Technical Paper: Analysis of Current Status of Audio Monitoring Applications

Video surveillance is an important part of the security system. It is a comprehensive system with strong prevention capabilities. It is intuitive, accurate, timely, and informative. Most of the traditional monitoring systems do not have sound. People can only see silent images. Audio monitoring has not been well promoted. Audio monitoring, as a branch of the security industry in recent years, has been rapidly developing, and its application points have been expanding in recent years.

At present, there are many fields for audio monitoring applications:

Procuratorate, Prison, Public Security and other units

In some special venues and occasions, the state requires video to have audio synchronization. For example, the Procuratorate interrogates simultaneous audio and video recording systems, the Public Security Bureau's pre-approval system, and the detention center's prison supervision system. Tiananmen Square, the Supreme Court, the National Bureau of Letters and Visits and other important state agencies, as well as public transportation hubs such as the Beijing Subway and the Capital Airport, also have audio surveillance.

It is worth mentioning that audio monitoring in prisons, in addition to the forensic function, can also play a pre-warning role, such as the discovery of "Prison fight." Most people's speaking voice intensity is within 50 decibels, and the distance traveled is about 30 meters. When the volume is higher than a certain decibel, it can play an alarm function, which will play a role in avoiding causing more damage.

In addition, audio monitoring has applications in highways, schools, and banks.

Civil Domain - Home Applications

In the face of fiercely competitive market conditions, many different companies in the field of security have developed their own territories in the civilian market. The family also has a lot of applications, such as a thief in the house, he wants to see what he is doing, and sometimes he can't hear the sound, just watching the picture is like a pantomime. The requirements of customers are also getting higher and higher. The reason is that people's awareness of safety precautions is stronger than before. On the one hand, people have more experience with products and have higher requirements on their application. In addition, the price of the pickups is not expensive. In general, for a few tens of bucks, for better one hundred bucks, more than one hundred household applications are already very effective. The average family can afford it.

For audio and video integration monitoring, the industry figures this analogy: the camera is the "eye" and the pickup is the "ear." The images seen by the eyes and the sounds heard by the ears are transmitted through the nervous system such as cables, optical fibers, networks, etc., to the hard disk recorders as brains to form a basic video recording system. What obstacles does this flexible ear encounter in the application process and how does it respond?
 

Audio monitoring noise processing is difficult

Different areas of the environment bring different problems, audio monitoring equipment requirements are also different. Pickup noise reduction needs to solve two problems: one is to reduce the interference from ambient noise, and the other is the noise from the circuit itself. The noise of the circuit itself is relatively easy to solve, and the environmental noise problem is more complicated and difficult to solve. For example, in the outdoors, wind noise and road noise are the main sources of influence, while in the room, although the relative area is small, the echo is also a problem. For areas with large areas, such as for *, entry and exit, law and order, letters and visits, vehicle management offices. The public security supervision system in the lobby is open and noisy. It requires a high sensitivity of the pickups, a wide range of sound, and strong anti-noise performance.

To reduce interference, first understand what kind of noise is, and the noise that affects the pickup usually includes: ambient noise, interference noise, noise of the pickup itself, current noise, pickup whistles, problems with the VCR and the capture card itself.

How to solve the noise problem

Ambient noise is unavoidable, but you can choose a better noise reduction microphone with noise reduction. There are many kinds of interference noise, such as AC interference, etc. This can be solved by universally connecting the shielded cable, but it can not be completely ruled out, and anti-jamming cable can also be used; there are also many problems with the VCR, mainly because some manufacturers do not pay attention to audio quality, resulting in late The sound quality is very poor, so is the acquisition card. This time, you need to design a microphone for a specific network camera, the recording effect will be better; but also pay attention to the user to check whether the speaker is too close to the pickup, speaker's Feedback to the pickup will result in howling and try not to test in the same room.

summary:

For the development of audio monitoring, monitoring video and audio synchronization is the development trend in the field of security. At present, the audio and video synchronization monitoring mode has become an industry consensus. In general, audio monitoring is an important part of the security industry. At present, the audio monitoring market is constantly improving and expanding. In the face of good opportunities, audio monitoring companies are actively welcoming the tide of the market, and in the face of some issues, the technology needs to continue Promote.