For the normal audio microphones in the market, audio CCTV microphone has three wires, which represent the power supply positive(red wire), audio positive(white wire), ground (black wire: power supply, audio negative). The normal audio monitoring power supply must use DC12V regulated power supply, and should not use switching power supply. General speaking, the CCTV microphone will be installed in the central of surveillance area, but it will also change according to detailed user's actual monitoring environment. For example, some bank counters use then to serve as the audio system of the window intercom, and teacher's podium needs multimedia system because of lecture, etc.
Because CCTV microphone only has three wires, a line must be separated from the common line with the audio positive before the backend device is connected.
1. Active speaker with built-in amplifier(Most of CCTV microphone are omnidirectional so there is no distinction between left and right channels)
2. Amplifiers, mixers, etc
4. Walkman headphones
5. Audio frequency divider
6. Computer host
8. Sound card or another audio device
We must attend to this because audio surveillance microphone circuit principle is different with microphone(it including enlarge, noise reduction, echo progress and circuit), so forbid connect to MIC in interface about input&output over 1Vpp "Line Out"audio signal. All CCTV microphone must connect to Line in input interface.
It must be noted that the principle of the CCTV mic circuit is different from that of the microphone (it includes amplification, noise reduction, echo processing, etc.). Therefore outputs "Line Out audio signal above 1Vpp, so it is strictly forbidden to access the MIC access port. All audio monitoring must be connected to the Line In linear input.
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