Intercom working principle signaling processing

Date:Jan 26, 2018

CPU generates CTCSS / CDCSS signal after amplification adjustment, into the voltage-controlled oscillator for modulation. After receiving the low-frequency signal obtained after the frequency discrimination, part of the amplified and sub-audio band-pass filter to filter shaping, into the CPU, compared with the preset value, the results of the control audio amplifier and speaker output. That is, if the same as the preset value, turn on the speaker, if different, turn off the speaker.