You may have noticed over the past year or so the introduction of high definition CCTV that runs over coax cable – this type of CCTV was basically created for the millions of people who have an analogue CCTV setup but want to upgrade to better HD images.
The First was called HD-SDI, it’s been available for about two years now, at first was incredibly costly but as with most products – the increase in manufacturing has seen a dramatic drop in price. It is now proving a very popular 1080P CCTV Format – especially with people who are upgrading from an old analogue system.
The only downside is unlike analogue video signal, which can run about 200 metre’s, the HD digital signal can only run about 75 – 100 metres before it will need repeaters to increase the distance. Up to 5 repeaters can be used in one line to increase the video signal distance.
And then there were Two.
Introducing HD-CVI – it has been available for less than a year and is most commonly available in 720P resolution. It is much cheaper than HD-SDI (although half the resolution), in fact it is at the same price level as analogue CCTV even though it is twice the resolution.
Another positive is the fact HD-CVI video signal can transmit up to 500 metres on a single coax cable and does not require any repeaters – but be aware like any analogue signal this may deteriorate over distance and effect the video image quality.
The more the merrier?
Now we have suddenly seen the introduction of another two formats in as many months – AHD and HD-TVI. Both of these work in the same way as HD-CVI and offer same benefits.
The problem is, none of these formats are inter-compatible, meaning you cannot use a HD-SDI camera with a HD-CVI recorder and vice-versa. So make sure when you are purchasing a HD over Coax system that you buy everything in the same format.
And who will win?
Well the only winner will of course be IP CCTV! Which has higher resolutions than all the above, and will continue to become more competitive over time.
However, thanks to currently offering better value for money there is a place for all HD over Coax formats, while HD-SDI has been around the longest, the other formats have been invented by some of the largest manufacturers in the world. It would be nice if the manufacturers could find a way for each format to work together, this could uniform HD over coax and offer customers far more choice which in turn would give IP CCTV a real competitor – but that’s unlikely.