeiDou-1 uses
satellites in geostationary orbit.
This means that the system does not
require a large constellation of satellites, but it
also limits the coverage to areas on Earth where
the satellites are visible.
The area that can be serviced is from
longitude 70°E to 140°E and from latitude 5°N to
55°N. A frequency of the system is 2491.75 MHz.

82. Completion [
The first satellite, BeiDou-1A, was launched on
October 31, 2000. The second satellite, BeiDou-1B, was
successfully launched on December 21, 2000. The last
operational satellite of the constellation, BeiDou-1C,
was launched on May 25, 2003.
Position calculation
In 2007, the official Xinhua News Agency reported
that the resolution of the BeiDou system was as high as
0.5 metres. With the existing user terminals it appears
that the calibrated accuracy is 20m (100m,
uncalibrated).

83. Terminals
In 2008, a BeiDou-1 ground terminal cost around
CN¥20,000RMB (US$2,929), almost 10 times the price of
a contemporary GPS terminal. The price of the terminals was
explained as being due to the cost of imported microchips.
At the China High-Tech Fair ELEXCON of November 2009 in
Shenzhen, a BeiDou terminal priced at CN¥3,000RMB was presented.
Applications
Over 1,000 BeiDou-1 terminals were used after the 2008
Sichuan earthquake, providing information
from the disaster area. As of October 2009, all Chinese border guards
in Yunnan are equipped with BeiDou-1 devices.
According to Sun Jiadong, the chief designer of the navigation
system, "Many organizations have been using our system for a while,
and they like it very much."

84. Global system (BeiDou Navigation Satellite System
or BeiDou-2)
Description
Older BeiDou-1, but rather supersedes it
outright. The new system will be a constellation of
35 satellites, which include 5 geostationary orbit
satellites for backward compatibility with BeiDou-1,
and 30 nongeostationary satellites in medium
earth orbit and 3 in inclined geosynchronous orbit),
that will offer complete coverage of the globe.

85. Accuracy
There are two levels of service provided; a free service
to civilians and licensed service to the Chinese government
and military.
The free civilian service has a 10-meter location-
tracking accuracy, synchronizes
clocks with an accuracy of 10 nanoseconds, and measures
speeds to within 0.2 m/s.
The restricted military service has a location accuracy
of 10 centimetres, can be used for
communication, and will supply information about the system
status to the user.
To date, the military service has been granted only to
the People's Liberation Army and to the Military of Pakistan.

86. Constellation
The new system will be a constellation of 35 satellites, which
include 5 geostationary orbit (GEO) satellites and 30 medium Earth
orbit (MEO) satellites, that will offer complete coverage of the globe.
The ranging signals are based on the CDMA principle and have
complex structure typical of Galileo or modernized GPS. Similar to the
other GNSS, there will be two levels of positioning service: open and
restricted (military).
The public service shall be available globally to general users.
When all the currently planned GNSS systems are deployed, the users
will benefit from the use of a total constellation of 75+ satellites,
which will significantly improve all the aspects of positioning,
especially availability of the signals in so-called urban canyons.
The general designer of Compass navigation system is Sun
Jiadong, who is also the general designer of its predecessor, the
original Beidou navigation system.

87. Frequencies
Frequencies for Compass are allocated in four bands:
E1,
E2, E5B, and E6 and overlap with Galileo. The fact of
overlapping could be convenient from the point of view of
the receiver design, but on the other hand raises the issues of
inter-system interference, especially within E1 and E2 bands,
which are allocated for Galileo's publicly regulated service.
However, under International Telecommunication
Union (ITU) policies, the first nation to start broadcasting in a
specific frequency will have priority to that frequency, and
any subsequent users will be required to obtain permission
prior to using that frequency, and otherwise ensure that their
broadcasts do not interfere with the original nation's
broadcasts. It now appears that Chinese Compass satellites
will start transmitting in the E1, E2, E5B, and E6 bands

88. It now appears that Chinese Compass
satellites will start transmitting in the E1, E2,
E5B, and E6 bands before Europe's Galileo
satellites and thus have primary rights to these
frequency ranges.
Although little was officially announced by
Chinese authorities about the signals of the
new system, the launch of the first Compass
satellite permitted independent researchers not
only to study general characteristics of the
signals but even to build a Compass receiver.

89. Compass-M1
Compass-M1 is an experimental satellite launched
for signal testing and validation and for the frequency
filing on 14 April 2007. The role of Compass-M1 for
Compass is similar to the role of the GIOVE satellites for
the Galileo system. The orbit of Compass-M1 is nearly
circular, has an altitude of 21,150 km and an inclination of
55.5 degrees.
Compass-M1 transmits in 3 bands: E2, E5B, and E6.
In each frequency band two coherent sub-signals have
been detected with a phase shift of 90 degrees (in
quadrature).
These signal components are further referred to as
"I" and "Q". The "I" components have shorter codes and
are likely to be intended for the open service.

90. The "Q" components have much longer codes, are
more interference resistive, and are probably intended
for the restricted service. IQ modulation has been the
method in both wired and wireless digital modulation
since morsetting carrier signal 100 years ago.
The investigation of the transmitted signals started
immediately after the launch of Compass -M1 on 14
April 2007. Soon after in June 2007, engineers at CNES
reported the spectrum and structure of the signals.
A month later, researchers from Stanford
University reported the complete decoding of the “I”
signals components. The knowledge of the codes
allowed a group of engineers at Septentrio to build the
COMPASS receiver and report tracking and multipath
characteristics of the “I” signals on E2 and E5B.

91. Characteristics of the "I" signals on E2 and
E5B are generally similar to the civilian codes of GPS
(L1-CA and L2C), but Compass signals have
somewhat greater power.
The notation of Compass signals used in this
page follows the naming of the frequency bands
and agrees with the notation used in the American
literature on the subject, but the notation used by
the Chinese seems to be different and is quoted in
the first row of the table.

