Category: Applications

SDR4Space: Software Tools for SDR Based Satellite Ground Stations

Over on Reddit we've seen that SDR4Space, a provider of a satellite ground station receiver hardware and software has released a free feature limited lite version of their embedded software over on their GitHub page. In the Reddit comments the software is explained as follows:

It's a command-line tool using scripts, for SDR users. You can write your own scripts to: record IQ samples, predict satellite passes, start a record for a specific satellite and correct doppler at the same time.

It's also useful to record narrow subband IQ streams ( example: 48kHz wide instead of 2.048 MHz on rtlsdr, a single signal on HF is only few kHz wide).

You can work on IQ files: cut, resample, merge, convert formats and so on.

Having said that you can recognize features from predict, rx_sdr/rtl_sdr ,rtl_power/rx_power.

Regarding installation, a Debian package is provided, installing application and some examples in /opt/vmbase directory. Most of dependencies are installed by the package. But you should install SoapySDR and Soapy drivers for your SDR device first by yourself if not yet done !

To understand how it works, the best is perhaps starting download TLE and print a passes list, using scripts in ./sat/ directory.

For the next SSTV event I'd try to run unattended reception of ISS (from ./sat/sat_receiver directory).

From the examples, it appears that you can script a fully automated doppler corrected satellite signal receiver with the SDR interface connecting through Soapy, and all the DSP handled by the SDR4lite library.

SDR4Space Logo

Frugal Radio: How To Decode L band Satellite ACARS and CPDLC messages with JAERO and your SDR

In the latest episode of his YouTube series on Aviation monitoring Rob explores how to decode L-band satellite ACARS (Aircraft Communication Addressing and Reporting System) and CPDLC (Controller Pilot Data Link Communications) messages using JAERO, an SDR like an RTL-SDR, and a appropriate L-band antenna such as our RTL-SDR Blog Active L-Band Patch (currently out of stock).

In the video Rob shows examples of what you might receive such as CPDLC ATC instructions, digital ATIS information, arrival information and suggested landing data configuration instructions. He goes on to show satellite coverage maps, what hardware is required to receive these signals, and finally how to setup the receiving and decoding software.

How To Decode L band Satellite ACARS and CPDLC messages with JAERO and your SDR

A KerberosSDR Based Radio Direction Finding RC Boat

If you weren't already aware KerberosSDR is our 4-channel phase coherent capable RTL-SDR unit that we previously crowdfunded back in 2018. With a 4-channel phase coherent RTL-SDR interesting applications like radio direction finding (RDF), passive radar and beam forming become possible. It can also be used as four separate RTL-SDRs for multichannel monitoring.

KerberosSDR is soon to be replaced with the upgraded KrakenSDR, which will begin crowd funding on Crowd Supply later this year. Please note that we have had some pandemic related delays finalizing the design, but progress is being made.

Recently we came across a brief demonstration video on YouTube where it appears that students have embedded a KerberosSDR into an RC boat. The boat carries four direction finding antennas connected to the KerberosSDR and autonomously navigates towards a signal source.

KerberosSDR Direction Finding RC Boat
Kerberos SDR project result

KerberosSDR direction finding #2

Decoding NOAA on an Debian Chrooted Android Smartphone

Over on Reddit Ian Grody (u/DutchOfBurdock) has posted about his success in using a modded Android smartphone to run an RTL-SDR Blog V3 and NOAA decoder software all within the phone itself.

In the past we posted about Ian's work in getting rtl_power scans to work in conjunction with the Tasker app, in order to generate automated frequency scans on his phone on the go. His more recent work from the past year includes showing us how it's possible to install Debian chroot on an Android phone, and run Linux software like GQRX, GNU Radio, DSD, rtl_433, multimon-ng and dump1090 directly on the phone with an RTL-SDR.

His latest Reddit post shows that the NOAA-APT decoder also runs well on the Debian chroot, leading to a truly portable NOAA decoding setup. He notes that he is now working on the possibility of Meteor M2 decoding on the phone.

