(1) The document describes a mobile phone sniffer circuit that can detect the presence of an active mobile phone within a 1.5 meter radius. (2) It works by using an antenna to capture radio frequency signals, which are then converted to a voltage and used to trigger an alarm with a buzzer and LED. (3) The circuit can detect incoming and outgoing calls, texts, and video transmissions even when the phone is on silent mode.

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Sariga Gopal C P

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First of all we thank Lord Almighty for his grace and mercy which helped us reach this far with our project.
In the successful completion of this project we thank our principal Dr.Mini M.G, for providing all
arrangements and help in the preparation of our project.
We also thank our Head of Department Mrs.Eliswa Laiju for her valuable advices.
We would like to thank our project coordinator Miss.Veena Mathew, Asst. Professor, EEE Department,
for giving us technical advice and timely instruction, without which we could never have been able to
complete the work in time.
Finally we would like to express our sincere gratitude to our project guide Mr.Manu Madhavan, Asst professor
Electrical and Electronics Department, for his valuable advice.
Then I take this valuable opportunity to thank each and every person who has
been helpful in the successful completion of our project.

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Mobile Sniffer is a very essential security checking equipment in this century used to detect switched on mobile
phones in areas where use of mobile phones are banned like examination halls, confidential rooms, etc.
The motive behind our project is to find a solution to overcome this problem. Hence we name our project as
Mobile Sniffer. A buzzer and led is used to detect the mobile phones within a radius of 1.5m.

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Previously, there was no technology to detect the cell phones in the examination hall and in cell phone
restricted areas.
There is manual checking and there is still a chance of having the cell phone with the person if he is not
checked properly.
So to avoid this problem, an automatic detection of cell phone is introduced.
Cell phone detector is a circuit used to detect the presence of an active mobile phone in mobile restricted areas
circuit detect the mobile phone automatically by capturing the transmission signal from mobile
phone, it can sense the cell within the range of 1-1.5m.
Motivation Cell phones are used in good way and also in a bad way. When the class is going on,
students intend to use their cell phones and not listening to what is being taught.
These days, students are also carrying their cell phones to the examination halls to copy which would help
them to get good marks. To avoid this problem, the cell phone detector is introduced

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This pocket size instrument can detect the presence of an activated mobile phone within a certain range.
So, it can be used to prevent use of mobile phones in examination halls, confidentiality rooms, etc.
It is useful for detecting the use of mobile phone for spying and unauthorized video transmission.
The circuit can detect the incoming and outgoing calls, SMS and video transmission even if the mobile phone
is kept in silent mode.
The moment it detects RF transmission signal from an activated mobile phone, it starts sounding a beep alarm
and the LED blinks.
The alarm continues until the signal transmission ceases. The circuit is assembled on a general purpose PCB
as compact as possible enclosed in a small box like a mobile case. The miniature 12 V battery of a remote
control can be used for power supply purpose.
After any switched on mobile phone is detected within range, the authority will come to know that someone
has penetrated the area using a switched on mobile phone. For informing authority purpose,
some form of warning media either visual or audio or both will be used. After being informed,
the authority person can easily locate the person who has entered the area with a switched on mobile phone.
Thus, unauthorized use of mobile phone is prevented easily.

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 The objective includes building a mobile detector to locate an active phone within one and a half radius.

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The ubiquity of cell phone has made communication easier and faster, as integrating the world into a global
village as people who are in different geographic location are connected in seconds, but there is great need
to limit the use of cell phone at particular places and at particular times.
Hence the use of an intelligent mobile sniffer is guaranteed.
Previously there was no technology to find the presence of an active mobile phone in mobile restricted areas.
There is manual checking and there is still a chance of having mobile phone if a person is not checked
properly. To avoid this cell phone detector circuit is introduced.
Each hand set in a cell is allocated a particular frequency for its use. The mobile phone transmits short signals
at regular intervals to register its availability at nearest base station.
Mobile always tries to keep connection with nearest base station in the examination halls and confidential
rooms. To avoid this we are introducing a project called
“CELLPHONE DETECTOR/MOBILE SNIFFER”

