AHD, TVI or CVI Analogue Hi Definition
This is the latest advance in CCTV technology. It is the modern replacement for composite video (analogue).
This new technology addresses some of the issues which can occur with HD-SDI CCTV systems, for example, maximum camera cable run without using signal repeaters and also can be used with RG59 coax, CAT5 cable or ready made cable kits.
This gives the end-user flexibility on what cable to use on installation and can make the upgrade of an existing CCTV system more flexible.
With regard to image quality, i.e. resolution, at present Hi Definition, analogue, CCTV comes in two resolutions: 720p (1280 x 720 pixels) and 1080P (1920 x 1080 pixels).
Therefore, 1080p is roughly twice the resolution of 720p, but also about twice the price.
In the near future we will be introducing a range of 4.0MP Hi Definition CCTV cameras and DVRs.
There are several manufacturers that have produced Hi Definition analogue CCTV formats. They are:
1) AHD (analogue Hi Definition) Next Chip South Korea
2) CVI (Hi Definition composite video interface) Dahua China
3) TVI (Hi Definition transport video interface) Techpoint USA
It is important to note that the equipment made by these manufacturers is not interchangeable. Hence, you cannot use an AHD camera, with a CVI or TVI DVR, for example or vice versa. (Our DVR's will take TVI & AHD cameras)
It is hard to know which, if any, format will dominate the market. As a wholesaler this is a very important for me but also for the end-user.
Each manufacturer will be producing 720p and 1080p Hi Definition analogue CCTV so there is no difference there. In terms of cost TVI, AHD and CVI are very similar.
In addtion, all these formats relate to the transmission of the video signal, not the image processor in the CCTV camera. These will continue to be dominated by Sony, Panasonic, Next Chip and Sharp etc.
AHD is made by next chip and they do not produce any finished CCTV products they just supply the chips and software to manufacturers of AHD CCTV cameras & DVRs, this is the same for TVI. These companies need vast volumes and so they will be no limit on supply.
CVI is from Dahua who are a very large manufacturer of CCTV cameras and DVRs, at present other manufacturers of CCTV are using DAHUA chips and software under license which could lead to conflicts of interest in the future.
So is there much difference in image quality.
Of the three formats, we thought AHD was not quite as good as CVI or TVI during the day, but the difference was very slight and probably not noticeable to most customers. We thought the AHD and TVI night time images when the camera had switched to black and white and with the IR on was noticeably better than CVI.
There are many more manufacturers of AHD & TVI DVRs then CVI and there is more choice in AHD and TVI DVRs than CVI. The software features of each model vary slightly in their interfaces, but there is very little difference in the common features, i.e. networking, mobile apps, motion detection etc. The AHD and TVI formats allow each manufacturer the ability to add more flexibility and performance to the DVRs function, where in the CVI case they control these features.
The big advantage that AHD and TVI both have over CVI is that AHD & TVI cameras and DVRs can be set to composite video (analogue) This means that the new AHD and TVI DVRs can be used with older composite video CCTV cameras and new AHD and TVI CCTV cameras can be used with old composite video D1 and 960H DVRs when set to analogue.
So which format to buy.
Most manufacturers supply both Hi Definition analogue CCTV cameras and CCTV DVRs that support several formats. Our lastest DVRs automatically detect which format of CCTV camera has been connected whether it is TVI, AHD or old composite video. We sell a range of CCTV cameras that the output format can be selected by a simple switch on the camera to give all formats, i.e. TVI, AHD, CVI and composite video. Therefore, you can try most combinations of format to see which you think is best.
1) Cost: AHD & TVI CCTV cost is very little more than the old composite video (CBVS) but is about 2 times the resolution in 720p and 4 times the resolution in 1080p
2) Wiring: Can be wired in RG59 coax, CAT5 cable,CAT6 cable or ready made cable kits.
3) Long cables: Runs upto 350m without boosters.
4) Backwards compatible with older analogue (CBVS) CCTV equipment.
5) Very easy to install