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PRO 2, Decimator (1 or 2), RED camera and Modulus video distortion


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#1 William Demeritt

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Posted 03 March 2011 - 09:59 PM

Alright, I've been dealing with an issue the last few months, and I thought I'd pose it here to see if anyone else can offer an idea.

Whenever I fly a RED One with my Decimator 2 (also occurs on Deci 1), my PRO 2 monitor sees the image just fine, but the video transmitted via Modulus 2000 looks distorted on the client monitor. Anytime I shoot with a camera that's SD output (35mm/16mm video tap, etc), the wireless video image looks good without any sign of this distortion.

I should have taken a photo of the "distortion", keep forgetting to, but simply describing it: roughly 1/5 of the way down from the top of the image, the image "bends" to the right in a sizable bar. Further, the overall image doesn't sit right or square on the monitor.

- I've encountered this issue after having my Modulus 2000 repaired by David Hable, trying a Decimator 2 and Deci 1, flying with multiple RED One camera bodies over the months. Even tried it with a Modulus 3000, same issue.
- Tried powering the RED off my sled (using the 12v ONLY block, so monitor and video accessories were powered off separate battery).
- Decimators were powered off d-tap on the camera's onboard battery, as well as powered off my sled on the camera port.
- Monitors that replicate this issue include: 3 different models of handheld NTSC monitors, various tabletop client monitors, etc.

RED One constitutes a significant number of my jobs, so I'd love to try and track down this issue and solve it once and for all.

Any thoughts?
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#2 Alec Jarnagin SOC

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Posted 03 March 2011 - 11:39 PM

Its a long shot, but what tuner are you using? In other words, you've tried multiple Decimators and Modus, but no mention of tuners. Does this happen on all monitors from various tuners?
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#3 Jess Haas SOC

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Posted 03 March 2011 - 11:55 PM

How do you have your video lines wired? Have you tried going directly form red to decimator to modulus leaving the sled and monitor out of the equation? Tried changing channels on the modulus? Sounds like distortion I have seen when either two signals are being fed to a device or when there is another signal interfering with a wireless signal. Also have you checked to make sure the decimator is set to NTSC? (I am sure the answer is yes but just thought I would throw it out there)

If you can scrounge up a red body and want to swing by my place sometime in the next few days with your gear I can help you try to work it out.

~Jess
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#4 William Demeritt

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Posted 04 March 2011 - 01:28 AM

Alec: I've previously experienced the issue with a CIT DX400 diversity tuner (even when the antennas have a strong signal, the distortion is present). Currently, the issue is reproduced on my Sony T1041U and a Viore 7" handheld LCD TV. Both of these receivers receive a wireless signal properly when I'm transmitting without a Decimator (tested most recently with an XDCAM with onboard down-converting, an Arri SR3 and Panavision Millenium.

Jess: I have PRO2 telescoping centerpost, and I usually wire up a RED job like so:

- HDSDI1 -> BNC (I've tested numerous shorty cables, all that are good to carry HD images) -> Decimator (1 or 2) HD-SDI input
- SD output from Deci -> BNC -> PRO2 Upper Junction BNC [an image now appears on my monitor]
- Vid/Pwr -> PRO-Modulus cable (I've tested 2, as I own 2) -> Modulus 2000 Power

Whenever I've wired up the cameras that transmit just fine, it usually goes like this:

- Panavision Millenium -> BNC -> BNC Connector on PRO Upper Junction. [image now appears on my monitor]
- Vid/Pwr -> PRO-Modulus cable (I've tested 2, as I own 2) -> Modulus 2000 Power

I haven't tried going from Decimator 2 to Modulus yet, I honestly hadn't thought to try that yet.

I have tried changing channels, the distortion follows on every channel, and definitely seems separate from the usual/occasional interference.

I agree. Honestly, the distortion reminds me of watching old VHS tapes that are low, low quality.

Yes, definitely set to NTSC. Also, just to be sure, the Deci is manually set to 4:3 (although I have tested it with 16:9, still happens).
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#5 Janice Arthur

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Posted 04 March 2011 - 10:36 AM

William

Have u tried the dip switches at the back of the
Redbyte? I think they could help.

Good luck

JA

(sorry reread and u clearly have, was thinking of my redbyte 2 which has
Lots of settings. )

William

One more point is that the bent video u describe has been a form of overmodulated
Video or too much iris. This is what I've seen on video signals before.
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#6 Charles Papert

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Posted 04 March 2011 - 01:16 PM

As suggested, try the Decimator the Modulus directly, and also try hardwiring to an SD monitor instead of transmitting, both direct from the Decimator and through the sled (come out through the BNC at the bottom).

Also if you can pick up a BNC terminator, put that one the BNC connector on the Modulus.

So many variables!
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#7 William Demeritt

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Posted 04 March 2011 - 01:54 PM

Janice: I now have the Deci 2, and the number of DIP switches truly boggles the mind. I have played with the 16:9-4:3 and NTSC-PAL switches. May give them all a run through soon, just to be thorough.

Charles: the many variables are driving me bonkers. However, a BNC terminator on the Modulus sounds like a good idea. In the next few days, I'm going to try to borrow a RED body and lens (and battery) from a friend who owns a package, just to see if I can track it down when I'm not on set.
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#8 SergeiFranklin

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Posted 16 March 2011 - 10:37 AM

I put a video distribution amp in my PRO years ago. It improved the Modulus as it is getting a correct video signal level.
I have info here http://earthvideo.net/stcmmod.html
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