94. OPERATION
In December 2011, the system went into operation on a trial
basis. It has started providing navigation, positioning and timing data
to China and the neighbouring area for free from 27 December.
During this trial run, Compass will offer positioning accuracy
to within 25 meters, but the precision will improve as more satellites
are launched.
Upon the system's official launch, it pledged to offer general
users positioning information accurate to the nearest 10 m, measure
speeds within 0.2 m per second, and provide signals for clock
synchronisation accurate to 0.02 microseconds.
The BeiDou-2 system began offering services for the Asia-
Pacific region in December 2012. At this time, the system could
provide positioning data between longitude 55°E to 180°E and from
latitude 55°S to 55°N.

95. COMPLETION
In December 2011, Xinhua stated that “the basic
structure of the Beidou system has now been established,
and engineers are now conducting comprehensive system
test and evaluation.
The system will provide test-run services of
positioning, navigation and time for China and the
neighboring areas before the end of this year, according
to the authorities.
"The system became operational in the China
region that same month. The global navigation system
should be finished by 2020. As of December 2012, 16
satellites for BeiDou-2 have been launched, 14 of them
are in service.

97. IRNSS
(INDIAN NAVIGATION SATELLITE SYSTEM)
The System: Fregat Design Ambiguity Steered
Galileo Wrong
November 1, 2014 By GPS World staff

98. Cross-Installed Hydrazine, Helium Lines
Froze Thrusters the root cause of the anomaly
that sent two Galileo satellites into the wrong
orbit on August 22 was a shortcoming in the
system thermal analysis performed during stage
design, and not an operator error during stage
assembly, according to findings by an
independent inquiry board.
The independent inquiry board was
created by Arianespace,

99. According to ISRO, the document is being
released to the public to facilitate research and
development and to aid the commercial use of the
IRNSS signals for navigation-based applications.
Registration is required for ICD download
access at a new IRNSS website.
At the moment, only the ICD is available at
this website.
The next IRNSS satellite launch is scheduled
for the second week of October.
The most recent launch was in April, of the
second IRNSS satellite, IRNSS-1B.

100. IRNSS is an independent regional navigation
satellite system being developed by India.
It is designed to provide accurate position
information service to users in India and the region
extending up to 1,500 kilometers from its
boundary.
IRNSS will provide two types of service:
Standard Positioning Service (SPS)
and Restricted Service (RS).
It is expected to provide a position accuracy
of better than 20 meters in the primary service
area.

101. NovAtel Supplies Reference Receivers for IRNSS
Ground Segment
December 23, 2013 By GPS World staff
NovAtel Inc., a manufacturer of GNSS precise positioning
technology, has announced an agreement with the Indian
Space Research Organisation (ISRO) to supply reference
receiver products for use in the Indian Regional
Navigation Satellite System (IRNSS) ground segment.
India-based Elcome Technologies Pvt. Limited, a sister
company to NovAtel in the Hexagon Group of Companies,
will provide local integration, training and technical.

102. • IRNSS Success
• The Indian Regional Navigation Satellite System (IRNSS)
successfully launched
• its first satellite on July 1 from the Satish Dhawan Space
Centre at Sriharikota
• spaceport on the Bay of Bengal. An Indian-built Polar
Satellite Launch Vehicle
• PSLV-C22, XL version, carried the 1,425-kg satellite
aloft.
• IRNSS-1A is the first of seven satellites that will make up
the new constellation:
• four satellites in geosynchronous orbits inclined at 29
degrees, with three more
• in geostationary orbit. IRNSS-1A is one of the
geosynchronous satellites.

104. The Indian Regional Navigation Satellite
System (IRNSS) successfully launched its first
satellite on July 1 from the Satish Dhawan Space
Centre at Sriharikot spaceport on the Bay of Bengal.
An Indian-built Polar Satellite Launch Vehicle
PSLV-C22, XL version, carried the 1,425-kg satellite
aloft.
IRNSS-1A is the first of seven satellites that
will make up the new constellation: four satellites in
geosynchronous orbits inclined at 29 degrees, with
three more in geostationary orbit. IRNSS-1A is one
of the geosynchronous satellites.

105. Following launch, the master control facility
conducted five orbit maneuvers to position the satellite
in its circular inclined geosynchronous orbit (IGSO) with
an Equator crossing at 55 degrees east longitude.
Reports indicate that orbitraising maneuvers have
been completed, and all the spacecraft subsystems have
been evaluated and are functioning normally.
IRNSS-1A’s drift eastward from 47 degrees east
longitude on July 10 was gradually slowed, and the
satellite achieved its assigned inclined geosynchronous
orbit, with a 55-degree East equator crossing, by July 18.
The orbit inclination is 27.03 degrees.

106. Payloads. IRNSS-1A carries two types of
payloads, navigation and ranging.
The navigation payload will operate in L5
band (1176.45 MHz) and S band (2492.028
MHz), using a Rubidium atomic clock.
The ranging payload consists of a C-band
transponder that facilitates accurate
determination of the range of the satellite.
IRNSS-1A also carries corner-cube retro-
reflectors for laser ranging. Its mission life is 10
years.

107. IRNSS Signal Close up
By Richard Langley, Steffen Thoelert, and Michael Meurer
The spectrum of signals from IRNSS-1A, the first satellite in the
Indian Regional Navigation Satellite System, as recorded by German
Aerospace Center researchers in late July, appears to be consistent with a
combination of BPSK(1) and BOC(5,2) modulation.
Figure 1 shows that, centered at 1176.45 MHz, the signal has a single
symmetrical main lobe and a number of side lobes characteristic of the signal
structure that the Indian Space Research Organization (ISRO) announced
would be used for IRNSS transmissions in the L-band.
Figure 2 shows the corresponding IQ constellation diagram. Further
analysis will be required to sleuth additional signal details as ISRO, so far, has
not publicly released an IRNSS interface control document describing the
signal structure in detail.

110. Quasi-zenith Satellite System (QZSS)
watching Japan From Above
As mobile phones equipped with car navigation or GPS (*1) have
become widespread, positioning information using satellites is
imperative to our lives. To specify a location, we need to receive signals from
at least four satellites. However, in some urban or mountainous areas,
positioning signals from four satellites are often hampered by skyscrapers or
mountains, and that has often caused significant errors.
The QZSS consists of a multiple number of satellites that fly in the
orbit passing through the near zenith over Japan. By sharing almost
the same positioning signals for transmission with the currently
operated GPS as well as the new GPS, which is under development
in the U.S., the system enables us to expand the areas and time
duration of the positioning service provision in mountainous and urban
regions in Japan.

