Is closed circuit HDTV a possibility?

March 12, 2007 11:01 AM

Is closed circuit HDTV a possibility?

My company has had video upgrades in discussion for a little over a year now and we still haven't found a solution that we are satisfied with. We initially were going towards an all digital camera network run through GigaBitE and Cat6 cable. After looking over some configuration, I have not been all that impressed with the quality or the ease of use.

I have brought up that it is getting to the point that if we are looking at anything new that it should be HD compatible.

From my home use experience I can get HDTV signals through a simple RG59 coax cable that runs from my HDTV (w/ tuner) to my antenna on my roof. I've been very pleased with the quality that comes out of this and am now wondering if implementing something similar for our work camera network is feasible.

My question is, are there any close circuit HDTV setups available on the market today? My vision is to be able to plug in each of our cameras into a encoder/modulator/broadcaster device that is able to set each camera on a digital channel in the VHS band and available to an HDTV tuner on this coax network.

This seems to have 3 big benefits that I can see right now:
1. Our existing camera hardware, even though not HD currently, can be used on this network. Over time we can upgrade cameras to produce true HD video to broadcast on this network.
2. Ease of use for the employees. Everyone knows how to flip through channels on their television and the end result would be a similar interface.
3. I'm assuming that the coax HDTV network can be daisy chained so that the cable goes to each encoder/modulator/broadcast box and out the other end. With the Cat6 network that we were looking at each camera had to have an individual wire going to a centralized gigabit switch. This would mean a lot of wires.

The only downside that I can see to setting things up this way is that the signals will be a one-way thing. W/ the Cat6 network we had the option of pan/tilt/zoom cameras that could be controlled from a monitoring station. This may not be possible with close circuit television.

Thoughts and ideas are really needed badly here. I would also like any links to equipment that has implemented what I have in mind. We may even need a consulting group to bring in on the project so that it is done "right."

Bonus question: what would be a good DVR that has HD tuner capabilities and where video files that are recorded with the DVR are accessible over a computer network? The video files need to be computer accessible as well, as in no nasty DRM on top of the files or a horribly proprietary format. We produce our own video here.

Thanks for all your input!

posted by nickerbocker to technology (7 comments total)

I'm not an expert, but a quick Google for "closed circuit HD" turns up a pan/tilt/zoomable HD camera.
posted by designbot at 11:21 AM on March 12, 2007

designbot: the pan,tilt, zoom features are controlled via "VISCA protocol" via RS-232C or RS-422. Meaning, that extra wiring would have to be implemented to control the camera. The advantage of the Cat6 cameras is that one cable could be used to pull video data off of the camera as well as control the pan/tilt/zoom features.

Although there may be no end problem with going this route, the camera also does not feature a broadcaster. The only option would be to take the component cable (Analog Y/Pb/Pr) and run that into a broadcast box that I still haven't found or know if they exist yet.

Our current setup is a plethora of composite over BNC and RCA cables that come into a switch board and we then have to plug directly into our monitors/VCRs to record the video feed from that camera. This is undesirable as it creates execess setup time. Ultimately, I think that if the signals were broadcasted over the VHS band then the all the camera signals could run down one wire and appear on our DVRs/VCRs/televisions on channels much like broadcasted television is handled now.
posted by nickerbocker at 11:45 AM on March 12, 2007

VHS is not a band for transmission. Are you talking about grabbing all these various feeds and putting them into a "broadcast box" (your words, for I do not know enough broadcasting tech to even guess what it should be called), which then multiplexes them over a plain old RF line (maybe a digital RF line, but still) that goes to all your users? That sounds really neat, but also really expensive, and illegal if your cable ends are not properly terminated, as you would be broadcasting on licensed spectrum (albeit likely under the threshold of interference or even detection).
posted by Xoder at 1:05 PM on March 12, 2007

I'm sorry. I did not mean VHS I mean VHF which I assure you, is a band like UHF is a band of frequencies. As for cable termination, this is a non-issue as I am not broadcasting via an antenna but rather, a closed-circuit network (thus avoiding the involvement of the FCC). The closed-circuit network will be shielded, as all RG59/58 (aka coax) cable is.

As for the setup, Closed Circuit TV has been in existence for ever now. And although I don't think it operates on the VHF or UHF bands it works similarly. Each camera is assigned a channel and the viewer can flip through those channels like they do on a TV.

If I'm having to explain this stuff to you then you obliviously are not in a position to answer my question so I don't know why I'm waisting my time with this post other then to clarify that I meant VHF not VHS.
posted by nickerbocker at 2:57 PM on March 12, 2007

The HD going into your TV from the antenna on your roof works very, very differently to your analogue CCTV system. The signal over that RG59 coax into your HD set contains a small number of signals with a very complex modulation scheme, each of which contains a large digital datastream. Each of these datastreams contains several heavily compressed HD services multiplexed together. To produce these signals is non-trivial, and requires (very) expensive hardware - it's really nothing like separately modulating and combining analogue TV signals.

HD signals have a much higher bandwidth than SD (standard definition) TV signals, and for this (and other reasons) they are generally not moved around in the analogue domain; sending analogue HD signals down your Cat5 cabling (even if you could get the boxes together to do so) wouldn't work very well. Likewise uncompressed HD has a very, very high data rate (1.5GB/s) and UTP network cable won't be good enough to get it very far - not to mention that cameras with uncompressed digital outputs (usually using a protocol called HD-SDI) are expensive items. So you really do have to compress, multiplex and modulate to get it over a coax. And then you'd need HD tuner/decoders for each set. Plus HD sets. It'd be expensive.

HD to IP adapters are available, but they're also expensive devices, aimed at the broadcasting and videoconferencing markets. Stuff like this doesn't come cheap. The market leaders in security video-over-ip are (afaik) axis, and they don't offer any HD products (yet) which probably means there isn't much demand for them (yet.)

To put all this in context I work for a (large, broadcasting) company that runs an internal TV network. Currently this is done with traditional UHF modulation and combining of composite analogue video. A few years ago they investigated moving to a DVB (not even HD) setup and decided that it cost way, way more than any conceivable benefits would justify (£100s/viewer/year vs pennies for the analogue system.) Although HD would offer more benefits, the expense goes up by an order of magnitude - not least because the coax distribution would need to be upgraded to a higher bandwidth.

If I was you, I wouldn't look into distributing live HD; go for a cheapskate analogue SD distribution, and store HD video on a video server attached to each camera that you can review later if there's an incident; as you suggested, you could network them and download relevant material when needed.
posted by Luddite at 5:51 PM on March 12, 2007

Sorry, I just realised that I thought you were after a security CCTV system but after reading your question, I'm not so sure. If you're actually willing to throw kilobucks at it I can probably point you to various suppliers.
posted by Luddite at 5:55 PM on March 12, 2007

If you don't mind dedicating a PC to the project you could look into Machine Vision cameras. They make firewire and gigabit ethernet models which go up to 4 Megapixel. With the right software you can record to hard disk in any format you like. The downside is the cameras cost over $2k each, and you'll probably need a better lens than you would normally use for cctv cameras.

Otherwise, the Sony BRCH700 is the only "packaged" HD CCTV camera I know of, but it's like $9k.
posted by Popular Ethics at 9:58 PM on March 12, 2007