10. Trigger
stage
Antenna Converter
stage
Timer stage
Piezo
buzzer
LED
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ANTENNA: It is used to catch the RF signal. And a 5 inch long antenna is used here. It is the first block;
it can sense the RF transmission signal of specific frequency.
It can only capture the signal of huge energy with high frequency.
CONVERTER: Next block is a converter; here we use an operational amplifier as converter for
converting minute amount of current to a level of voltage required for switching purpose.
IC 3130 is used for it and the configuration of IC is current to voltage converter. It is an 8 pin IC
TRIGGER STAGE: Next block is a trigger stage; it is a bipolar junction transistor.
And it is used as a switching device and to trigger next stage. BC 548 is taken as trigger stage.
It also consists of a LED it is used as an indicator and the power for the working of LED is
provided by the transistor.
TIMER STAGE: Next block is timer stage, it is a monostable 555 timer;
it is used to provide proper working power for the buzzer. NE 555 IC is used here.
Monostable mode of operation needs a trigger, and for this we use BC 548 as trigger. This bipolar transistor
can provide suitable triggering for 555 timers.
PIEZO BUZZER: Last block is a Piezo buzzer; is also used for indication power required for the working
of buzzer is taken from the timer stage. A 9-12v Piezo buzzer is used here.

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Complete design of mobile sniffer , it consist of four stages
 RF stage/capturing stage
 Converter stage
 Trigger stage
 Timer stage
 RF stage is a capturing stage it consist of an antenna and a disk capacitor.
 Frequency of RF signal is 0.9 to 3GHz
RF is an EM wave so we can use the equation

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C=ʎF ; where C is the speed of light =3*10^8
F is the frequency of RF signal =0.9-3GHz
ʎ= (3*10^8)/ (3*10^9)
= 0.1=10cm
Antenna height
= ʎ/4=10/4
= 2.5cm ≈1 inch
So antenna height =5inch STD
Here there is a disk capacitor whose lead is 18mm with spacing 8mm.
It is used to capture the signal of GHz, and we need a uf range capacitor.
So we use 0.22uf capacitor (C3) STD

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 Next is a converter, a current to voltage converter. It is an op amp; ic3130 is used.
C3 dischargers via R2 so it is in kilo ohm range
i.e. R2= 100K STD
 Here input is given to the inverting terminal of op amp, to maintain its stability we need a high value
resistance and uf range capacitor
i.e. R1 = 2.2M STD andC4= 100uf STD

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 In current to voltage converter Vo =-Is*R3
Here the current is in uA range and voltage is in v range
so resistance must be in mega ohm range.
i.e. R3=2.2MΩ STD
Now switching device / trigger stage is a transistor
BC 548 is used for this purpose.
Here assume R4 absorbs 20% of Vcc
thenVR4 = 20%Vcc
=12*(20/100)
=2.4V
Let Ic =2mA; then IcR4=2.4V
Then R4= (2.4)/ (2*10^-3) = 1.2K
So we take R4=1k STD

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For BJT is on, it is in saturation mode so Vbesat=0.8V and Vcesat=0.2V
,here Ic is in mA range and Ib is in uA range,
so C6 is chosen in uf range to create base bias of BJT in order of volt.
So we take C6= 0.1uf
Voltage across LED=Vcc-Vcesat
=12-0.2
=11.9V
In monostable 555 timer, we know T=1.1RC
Here it is T=1.1*R6*C9
Take T=0.1s and assume C9=4.7uf
Then R6= (0.1)/ ((1.1)*(4.7*10^-6)) =19K
So we take R6=15k STD

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Circuit consist of a 5 inch long antenna, it is used to capture the RF signal from an active mobile .it is
followed by a disk capacitor .
 Then a current to voltage converter IC 3130 is used here, it is an op amp ic. It is also act as a amplifier.
 There is a switching device i.e. a transistor it is used to provide suitable triggering for 555 timer, it is also
used to drive a LED. LED is used for indication.
 And sniffer circuit consist of 555 timer it used to provide output for a buzzer, it is a Piezo buzzer 9-12V is
used.

