Is there something special with the Z1 Firewire ? at DVinfo.net

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Sony HVR-Z1 / HDR-FX1
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Old August 13th, 2007, 05:28 AM   #1
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Is there something special with the Z1 Firewire ?

... or is it somehow to "weak" ?

Hello :)

I've just got a 10 meter firewire cable to connect my Z1 to Adobe OnLocation. A very high quality cable. But it won't work. Other devices like a Sony TRV900 or my DV cassette deck work fine with the same cable. With a 1 meter cable the Z1 works too. So what's different with the Z1 firewire output ?

Tanks for any help or idea!

Peter
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Old August 13th, 2007, 09:13 AM   #2
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I have used in the past the Z1 with a cable same lenght as yours, no problems at all. What are you filming, DV or HDV? I was doing DV at the time.

There should be nothing different with the output... IEEE 1394 is a standard, all devices should be the same.
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Old August 13th, 2007, 12:10 PM   #3
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Wow, 10 meters is pretty far for firewire. It may work, but I don't think it's up to the firewire specs:

http://www.firewiredirect.com/firewi...s/cables.shtml

Quote:
The maximum cable length for connecting device to device with a 400Mbps cable is 4.5-meters (14.85ft). The Firewire specification calls for 10 meter (32ft) cables that may be used in conjunction with a repeater when it is necessary to extend FireWire cables over long distances. FirewireDirect does not offer these cables at this time because tests have shown them to be unreliable in some situations.
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Old August 13th, 2007, 12:33 PM   #4
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I just double-checked my cable and it is 25 feet long, bought from B&H (see http://www.bhphotovideo.com/c/produc...to_6_pin.html).

They also sell the in-line amp (http://www.bhphotovideo.com/bnh/cont...arch&Q=*&bhs=t) - I bought two of them together with several cables but never got to test them (moved up to component).

What determines the length of any cable running digital signal is its capacitance - all those ones and zeros could run theoretically for ever, but the capacitance rounds off the straight edges of the digital "ups and downs" and makes the cable unsuable beyond a certain length. Even though a cable might be "high quality" as far as durability, ruggedness... what metters is the internal capacitance.
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Old August 13th, 2007, 02:27 PM   #5
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Thanks so far ...

I am aware of 10 meters beeing verly long for Firewire. But why would the TRV900 and DV-Deck work and the Z1 not. Z1 also works with a short cable. So maybe it hasn't enough "power" or something like that.

I guess I have to live with that.

But still interrested in further ideas.

Peter
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Old August 13th, 2007, 09:46 PM   #6
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Not likely to be a matter of power. One might surmise that the Z1 is sending less clean data so has less tolerance of degradation; but I'd be surprised and Ervin has successfully used the same length of cable. Given Boyd's data one would expect that a 10m cable to be marginal and actual performance depend on specifics of the gear connected.
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Old August 14th, 2007, 07:36 AM   #7
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Well, let’s just go back up top for a minute and define “quality”. I don’t know what cables are the German stores selling, but if I go in any electronics store here and ask for a “high quality” cable, I will invariable be shown a thick Monster Cable product, painted in shiny bright colors, with some nice looking color rings on the golden plated connectors. About half a year ago, I bought a pre-programmable DVD recorder with built-in tuner, S-Video and composite inputs, firewire and USB (for burning pictures into DVD slideshow directly in the unit), AND HDMI output, all for around $175. When I asked for an HDMI cable, the salesperson happily pointed toward a Monster Cable costing almost $200. I asked him (I know, it was impolite): are you insane? The quality of a cable to me (an electronics technician) is defined by its electrical characteristics and not its appearance!

So Peter, if you have access to an electronics lab over there in Munchen, take those two cables in for some measurements. I bet you will find that the one that’s working has a lot lower capacitance compared to the long one. Every cable has a “capacitance per foot” rating – the longer the cable, the higher the total capacitance. Typically a good cable has around 15 pF capacitance per foot, multiply that by the length of the cable to get the total capacitance. I have not researched the firewire protocol technical data, but it looks like 15x25 feet = 375 pF is within limits, whereas 15x33 feet (10 meters) = 495 pF is too high and starts rounding off the leading and trailing edges of the square digital pulse causing the recording device to fail to recognize the data.

If you have to work with firewire over the given length, then you will have to buy a repeater!

Re: your question ("why would the TRV900 and DV-Deck work and the Z1 not"), I would speculate that the internal capacitance of the Z1 is higher than that of the other units you mention. The resulting capacitance (Z1 + cable), that's what the receiving unit will "see", and find acceptable or not.
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Old August 14th, 2007, 08:47 AM   #8
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Ervin,

As an electronics technician myself, I can tell you that there are two things working against the long cable runs. The capacitance per foot along with the resistance of the cable itself, will set up an RC network that will attenuate certain frequencies. The other aspect is the resistance of the cable itself which will attenuate the voltage levels of the signals over the long haul. This is the what the repeater does. It boosts the voltage levels back to nominal values. Once the voltage dips, as you know, the logic can't detect a 1 from a 0.

The reason Peter may have gotten away with using the longer cable on older DV equipment might have to do with transfer rate. The older stuff barely cracks 100mbs on FW400. The newer stuff, like the Z1, often maintain a higher transfer rate. That higher rate (and thus higher frequencies passing through the cable) could be attenuated by the cable capacitance as you mentioned. To a degree, inherent noise can play a part also. That's where the use of oxygen free copper comes into play.

-gb-
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Old August 14th, 2007, 09:03 AM   #9
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Thank you for completing "the picture". In camcorders, firewire was originally envisioned as a means of transfer of digital data to editing devices. With certain limitations it can be used for signal transfer for example in live situations, but we have to live with it's limitations... this is why I navigated away from firewire and now use component in my church setup.
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