112. Furthermore, the
QZSS aims at
improving
positioning
accuracy of one
meter to the
centimeter level
compared to the
conventional GPS
Error of tens of
meters by transmitting
support signals and
through other
means

113. In order to have at least one quasi-zenith satellite
always flying near
Japan's zenith, at least three satellites are
necessary. The first quasizenith
satellite "MICHIBIKI" carries out technical and
application
verification of the satellite as the first phase, then
the verification
results will be evaluated for moving to the second
phase in which the
QZ system verification will be performed with three
QZ satellites
Launch date: September 11, 2010

114. Some of you who usually use
car navigation may feel that the
Current system has enough
functionality. However, the
satellite positioning system
is not just for car navigation.
It is imperative for mapping,
measurements
for construction work,
monitoring services for
children and senior citizens,
automatic control of agricultural
machinery, detecting earthquakes
And volcanic activities, weather forecasting and many other applicable fields.
Therefore, an improvement in accuracy and reliability is called for from
various areas. New service using more accurate positioning data may be
born when positioning accuracy is further improved by the QZSS thus we
can capture location information with an error of within one meter.

115. Future MICHIBIKI activity
The MICHIBIKI was launched by the H-IIA Launch Vehicle No.
18 on
September 11, 2010. After being injected into the quasi-zenith orbit,
the
MICHIBIKI is now under a three-month initial functional verification.
Then, its technical and application verification will be carried
out in cooperation with concerned organizations. (During the
verification, we can receive signals from the MICHIBIKI.
However, in the early stage, we will place an alert flag as we
verify the accuracy of information contained in its signals. To use the
MICHIBIKI, please use a special receiver, which is specially processed to
not exclude MICHIBIKI data from your positioning calculation even
though an alert flag is in effect. In addition, please be aware that
positioning accuracy may deteriorate compared to that using only the
GPS.)

116. You cannot receive
MICHIBIKI signals
through a
commercially available
GPS receiver such
as a car navigation
system, but you can
do so by modifying a
conventional device.
We heard that there
are some machines
that can receive MICHIBIKI
signals by improving software. JAXA and related organizations
are now promoting receiver manufacturers to cop with
MICHIBIKI signal reception.

118. Doppler Orbitography and Radiopositioning
Integrated by Satellite (DORIS)
is a French satellite
system used for the
determination
of satellite orbits
(e.g. TOPEX/Poseidon)
and for positioning.

119. Principle
Ground-based radio beacons emit a signal
which is picked up by receiving satellites. This is
in reverse configuration to other GNSS, in which
the transmitters are space-borne and receivers
are in majority near the surface of the Earth.
A frequency shift of the signal occurs that
is caused by the movement of the satellite
(Doppler effect). From this observation satellite
orbits, ground positions, as well as other
parameters can be derived.

120. Organization
DORIS is a French system which was initiated and is
maintained by the French Space Agency (CNES).
It is operated from Toulouse.
Ground segment
The ground segment consists of about 50-60
stations, equally distributed over the earth and ensure a
good coverage for orbit determination. For the
installation of a beacon only electricity is required
because the station only emits a signal but does not
receive any information. DORIS beacons transmit to the
satellites on two UHF frequencies, 401.25 MHz and
2036.25 MHz.

121. Space segment
The best known satellites
equipped with DORIS
receivers are the altimetry
satellites TOPEX/Poseidon,
Jason 1 and Jason 2. They
are used to observe the
ocean surface as well as
currents or wave heights.
DORIS contributes to their
orbit accuracy of about 2 cm.
Other DORIS satellites are the Envisat, SPOT, HY-2A and
CryoSat-2 satellites.

122. Positioning
Apart from orbit determination, the DORIS
observations are used for positioning of ground
stations.
The accuracy is a bit lower than with GPS,
but it still contributes to the International
Terrestrial Reference
Frame (ITRF).

123. DORIS
The Doppler Orbitography
and Radio-positioning
Integrated by Satellite
instrument is a microwave
tracking system that can be
utilized to determine
the precise location of the
ENVISAT satellite. Versions of the DORIS instrument
are currently flying on the SPOT-2 and Topex-
Poseidon missions.

124. DORIS operates by measuring the Doppler
frequency shift of a radio signal transmitted from ground
stations and received on-board the satellite. The
reference frequency for the measurement is generated by
identical ultrastable oscillators on the ground and on-
board the spacecraft.
Currently there are about 50 ground beacons
placed around the globe which cover about 75% of the
ENVISAT orbit. On board measurements are performed
every 7 - 10 seconds.
Precise Doppler shift measurements are taken
using an S-band frequency of 2.03625 GHz, while a
second VHS
band signal at 401.25 MHz is used for ionospheric
correction of the propagation delay.

125. On the ground, DORIS data is used to
create precise orbit reconstruction models
which are then used for all satellite instruments
requiring precise orbit position information.
In addition, DORIS operates in a Navigator
mode in which on-board positioning calculations
are performed in real-time and relayed to the
ground segment.

127. GLONASS (Week 9)
GLONASS (Russian:
acronym for "Globalnaya
navigatsionnaya
sputnikovaya sistema" or
"Global Navigation Satellite
System", is a space-based satellite navigation system operated
by the Russian Aerospace Defence Forces.
It provides an alternative to Global Positioning System
(GPS) and is the second alternative navigational system in
operation with global coverage and of comparable precision.

128. Manufacturers of GPS devices say that adding
GLONASS made more satellites available to them, meaning
positions can be fixed more quickly and accurately, especially
in built-up areas where the view to some GPS satellites is
obscured by buildings.
Development of GLONASS began in the Soviet Union in
1976. Beginning on 12 October 1982, numerous rocket
launches added satellites to the system until the constellation
was completed in 1995. After a decline in capacity during the
late 1990s, in 2001, under Vladimir Putin's presidency, the
restoration of the system was made a top government priority
and funding was substantially increased.
GLONASS is the most expensive program of the
Russian Federal Space Agency, consuming a third of its budget
in 2010.

