Sony PD-150 colour bars are not broadcast standard ! at DVinfo.net

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Sony VX2100 / PD170 / PDX10 Companion
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Old August 28th, 2004, 02:02 PM   #1
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Sony PD-150 colour bars are not broadcast standard !

Hello,

Did you ever measured using a waveform monitor the PAL colour bars that Sony PD-150 generates ? They do not meet the EBU standard at all. They are attenuated. How can that be possible ? Why such an expensive camcorder does not generate usable colour bars ?

Any comments about this topic will be appreciated.
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Old August 28th, 2004, 02:32 PM   #2
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As far as I remember the VX2000 (PD150) color bars are OK. EBU uses 100% and 75% color bars as well. The latter mainly for analog transmission chain testing. What do you mean by "attenuated"?
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Old August 29th, 2004, 05:46 AM   #3
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look at this

Hello Andre

This is a screenshot of the tektronix waveform monitor. As you can see, the bars are attenuated. They are not 75% or 100% colour bars.

http://www.wakehosting.com/upload/files/ygqnAuSm/WFM_screenshot.jpg

Thanks !!
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Old August 29th, 2004, 11:31 AM   #4
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The bars are the 75% bars/100%saturation/75%white bars which are one of the types used in broadcast. I just verified the bars once again on my VX2000 and get the same type of bars.
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Old August 29th, 2004, 11:39 AM   #5
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so

What do you mean then ? Do I have a malfunction on my camera ?

Thanks for you help.
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Old August 29th, 2004, 12:16 PM   #6
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No, everything is OK with yr cam. You just have to remember that the brightest whites(and colors) that your cam can reproduce are somewhat higher. Those reduced amplitudes in the bars are close to the averages in real live scenes and are thus best for subjective image color evalutions.
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Old August 29th, 2004, 04:04 PM   #7
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Andre,

I strongly belive that colour bars from Sony PD-170 are not correct because I did a test. I recorded colour bars from Sony PD-170 on tape and then I reproduced that tape from a Sony DSR-570 DVCAM while monitoring the composite output of the 570 through a tektronix waveform monitor. And what happened ? Colour bars were identical that the snapshot: absolutely attenuated and the luminance not reaching 0,7 V at all.

Why am I so worried about this issue ? Well, we used to use the Sony PD-170 colour bars generator to test long coaxial video lines and we were monitoring, at the end of the line, the video signal with a waveform monitor in order to see how attenuated was, and how were the levels of luma and chroma. Soon we realized that colour bars from that camcorder do not meed broadcast standard levels so now we test the lines using a portable test signal generator from tektronix (TSG95), or if that is not possible we use a regular full-size DVCAM (like sony DSR-570) or some DVCPRO's because its composite output is more reliable as far as levels are concerned.

That's all. If someone can reproduce the test and get the same problems with PAL equipment I would like to know it please.

Best Regards,

Robert Moix.
Broadcast Engineer.
r.moix@unitecnic.com
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Old August 29th, 2004, 09:45 PM   #8
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Very disturbing.

You might be right about the analog output levels not being reliable. I once compared the analog output from a large format Sony DVCAM VCR and my PDX10: the composite output from the VCR looked better than the camera's S-video out. Pure speculation, but I wouldn't be surprised if Sony saved bucks by putting in some lame DA converters in the prosumer cameras.
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Old August 30th, 2004, 04:32 AM   #9
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Robert, You will indeed not reach the 700mV level with the 75% signal, only somewhat more than 500 mV. There is no problem for using 75% signals for cable (and other linear devices)measurements. You only have to take in account that the generated signal is a 75% colorbar.The output signal at the end of the ideal coax will remain a 75% signal. B.t.w. although colorbars can give you an indication on the luma/chroma attenuation, there are more specific signals available like "2 T" and filled "20 T" pulses which show the amplitude and group delay properties of the coax connection
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