RTL2832U: Building a FM Receiver with GNC on Windows

Question

I have been using SDRSharp for quite some time, listening to various stations, and I wanted to divulge more into how I can create tools using GNURadio.

I downloaded GNURadio Companion 3.8.0.0 and ran through the first three lessons.

I was following lessons from the official GNURadio.Wiki using the said V3 RTL-SDR Dongle (RTL2832U R820T2 TCX0 + BIAST + HF)

I have encountered trouble when creating the FM receiver as per lessons. Due to my hardware being different than what the lesson used, I did make a few revisions to the parameters of the flow graph.

1. I used a sample rate of 2.4e6 (2.4 MS/s) which is the max stable sample rate of the said dongle
2. I used the RTL-SDR Source Block as opposed to the UHD Block
3. I set the stop frequency to 2e9 as this dongle will not go as high as 6GHz

After these changes, I assume all is set, and Generate/Execute the flow graph. I am greeted with the following error:

Executing: C:\Program Files\GNURadio-3.8\gr-python27\python.exe -u D:\GNURadio\TutorialsFromGNUDotOrg\FM_Radio_Receiver.py

gr-osmosdr 7da9989b (0.1.5git) gnuradio 3.8.0.0
built-in source types: file osmosdr rtl rtl_tcp uhd hackrf bladerf airspy redpitaya spyserver 
[INFO] [UHD] Win32; Microsoft Visual C++ version 14.0; Boost_106000; UHD_3.14.1.HEAD-0-g0347a6d8
[ERROR] [X300] X300 Network discovery error receive_from: An existing connection was forcibly closed by the remote host
[ERROR] [UHD] Device discovery error: receive_from: An existing connection was forcibly closed by the remote host

I know I can hit the frequencies in question, as I tune to them on SDRSharp. I also know the RTL-SDR Source block should be used as the documentation states:

 * RTL2832U based DVB-T dongles through librtlsdr

I start to think, maybe I don't have this library? I then open terminal and type python I proceed to check if librtlsdr is installed by typing:

import librtlsdr 

I get an import error, 1No module named librtlsdr I assume this is the problem, so I proceed topip install librtlsdr` and I am greeted with:

ERROR: Could not find a version that satisfies the requirement librtlsdr (from versions: none)
ERROR: No matching distribution found for librtlsdr

The latest GNU, 3.8.0.0, is using Python (Python 2.7.10) and my PIP Error shows:

DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support

Is this missing library the problem, and if so, how can I import it so the GNC can work as expected?

Answer 1

For those who encounter this issue, be sure to enter a device argument. This was not a library issue. The message

[ERROR] [UHD] Device discovery error: receive_from: An existing connection was forcibly closed by the remote host

Was due to no device being found.

I had to set rtl=0 in the Device argument section. See flow Graph below.

New question, how can you determine what device argument you shall enter?

Answer 2

To give you a better answer, please answer the following questions: - what OS are you using? - how did you load GNU Radio 3.8? - have you tried using pip3 and python3? Try running the procedures in https://wiki.gnuradio.org/index.php/ModuleNotFoundError

You say "I downloaded GNURadio Companion 3.8.0.0", but you didn't say your source for it. Did you build the flowgraph yourself with GNURadio Companion 3.8.0.0, or did you load the https://raw.githubusercontent.com/gnuradio/gr-tutorial/master/examples/tutorial6/gr-tutorial-broadcast-fm-rx.grc ? It was written for GR 3.7.

Try this: - terminate SDRSharp - eject your dongle - reboot your computer - connect the dongle - try it again