[Discuss-gnuradio] Limiting TX output

[Brian Johnson]

Can anyone tell me if there is something I can do in the existing GNU software which will limit the output of a TX daughter board to a preset maximum?  We are using the LFTX daughter boards.

 

We are running the TX output to an amp that will boost the signal up to ~8 watts, and are already using the gain settings to adjust the TX output.  The problem is that voice transmission has a lot of spikes on things like ‘p’ and ‘c’ sounds or blowing into the microphone.  To prevent blowing the amp we have had to adjust our TX gain such that the spikes stay below ~170mV (peak-to-peak).  With this we are only getting about 2-3 watts PEP on normal speech.  We would like to allow more gain – getting us closer to 8 watts – and just “clip” the spikes to protect the amp.

 

I know this can be done in hardware between the USRP and amp, but would rather do it in software if possible. 

 

Brian Johnson

Kutta Consulting Inc.

Work: 602-896-1976

Cell   : 623-451-9417

www.kuttaconsulting.com