19. This project is very useful for the private meetings, examination hall, defence establishments, military
camp, Hospitals; Petrol pumps etc., where the uses of an active Mobile Communication (GSM) device
are prohibited.
 It is used to prevent spying and unauthorised video transmission.
 This device can detect objects within a radius of 1.5 meters in a given area.
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20. The circuit can detect the incoming and outgoing calls, SMS and video transmission
even if the mobile phone is kept in the silent mode.
Used to detect hidden mobile phones.
Circuit is simple and portable.
 It is economical and there is no need of expert hands.
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21. It is short ranged i.e., the circuit sense the presence of an active mobile phone only within the
range of 1.5 meters.
 And the circuit cannot sense a phone if it is switched off or in airplane mode.
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Figure shows the bread board or mobile sniffer. From the figure it is clear that the circuit can detect the
mobile phone within the range of 1.5m. Here we can see a buzzer and a LED they are used for the indication.
At the moment when the bug detects the presence of RF signal it starts
beeping an alarm and LED glows.
The circuit can detect the incoming and outgoing calls, SMS and video transmission even if the mobile phone
is kept in the silent mode.
The alarm continuous until the transmission of RF signal ceases. This subsystem comprises the capturing RF
transmission stage, the current to voltage converter, the trigger stage, Timer stage.
The capture stage can capture all frequencies in the mobile communication spectrum from 0.9 to 3 GHz with
a wavelength of 3.3 to 10 cm.
This stage uses a 0.22μF disk capacitor (C3), this capacitor stores energy and transfers the stored energy in
the form of minute current to the inputs of the current to voltage converting stage.
The current to voltage converting stage converts the minute current from the previous stage into the
corresponding output voltage by using a current to voltage convertor operational amplifier (CA3130).
This stage helps trigger the timer stage and provide an Invisible alert about the transmission mobile data
occurrence.
The trigger used here is a mono-stable timer (NE555).

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Printed Circuit Board (PCB) is a piece of art. The performance of an electric circuit depends upon the design
and layout of the PCB.
A PCB mechanically supports and connects components by conductive pathway, etched from copper sheets
laminated on to insulate d substrate.
PCBs are used to rotate electrical currents and signal through copper tracts which are firmly bonded to
an insulating base.
Hardware of a system can be easily changed and it is the better way to check whether the circuit is working.
Here the figure 5.1 shows the PCB layout of mobile sniffer. As previously said it can sense the presence of a
mobile in restricted areas. Here also the indicators are LED and buzzer. If the phone is in range it start
working and it is easy to find the cell phone.

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PCB LAYOUT

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As a conclusion, this project had successfully detected the mobile phones when it is located at particular areas
such as mosque, library, meeting rooms and lecture halls.
But the problems for this design is that it can only sense the frequency of the mobile phones, it cannot detect
how many of mobile phones been used. And also this circuit is short ranged.ie, it can only detect the mobile
phones at arrange of 1.5 meters.
However, by detecting the presence of the mobile phones, it can alert to user to silent or switch off their
mobile phones from those particular areas.
By designing this project, it can be used to help the management system for preventing the usage of mobile
phones for those particular areas.
This design can help to prevent the noise interruption and maintain the peace environment to the other
people in those areas.
This detector circuit also can help to discipline the people from using the mobile phones in the prohibited
areas.
The users also can helping each other to alert between themselves.

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Suggestion and Recommendation for Future Work
his project has been developed and implemented. However, it can be improved to target more advanced
and better application in the next stage of research.
For future improvement, there are several suggestions stated below:
1. Another sensor design can be develop to detect how many phones available in that particular zone / area
2. Increase the range of the detection area (range can be wider)
3. Develop automatic system:
a) Single way transmission - host will give message to receiver
b) 2 ways transmission and receive - host need to know the mobile status
c) 2 ways transmission and receive + automatic with phone preset
d) 2 ways + automatic switch mode (2 ways)
e) Automatic switch to silent in silent mode zone
f) Away silent zone, switch back to previous/ genera

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