longest firewire

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mino

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Just got DV rack trial. I don't have a laptop so to play with it I would have to use firewire on my PC. Anyone know what the longest firewire cable you can get is? and how much?
 
Re: longest firewire

Firewire cables are limited (by IEEE1394 specification) to 14.5 feet. Any longer than that is out-of-spec and shouldn't work.

Now, with that said, I have a Laird 30' cable, and it works fine, and I've heard good reports about the Laird 75'. But I would be very cautious about using any inexpensive long cable... the cables have to be specially designed somehow to work longer than 14.5 feet.
 
Re: longest firewire

[quote author=Barry_Green link=board=Events;num=1100205605;start=0#4 date=11/11/04 at 19:40:53]Firewire cables are limited (by IEEE1394 specification) to 14.5 feet.  Any longer than that is out-of-spec and shouldn't work.[/quote]


Hmm....I just ordered a 15 foot cable from them, 4pin/4pin, to connect my DVStorm to my JVC mini/vhs recorder. I also planned to use it for connection of lap top (DvRack) to DVX in the field. Their site claims it will work, or send it back. Guess I can't argue with that. ;D If successful, I'll get a second one.

After reading Barry's comment on the limit of 14.5 foot, I guess I could always get a 10 footer to be safe. I'll let you know....
 
Re: longest firewire

The standard Firewire cable length has been defined (proposed) at 14.5 feet (4.5m) for 400 Mhz signalling isosynchronious data tranfert ratew. This was about what was needed and accepted for local highspeed interconnection (cfr SCSI). Two things happened: DV entered the Firewire world in an S100 (100Mhz) mode which allows longer standard cables, and secondly, better cables were developed allowing even an S400 mode on 30'+ cables if the environment is not too harsh.
 
Re: longest firewire

Although standard DV cables are "at ease" with S100, there are situations where electromagnetic fields and even more, groundloops can - just like in audio -interfere with the datastream resulting in corrupted packets, finally resulting in resynchronizing which means frame losses. So, if closeby dimmers are used, or the equipmemt at both ends of the firewire cable needs to be grounded (not the best idea) there is a risk for that kind if problems. It's not a hum problem like in audio, but the high freq components (transients) which cause these problems.
 
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