24-11-2012, 12:24 PM
JAMMERS
[attachment=40949]
THE PRESENT SCENARIO
• THE ADVANCED COMMUNICATION
SYSTEM IS VASTLY USED NOWADAYS
• UNFORTUNATELY THE
COMMUNICATION SYSTEM IS ALSO
USED AGAINST THE SOCIETY AND
HUMANITY EVEN FOR PERSONAL
GAINS
JAMMER AS A REMEDY
• JAMMING is the act of intentionally
directing electromagnetic energy at
a communication system to disrupt
or prevent signal transmission.
• A JAMMING device transmits on the
same frequencies as the target
hence disrupting the
communications.
THE BASIC CONCEPT
· Voltage-controlled oscillator - Generates the
radio signal that will interfere with the cell phone
signal
· Tuning circuit - Controls the frequency at which
the jammer broadcasts its signal by sending a
particular voltage to the oscillator
· Noise generator - Produces random electronic
output in a specified frequency range to jam the
cell-phone network signal (part of the tuning
circuit)
· RF amplification (gain stage) - Boosts the
power of the radio frequency output to high
NOISE GENERATOR
• Noise will help in masking the jamming
transmission,
making it look like random "noise" to an outside
observer.
• The noise generator used is based on the avalanche
noise generated by a Zener breakdown
phenomenon.
• The noise generator circuit consists of:
– A standard 6.8 volt Zener diode with a small
– reverse current
– Transistor buffer
– National LM386 audio amplifier function as:
• Small signal amplifier
RF POWER AMPLIFIER
• Two RF power amplifiers were used to
achieve the required output power (i.e.
34dBm).
• The first stage power amplifier was the
MAR-4SM from Mini-Circuits it has a gain
of 8dB for frequency range from DC to
1000 MHz
• so the output of this stage should be
5dBm
• for the -3dBm output of the VCO
[attachment=40949]
THE PRESENT SCENARIO
• THE ADVANCED COMMUNICATION
SYSTEM IS VASTLY USED NOWADAYS
• UNFORTUNATELY THE
COMMUNICATION SYSTEM IS ALSO
USED AGAINST THE SOCIETY AND
HUMANITY EVEN FOR PERSONAL
GAINS
JAMMER AS A REMEDY
• JAMMING is the act of intentionally
directing electromagnetic energy at
a communication system to disrupt
or prevent signal transmission.
• A JAMMING device transmits on the
same frequencies as the target
hence disrupting the
communications.
THE BASIC CONCEPT
· Voltage-controlled oscillator - Generates the
radio signal that will interfere with the cell phone
signal
· Tuning circuit - Controls the frequency at which
the jammer broadcasts its signal by sending a
particular voltage to the oscillator
· Noise generator - Produces random electronic
output in a specified frequency range to jam the
cell-phone network signal (part of the tuning
circuit)
· RF amplification (gain stage) - Boosts the
power of the radio frequency output to high
NOISE GENERATOR
• Noise will help in masking the jamming
transmission,
making it look like random "noise" to an outside
observer.
• The noise generator used is based on the avalanche
noise generated by a Zener breakdown
phenomenon.
• The noise generator circuit consists of:
– A standard 6.8 volt Zener diode with a small
– reverse current
– Transistor buffer
– National LM386 audio amplifier function as:
• Small signal amplifier
RF POWER AMPLIFIER
• Two RF power amplifiers were used to
achieve the required output power (i.e.
34dBm).
• The first stage power amplifier was the
MAR-4SM from Mini-Circuits it has a gain
of 8dB for frequency range from DC to
1000 MHz
• so the output of this stage should be
5dBm
• for the -3dBm output of the VCO