FPGA Central

I am currently doing a syllabic compander trying to compress a audio signa
from 16 bits sampling rate 8000Hz to 8bits.

Normally a compander like those using a-law, u-law is an instaneous on
and different from syllabic compander which may have the attack tim
constant and decay time constant for adaptive control of the volume.
trying searching for information from the web and IEEE papers but th
information is limited.

I would like to ask how to implement a syllabic compander (both compresso
and expressor). I wonder if a standard a-law, u-law compander together wit
AGC (audio gain control) can work like a syllabic compander.

bachbeethoven200 wrote:
> I am currently doing a syllabic compander trying to compress a audio signal
> from 16 bits sampling rate 8000Hz to 8bits.
>
> Normally a compander like those using a-law, u-law is an instaneous one
> and different from syllabic compander which may have the attack time
> constant and decay time constant for adaptive control of the volume.

yes exactly right
I
> trying searching for information from the web and IEEE papers but the
> information is limited.
>
dbx makes many companing systems...they may have some information.


> I would like to ask how to implement a syllabic compander (both compressor
> and expressor).

thats expander, you just need to make a compressor and expander that
have matched attack and decay times and compression expansion curves so
that the signal ends up the same as it was... a 2:1 slope will reduce
the dynamic range in dB (and bits required) by about 1/2

It is difficult to get the attack and decay times and curves match
preciesly (using analog circuits) so there is often problems during
transients...

Mark