13 October 2013

QtRadio running on Ubuntu 13.04 with USRP

After a day slaving over a hot compiler, I managed to get QtRadio working with my USRP B100 and BasicRx.  I achieved this using code from the ghpsdr3-alex repo.

It looks good on a 27 inch  WQHD monitor with a 2560 by 1440 pixels screen.  I have it resampling from the default 250kHz rate down to 192kHz.  It does seem fairly CPU intensive though, hitting a load of 5.0 to 6.0 on my new Haswell I7 machine, with a modest bunch of other applications running that don't reach a load of 1.0 between them.  I built using the alex-conf.sh script instead of using configure itself, so I've hopefully got an optimised build.  I built QtRadio for release in QtCreator.

Here's a screenshot of some 30m activity.

To get this working I had to bodge the usrp_server to detect my B100, which it didn't do initially. It turns out that it was hard-coded to expect a USRP1 device.  The following patch shows the simple change required to make it work with the B100.

diff --git a/trunk/src/usrp/usrp.c b/trunk/src/usrp/usrp.c
index a36e93c..c8e0f91 100644
--- a/trunk/src/usrp/usrp.c
+++ b/trunk/src/usrp/usrp.c
@@ -141,7 +141,7 @@ void setup_rx_queue(void) {
 bool usrp_init (const char *rx_subdev_par, const char *tx_subdev_par)
     uhd::device_addr_t hint;
-    hint["type"] = "usrp1";
+    hint["type"] = "b100"; // "usrp1";

     //discover the usrps and print the results
     uhd::device_addrs_t device_addrs = uhd::device::find(hint);

Once I'd built everything, I had to run two server processes before launching QtRadio.  I invoked them like so:

$ usrp_server  -r "A:A" --samplerate 192000
$ dspserver --lo 0

No comments: