CubicSDR and SoapyRemote on Orange PI PC

So I’m using remotely my RTL-SDR dongle connected to an Orange PI PC using GQrx on my desktop computer while on the Orange Pi PC I’m running the rtl_tcp server.

This combination works fine, but still some times I have some lag, not common, but it happens.

Anyway Gqrx is great, but I wanted to try another SDR programs, and one of those programs is Cubic SDR. Cubic SDR uses an abstration layer for accessing the SDR hardware either locally connected or over the network. So I wanted to see how the behaviour of CubicSdr, comparing to Gqrx when accessing the RTLSDR over the network.

Installing CubicSDR on the Desktop
I’ve not used the available binaries, but I’ve used the code from the Git repository: https://github.com/cjcliffe/CubicSDR. So far the git repository works fine.

I’m not posting here the instructions for building the CubicSDR because the full instructions are at the Cubic SDR wiki.

Just make sure, when compiling, to give the correct path to wxWidgets when building Cubic SDR.

So at the desktop, we need to obtain, build and install the following components:

• SoapySDR – Abstraction layer
• Liquid-dsp – The digital signal processing libs
• wxWidgets – The display widgets
• CubicSDR – The Sdr program itself
• SoapyRTLSDR – The Soapy abstraction layer driver for the RTLSDR USB type dongles. To use the dongles locally

Installing the above software we can use the attached locally RTLSDR dongle.

Installing SoapySDR Remote on the remote server
The remote server where my RTLSDR dongle is connected is an Orange Pi PC running Armbian. To let my desktop running CubicSDR program to access remotely the dongle, we need to install SoapySDR Remote that allows remote access to the SDR.

So at the remote server we need to obtain, build and install the following components:

• SoapySDR – The abstraction layer
• SoapyRTLSDR – The driver for our RTL USB dongle
• SoapySDR Remote – The server for remotely access the RTL dongle

So basically the instructions are something like this:

  mkdir ~/SDR 
  cd ~/SDR
  git clone https://github.com/pothosware/SoapySDR.git
  cd SoapySDR/
  mkdir build
  cd build
  cmake ../ -DCMAKE_BUILD_TYPE=Release
  make -j4
  sudo make install
  sudo ldconfig
  SoapySDRUtil --info

Building the SoapySDR remote:

 cd ~/SDR
 git clone https://github.com/pothosware/SoapyRemote.git
 cd SoapyRemote/
 cd build
 cmake ..
 make
 sudo make install

and build the RTLSDR driver:

  cd ~/SDR
  sudo apt-get install librtlsdr-dev
  git clone https://github.com/pothosware/SoapyRTLSDR.git
  cd SoapyRTLSDR/
  mkdir build
  cd build
  cmake .. -DCMAKE_BUILD_TYPE=Release
  make
  sudo make install
  sudo ldconfig

So at the end we should have the following outputs:

opi@opi:~# SoapySDRUtil --probe
######################################################
## Soapy SDR -- the SDR abstraction library
######################################################

Probe device 
Found Rafael Micro R820T tuner
Found Rafael Micro R820T tuner

----------------------------------------------------
-- Device identification
----------------------------------------------------
  driver=RTLSDR
  hardware=RTLSDR
  origin=https://github.com/pothosware/SoapyRTLSDR
  rtl=0

----------------------------------------------------
-- Peripheral summary
----------------------------------------------------
  Channels: 1 Rx, 0 Tx
  Timestamps: NO
  Other Settings:
     * Direct Sampling - RTL-SDR Direct Sampling Mode
       [key=direct_samp, default=0, type=string, options=(0, 1, 2)]
     * Offset Tune - RTL-SDR Offset Tuning Mode
       [key=offset_tune, default=false, type=bool]
     * I/Q Swap - RTL-SDR I/Q Swap Mode
       [key=iq_swap, default=false, type=bool]

----------------------------------------------------
-- RX Channel 0
----------------------------------------------------
  Full-duplex: YES
  Supports AGC: YES
  Stream formats: CS8, CS16, CF32
  Native format: CS8 [full-scale=128]
  Stream args:
     * Buffer Size - Number of bytes per buffer, multiples of 512 only.
       [key=bufflen, units=bytes, default=16384, type=int]
     * Buffer Count - Number of buffers per read.
       [key=buffers, units=buffers, default=15, type=int]
  Antennas: RX
  Full gain range: [0, 49.6] dB
    TUNER gain range: [0, 49.6] dB
  Full freq range: [23.999, 1764] MHz
    RF freq range: [24, 1764] MHz
    CORR freq range: [-0.001, 0.001] MHz
  Sample rates: [0.25, 3.2] MHz

And SoapySDR should have the following configuration:

opi@opi:~# SoapySDRUtil --info
######################################################
## Soapy SDR -- the SDR abstraction library
######################################################

API Version: v0.5.0-gfec33c63
ABI Version: v0.5-2
Install root: /usr/local
Module found: /usr/local/lib/SoapySDR/modules/libremoteSupport.so
Module found: /usr/local/lib/SoapySDR/modules/librtlsdrSupport.so
Loading modules... done
Available factories...null, remote, rtlsdr, 

So all we need is to start our server:

opi@opi:~# SoapySDRServer --bind
######################################################
## Soapy Server -- Use any Soapy SDR remotely
######################################################

ba73bc08-3d0f-1458-8337-93d5a4502801
Launching the server... tcp://[::]:55132
Server bound to [::]:55132
Launching discovery server... 
Press Ctrl+C to stop the server

Using CubicSDR and SoapySDRRemote
So all we need is now on the startup SDR device screen selection add (by pressing the Add button) the remote IP of the Orange Pi PC server to access remotely the RTLSDR dongle.

My Orange PI PC IP address is 192.168.1.19:

CubicSDR device selection

And here it is the CubicSDR in action.

CubicSDR in action

Conclusion and final notes
The CPU usage and temperature on the Orange PI PC is not a problem when using the server. CPU usage floats around 40%, and no meaningful or worrying changes on the CPU temperature. So the Orange PI PC is up to the task without any issues when serving data with SoapySDRRemote.

Also with CubicSDR and SoapySDRRemote, I’ve experienced no lag when changing frequencies, namely when dragging the frequency selector.. It seems that all changes are instantaneous and note that my desktop connects to the remote server through a 200Mbps PLC and only then it is cable network to the Orange Pi. According to my desktop PC network widget, when receiving data, I have around 6.5Mbps of data comming in when using the maximum sample rate of 3.2MHz.

Also it took me a while to get used to the CubicSDR user interface, but overall for things like fine tuning, since it has a dedicaded codec screen, is much better than Gqrx.

CubicSDR fine tuning

Also one great feature is if we keep dragging the spectrogram window, the central frequency changes so it keeps up with the SDR bandwidth, shile in Gqrx we need to dial in.

Still I’m using Gqrx and rtl_tcp since CubicSDR has no data output, other then piping audio. Gqrx can pipe to UDP, that allows the decoding of digital modes locally or on other servers without messing around with PulseAudio and Jackd.
Also bookmarking isn’t as direct/easy as with Gqrx. Not sure if I can give labels/names to bookmarks and search them, like I can in Gqrx, but then the problem might be between the chair and computer…

Anyway CubicSDR is a great SDR application and the future looks bright.

I do recommend to give it a test drive.