pc cctv
- Thread starter Spinal2k2
- Start date
SB118 said:heh, i tried explaining it back in post #28 but you did a better job of it than me
Meh, evidentally not:
Energize said:
Dude, forget the cable. It's NOTHING like an RF signal you were talking about earlier output from your VCR.
Can I ask, do you have any experience of this, at all? I'm talking about high-end BNC cameras etc. This is the superior connection you can get. I know obviously the OP isn't going to fork out £££ for a high end kit, but ultimately, it's the best. Please, I feel like I'm repeating myself as are you.
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Oblivious said:
Indeed.
Energize said:
OK - we're both fighting a lost battle. Leave it here.
edit - you didn't spot my edit to my post above so:
It's NOTHING like an RF signal you were talking about earlier output from your VCR.
Can I ask, do you have any experience of this, at all? I'm talking about high-end BNC cameras etc. This is the superior connection you can get. I know obviously the OP isn't going to fork out £££ for a high end kit, but ultimately, it's the best. Please, I feel like I'm repeating myself as are you.
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Energize said:
ARGH! NO IT ISN'T!
I can run a 5m coax and get a good picture. I could run a 105m coax and STILL have a good picture.
Please stop trolling, it's making my teeth hurt. I'm off to bed now, i've got to go and finish installing 16 cameras tomorrow (or tuesday, depending on how crappy the access is), and every damn one of them is BNC & coax!
[/migraine]
Wikipedia says
"A composite video signal is an analog video signal with color information modulated on a subcarrier. It is a standard for analog video signals."
Anlogue cant be compressed, there is not enough bandwidth in a normal cable for uncompressed analogue video. So either this is some sort of super cable that has enough bandwidth or its not an analogue signal.
"A composite video signal is an analog video signal with color information modulated on a subcarrier. It is a standard for analog video signals."
Anlogue cant be compressed, there is not enough bandwidth in a normal cable for uncompressed analogue video. So either this is some sort of super cable that has enough bandwidth or its not an analogue signal.
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Energize said:So they use a compressed digital signal then like I said ntl did then, you could have just said that
Not necessarily, and as mentioned co-ax cable can be very high quality for both analogue and digital signals
IIRC there are a number of analogue systems for sending video down a co-ax type cable, with the quality determined by the source and the to a lesser extent the cable.
The stuff used in TV setups tends to be pretty poor (and cheap), the stuff used in other setups can be much higher quality with the result that even if the source is the same the signal isn't affected as much by things like intereference.
NTL's old analogue system used the same cabling as is currently used in many of their digital areas, and the picture there was fine (carrying 20-30+ channels with stereo).
With home systems I beleive the reason for things like SCART, RGB and Componant is because it's much easier and cheaper to send the signal along multiple conductors than to modulate it and send it down the same conducter (as happens with broadcast TV etc).
Werewolf said:Not necessarily, and as mentioned co-ax cable can be very high quality for both analogue and digital signals
IIRC there are a number of analogue systems for sending video down a co-ax type cable, with the quality determined by the source and the to a lesser extent the cable.
The stuff used in TV setups tends to be pretty poor (and cheap), the stuff used in other setups can be much higher quality with the result that even if the source is the same the signal isn't affected as much by things like intereference.
NTL's old analogue system used the same cabling as is currently used in many of their digital areas, and the picture there was fine (carrying 20-30+ channels with stereo).
With home systems I beleive the reason for things like SCART, RGB and Componant is because it's much easier and cheaper to send the signal along multiple conductors than to modulate it and send it down the same conducter (as happens with broadcast TV etc).
Thank you Werewolf! Anyway, I'm off to bed. Energize has done well at giving us all headaches trying to explain the differences between RF and how BNC cctv cameras work and I still don't think the confusion has been liberated. Night.
Werewolf said:Not necessarily, and as mentioned co-ax cable can be very high quality for both analogue and digital signals
IIRC there are a number of analogue systems for sending video down a co-ax type cable, with the quality determined by the source and the to a lesser extent the cable.
The stuff used in TV setups tends to be pretty poor (and cheap), the stuff used in other setups can be much higher quality with the result that even if the source is the same the signal isn't affected as much by things like intereference.
NTL's old analogue system used the same cabling as is currently used in many of their digital areas, and the picture there was fine (carrying 20-30+ channels with stereo).
With home systems I beleive the reason for things like SCART, RGB and Componant is because it's much easier and cheaper to send the signal along multiple conductors than to modulate it and send it down the same conducter (as happens with broadcast TV etc).
As in high enough quality to give enough bandwidth to allow for uncompressed video without any information lost? That would clear everything up.
Energize said:
There is loads of bandwidth for an analogue signal on co-ax cable - look at how NTL for example used to do it (and still do in some areas and had upwards of 30 channels + the cable modem frequencies), or the typical TV set - it's getting 4-5+ analogue channels down a single cable, the problems come due to the degredation of the signal at the connections, and the low quality cables etc.
Energize said:
Yes.
You won't get as many channels, especailly with HD type signals but the cable is just the transport medium for the signal (like RF for wireless broadcasts etc), you can get a loads of bandwidth from co-ax cable if you use decent equipment and cables (the stuff NTL use for example is many times better than we normally use for home TV).
It's only a limit when you need a LOT of different channels the same as any of the transport mediums used.
It's the same reason they are so keen to shut down the analogue TV transmitters, or Sky were so keen to move over to Digial for the Satalites
Energize said:
I think with them it's because it's a clearer signal than you'd get by mixing the 3 channels, but that is probably as much down to the costs involved in doing it properly down a single conducter as anything else.
Much of the history of TV/Video formats is a serious of clever bodges to allow them to advance the quality/systems cheaply and easily with the technology of the time.
The whole PAL/NTSC thing for example is largely due to it being easier to get the timing right if you set it as close as possible to the mains frequencies, as is the way they bodged Nicam stereo to get it to work on VHS.