How does the wireless intercom system work?

We all know that the wireless intercom system is widely used in our daily life. It has the characteristics of flexibility, easy operation, fast voice transmission, and economical use. It is the basic means to realize production scheduling automation and management modernization. What is the principle of wireless intercom system?

1. Launch part:

The phase-locked loop and voltage-controlled oscillator (VCO) generate the transmitted RF carrier signal, which is buffered and amplified, stimulated, amplified, and power-amplified to generate rated RF power. .

2. Receiving part:

The receiving part adopts the super-heterodyne mode of double frequency conversion. The signal input from the antenna is amplified by the radio frequency after passing through the transceiver conversion circuit and the band-pass filter. The first local oscillator signal of the phase locked loop frequency synthesizer circuit is mixed at a first mixer and generates a first intermediate frequency signal. The first intermediate frequency signal is further removed from the clutter signal of the adjacent channel through the crystal filter. The filtered first IF signal enters the IF processing chip, and is mixed with the second local oscillator signal again to generate the second IF signal. Generate an audio signal. The audio signal enters the volume control circuit and power amplifier to amplify through amplification, band-pass filter, de-emphasis and other circuits, drives the speaker, and obtains the information that people need. wireless signal jammer

3. Modulation signal and modulation circuit:

The human voice is converted into an audio electrical signal through a microphone, and the audio signal is directly modulated by a voltage controlled oscillator through an amplifier circuit, a pre-emphasis circuit and a band-pass filter.

4. Signal processing:

The CTCSS/DTCSS signal generated by the CPU is amplified and adjusted, and then enters the VCO for modulation. After receiving the low-frequency signal obtained after frequency discrimination, a part of it is filtered and shaped by amplifying and sub-audio band-pass filter, and then enters the CPU, which is compared with the preset value, and the result is used to control the output of the audio power amplifier and the speaker. That is, if it is the same as the preset value, turn on the speaker, if not, turn off the speaker.