Category: Airspy

Simple dPMR Decoder Plugin for SDR# Released

Over on rtl-sdr.ru programmer Vasili has released his latest SDR# plugin which is a dPMR decoder (note that this site is in Russian). dPMR is short for "Digital Private Mobile Radio" and is an open non-proprietary digital voice protocol. Vasili writes:

Simple dPMR decoder. No external dependencies, no settings, uses SDR # audio path. Designed for listening to unencrypted dPMR channels.

To install the plugin simply copy the dll's from the zip file into the SDR# folder, then copy the line from the magline.txt text file into the plugins.xml file which can be opened with any text editor.

We note that there is also an open source version of DSD which includes a dPMR decoder which we posted about here.

Simple dPMR Decoder Plugin for SDR#

Running SDR# On Ubuntu 20.04 Linux via WINE

SDR# is a very popular Windows SDR program often used with the RTL-SDR and Airspy SDR. One drawback is that it lacks native Linux compatibility. In the past it has been possible to run SDR# via WINE, however some newer updates were thought to have broken that ability. WINE is a Windows emulator that allows some Windows programs to run under Linux.

However, recently on Twitter we've seen a Tweet by @albinstigo indicating that SDR# can indeed run on Ubuntu 20.04 via WINE 5.0. In a Tweet he explains the steps which are quite simple:

  1. Install WINE via apt.
  2. Install dotNET 4.8 via winetricks.
  3. Install the Verdana font via winetricks.
  4. Enjoy SDR

One limitation is that the emulated SDR# cannot connect to the SDR natively via the USB. So you will need to use TCP server software such as rtl_tcp or SpyServer to get it to work. Basically, run the server on the native Linux environment, then connect to it in SDR# running on the emulated Windows environment.

SDR# Updates: RTL-SDR Enhanced Mode, AM Co-Channel Canceller for MW DX

Over the past few days SDR# has been updated again adding several new great features. The first is an "RTL-SDR Enhanced" front end driver, which is actually Vasili's front end driver that was released a few years ago. This front end enhances the capabilities of the RTL-SDR as it exposes features like decimation and individual gain control. We note that the current version appears to have a bug preventing enhanced mode from starting, but we expect that it will be fixed again soon. Vasili's File Player has also been added, and this allows for easy playback of RTL-SDR IQ files.

The second feature added recently is an AM Co-Channel Canceller which is could be quite a big feature for medium wave (MW)/broadcast AM DXers. When DXing MW a problem is that you'll often encounter is two stations that are on or almost on the same frequency. This is either due to neighbouring countries not agreeing on frequencies, long range DX antennas picking up further than the intended broadcast range, or from malicious jamming as with the Chinese Firedrake. With a standard radio or demodulation algorithm such a situation makes either both stations impossible to listen to, or only the strongest station will be heard. However, the new AM Co-Channel Canceller plugin in SDR# uses clever DSP algorithms to allow one of those channels to be effectively removed, allowing you to listen to the other station clearly.

Over on the SWLing blog Guy Atkins has written up a comprehensive review and tutorial of the Co-Channel canceller plugin. We've also seen a few examples up on YouTube already, and the video posted below shows user "SDR-radio" in Japan experiencing a South Korean station blocking out a weak local Japanese station. Enabling the plugin allows the weaker station to be heard.

SDR# (SDRSharp): AM Co-Channel Canceller plugin

SDR Sharp Slicer Now Supports RTL-SDR and other SDRs

Youssef, Author of the SDR# software has recently updated SDR#, now extending the Sharp Slicer functionality which we posted about earlier to RTL-SDR and other supported software defined radios. The latest version of SDR# can be obtained from the Airspy Downloads page as usual.

This feature allows SDR users to open multiple instances of SDR#, each able to tune to a seperate signal within the currently tuned frequency range of the SDR. This is somewhat similar to the old multi-VFO plugin from rtl-sdr.ru, however the advantage of Slicer is that you can have seperate spectrum and waterfall graphs for each signal.

Other recent changes include 'true dBFS' automatic scaling, where 0 dBFS now indicates that the ADC is likely saturated.

SDR# Sharp Slicer Monitoring 5 Broadcast FM Stations Simultaneously.

