Category: Airspy

GQRX and gr-osmosdr now with support for SpyServer

Thanks to the work of Lucas Teske, GQRX is now able to connect to SpyServer servers. SpyServer is the IQ streaming server software solution developed by the Airspy SDR developers. It can support Airspy and RTL-SDR devices, and can be used to access these SDRs remotely over a network connection. It is similar to rtl_tcp, but a lot more efficient in terms of network usage, meaning that it performs well over an internet connection. On a previous post we have a tutorial about setting up a SpyServer with an RTL-SDR.

The code modified by Lucas is the gr-osmosdr module, and Lucas' code can be downloaded from his GitHub at github.com/racerxdl/gr-osmosdr. It doesn't yet appear to have been merged into the official osmocom branch. The gr-osmosdr module is a generic block used to access various SDR hardware, so any software that utilizes it (such as GNU Radio) should be able to connect to a SpyServer connection too.

Browsing the UHF Satcom Band via SpyServer

Over on YouTube Corrosive has published a video of him browsing through the UHF Satcom band with a remote Airspy SDR being streamed via SpyServer. The UHF-Satcom band is anywhere between 243 - 270 MHz and contains fairly strong signals from many several US satellites that can be received with a simple antenna. Some of the satellites are simple repeaters without security, and pirates from Mexico and South America often hijack the satellite for their own personal use. So it can be quite interesting to look for pirate conversations and sometimes SSTV images. Reception of these satellites is generally available in Canada, US, Mexico, South America, Europe and Africa.

UHF Satcom Transponders Close Up on the Airspy SDR

Decoding 12 AERO Channels Simultaneously with an Airspy, Outernet Patch Antenna and SDR-Console V3

In a post uploaded last month we noted that Outernet was selling off some of their old L-Band satellite antennas cheaply. Nils Schiffhauser (DK8OK) decided to take advantage of the sale and bought one. Now Nils has created a blog post that shows how he's been able able to decode 12 L-Band AERO channels simultaneously with the Outernet L-band antenna, an Airspy R2 and SDR-Console V3. AERO is the satellite based version of aircraft ACARS, and it's L-band signals contain short ground to air messages like weather reports and flight plans. Multiple channels are often in use at any one time.

To achieve this Nils uses the multi-channel tuning capabilities of SDR-Console V3, which allows him to open up 12-channels, each tuned to a different AERO frequency. He then opens up 12 instances of the AERO decoder known as JAERO, and then uses VB-Cable to pipe the audio from each channel into a JAERO instance. Nils writes that the key to making JAERO run with multiple instances is to install JAERO into different folders on your PC, and give each JAERO.exe a unique file name like JAERO_1.exe.

He collects all the data into a program called Display Launcher and Nils notes that the whole set up has been stable digesting 54,000 messages over the last 24 hours. 

12x JAERO Decoders Running
12x JAERO Decoders Running

QuestaSDR Android App now with Remote Network Streaming: RTL-SDR, Airspy, SDRplay Supported

Back in April we posted about QuestaSDR, which had just released the Android version of its SDR software. Recently QuestaSDR programmer 'hOne' wrote in and noted that a new update has enabled remote streaming in QuestaSDR.

To get set up, just run the Windows version of QuestaSDR on a PC, and open the "SDR Server" app. Once the server is running, you can connect to it via the Android version of QuestaSDR over a network connection. The server supports the RTL-SDR, Airspy and any ExtIO compatible device such as SDRplay units. As far as we're aware, this is the only Android app that currently supports streaming from non rtl_tcp compatible units such as the Airspy and SDRplay.

hOne has been able to run an Airspy at the maximum bandwidth of 10 MSPS through his network connection. He also notes that you can now zoom into the IF spectrum in detail by using the new "IF Spectrum" plugin.

hOne also notes that the streaming feature is currently in beta, and any bugs/suggestions or feedback are welcome.

QuestaSDR Streaming over a network connection with an Airspy
QuestaSDR Streaming over a network connection with an Airspy
AirSpy windows server, android client LAN Remote

Video Comparing the RSP-1A Against the Airspy HF+, and Testing out the Airspy HF+ R3 Mod

Over on YouTube icholakov has uploaded two new comparison videos. The first compares the Airspy HF+ against an RSP-1A on HF signals with a W6LVP receive loop antenna in a noisy suburban backyard in Florida.

