F5: BNC Cable ..Analog /digital

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Donny 123

Veteran
Apparently Ive been using analog BNC cables to my camera monitors.. Pana 9" and TV logic 5".. didn't even know there was a difference ..?
On camera monitor is ofcourse very short cable 50cm.. and 9" is about 4m I guess ..

Should I change to HDSDI digital BNC,s.. ? .. whats the difference

Thanks
 
Well I think its different here. In that it works or doesnt, but wont stop working later?

There do seem to be some resistance (ohms) variants.. https://en.wikipedia.org/wiki/BNC_connector#Compatibility

My steadicam had SD down the post (super skinny little lead) and didnt work after I re rigged it with HD monitor/SDI camera and I had to replace the cable - but it didnt work from the outset!

I guess you could have problems with long cable runs etc.

S
 
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Very short cables it makes no difference. The digital coax will maintain higher frequency response over longer lengths. A digital pulse is ideally an infinite bandwidth square wave. As cable frequency response drops off with length the corners of the pulse get rounded off until the receiving circuit can no longer detect the leading edge of the pulse.
 
The cables themselves aren't really "digital" or "analog" They're just higher and lower quality, and that includes shielding, which protects the wires from external interference. The longer the cable run the more important to use a high quality cable. As we move from single link HD-SDI to 3G SDI, we double the data rate on the sable. To 6G, doubled again. To 12G doubled again. And this means shorter and shorter pulses of interference will cause the receiver to receive erroneous reads.
 
It's not like a car leaking oil in that there is no continuing deterioration in performance over time. It won't work one day and suddenly fail the next (unless you damage something, of course). Remember that the whole motivation for designing SDI to use 75 ohm coax and BNC connectors in the first place was so TV stations and post houses could keep most of their existing infrastructure of expensive cabling in place that was originally built for analog video. (The cost of pulling and laying the wires in trays and under floors far exceeds the actual value of the cable in many cases.) As SDI bit rates have increased, the maximum reliable length of a run of old cable has decreased -- but for lengths of a few feet, it shouldn't be a problem.

- Greg
 
Not really - running a high wattage lamp on a thin cable would start fine and have problems down the road - it was a reasonable question
 
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