[Discuss-gnuradio] Audio sink/source issues and some other questions

[Adrian Musceac]

Hi,

I'm working on this Linux SDR transceiver application (
http://qradiolink.org ) which is entirely based on Gnuradio. I use the
standard Alsa audio sink and source for analog transmission and
reception.

I've encountered the following problems: sometimes the audio has
delays of up to two seconds upon starting the transmit flowgraph.
Other times it works well. Also, sometimes the received audio is sped
up and sounds like Donald Duck. There is nothing special happening in
the background at these times, and CPU load is low (10%). As a
workaround, I wrote my own sink and source to direct the audio
straight to Pulseaudio. But I'd like to keep native Alsa support from
Gnuradio.

Another problem I have is that I'd like to do a mixed mode repeater
(from digital to analog and viceversa). My radio (USRP B200) is full
duplex so I should be able to do that. However, I can't figure out how
to do that in a single flowgraph (TX and RX). If I set the source
parameters to use the TX/RX antenna, any time I switch from RX to TX,
the sink moves automatically to port RX2 which means I'm receiving my
own transmission. I'd like to be able to disable the automatic switch
of antenna without stopping the RX flowgraph. Is that possible?

Appreciate any help.

Adrian