Quanzhou TESUNHO Electronics Co.,Ltd
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Fax:86 595 2208 2266
The working principle of the walkie talkie is as follows:
1. The launching part:
The phase-locked loop and the voltage controlled oscillator (VCO) produce the transmitted radio frequency carrier signals, which are amplified and amplified to stimulate the amplifier and amplifier to generate rated radio frequency power. Through the antenna low pass filter, the harmonic components are suppressed, and then the antenna is sent out through the antenna.
2. The receiving part:
The receiving part fuses the amplified signal from the radio frequency and the first vibration signal from the phase-locked loop frequency synthesizer circuit in the first mixer and generates the first intermediate frequency signal. The first intermediate frequency signal further eliminates the clutter signal of the adjacent channel through the crystal filter. The first intermediate frequency signal after filtering enters the medium frequency processing chip, and the second vibration signal is mixed again to generate second intermediate frequency signals. The second intermediate frequency signal is amplified and frequency discriminating after filtering the fuelessness signal through a ceramic filter, and the audio signal is produced. Audio signals are amplified, band-pass filters, and aggravated circuits, into the volume control circuit and power amplifier to enlarge, drive the loudspeaker, and get the information that people need.
3. Modulation signals and modulation circuits:
Human voice is converted into audio signal by microphone.
4. Signaling processing:
The CTCSS/CDCSS signal generated by CPU is amplified and adjusted to enter the voltage controlled oscillator for modulation. After receiving the frequency discriminator, a part of the band-pass filter, which is amplified and subaudio, is filtered and shaped into CPU, which is compared with the presupposition value to control the output of the audio power amplifier and the loudspeaker. If it is the same as the preset value, turn on the loudspeaker and switch off the loudspeaker if it is different.
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