RED HD-SDI jitter?

[Luis Ismael]

"We discovered a potential issue recording the HD-SDI output from the Red Camera. Using our $25K Tektronix WFM-700 waveform monitor, we discovered that the HD-SDI output from the Red (firmware vr 17) is well outside the SMPTE specs in jitter, rise/fall times and overall signal integrity.

We measured the Red HD-SDI jitter (at 100 Khz filter) to be in the 350 pS range. The max SMPTE jitter allowed is 133 pS, the XDR measures around 120 pS. The Red HD-SDI rise and fall times were in the 400 pS range. The max SMPTE rise and fall time is 270 pS, the XDR measures around 190 pS.

The HD-SDI "eye" opening provides an overall evaluation of the signal integrity. Ideally the eye should be wide open and stable. The Red camera HD-SDI eye shows a lot of reflection issues and has been closed down. The XDR eye is wide open and shows almost no reflection problems.

Regardless of these issues, we were able to record and playback video from the Red camera into the Flash XDR. While the HD-SDI input (from the Red) showed many problems, the loop-thru output from the XDR was clean. We tested with a 1-meter high-quality HD-SDI-cable.

So, while successful, I would caution everyone using the Red camera with the XDR/nano (or other HD recorders) to consider adding an HD-SDI reclocker or keeping the HD-SDI cable length to a minimum.

Red does specify that the HD-SDI output is for monitoring purposes only. However, the current HD-SDI output clearly does not meet SMPTE standards and may be incompatible with any HD-SDI device."

I been trying to connect a sony recorder EX-30 and a strange thing happens:
If i send 30p signal to the vtr i will get image, but if i change to 24 or 25 p the image goes black.
Could this HD-SDI jitter that Mike it´s talking about it be the problem.

Any ideia?

 

[Luis Ismael]

Red team... any ideia?

 

[Bastiaan Houtkooper]

It's been discussed a lot, because it also effects the BlackmagicHDlinkPro box.

 

[Alexandre Bouchard]

The AJA HD10DA is cleaning up the jitter from the Red One very well.

 

[Luis Ismael]

Thanks Alexandre