4. CONTENTS
• What is a sniffer ?
• What is IMEI?
• Designing of the sniffer
Sniffer base station
Unidirectional Antenna
Tracking software
• Working of sniffer device
• Advantages
• Limitations
• References
5. What is a Sniffer?
• The sniffer is basically a transceiver that works in the frequency
which is in the special unused range that is operated by the service
provider or at a frequency that is much different than the one that is
being used.
• For the detection of lost mobile SNIFFER plays a vital role .
• The sniffer device has to be designed precisely and size should be
reduced for easy mobility for the purpose of detection .
7. What is IMEI?
International Mobile Equipment Identifier
•
Each mobile device has a globally unique IMEI
•
15 digit unique code
•
identify-GSM/DCS/PCS phone
•
IMEI number is transmitted and checked against a data base of black listed or grey
listed phones in the network’s EIR (Equipment ID Register), if match found then the
network can perform different actions.
•
Used for blocking of call made by unauthorized person once the mobile is reported
as stolen
8. Gray List
Allow the Phone to be used, but can be
tracked to see who has it.
Black List
Listing the phone from being used on any
number where there is an EIR match
10. Designing of the Sniffer
The sniffer device can be called as a mobile base station
that includes the following important components:
•
Sniffer base station
•
Unidirectional antenna
•
Tracking software
11. Small Base Station
• Facilitates wireless communication between the user equipment
and the network
• Sniffer is a small base station which includes transceiver section.
• It operate at a frequency that is much different from the
frequency of the current cell
• Frequency generated by transceiver is around 900MHz(VHF)
• Hence a proper cooling of the oscillator circuit, generating the
high frequency, has to be ensured.
12. Unidirectional Antenna
• Antenna is a device which works at specified frequency
range for transmitting or receiving the data signal.
•Acts as the eyes of the sniffer for the purpose of the
detection.
• Transmission power depends on lobe pattern which
varies from one antenna to the other.
• The power radiated by the antenna should be properly
designed in order to avoid interference with the near by
cells.
• Effective gain has to be taken into account as this
shows the ability of the antenna to capture the signal
that the lost mobile is transmitting.
(Unidirectional Antenna Radiation
Pattern)
13. Design Parameters of Antenna
• The shape of the radiation system is independent of R, as long R is chosen to be
sufficiently large and much greater than the wavelength.
• other factors : gain and directivity
• Gain [G( , )]= ratio of the antenna radiated power density at a distant point to the
total antenna input power (Pin).
• Directivity [D( , )]= the ratio of the antenna radiated power density at a distant
point to the total antenna radiated power (Prad) radiated isotropically.
14. Design Parameters of Antenna
• Another factor: radiated power intensity U and total radiated power Prad
satisfy the below relationship; 2
Prad =
U sin d d
0 0
• The average power that gets radiated is given as:
Pavg = Prad/4π (watts per steradian)
•Total incident power is:
Pin = Prad+Pl
• The power gain of the antenna is given as:
gp = 4πU/Pin
• The ratio of gain power to the directive gain is referred as a measure of
efficiency of the antenna:
gp/gd = Prad/(Prad+Pl)
15. Contd..
• effective area = aperture or capture area that is exposed to the em
waves and is related to the directive gain of the antenna through the
relation;
Aeff = gdλ2/4
• Effective area and gain vary directly for a given frequency and
efficiency .
• Unidirectional antenna = high gain and high directivity (for long
distance communication and better signal quality)
• Orientation of the antenna = fixed in one particular direction
16. Software for Tracking
• Software helps in the process of creation of the data base
and this is mainly done using a Random Access
Memory(RAM).
• Lost IMEI number is embedded in the chip.
• It has the input as the IMEI number of the lost mobile
phone from the RAM using the SQL query.
• Programming is done with C or Java, but C is most
preferred as it is easily embedded within the chips.
17. Working of the Sniffer
The entire working of
the sniffer is
categorized in two phases :
• Before Sniffer increases the frequency
• After Sniffer increases the frequency
19. After Sniffer Increase The Frequency
Fig: The lost mobile phone connection establishes a
connection with the sniffer
20. Sniffer tries to communicate with the lost mobile phone
Fig: Sniffer trying to communicate with the lost
mobile phones.
21. Advantages
• Useful in detection of lost mobile on a large
scale
• Overall effective cost of the design and
detection is low
• Low power consumption
the
22. Limitations
Certain boundaries :
• Power of the mobile should be good enough
• Mobile should not been in shadow region
Note: “Method can been improved by using modern technology and devices”
23. References
•Schiller, “Mobile Communication”, Pearson Education 1
Edition, 7th reprint -2003.
•R. S. Satya Sri Ambica, P. Padma Priya, Dr.N.Srinivasu,
“Sniffer Technology to Detect Lost Mobile ”, International
Journal of Engineering Trends & Technology, volume
4,issue4 –April 2013.
• Puthiyavan,U., “Enhancing User Privacy- Location Based
Search Using MEMD” , IEEE International Conference on
Portable Information Devices 2007, May 2007, Pp-1-5.
