Cctv audio mic should have good results, in addition to the high-cost performance and excellent circuit design of the cctv microphone itself, as well as the audio processing at the back end of the capture card and the audio processing of the computer motherboard; the embedded host has its own independent audio processing circuit.
The audio processing of the mainstream Hikvision, Dahua and other acquisition cards and the the embedded host is not bad. To monitor the power supply of the audio monitoring, try to use a linear power supply, such as a silicon steel transformer and a notebook switching power supply specification, because some cctv microphones can't be used with cameras switching power supply. There are no strict requirements on the cable for the cctv audio microphones, the telephone line, network cable, shielded cable and multi-core sheathed control line can be used. When wiring, try to avoid strong electromagnetic interference such as AC strong electricity.
1. At present, the monitoring project is more and more important for the recording of audio. It not only requires recording images, but also records the sound of the scene, and synchronizes video recording during playback of images and sounds to more comprehensively restore the scene. In a legal monitoring place, Party A’s call for simultaneous video and audio recording is getting higher and higher;
2. A place for purely on-site sound collection, typically using a window intercom microphone;
3. The less rigorous place for live sound recording can be recorded on-site using the voice recording function of the telephone recording card or USB recording box, and the audio cable of the audio monitor can be replaced by telephone. (Telephone recording is usually done by off-hook voltage control)
1. The performance parameters of the monitoring microphone are varied. Some parameters are exaggerated, some parameters are useless, some parameters are wrong. It is no problem that the parameters are only referenced data for the performance of the cctv microphone. In fact, what we really care about is the playback effect of the sound. The effect is to achieve the situation that the normal person hears.
2. Most of the surveillance audio monitor is active cctv mic, which needs to be powered extra. Generally, they are all used widely voltage, and 10-18V is basically no problem. The cctv microphone generally has a front audio amplifier circuit, which can directly drive the earphone, and also has an AGC automatic gain circuit.
In order to enlarge the collected sound, the area of the sound is proportional to it, but in the range of 100 square meters, the clarity of the periphery and the voice is inversely proportional.
3. The distance of the audio transmission of the voice pickup can generally reach 1000 meters. This parameter can be coped with the general situation, and the choice of the cable for the voice pickup is also very random. The telephone line, the sheathed multi-core cable, the network twisted pair, small size coaxial cable, shield lines, etc., can be transmitted as audio.
4. The range of sound that can be heard by the human ear, that is, the frequency that can stimulate the operation of the audio monitor is 50 Hz - 10 KHz.
5. For the audio monitoring sensitivity is marked as -40dB, it is triggered by a special transmission frequency in an approximate vacuum environment. This is a useless parameter, and the microphone can sense it enough.
6. The output impedance of the sound pickup is generally marked as 600 to 1000 ohms unbalanced;
7. The microphones used to monitor the voice pickup are directional and omnidirectional and are generally omnidirectional.
8. The output signal amplitude of the monitoring pickup is generally marked as 2.5Vpp/-25db.
9. The operating current of the monitoring pickup is generally within 30 mA.
In fact, the most important thing to cctv microphone is the design of the noise reduction circuit. The audio monitor of poor quality will have a large current noise after the amplified sound is amplified.
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