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open gear de-embedder cards making nose???

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Patrick Spohrer
open gear de-embedder cards making nose???
on May 26, 2012 at 4:54:09 pm

We are using a Blackmagic Design open gear frames
with 8 BMD cards in it. In it are five de-embedder cards (what are
call "SDI to audio). We also have one BMD Open Gear sync generators.
We are using Panasonic HD Cameras (AG-HPX370's and AG-HPX250's). The
switcher is a For-A 1.5m/e 20 input HD-SDI switcher. The mixer is a
Mackie 1604VLZ Pro 3/

The HD-SDI output of the cameras goes into the de-embedder cards. The video
then goes on to the switcher. The audio comes out of the de-embedder card
and goes into the line-level inputs on the Mackie mixer. We know our
wiring is correct.

The system de-embeds the audio perfectly. However, when we turn one of the
cameras off (for example to change batteries), the audio goes insane -
making a clicking sound into the mixer. We believe there is a problem
with your cards. When you pull video from card it should just go quiet.

all 4 of the cards do it and one of the cards is DOA.

any ideas?

-patrick


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Jeff Hartman
Re: open gear de-embedder cards making nose???
on May 28, 2012 at 3:05:59 pm

Just to clarify: when the SDI feed goes away, do you get one pop and then silence, or is it continuous noise?

A single pop isn't necessarily a surprise: the D>A converter will be going almost instantly from its last known value to zero volts. But that should be the end of the noise (until the SDI comes back on).

-- Jeff


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Patrick Spohrer
Re: open gear de-embedder cards making nose???
on May 28, 2012 at 4:45:13 pm

It is a continuous clicking sound.

-patrick


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Justin Strauber
Re: open gear de-embedder cards making nose???
on May 28, 2012 at 4:28:36 pm

Yes, the BMD De-embedders tend to make random popping noises when there is no input signal. If your input signal was just black with no audio, you'd get silence. Unfortunately when there is no signal, the card seems to interpret the lack of signal as 'noise' and make random popping noises. Our Ross switcher sees no input as digital 'snow' and I assume the BMD devices do something of the same.


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