Automatic fader; any ideas?

Ramon Question

Nov 20, 2013 00:00

Hi,

Anybody a idea of how to design an automatic fader?

The fader should be triggered if signal (speech) is present on an input and the fader should ramp up from -3dB to 0dB in a period of 2 to 3 seconds.

It should also have a 'hold' time of about 1 second to maintain 0dB if speech drops for less than 1 second.

Thanks.

In addition to this question:

the signal (line level, max 0dB) is connected to the analog opamp stage (0dB gain) and is feeded (symmetrical) to the Codecs (AD1938) + and - input: what is the level inside the DSP (1442)?

Thanks again.

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Ramon Reply

Nov 20, 2013 00:00

Thanks Miguel,

The external signal connected is the same signal which should trigger the ‘module’ which than should ramp up in a couple of seconds; the output of this module should be the same signal.

So this signal is not the trigger to feed another signal through.

I understand what you mean with such ducking system, but I only have 1 signal to start this ‘event’ and it is this same signal which should be feeded into the rest of the design at 0dB.

Regards,

Ramon

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ADIApproved Reply

Nov 20, 2013 00:00

Hi Ramon:

Use a dynamic processor with an external detector for this purpose. People have used this for ducking musing when speech is present (for example when DJs start talking and music needs to duck). I would be worried about your range -3B to 0dB is not so much.

Dynamic processors have a hold time included. Let us know if you need more specific info on this.

I'll let the applications engineer answer but I'm pretty sure that if you input a 0dB FS you will get a one in 5.23 inside the DSP, althought I'm confused and don't really know if this is what you are asking.

Regards

Miguel

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Ramon Reply

Nov 24, 2013 00:00

Hi Miguel,

Thanks a lot for thinking this out. We will try this and let you know.

Kind regards,