Results appear to be quite similar for most signals, although we noted better performance from the HF+ on some particular weak signals surrounded by strong AM stations in the test such as the 810 kHz signal at 3:37, but lower noise on some signals received by the RSP-1A such as at 9:32. The tests were performed with a stock HF+ without any firmware updates applied so it's possible that the updates could improve results further.

In the second video icholakov performs the R3 mod on his Airspy HF+ and compares the results before and after. It appears that shorting R3 improves reception on MW slightly, and has little effect at higher frequencies. We also note that the R3 mod is mostly designed to mostly improve VLF/LF reception which is not tested in the video.

W6LVP receiving loop: Airspy HF+ vs. SDRPlay RSP-1A

Airspy HF+ R3 Modification test

Using the Airspy HF+ as a Power Meter By Calibrating it with a Resistor

Over on YouTube, Leif (SM5BSZ) has uploaded a video where he shows how the Airspy HF+ can be used as an accurate power meter for RF signals. Leif notes that if the noise figure (NF) or minimum discernible signal (MDS) of an SDR is known, then it is possible to use that SDR as a power meter by calibrating it with a resistor (dummy load) at room temperature. To determine power levels Leif uses the signal diagnostics plugin which is built into SDR#. He writes in the video description:

When the noise figure (NF) or minimum discernible signal (MDS) of a software defined radio (SDR) is known we can use that radio as a power meter just by calibrating it on a room temperature resistor. Here the Airspy HF+ is used to demonstrate the principles. Note that MDS depends on the temperature. Manufacturer data is for a warmed up unit. Cold units have significantly lower MDS. Note the observations on bad adapters and attenuators towards the end of the video. One conclusion is that the HF+ is EXCELLENT in keeping common mode currents on the USB as well as on the antenna cable outside. They do not enter the receiver provided that the nut holding the SMA connector is firmly tightened.

In another video Leif also tests out a pre-production version of a HF+ preselector currently being designed by Youssef (designer of the HF+) by measuring the filter responses.

Thomas N1SPY Demonstrates Receiving SSTV Images from the ISS

Earlier in the month the International Space Station (ISS) was transmitting SSTV images down to the earth for anyone to receive an decode. The ISS does this several times a year to commemorate special space related events, such as the day Yuri Gagarin (first man in space) was launched.

In the video Thomas explains why the ISS does this, how to track the ISS, and then he demonstrates actually receiving and decoding the signal. Thomas uses an Airspy HF+ to receive the signal on 145.8 MHz, however an RTL-SDR could do the same job. For decoding he uses the MMSSTV software.

For new on when the ISS might transmit SSTV again, keep at eye on the ARISS Blog, and the ISS Ham Twitter page.

2018: Thomas N1SPY receives SSTV signals from the ISS

Testing the Airspy with the New And Improved Version of ADSBSpy

Airspy have recently released an update to their ADSBspy decoder, which is an Airspy One/R2 compatible decoder for 1090 MHZ ADS-B signals. According to 'prog', the software developer of ADSBSpy, his setup can see almost double the number of aircraft and with fewer false positives when using the updated software. Prog writes that the secret to the improvement is some reworked DSP code that aims to exploit oversampling in the Airspy to the maximum.

We compared the new (1.0.0.38/39) decoder against the old decoder (1.0.0.37) which used to get similar performance to dump1090. The test setup was two Airspy dongles connected to a dipole antenna via a splitter, with our Triple Filtered ADS-B LNA used by the antenna. One Airspy was used to power the LNA via it's bias tee, and both units received the same amplified signal. We found indeed that the new version of ADSBSpy receives a good number more aircraft in our set up, and an increased number of ADS-B messages too.

It seems that most of the additionally received aircraft must be from extremely weak signals, because when looking in Virtual Radar Server the extra aircraft usually only show their ICAO and maybe altitude and speed until they get closer.

So far this software appears to provide the best performance on ADS-B that we've seen so far, so if you are using an Airspy for ADS-B tracking we'd like to hear results from anyone who upgrades.

The New ADS-B Spy Receives More Aircraft and Messages
The New ADS-B Spy Receives More Aircraft and Messages