KB6NU's Ham Radio Blog

///////////////////////////////////////////
HamPi and GNURadio

Posted: 20 Dec 2020 06:12 PM PST
http://feedproxy.google.com/~r/kb6nu...m_medium=email


Ham Pi is a distribution for the Raspberry Pi produced by Dave Slotter,
W3DJS.Â* Its notable because it includes more than 100 ham radio apps,
includingÂ* apps for running digital modes, antenna modeling apps, logging
app, Morse Code apps, and software-defined radio apps.

Its the SDR apps that Im most interested in. Shortly after I installed
HamPi, I purchased an RTL-SDR dongle from Amazon.Â*

I plugged it into the RPi and shortly after I was receiving FM broadcast
stations with gqrx, an open-source SDR program. Next, I tried it with
CubicSDR, and it worked just fine with with this program as well. HamPi
also includes CuteSDR and SDRAngel, but I havent tried running those yet.

GNU Radio

HamPi also includes a build of GNU Radio. GNU Radio isnt an SDR program,
per se, but a set of tools that allows you to build your own SDR
application. Youre provided with a set of functional blocks that you
connect up to create an application. For example, the diagram below creates
an FM broadcast receiver.
Click to see the full-size image.

I got this flowgraph (thats the GNU Radio term for the diagram) from VE6EY.
As he puts it, an FM receiver is like the Hello, world program in other
programming languages.

I ran into several problems. The first problem is that I wasnt getting any
sound output. Rightly so, I guessed that I hadnt set up the audio sink
correctly. After playing around a short time with settings, I finally got
that to work.

The second problem is that the performance is terrible. Im now getting
sound, but the sound is distorted, and it appears as if the chain just cant
handle the data fast enough. It sounds kind of like when a DMR radio is
dropping packets.

I thought it might be because the flowgraph was using the wxWidgets GUI
library. So, I changed the WX blocks to QT blocks, but that had no effect.
That was kind of disappointing.

I next tried getting some help from the discussion-gnuradio mailing list. I
got a bunch of replies—including one really snooty one—but none of the
solutions was readily implementable. I was hoping that someone would say
something like, Oh, yeah. Go into this file and change this parameter or
Run this command and everything will be fine. Instead, I was told that I
really should be running a 64-bit Linux and/or Im going to have to re-build
GNU Radio.

I really would like to get GNU Radio up and running on this Raspberry Pi 4,
so Ill probably end up doing something along those lines, but its going to
be more work than I anticipated.



The post HamPi and GNURadio appeared first on KB6NUs Ham Radio Blog.