129. By 2010, GLONASS had
achieved 100% coverage
of Russia's territory and
in October 2011, the full
Orbital constellation of 24
satellites was restored,
enabling full global coverage.
The GLONASS satellites'
designs Have undergone several upgrades, with
the latest version being GLONASS-K.

130. INCEPTION and DESIGN
The first satellite-based
radio navigation system
developed in the Soviet
Union was Tsiklon, which
had the purpose of
providing ballistic missile
submarines a method for accurate positioning.
Thirty One (31) Tsiklon satellites were launched
between 1967 and 1978.

131. The main problem with the system was that, although highly
accurate for stationary or slow-moving ships, it required several hours of
observation by the receiving station to fix a position, making it unusable
for many navigation purposes and for the guidance of the new generation
of ballistic missiles. In 1968–1969, a new navigation system, which would
support not only the navy, but also the air, land and space forces, was
conceived. Formal requirements were completed in 1970; in 1976, the
government made a decision to launch development of the "Unified Space
Navigation System GLONASS".
The task of designing GLONASS was given to a group of young
specialists at NPO PM in the city of Krasnoyarsk-26 (today called
Zheleznogorsk). Under the leadership of Vladimir Cheremisin, they
developed different proposals, from which the institute's director Grigory
Chernyavsky selected the final one. The work was completed in the late
1970s; the system would consist of 24 satellites operating at an altitude of
20,000 km in medium circular orbit. It would be able to promptly fix the
receiving station's position based on signals from 4 satellites, and also
reveal the object's speed and direction.

132. The satellites would be launched 3 at a time on the
heavy-lift Proton rocket. Due to the large number of
satellites needed for the program, NPO PM
delegated the manufacturing of the satellites to PO
Polyot in Omsk, which had better production
capabilities.
Originally, GLONASS was designed to have an
accuracy of 65 m, but in reality it had an accuracy of
20 m in the civilian signal and 10 m in the military
signal.[6] The first generation GLONASS satellites
were 7.8 m tall, had a width of 7.2 m, measured
across their solar panels, and a mass of 1,260 kg.

133. Achieving Full Orbital Constellation
In the early 1980s, NPO PM received the first prototype
satellites from PO Polyot for ground tests. Many of the produced parts
were of low quality and NPO PM engineers had to perform substantial
redesigning, leading to a delay.
On 12 October 1982, three satellites, designated Kosmos-
1413, Kosmos-1414, and Kosmos-1415 were launched aboard a Proton
rocket. As only one GLONASS satellite was ready in time for the launch
instead of the expected three, it was decided to launch it along with
two mock-ups. The American media reported the event as a launch of
one satellite and "two secret objects.
" For a long time, the Americans could not find out the nature
of those "objects". The Telegraph Agency of the Soviet Union (TASS)
covered the launch, describing GLONASS as a system "created to
determine positioning of civil aviation aircraft, navy transport and
fishing-boats of the Soviet Union".

134. From 1982 through April 1991, the Soviet Union successfully
launched a total of 43 GLONASS-related satellites plus five test
satellites.
When the Soviet Union disintegrated in 1991, twelve
functional GLONASS satellites in two planes were operational; enough
to allow limited usage of the system (to cover the entire territory of
the country, 18 satellites would have been necessary.)
The Russian Federation took over control of the constellation
and continued it development. In 1993, the system, now consisting of
12 satellites, was formally declared operational and in December 1995,
the constellation was finally brought to its optimal status of 24
operational satellites.
This brought the precision of GLONASS on-par with the
American GPS system, which had achieved full operational capability а
year earlier.

135. Economic Crisis And Fall Into Disrepair
Since the first generation satellites operated for 3 years
each, to keep the system at full capacity, two launches per
year would have been necessary to maintain the full network
of 24 satellites.
However, in the financially difficult period of 1989–
1999, the space program's funding was cut by 80% and Russia
consequently found itself unable to afford this launch rate.
After the full complement was achieved in December 1995,
there were no further launches until December 1999. As a
result, the constellation reached its lowest point of just 6
operational satellites in 2001.
As a prelude to demilitarisation, responsibility of
the program was transferred from the Ministry of Defence to
Russia's civilian space agency Roscosmos.

136. Renewed Efforts and Modernization
Although the GLONASS constellation has reached
global coverage, its commercialisation, especially
development of the user segment, has been lacking
compared to the American GPS system.
For example, the first commercial Russian-made
GLONASS navigation device for cars, Glospace SGK-70, was
introduced in 2007, but it was much bigger and costlier than
similar GPS receivers.
In late 2010, there were only a handful of GLONASS
receivers on the market, and few of them were meant for
ordinary consumers. To improve the situation, the Russian
government has been actively promoting GLONASS for
civilian use.

137. Third Generation
GLONASS-K is a substantial improvement
of the previous generation: it is the first
unpressurised GLONASS satellite with a
much reduced mass (750 kg versus 1,450 kg
of GLONASS-M). It has an operational lifetime
of 10 years, compared to the 7-year lifetime
of the second generation GLONASS-M. It will
transmit more navigation signals to improve
the system's accuracy, including new CDMA
signals in the L3 and L5 bands which will use
modulation similar to modernized GPS, Galileo and Compass.
The new satellite's advanced equipment—made solely from Russian
components—will allow the doubling of GLONASS' accuracy. As with the
previous
satellites, these are 3-axis stabilized, nadir pointing with dual solar arrays.
The first GLONASS-K satellite was successfully launched on 26
February 2011.

138. GLONASS Bellyflop
A Russian Proton-M rocket
carrying three GLONASS
navigation satellites
crashed soon after liftoff on
July 2 from Kazakhstan’s Baikonur
cosmodrome. About 10 seconds
after takeoff at 02:38 UTC, the
rocket swerved, began to
correct, but then veered in the
opposite direction. It then flew
horizontally and started to come apart with its engines in full
thrust. Making an arc in the air, the rocket plummeted to
Earth and exploded on impact close to another launch pad
used for Proton commercial launches.

