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-   -   Long FireWire Cables (https://www.dvinfo.net/forum/open-dv-discussion/4615-long-firewire-cables.html)

Steven Digges October 27th, 2002 11:18 PM

Long FireWire Cables
 
Does anybody have experience using 70 foot or longer FireWire cables between an XL1 and the record deck? I have a need to do this but am very skeptical about the potential signal loss.

Videonics offers a 50-meter (164ft.) cable with a passive filter for $499.00 - What is the data rate (MBS) for this cable? What makes this cable worth 5 x more than others?

TecNec and others offer the same length cable for about $120.00 with no filter. I believe these cables will carry about 100 Mega Bites Per Second (FireWire standard is 400 MBS). Is 100 MBS enough for the camera signal to maintain its integrity all the way to the record source?

Any information will be appreciated.

Steve

Zac Stein October 28th, 2002 12:57 AM

100mbit will handle the 3.6mb the dv stream needs.

Signal loss is not an occurance in digital, it is cut outs. Either you will have full signal or nothing at all, as soon something looses packets of data, the entire large sum of data it belonds too is redundent.

50 metres should be fine for a network cable as long as you keep it away from strong magnetic fields, ie power plugs, and lay at right angles over power cords. Use nice insulated cable too, good cable should be around 0.20 c USD per a metre, so dont let people rip you off, and any good computer hardware store will custom cut and clamp the cable for u with the plugs on the end.

You will need a crossover cable if you are running a direct connection from 1 computer/adapter box directly to a computer, or aa switch with a built in crossover. Dont use a hub, switch is slightly more money and far better as it offers dedicated bandwidth to each port, not shared bandwidth.

Firewire cables are a different story, they should be at around 5-10 metres at most to run without packet loss and reliable. You will need a signal boost amplifier for anything beyond that.

kermie

Rob Lohman October 28th, 2002 03:29 AM

I thought firewire cables could run 100 metres... but my mind might
be playing tricks on me here, so best to assume Kermie is right
here. If you are going to record straight over your network make
sure you have quality network cards (like Intel or 3Com) instead
of no names (cause these tend to not go for the maximum band-
with which you WILL need for 3.6 mb/s DV stream). Also make
sure your harddisk is clean on the other end and that this machine
is not running any other applications at that moment. I've had
some very good results capturing over 100 mbit to a server. I'm
using Intel network cards and a good quality CAT5 cable.

Good luck.

Steven Digges October 28th, 2002 09:29 AM

camera cables
 
Thanks for the input. I am not cabling a network. I do a lot of event coverage work. I need to send the camera signals long distances to my Videonics MX-Pro Switcher. I am currently using 75 foot S-cables (yes there is some loss in image quality). I am trying to decide if it is worth it to upgrade the switcher and cables to DV. If I can be assured there will be no packet loss then the answer is yes. As you mentioned my understanding is that FireWire should be limited to 10 meter runs. Some catalogs that sell the 50 meter cables “claim” that as long as you are using them for the camera signal you will be OK to go the long distance. Maintaining DV quaility all of the way through the system would be a beatiful thing. I'm sceptical, 50 meters is a long way to send that signal, packet loss would be devastating.

Zac Stein October 28th, 2002 09:35 AM

all u can do is get one and do lots of test footage, if you get problems then return... if they won't let you test it then you shouldn't buy it, simple as that.

Sending a digital signal would be infinatly better than a s-video signal, that has a hard and fast 5 metre rule, after that you are getting loss after around 10 meters it becomes visable to the eye.

Just test and re-test, you could always at the very start run both systems for safety sake, i know it is a bit of borrowing extra equipment and stuffing around, but i am sure once you work out the bugs you will be happy.

kermie

Jeff Donald October 28th, 2002 10:19 AM

If you don't have an immediate need to do so the second generation of FireWire is due soon (probably January '03) and one of the specs is much longer cable runs. I think I recall reading lengths of up to 300 or 400 feet without amps. The speed will double also to counter USB 2.0. It is backward compatible. so, what does this mean for you? Either wait and get a good deal on old FireWire switcher etc. or get new switcher and longer runs. It's a win-win situation if you can wait.

Jeff


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