Below is his video from last year demonstrating SDR GQRX and GNU Radio running on the Debain chrooted phone.

GQRX, GNU Radio, Rooted Android

Decoding and Logging GPS Coordinates From Wireless Smart Meters

Back in April we posted about "Hash's" RECESSIM YouTube series on hacking electricity smart meters using a software defined radio. Recently his series continues with a video on decoding and logging the GPS coordinates sent by the smart meters used in his area. Using a car, SDR and laptop he was able to drive down the freeway collecting smart meter data as he travelled, decode the data, and plot it on a map. In his video Hash explains why there is GPS data in the signal, and how he was able to reverse engineer and determine the GPS data.

Smart Meter Hacking - Decoding GPS Coordinates

Tech Minds: Remote SDR V2 with Orange Pi and Transmit Capable

In his latest YouTube video Tech Minds explains and demonstrates Remote SDR V2, which is software that allows you to easily remotely access either a PlutoSDR, HackRF or RTL-SDR software defined radio. It is designed to be used with the amateur radio QO-100 satellite, but version 2.0 now include multiple demodulation modes, NBFM/SSB transmission capability, CTCSS and DTMF encoders, modulation compression and a programmable frequency shift for relays.

In his video Tech Minds shows how to install Remote SDR V2 onto an Orange Pi via the SD card image, how to access the web interface, and how to access and use the connected SDR.

Remote SDR V2 with Orange Pi and Transmit Capable

We note that the code is designed to be run on Orange Pi boards, which are low cost single board computers similar to Raspberry Pi's. However over on Twitter @devnulling has indicated that his own fork of the code should run on x86 systems. Aaron @cemaxecuter is also working on including it into a DragonOS release.

The image below demonstrates a typical Remote SDR V2 transceiver setup with two HackRFs.

A full QO-100 Transceiver Setup with Remote SDR V2 and two HackRF's.

European GNU Radio Days: Presentation on gr-rpitx

J.-M Friedt has created a block for GNU Radio called gr-rpitx which allows a Raspberry Pi to be used directly as an output RF sink in GNU Radio. If you were unaware, RPiTX is software that allows you to turn your Raspberry Pi into a transmit capable SDR without any additional hardware apart from a wire antenna connected to a GPIO pin. It works by modulating a GPIO pin in a way to generate any arbitrary signal modulation. gr-rpitx allows this software to be used directly within GNU Radio.

In his presentation uploaded early for the upcoming online European GNU Radio Days conference, J.-M Friedt explains how gr-rpitx works, and shows how you can easily connect any flowgraph to the gr-rpitx output sink. His examples demonstrate retransmitting broadcast FM using an RTL-SDR, broadcasting digital signals like DRM, and how gr-rpitx and RTL-SDR could be used as part of a basic scalar network analyzer.

gr-rpitx uses the GPIO4 output of the Raspberry Pi to generate a radiofrequency stream fed by a GNU Radio signal processing flowchart with sample rates up to 400 kS/s.

European GNU Radio Days/SDRA presentation about gr-rpitx (J.-M Friedt)

Frugal Radio: A Review of the NooElec Inmarsat Patch Antenna Bundle

In his latest video Rob from Frugal Radio has reviewed the NooElec Inmarsat Patch Antenna Bundle. The US$79.95 bundle includes a PCB patch antenna, Inmarsat SAWBird LNA, SMA DC Block, SMA Barrel adapter and SMA pigtail. In the video Rob tests the bundle out on various AERO signals using the JAERO software, before moving on to compare the bundle with our own RTL-SDR Blog Active L-Band Patch antenna. The comparison results show that our $49.95 L-band antenna is better by about 5-6dB in SNR.

Our RTL-SDR Blog Active L-Band Patch antenna set is available on our store. However, please note that this antenna is currently in short supply due to the global electronics supply chain shortage. We expect to be sold out within a few days but we are aiming to be able to restock within 1-2 months from now.

Review : NooElec L Band Inmarsat Patch Antenna Bundle