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Does JVC's GY-HD100u offers a component HD output ?


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#1 etiennecaron

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Posted 15 March 2006 - 10:10 PM

I'm not familiar with new HDV camera and the HD world... but i'm little bit comfuse to understand if the JVC's GY-HD100u really got HD output. When i'm reading spec. of this camera, it doesnt mention any HD/SD-SDI output (as mention with the Canon XL-H1 perhaps). But when i'm reading on the Wafian web site (http://www.cineform....#HD100U_Support), its says that the JVC is HD ouput... i'm more confuse...

Whats going on ?

thanks again
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#2 Mitch Gross

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Posted 15 March 2006 - 11:52 PM

It has a 3-wire component DH out, just like the Sony F900. The Canon has an HD-SDI out, just like the Panasonic Varicam. You can get a box to switch one output form to the other. There are those who would argue the quality of one output form v. the other, but certainly the single port HD-SDI is easier to use in the field.
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#3 Phil Rhodes

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Posted 16 March 2006 - 07:38 AM

Hi,

Yes, but it's on RCAs. RCAs are not impedance matched connectors, and the insertion loss is awful. This manifests itself as streaking and ringing on an HD monitor.

Phil
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#4 Hal Smith

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Posted 16 March 2006 - 08:08 AM

Hi,

Yes, but it's on RCAs. RCAs are not impedance matched connectors, and the insertion loss is awful. This manifests itself as streaking and ringing on an HD monitor.

Phil


At the risk of starting a "flame" thread - where did you hear that? An RCA is less than an inch long. A pretty good estimate of whether or not an impedance "bump" will create a problem is that anything less than 1/20 wavelength long doesn't create any problems. An RCA plug is 1/20th wavelength at 590 MHZ. The component video channels coming off an HD camera wouldn't have any frequency components anywhere near that high. If you use RCA's wired with 75 ohm cable I would never expect the slightest problem. However, that does not include using RCA plugs wired with audio cable. Now you've got all sorts of potential problems including mismatched cable (not close to 75 ohms) and possibly imperfectly shielded spiral, not braided, shielding, both of which can create impedance discontinuities much, much longer than one inch. Now you do have the potential for significant video standing waves in your system with all the ringing and streaking that goes along with that.

The first thing I'd check with standing wave problems is the termination at the end of the video line. There aren't that many video engineers left who really understand why you must terminate a video line once with an external 75 ohm terminator if the equipment itself doesn't terminate the line. That is automatically the situation with loop throughs - a line looping through multiple pieces of equpment terminates once at the far end of the line. Prosumer gear often is internally terminated, if you use tee connectors to loop through gear with internal terminators you load the line down too much - two pieces of gear internally terminated at 75 ohms tee'd together will load the line down to 37.5 ohms. Now you've got standing wave problems plus video that's getting excessively loaded down and no longer at standard voltage levels. If you have to drive multiple terminated inputs with one video line, use a video DA, that's one of the things they're for.

Edmond, OK
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#5 etiennecaron

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Posted 16 March 2006 - 09:29 AM

Thanks for your respond Hal,

But, if Analog Component can carry HD with the JVC and Canon is HD/SD-SDI... witch one can i use very long cables to plug into my HD recorder.

In a sens... witch one will lose quality of the signal if i put my camera in a 100 feets crane ? What is the limit of Analog component trought RCA cable?


thanks again guys...

etienne
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#6 Phil Rhodes

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Posted 16 March 2006 - 05:43 PM

Hi,

The more robust signal is the HD-SDI, certainly - at least, it'll more plainly tell you if you have a problem, because the failure mode is much more objectionable.

Yes, I terminated the HD100 lines. The BNC cables had BNC-RCA adaptors on the end, which means that the entire mismatched assembly is probably near to two inches long and has four interface surfaces in it, any of which could contribute to the very obvious problem. Of course it's possible that JVC's back end electronics are a bit off whack...

It's not apalling - most home users will be very happy with it because it will interface to many more home-user type pieces of equipment than HD-SDI will. I just mourn the lack of an HD-SDI output on this otherwise rather nice little camera.

By the way, have you actually compared connectors on an insertion loss analyser? Even the difference between cheap and expensive BNCs is very easily discerned.

Phil
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