Now the monitoring installations are all network cameras by default, so most of our technical articles are aimed at network cameras. Of course, some friends will ask analog cameras in the background, especially about AHD, TVI and CVI cameras. Several friends have asked .
Although it is not used much, it is still a separate article to discuss with you.
AHD, TVI and CVI are analog high-definition surveillance cameras.
AHD analog high-definition camera is a kind of analog camera. It operates like a traditional analog device and transmits with a common video cable SYV-75-3 or 75-5 coaxial cable, but it can achieve low cost, long distance, anti-interference, Mega-pixel HD video transmission without delay.
HDTVI high-definition video transmission interface camera, it is a high-definition video transmission specification based on coaxial cable.
HDCVI high-definition composite video high-definition video camera is a high-definition video transmission specification based on coaxial cable, which uses analog modulation technology to transmit progressively scanned high-definition video. HDCVI technology adopts self-adapted technology with independent intellectual property rights to ensure that high-quality HD video of at least 500 meters is transmitted on coaxial cables of 75-3 and above specifications, breaking the transmission limit of existing HD video transmission technology.
In use, CVI, TVI, AHD all follow the analog SD transmission channels and methods, which can reduce the complexity of construction deployment, reduce the cost of auxiliary materials and maintenance complexity, as well as the technical requirements for construction personnel; applicable to the upgrade of the old system The transformation can easily upgrade SD to HD without changing the original system.
CVI, TVI, AHD realize high-definition transmission on coaxial cable, and the transmission distance increases significantly; all have the effect of higher definition and no bright color crosstalk than ordinary analog; farther than SDI transmission, strong anti-interference ability; Compared with network HD, it has the characteristics of no delay, lossless image and convenient operation.
Because there is a customer who changed the simulation to high-definition, the video cable is long and there is a section sealed in the wall, and rewiring is difficult, so consider using coaxial high-definition. Prepare to choose one of CVI, TVI and AHD. Because AHD is relatively new and is not as well-known as CVI (not easy to price), so first test AHD. Sending is AHD's 8-channel DVR (supports AHD-M, 960P), and supporting 960P camera. Test immediately after delivery. The 960P image effect is very bright and sharp, and it does have a 130w pixel effect, which is basically equivalent to a webcam. After the 200-meter video cable test, the image was not significantly degraded by naked eyes. The effect is still good. But the backend also has the following problems.
1. First of all, DVR is divided into 4 modes: digital mode (support 8-channel 1080P, 960P AHD-M), analog mode (support 8-channel 720P AHD-L, D1, etc.), 4-channel network 1080P mode, 1-channel network 1080P+ 8-channel 720P mode. If the analog camera cannot be connected in the high-definition 960P mode, the 960P with a good image cannot be connected after the analog camera is connected. Therefore, my 960P HD can only run independently and cannot coexist with analog cameras. I asked the dealer if he could make a model like 4-way 960P+4-way D1. He said no.
2. AHD-M models seem to support up to 8 channels now. Some other programs are 16-32. Most of my customers now use 16-channel (or above) DVRs, so it is not yet fully replaceable.
In fact, AHD's DVR still has many advantages, such as analog, coaxial, and network universal. It is compatible with analog and quasi-high-definition coexistence to a certain extent. In addition, with the open plan, there are indeed certain prospects. However, as mentioned above, there are still many practical application problems, so currently we can only wait and wait and see.