sustain
Thread Summary
The user sought an algorithm in Sigma Studio to limit signal levels above a certain threshold and boost those below, while leaving signals below a threshold untouched or cut to zero. The solution involved using a gain/limiter combination, increasing the gain, and placing two such groups in series, achieving a nearly constant output of -3dB over a 0dB to -40dB range. The user also needed a simple GPIO-controlled mute and invert function, which was addressed using a GPIO pin to switch between signal paths.AI Generated Content
Hi you all,
I would like to have an algorithm that makes a kind of sustain. It shall limit levels higher than a given value and increase those, which are lower. Signals lower than a given threshold shall be untouched or cut to zero.
Searching through the help I've found a compressor "standard rms" which seemed to could help to do the job, but as so many others described in the help, it is missing in my sigma studio - or I can't find it.
Further I would like to have a mute and an invert for a signal, which are simply switched by a GPIO line. I don't want to write some words via I2C for such a simple task.
--- Thank you, Brett, for your really helpfull AN 951 ---
It seems to me, many things are possible with Sigma Studio an most are simply done, but not always it is easy to find out, how...............
Kind Regards
Rasterjannik
Hi,
Not all algorithms in SigmaStudio are supported by all the processors. For example, if you're using a chip with an older DSP core, such as the popular ADAU1701, the fancier compression blocks are missing. However, you'll find a Limiter block under "Dynamics Processors - RMS" that may serve your needs. It's shown below in a schematic that uses a GPIO pin to select between two different signal paths. If you're running a ADAU1701 mini eval board, pressing the center one of its three push-buttons will switch to the limiter with a 6dB higher threshold, resulting in more volume at the output (assuming your input is strong enough to reach the thresholds).
ez.analog.com/.../5076.6502652c2cc2c87134b2ef7170a6ea74.html
If the limiter doesn't suit your needs, you can build a more complex compressor from elementary blocks, for example, see https://ez.analog.com/message/60396#60396
Hi Robert,
thank you for your nice advice. I will try it and make some experiments with it. Than i will tell here about the results.
kind regards
Rasterjannik
Hi Robert,
I've play a little with your solution an now it works. I have taken the gain/limiter combination, increased the gain and than put two of these groups in series. Now I have over a range of 0dB to -40dB a nearly constant output of -3dB. That is fine.
Thank you
kind regards
Rasterjannik
Please log in to reply.