Digital signals use complex modulation techniques, such as QPSK. These signals are very stable in the presence of jammers. But the signal relies on a handshake between the sender and receiver to identify and determine security Settings and advanced transmission methods. If the jamming device sends the initial packet, the receiver will start its state machine to establish two-way data transmission. The jammer will return to the starting point instead of completing the handshake. This method traps the receiver in an infinite loop where it keeps trying to initiate a connection but never terminates it, effectively blocking all legitimate communication.
The most common types of such signal jammers are random noise, random pulse, tone, whistle, CW random key modulation, pitch, rotation, pulse, spark, recording, seagull, and pass through. These can be divided into two groups: the obvious and the subtle.
Obvious interference is easy to spot because they can be heard on the receiving device. It is usually noise of some type, such as tones (bagpipes), random key coding, pulses, music (usually distorted), erratic tones, very distorted sounds, random noise (hiss), and recorded sounds. Various combinations of these methods can be used, often accompanied by periodic Morse signal recognition signals, so that individual emitters can be identified and their effectiveness assessed. For example, China often uses jamming, digital radio stations).
The purpose of this interference is to prevent the reception of the sent signal and cause problems for the receiving operator. Early Soviet attempts to jam Western radio stations used the noise of diesel generators as transmitter interference.
Weak interference refers to interference in which the receiving device cannot hear the sound. The radio does not receive the incoming signal; To the operator, however, everything seems superficial. These are often technical attacks against modern devices, such as "squelch capture." Due to the FM capture effect, FM broadcasts can be blocked by simple, unnoticed unmodulated carriers. The receiver locks on to the largest carrier signal, so it will ignore the FM signal carrying the information.
Intentional communication jamming usually targets radio signals to disrupt combat control. A transmitter tuned to the same frequency as an opponent's receiving device and with the same type of modulation may have enough power to cover any signal receiver. When the power is very low, digital wireless jammer can interfere with signals such as Bluetooth and WiFi.
In some cases, jammers will work by transmitting radio signals, which can interfere with communications by reducing the signal-to-noise ratio.