139. Despite the loss, GLONASS still has a full
operating constellation of 24 satellites. The
crash was broadcast live across Russia. Fears of a
possible toxic fuel leak immediately surfaced
following the incident, but no such leak has
been confirmed.
The rocket was initially carrying more than
600 tons of toxic propellants. No casualties or
damage to surroundings structures or the town
of Baikonur have been reported.

140. The crashed Proton-M rocket employed a DM-03
booster, which was being used for the first time since
December 2010, when another Proton-M rocket with the
same booster failed to deliver another three GLONASS
satellites into orbit, crashing into the Pacific Ocean 1,500
kilometers from Honolulu.
A Russian government investigation revealed that at
least “three of six angular rate sensors [on the booster stage]
were installed incorrectly,” to be specific, upside-down.
Examination of the wreckage discovered traces of
forced, incorrect installation on three sensors. Assembly-line
testing at the factory failed to detect the faulty installation.

141. This rendered the system completely unusable to
all worldwide GLONASS receivers. Full service was
subsequently restored. “Bad ephemerides were uploaded
to satellites.
Those bad ephemerides became active at 1:00
a.m. Moscow time,” reported one knowledgeable source.
GLONASS navigation messages contain, as they do
for every GNSS in orbit, ephemeris data used to calculate
the position of each satellite in orbit, and information
about the time and status of the entire satellite
constellation (almanac); user receivers on the ground
processed this data to compute their precise position.

142. Trouble Chronolog.
The constellation suffered a second failure
two weeks later. On April 14, eight GLONASS
satellites were simultaneously set unhealthy
for about half an hour, meaning that most GLONASS
or multi-constellation receivers would have ignored
those satellites in positioning computations.
In addition, one other satellite in the fleet was
out of commission undergoing maintenance. This
might have left too few healthy satellites to
compute GLONASS-only receiver positions in some
locations.

143. Advantages and Disadvantages Global
Positioning System
GPS stands for global positioning system which was
created by US department of defense for the navigation
of military in any part of world under circumstances.
But with the time, this system is now being used
for many other purposes and GPS system has proved to
be a revolutionary technology in today's world.
There are several advantages of GPS at present and
in contrast to that there are some disadvantages also.
Some of them are:

144. Advantages of GPS:
• GPS is extremely easy to navigate as it tells you to the direction for each
turns you take or you have to take to reach to your destination.
• GPS works in all weather so you need not to worry of the climate as in
other navigating devices.
• The GPS costs you very low in comparison other navigation systems.
• The most attractive feature of this system is its 100% coverage on the
planet.
• It also helps you to search the nearby restaurants, hotels and gas stations
and is very useful for a new place.
• Due to its low cost, it is very easy to integrate into other technologies like
cell phone.
• The system is updated regularly by the US government and hence is very
advance.
• This is the best navigating system in water as in larger water bodies we are
often misled due to lack of proper directions.

145. Disadvantages of Global Positioning System
• Sometimes the GPS may fail due to certain
reasons and in that case you need to carry a
backup map and directions.
• If you are using GPS on a battery operated device,
there may be a battery failure and you may need
a external power supply which is not always
possible.
• Sometimes the GPS signals are not accurate due
to some obstacles to the signals such as buildings,
trees and sometimes by extreme atmospheric
conditions such as geomagnetic storms.

146. WHAT IS GALILEO? (Week 10)
Galileo is Europe’s own
global navigation satellite
system, providing a highly
accurate, guaranteed global
positioning service under
civilian control.
It is inter-operable with GPS and Glonass, the US
and Russian global satellite navigation systems.

147. By offering dual
frequencies as
standard, Galileo
is set to deliver
real-time positioning
accuracy down to
the metre range.

148. It will guarantee availability of the service under
all but the most extreme circumstances and will
inform users within seconds of any satellite failure,
making it suitable for safety-critical applications
such as guiding cars, running trains and landing
aircraft.
On 21 October 2011 came the first two of four
operational satellites designed to validate the
Galileo concept in both space and on Earth.

149. Two more followed on 12 October 2012. This
In-Orbit Validation (IOV) phase is now being
followed by additional satellite launches to reach
Initial Operational Capability (IOC) around mid-
decade.
Galileo services are designed with with
quality and integrity guarantees – this marks the
key difference of this first complete civil positioning
system from the military systems that have come
before.

150. The fully deployed Galileo system consists of
30 satellites (27 operational + 3 active spares),
positioned in three circular Medium Earth Orbit
(MEO) planes at 23 222 km altitude above the
Earth, and at an inclination of the orbital planes of
56 degrees to the equator.
Once the IOC phase is reached, The Open
Service, Search and Rescue and Public Regulated
Service will be available with initial performances.
Then as the constellation is built-up beyond that,
new services will be tested and made available to
reach Full Operational Capability (FOC).

151. Once this is achieved, the Galileo navigation
signals will provide good coverage even at latitudes
up to75 degrees north, which corresponds to
Norway's North Cape - the most northerly tip of
Europe – and beyond.
The large number of satellites together with
the carefully-optimised constellation design, plus
the availability of the three active spare satellites,
will ensure that the loss of one satellite should
have no discernible effect on the user.

152. Two Galileo Control Centres (GCCs) have been
implemented on European ground to provide for the
control of the satellites and to perform the navigation
mission management. The data provided by a global
network of Galileo Sensor Stations (GSSs) are sent to the
Galileo Control Centres through a redundant
communications network.
The GCCs use the data from the Sensor Stations to
compute the integrity information and to synchronise the
time signal of all satellites with the ground station clocks.
The exchange of the data between the Control Centres
and the satellites is performed through up-link stations.

153. (Week 11)
As a further feature, Galileo is providing a global
Search and Rescue (SAR) function, based on the
operational Cospas-Sarsat system. Satellites are therefore
equipped with a transponder, which is able to transfer the
distress signals from the user transmitters to regional
rescue co-ordination centres, which will then initiate the
rescue operation.
At the same time, the system will send a response
signal to the user, informing him that his situation has
been detected and that help is on the way. This latter
feature is new and is considered a major upgrade
compared to the existing system, which does not provide
user feedback.

