How to Solve the "Current Sound" of the CCTV Microphone

  • source: sizheng;
  • Time: 2018-12-25

Many times, after the normal connection of the CCTV microphone, some "current sound" will appear, which seriously affect the quality of sound. So what is the"current sound"?

Generally, it divided two categories of the noise that we experience when collecting sound: one is the environmental noise that is infested from the microphone, another is the noise generated by the device. Many users have known the noise generated by the device as "current sound" for some reasons. The cause of "current sound" is relatively complicated, and it has different performances. However, sometimes it's difficult to solve the problem by using "current sound". Once asked about the "current sound", many users often use the different description for the same sound, such as describe the broken sound into noise or harsh noise.


Some users mentioned that use of the post-processing methods to remove the "current sound", in fact, the "current sound" is hard to deal with by software. Even if it is disposed of, the human voice may not know what it is. So Sizheng technology teaches you how to solve the "current sound" of the cctv mic



1. AC noise(hum)

Usually due to the device, line filtering and poor shielding, the shielding of metal casing is better than the plastic casing.
Solution: Ground the device case through the wire, change the better shielding cable, or use the equalizer to cut off the audio below 60Hz.



2. Zizi sound

Solution: Usually shield twisted pair cable should be used due to the poor audio cable shielding .



3. Magnetic hum

Usually caused by electromagnetic leakage near the amplifier, such as power adapters, power transformers, city electric lines, etc.
Solution:  Keep the amplifier away


4. Sisi sound

This problem is difficult for non-technicians to solve due to the quality and performance of the equipment components, circuit design, wire of circuit board and grounding points.
Solution: You can get some improvement by using software to reduce the noise or sisi sound, or use high-end cctv mic.



5. Line induction

Solution: Due to the poor line shielding and the mixed sound of more than one of the above noises, we should choose a well-shielded shielded cable.



6. Cell phone interference

Someone is using a cell phone call nearby during recording, the most serious interference is when the phone dials and starts ringing.
Solution: Don't place the cell phone near the recording device when recording.


7. Monitor interference

This is due to the radiated noise generated by the line circuit and the field circuit when the monitor is working.

Solution: Keep the receiver or microphone away from the monitor.

solution-of-current-sound-in-cctv-microphone



8. Monitor line frequency crosstalk

This kind of interference is different from No.7. It is that the horizontal frequency signal of the display passes directly through the display cable to the graphics card, and then to the main board and then into the sound card. It can't be solved by moving the microphone away from the display. This kind of problem is easy to appear on some sound cards with poor anti-interference ability. According to the investigation of the onboard sound card, this problem is not easy to occur.
Solution: Only temporarily turn off the monitor during the recording process.

 

9. Host interface

Such interference includes electromagnetic radiated noise by the power supply of host, the main board, the CPU, the expansion slot hardware.
Solution: Change hardware such as power supply or motherboard. The investigation also found that the sound card that comes with the motherboard is not prone to such problems, because the motherboard and the sound card are designed together,  the designer considers the mutual interference problem.


10. Broken sound

The broken sound is not a noise, but some users misunderstanding is noise, so it's necessary to list it again, Generally, the recording amplification gain is too high, and the sound source is too close.

 

Solution:

1. CCTV microphone can't use the video cable to transmit the audio signal,  because the impedance doesn't match, it will produce noise. If you are short-distance transmission, it can use a network cable or telephone cable to transmit signal; if it is long distance transmission, it is necessary to use a shielding audio cable, the thickness of the line is greater than 0.5. In theory, the thicker the line, the better, but the project cost should be considered.

 

2. There is still a lot of people who don't pay attention to it. It is the power supply of CCTV microphone, it is necessary to use a 12V transformer or professional CCTV microphone power supply, which can reduce the interference of the AC signal. With the ordinary 12V switching power supply, the poor filter function and there will be a large current noise. The connector is preferably soldered with a shielded wire, which reduces the "current sound". If engineering budget allows for a separate power supply using the CCTV microphone specific power supply, the common power adapter has no filtering function, and the professional power supply of CCTV microphone has a good filter function to minimize the "current sound".


 
3. Select a big brand of CCTV microphones. Why choose the big brand, because it's very confusing in CCTV microphone market now, many small companies are squandering the product with the term "digital pickup". In fact, the effect is very poor. Try to choose a big brand of audio monitoring.

 

 

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