Testing Sharp Slicer: Multiple Spectrum Slices via SDR# with an Airspy SDR

Youssef the author of SDR# has recently released an update which adds a feature called "Sharp Slicer". This feature allows Airspy SDR users to open multiple instances of SDR#, each able to tune to a seperate signal within the currently tuned frequency range of the SDR. This is somewhat similar to the old multi-VFO plugin from rtl-sdr.ru, however the advantage of Slicer is that you can have seperate spectrum and waterfall graphs for each signal. This could be especially useful for monitoring multiple narrowband HF modes with an Airspy HF+ Discovery. 

To use Sharp Slicer you must have an Airspy SDR, be it an Airspy Mini/R2 or HF+/Discovery. Unfortunately it will not work with RTL-SDR or other SDRs. Once the SDR is running in SDR#, simply press the "+" button on the top left to open a new Slicer instance. It seems possible to open as many instances as you want, and probably the only limitation is your CPU. On our Intel i7-6700 we tested up to 8 instances running at the maximum bandwidth of an Airspy Mini, and the SDR# CPU utilization was only at 50%.

A nice touch is that you can also see the location of each VFO on the master SDR# instance, and the color can be changed on each Slicer instance.

Over on Twitter @ea3ibc has also been testing:

TechMinds: Using Public Online SDRs without SDR Hardware

This weeks video on the TechMinds channel explores the various online web SDRs that are available to access for free. Accessing these online SDRs does not require any hardware apart from a PC and internet connection, although of course you are then receiving signals from a different location to yourself. 

In the video he shows how to access the SDR# Spy Server Network which mostly consists of Airpsy and RTL-SDR units, the SDR-Console V3 Server network which consists of a wide array of different SDRs, the browser based WebSDR network which is mostly soundcard based SDRs but also RTL-SDR and other SDRs, and finally the KiwiSDR network which is made up of KiwiSDRs.

Using Software Defined Radio Without SDR Hardware - WebSDR

Standalone Windows FengYun-3 & MetOp HRPT Weather Satellite Decoder

Back in June we posted about Alan (@aang254)'s work on porting the GNU Radio gr-hrpt decoder over to GNU Radio 3.8. More recently Alan wrote in and wanted to share the news that he has recently released standalone Windows decoders for the MetOp and FengYun-3 weather satellites.

MetOp and FengYun-3 are both polar orbiting satellites that beam back high resolution weather satellite images. Unlike the NOAA polar orbiting satellites which transmit both the easy to receive APT and more advanced HRPT signal, these only transmit a HRPT signal at ~1.70 GHz, so a satellite dish and motorized tracking mount (or hand tracked) is required. You will also need an SDR capable of receiving over 3 MHz bandwidth such as an Airspy Mini or R2. Alan writes:

I recently got FengYun decoding working after the release of my MetOp decoder a while ago. Since gr-hrpt wasn't usable for Windows user without some major hassle, I made some standalone decoders (Windows builds included in the repo) for both MetOp and FengYun.

Decoding is done by first demodulating with the included flowcharts or @petermeteor's, then processed through the decoder which does Viterbi / Differential decoding. The output then needs to be deframed by MetFy3x or any other software that can do so.

https://github.com/altillimity/Satellite-Decoders

A few images!

https://twitter.com/SamuelArmstro18/status/1285647473881513989
https://twitter.com/ZSztanga/status/1285277472284708865
https://www.reddit.com/r/amateursatellites/comments/hwhb7q/my_longest_fy3b_image_yet_i_got_up_at_430_in_the/
https://twitter.com/HA6NAB_Tomi/status/1285300023350222848
https://twitter.com/ub1qbj/status/1286734822820532224/photo/1

You can learn more about these satellites on USA-Satcom's Cyberspectrum talk and slides.

Frugal Radio: Using an Airspy and RTL-SDR To Scan the UHF Military Airband in SDR#

In Frugal Radio's latest video he explores how you can use an Airspy or RTL-SDR dongle to scan the entire military UHF airband spectrum in a few seconds via SDR#. Frugal Radio notes that there are often many signals in the UHF milair band, but they can be difficult to find without a scanner.

In the first video he compares his Uniden BCT15X hardware radio scanner against an Airpsy, noting that his Uniden takes 1:10 minutes to scan the entire band, whereas the Airspy running SDR# with the frequency scanner community plugin can scan the same bandwidth in less than 2.5 seconds. Faster scanning means that you are less likely to miss an active signal. In the second video he tries scanning with an RTL-SDR and notes that it can scan the band in 9 seconds.

How to use Frequency Scanner to Search UHF MilAir in 2.3 seconds in SDR# using AirSpy R2

$25 RTL-SDR v3 Military Air band search in under 10 seconds! Frequency Scanner SDR Sharp plugin test