07-03-2012, 08:42 PM
mobile bug project report with complete designing of the components used
07-03-2012, 08:42 PM
mobile bug project report with complete designing of the components used
08-03-2012, 10:39 AM
to get information about the topic"mobile bug" full report ppt and related topic refer the link bellow
https://seminarproject.net/Thread-mobile-bug https://seminarproject.net/Thread-mobile...8#pid40628
18-03-2014, 04:48 PM
MOBILE BUG
MOBILE BUG.pdf (Size: 82.67 KB / Downloads: 24) This handy, pocket-size mobile transmission detector can sense the presence of an activated mobile phone from a distance of one- and-a-half metres. So it can be used to prevent use of mobile phones in ex- amination halls, confidential rooms, etc. It is also useful for detecting the use of mobile phone for spying and unauthorised video transmission. The circuit can detect both the in- coming and outgoing calls, SMS and video transmission even if the mobile phone is kept in the silent mode. The moment the bug detects RF transmis- sion signal from an activated mobile phone, it starts sounding a beep alarm and the LED blinks. The alarm contin- ues until the signal transmission ceases. An ordinary RF detector using tuned LC circuits is not suitable for detecting signals in the GHz frequency band used in mobile phones. The transmission frequency of mobile phones ranges from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm.
03-05-2014, 03:31 PM
MOBILE BUG
MOBILE BUG.doc (Size: 36.5 KB / Downloads: 18) Demo Circuit IC1 is designed as a differential amplifier Non inverting input is connected to the potential divider R1, R2. Capacitor C2 keeps the non inverting input signal stable for easy swing to + or – R3 is the feedback resistor IC1 functions as a current to voltage converter, since it converts the tiny current released by the 0.22 capacitor as output voltage. At power on output go high and LED lights for a short period. This is because + input gets more voltage than the – input. After a few seconds, output goes low because the output current passes to the – input through R2. Meanwhile, capacitor C1 also charges. So that both the inputs gets almost equal voltage and the output remains low. 0.22 capacitor (no other capacitor can be substituted) remains fully charged in the standby state. When the high frequency radiation from the mobile phone is sensed by the circuit, 0.22 cap discharges its stored current to the + input of IC1 and its output goes high momentarily. (in the standby state, output of the differential amplifier is low since both inputs get equal voltage of 0.5 volts or more). Any increase in voltage at + input will change the output state to high. Mobile Bug Normally IC1 is off. So IC2 will be also off. When the power is switched on, as stated above, IC1 will give a high output and T1 conducts to trigger LED and Buzzer .This can be a good indication for the working of the circuit. CONCEPT Mobile phone uses RF with a wavelength of 30cm at 872 to 2170 MHz. That is the signal is high frequency with huge energy. When the mobile phone is active, it transmits the signal in the form of sine wave which passes through the space. The encoded audio/video signal contains electromagnetic radiation which is picked up by the receiver in the base station. Mobile phone system is referred to as “Cellular Telephone system” because the coverage area is divided into “cells” each of which has a base station. The transmitter power of the modern 2G antenna in the base station is 20-100 watts. When a GSM (Global System of Mobile communication) digital phone is transmitting, the signal is time shared with 7 other users. That is at any one second, each of the 8 users on the same frequency is allotted 1/8 of the time and the signal is reconstituted by the receiver to form the speech. Peak power output of a mobile phone corresponds to 2 watts with an average of 250 milli watts of continuous power. Each handset with in a ‘cell’ is allotted a particular frequency for its use. The mobile phone transmits short signals at regular intervals to register its availability to the nearest base station. The network data base stores the information transmitted by the mobile phone. If the mobile phone moves from one cell to another, it will keep the connection with the base station having strongest transmission. Mobile phone always tries to make connection with the available base station. That is why, the back light of the phone turns on intermittently while traveling. This will cause severe battery drain. So in long journeys, battery will flat with in a few hours. How the capacitor senses RF? One lead of the capacitor gets DC from the positive rail and the other lead goes to the negative input of IC1. So the capacitor gets energy for storage. This energy is applied to the inputs of IC1 so that the inputs of IC are almost balanced with 1.4 volts. In this state output is zero. But at any time IC can give a high output if a small current is induced to its inputs. There a natural electromagnetic field around the capacitor caused by the 50Hz from electrical wiring. When the mobile phone radiates high energy pulsations, capacitor oscillates and release energy in the inputs of IC. This oscillation is indicated by the flashing of the LED and beeping of Buzzer. In short, capacitor carries energy and is in an electromagnetic field. So a slight change in field caused by the RF from phone will disturb the field and forces the capacitor to release energy. |
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