154. Experimental satellites
GIOVE-A and GIOVE-B
were launched in 2005
and 2008 respectively,
serving to test critical
Galileo technologies,
while also the securing
of the Galileo frequencies
within the International
Telecommunications
Union.

155. Over the course of the test period,
scientific instruments also measured various
aspects of the space environment around the
orbital plane, in particular the level of radiation,
which is greater than in low Earth or
geostationary orbits.
The four operational Galileo satellites
launched in 2011 and 2012 built upon this effort
to become the operational nucleus of the full
Galileo constellation.

157. • OPERATIONS
• This work package concerns the provision of
Operations services of the Galileo system in the
timeframe of the FOC deployment phase.
• It comprises the operations of all deployed spacecrafts
in the Galileo constellation, including launch and early
operations, in orbit tests, routine operations,
contingency recovery operations, orbit correction,
Operations of the Ground control and ground mission
segments facility both in the Galileo Control Centres
and in the remote sites, and the management of
telecommunication network.
• The contract with Spaceopal, company created by DLR
(DE) and Telespazio (IT) was signed on 25 October
2010.

158. • An investigation into the recent failed Soyuz launch of the EU's Galileo
• satellites has found that the Russian Fregat upper stage fired correctly, but
• its software was programmed for the wrong orbit. From the article: "The
• failure of the European Union’s Galileo satellites to reach their intended
• orbital position was likely caused by software errors in the Fregat-MT
An investigation into the recent failed Soyuz launch of the EU's
Galileo satellites has found that the Russian Fregat upper stage fired
correctly, but its software was programmed for the wrong orbit.
From the article: "The failure of the European Union’s Galileo
satellites to reach their intended orbital position was likely caused by
software errors in the Fregat-MT rocket’s upper-stage, Russian newspaper
Izvestia reported Thursday.
'The nonstandard operation of the integrated management
system was likely caused by an error in the embedded software. As a
result, the upper stage received an incorrect flight assignment, and,
operating in full accordance with the embedded software, it has delivered
the units to the wrong destination,' an unnamed source from Russian
space Agency Roscosmos was quoted as saying by the newspaper."

159. Limits of Compatibility: Combining Galileo PRS
and GPS M-Code
Although Galileo operates wholly under civil control, it does include
encrypted signals, including those of the Public Regulated Service or
PRS, which are broadcast near the new GPS military M-code signals at
the L1 frequency. Galileo’s design calls for PRS use by public safety
organizations such as police and fire departments and customs
agencies.

160. Because of its design, PRS could also be used for
military applications; however, the European Union
(EU) has not approved such use and several EU
members have gone on
record opposing it. Nonetheless, in light of a
continuing interest in combined use of M-code and
PRS, this article examines some of the technical
issues surrounding the subject.

161. An agreement signed in June 2004 between
the European Union and the United States
regarding the promotion, provision, and common
use of GPS and Galileo has opened a new world of
possibilities in satellite navigation.
Simulation studies of the combined use of
Galileo and GPS civil signals have demonstrated
that users may expect a clear enhancement of
performance in terms of positioning accuracy and
navigation solution.
The compatibility and interoperability that
the Galileo signal structure will offer with respect to
GPS is especially relevant in the E2-L1-E1 band.

162. After lengthy negotiations, the United States and
the EU agreed on the design of the Open Service (OS)
signals to be transmitted by Galileo and the future GPS on
L1. If we take a
more detailed look into the different waveforms,
however, we see that not only the Galileo Open Service
and the GPS C/A code have a common center frequency
on L1 but also the
Galileo Public Regulated Service (PRS) and the GPS
military M-code.
Because common center frequencies are certainly
the main prerequisite for interoperability, the combined
processing of PRS and military signals from Galileo and
GPS raises the possibility of offering a better positioning
and navigation solution.

163. One major point during the negotiations was the necessary
coexistence of the Galileo Public Regulated Service (PRS) and Open
Service (OS) with the GPS C/A and M-code, in particular on L1 where
the necessary separation between the different services played an
outstanding role.
Thus, the final frequency and signal structure resulted also in
the same L1 center frequency for the Galileo PRS and GPS M-code.
Our previous work evaluated the accuracy of a combined Galileo OS
and GPS C/A code service. This article will present the positioning
accuracy of a combined Galileo PRS and GPS M-code service from a
purely technical point-of-view.
No doubt that military and political considerations and
decisions would be necessary to realize such a combined service
in reality. However, this paper aims to show not only a benefit to use
of the interoperability between

164. From a political and military point of view, the question of a
combined Galileo PRS and GPS M-code service has clearly not been
addressed yet and probably it will require time consuming and lengthy
discussions in the future, if the negotiations ever take place.
Nonetheless, from a purely technical point of view it makes
sense to evaluate the pros and cons as well as the performance that
such a service could offer some day, and the time is certainly right for
doing that now.
Therefore, this article first evaluates the performance of the
two single services separately using identical assumptions. In order to
do so, a refined methodology is proposed to estimate the different
sources of error that contribute to the User Equivalent Range Error
(UERE), particularly the ranging error caused by reflected signals or
multipath.
Afterwards the same analysis is carried out for a combined
processing of Galileo PRS and GPS M-Code signals for a joint position,
velocity, and time solution.

165. Multipath Error
Multipath error is the most important
unavoidable source of error contributing to the
UERE, because it is very difficult to model. As we
saw, the ionospheric error indeed presents
worse values in a general case, but an
appropriate receiver would be able to eliminate
it or at least reduce its contribution with
corrections coming from SBAS or A-GPS.

166. IBS (Integrated Bridge System)
1. Navigation System
General
The total Navigation System is
based on «IBS» concept
(Integrated Bridge System)
The navigation system will
adopt and follow the latest
international standards for
Navigation Systems, defined by IMO and IEC.
Standards are followed for; Navigation radars, ECDIS, Speed
log, Echo sounder, DGPD/GPS,AIS, DPS and Autopilot/Track
pilot system, Multiloading Online Control Stability System.

