The design of the squelch circuit in the walkie-talkie is to solve the noise problem in the call quality.
The squelch function of the walkie-talkie is to strictly filter out excessive background noise, eliminate or suppress the background noise when no signal is received so that the speaker of the walkie-talkie remains silent when the signal is not received, and the squelch circuit is closed at this time. When the squelch is turned on, the horn sound will be heard.
The purpose of squelch is to strictly suppress the noise, but if the suppression is excessive, the weak call signal will also be restricted and cannot be received. Especially during long-distance calls, weak remote communication signals are suppressed along with noise, which is also undesirable. Adjusting the squelch is to reduce, suppress or eliminate useless noise so that it will not be transmitted through the speaker, but it is necessary to retain the call signal (even under the weak signal in the case of large noise).
To adjust the squelch is actually to adjust and select the level of the squelch circuit. When the signal level reaches a certain level, the squelch can be turned on, and when the signal level drops to a certain level, the squelch will be closed. If the signal level is too high, use weak signals may not be received, and if the signal level is too low, it may be interfered with by noise and other useless signals. The squelch function should be one of the most basic functions of the walkie-talkie.
The strength of the noise in the received signal is inversely proportional to the received signal. The stronger the signal, the weaker the noise; on the contrary, the weaker the signal, the stronger the noise.
The principle of setting the squelch level is based on the user's communication environment and communication requirements. When the user requires a longer communication distance, the received signal will become weaker at this time, which requires higher receiving sensitivity and a lower squelch level, or a shallower squelch adjustment. When the user's communication distance is relatively short and the received signal is strong, the receiving sensitivity can be lowered and the squelch level will be higher, or the squelch adjustment will be deeper, and the noise will be smaller.
When a discontinuity is found during the call, it means that the radio receiving signal is weak, or the communication distance changes during the call, and the voice cannot be heard. At this time, the squelch level should be lowered to increase the sensitivity. Under normal circumstances, the user uses it inside the unit, and the distance is not very far, and the level is set a little higher; while in the field, the distance is farther, and the level is set a little lower. Since each model has a different grade classification, sometimes it can only rely on experience, and the factory-grade setting can only be used as a reference.