167. The main Navigation sensors/systems:
- Dual Navigation ARPA Radar system (S and X-band)
- LPI Radar Sensor
- Fully duplicated ECDIS system with the charts server
- Fiber-optic gyro system
- Fully duplicated INS (Inertial Navigation System)
- Dual action speed log (water track speed and bottom track speed)
- Passive speed log (magnetic log or pressure log)
- Two independent satellite based position equipment (DGPS-
GPS/GLONASS;
different manufacturers)
- Satellite independent positioning system or Laser based positioning
system

168. - Automatic Identification System AIS
- Track-pilot system (functions as a transfer Autopilot)
- Meteorological instruments
- Xenon and Halogen search lights
- Whistle
- Navigation and signal lights
- Data recorder and play-back facility for Navigation
Information- Navigation Information Display
- Navigation Data servers for transferring the information
to IMCS C2 and ANCS-System
- Time server unit
- Dynamic Positioning System (DP-System)

169. • Wheel house consoles are part of the Navigation
System supply.
• Tentative wheel house arrangement is illustrated
in Appendix 1.
* Consoles will also house necessary additional
components for IMCS C2 and ANCS-System,
propulsion/steering system and for machinery
monitoring, required to be operated on bridge.
* All displays in the wheel house are high contrast
TFT-type displays. Display size and modes are
according to requirements.

170. 1.2 Navigation System integration with other
ship’s systems.
Following figure illustrates the navigation
System integration to other ship’s systems.
Navigation System to Engine Monitoring System
- Display of Engine and propulsion Information
to bridge operators
- Transfer of navigation information to Engine
monitoring system

171. Navigation System to IMCS C2 and AWW-System
- Transfer of Navigation Information data to IMCS
C2 and AWW-System
- Transfer of ARPA Tracked targets to IMCS C2 and
AWW-System
- Transfer of Route Information from NAV-System to
IMCS C2 -System
- Transfer of Route Information from IMCS C2 -
System to NAV-System
- Transfer of high speed hull motion information to
IMCS C2 and AWW-System

172. Navigation System to Dynamic position system
- Transfer of Navigation Information data to DP-System
- Transfer of Route information between NAV-System and
DP-System
Dynamic position system to IMCS C2 -System
- Transfer of route and command information from IMCS
C2 -System to DP-System
Dynamic position system and Propulsion Control system
- Transfer of Propulsion commands and feed-backs from
DP-System to Propulsion control system

173. • Navigation System and Dynamic position system
to Chart Server
• Enquires and its Parameters of specified Area in a
specified Scale using specified Palette.
- Building of Chart of specified Area in a specified
Scale using specified Palette.
Charts’s Contents is limited by a list of Chart Layers.
- Getting of Chart Object under a specified small
area.
- Getting of Alarms for a specified Area.

174. Chart Server to Navigation System and Dynamic
position system
Results of Enquires
- Electronic Chart of specified Area.
- List of Chart Objects.
- List of Alarms.

175. 2. Navigation System components
Following section contains main navigation equipment and
their standard and special
requirements
2.1 Dual Navigation ARPA Radar system (S and X-band)
Navigation Radar System is composed of following units:
- S-Band 30 kW down mast transceiver with 12’ antenna unit
- X-Band 25 kW down mast transceiver with 9’ antenna unit
- Two fully independent ARPA radar displays with built-in radar
inter switching unit
- Radars are operated from UPS power source (3phase
230VAC)
- ARPA displays are 23.1’’ TFT screens, conforming to the
standards for IMO ARPA systems

176. ARPA Radar system includes following special features:
- Transfer of tracked ARPA targets to ECDIS
- Transfer of user created synthetic map information from
ECDIS to ARPA displays
- Presentation of route information and track information from
ECDIS
- Presentation of curved EBL, initiated from ECDIS/Track
steering system
- Transfer of Radar Raw image to IMCS C2 and AWW-System
- Transfer of Tracked Targets to IMCS C2 and AWW-System, via
Navigation Data Server units
- Integration of ARPA displays to LPI-radar, control of LPI radar
and display of LPI radar video
information on ARPA display
- Radar transmission blanking output

177. 2.2 LPI Radar Sensor and Processor
LPI radar can be proposed
as option, but the
final specifications
for the performance
standardsare
defined at later
stage.LPI radar
could be fully
integrated to ARPA
radar system

178. 2.3 Fully duplicated Chart Server
- The world-wide database of Electronic Navigational Charts (ENC) for
all available standard scales. Weekly updates.
- Source data in S57 standard, V3.1 version or more recent.
- Display of all cartographic components in accordance with S52.
- Mercator projection with WGS-84 datum or:
-Transverse Mercator
- UTM (Gauss-Krьger)
- Polar; - Radar; - Cylindrical
- Orthographic; - Stereographic; - Gnomonic
- Base, Standard, Other Display as specified in IEC61174.
- More detailed information layers in accordance with Viewing Groups
specified in S57.
- All ECDIS Palettes: DAY-BRIGHT, DAY-WHITEBACK, DAY-BLACKBACK,
DUSK, NIGHT.
- Paper chart and Simplified chart symbols.

179. Basic queries:
- Building of a standard chart for a specified
Area,
Scale,
Projection,
Set of layers,
Shallow, Safety and Deep Contours,
Palette.
- Building of hierarchical objects tree under the requested
area. This gets information about all
objects on the Chart.
- Alarm selection. Finding of Alarms, e.g.:
Crossing of Safety Contour, Cautionary and special Areas
Approaching to an Obstruction

180. Additional functions:
- Displaying and use of Additionally Military Layers AML in
accordance with STANAG-7170 and
STANAG-4564 standards.
- Extracting and export of digital information about Objects
from Electronic Navigational Charts and AML.
- Receiving, Converting and Displaying of Sea Ice Charts
produced by National Ice Center or other organization. Sea Ice
Charts have been displayed as an additional chart layer
- Navigational Calculator allows to recalculate coordinates
between any 2 Ellipsoids in accordance with S60 standard.
- Use of DEM (Data Elevation Model) Databases to get
information about height of any point on the Earth.

181. 2.4 Fully duplicated ECDIS system
Two fully independent ECDIS are included in the
NAV-SYSTEM complying with following
standards:
- IMO resolution A.817(19), performance
standard for ECDIS
- IEC61174, Operation and performance,
method of testing
- IEC60945, EMC/Environment/General
requirements

182. Following main functions are included:
- Display of vector charts (IHO/S57 edition3) or Raster
charts (ARCS)
- Presentation of Additional Military Layers (AML)
- ECDIS Computers and displays are supplied from UPS
power source
- Two ECDIS computers are working in harmonised mode,
allowing automatic update of data
based in both ECDIS computers
- Continuous monitoring of ship position through multi-
sensor Kalman filter processing using;
GPS, DGPS SDME (through the water or ground tracking
speed log), gyro compasses and radar
echo reference

183. - Route planning and monitoring
- Grounding warning and safe depth contours
- Superimposing the radar raw video on the electronic chart
- Target vectors and data from the navigation ARPA tracked targets
- Onboard generated safety maps, routes and areas which can be
overlaid also on ARPA screens
- Area dependent and user defined notebook, which will inform user
automatically when the ship
reaches the programmed area
- Built-in voyage data logging feature, as required by ECDIS
performance standard
- Integration of Automatic Identification System (AIS) in order to
display other targets (carrying
AIS) on ECDIS screen. Read out of detailed ship information supplied
by AIS

184. ECDIS will accommodate a number of sensors to
be connected, with appropriate international
standards (IEC-61162-1)
Additional features for mine searching
operation:
- Mine searching plans initiated in IMCS C2-
SYSTEM, are transferred to ECIDS system
- Route plans, which are initiated in ECDIS, are
transferred to IMCS C2 and AWW-System
2.5

185. 2.5 Fiber-optic gyro system (Navigation Gyro System)
Navigation Gyro compass system includes following main
units:
- LFK95 Fiber-optic gyro compass
- Interface and power supply unit (IPSU)
- Navigation Gyro compass control panel
- Analog repeaters in steering gear room
- Digital repeaters in wheel house
- Transmitting Magnetic compass
- Switch over unit and facilities to select the System Gyro
Compass as the main source
for heading information to all navigation sensors (ARPA
displays, ECDIS, Track pilot etc.)

186. Fiber-optic gyro compass supplies the following
information to navigation system:
- Ship’s heading
- Ship’s rate Of Turn
- Ship’s Roll and Pitch information
- The ships heading information is available in
analog format (Stepper output) and in serial
format (IEC61162). The serial format is available
both in standard 4800b/s and on higher serial
transmission rates (up to 38.400b/s)
Navigation Gyro information is available in Ethernet
Data format via Navigation Data Servers

187. Fiber-optic gyro compass supplies the following
information to navigation system:
- Ship’s heading
- Ship’s rate Of Turn
- Ship’s Roll and Pitch information
- The ships heading information is available in
analog format (Stepper output) and in serial
format (IEC61162). The serial format is available
both in standard 4800b/s and on higher serial
transmission rates (up to 38.400b/s)
Navigation Gyro information is available in Ethernet
Data format via Navigation Data Servers

188. Following information is available in INS:
- Ship’s heading
- Ship’s Rate Of Turn
- Ship’s Roll and Pitch Information
- Body velocities; X, Y and Z
- Accelerations; X, Y and Z
Switch Over Unit (SOU) supplies the gyro
information on 64Hz and on 512Hz up date rate
and on HDLC protocol.
Sensors, which require fast update rate information,
are connected directly to INS.

189. Normal navigation systems (i.e. ARPA radars) can not scope with HDLC
protocols and high
speed data streams, therefore the information is transformed to a
commonly used (in navigation
systems) data formats.
The MIPSU is included in order to have System Gyro information
available also for Navigation
Systems/sensors
System Gyro information is available in Ethernet Data format via
Navigation Data Servers.
Following information is also available to DP-System
- Ship’s heading
- Ship’s Rate Of Turn
- Ship’s Roll and Pitch Information
- Body velocities; X, Y and Z
- Accelerations; X, Y and Z

190. 2.7 Dual action speed log (water track speed and bottom track
speed)
Dual Action speed log system is included in the Navigation system.
The system supplies both Water Track and Bottom Track information to
Navigation system
sensors.
Water track speed is used by ARPA, radars according to IMO rules.
The system has two-function log unit, working both on bottom track
principle and on water
track.
System includes required amount of interfaces to navigation systems,
and necessary amount
of speed repeaters, distributed in wheel house and engine control
room.
Water track speed log has the measuring frequency of 4Mhz and the
bottom track is working
on 150KHz frequency.

191. Bottom track speed log can be switched off at any time, in order to
stop the transmission
on 150KHz frequency.
The speed log system includes the following main units:
- Speed log electronic unit
- Speed log distribution unit
- Transducer unit with gate valve
- Four digital repeaters
- Speed log simulation unit (manual speed input facility)
- 200p/NM outputs to ARPA radars and Autopilot
- IEC61162-1 serial format outputs to ECDIS, Navigation Data Servers
etc.
Speed log information is distributed to IMCS C2 and AWW-System via
Navigation Data Servers.
Ship’s speed information to DP-System is also provided

192. 2.8 Echo sounder
Navigation echo sounder function is included in the
navigation system, as a part of standard
equipment for navigation.
Navigation echo sounder has the following units and
features:
- Graphical display, which is also used as «play-back»
media for depth history.
- Transducer
- IEC61162-1 outputs to other Navigation systems
Echo sounder information is distributed to IMCS C2 and
AWW-System via Navigation Data
Servers.

193. 2.9 Two independent satellite based position equipment
(DGPS - GPS/GLONASS)
Two independent satellite based (DGPS - GPS/GLONASS)
receivers are included in the
Navigation System.
Following special features are included:
- Possibility to receive correction signals from external
differential correction source (RTCM- 104
format)
Position information to IMCS C2 and AWW-System is
transferred via Navigation Data Servers.
Position information output to DP-System is also
provided.