Roundup of Software Defined Radios

New software defined radio (SDR) products are popping up every few months these days so we thought we’d compile a big list of available SDRs.

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Decoding Digital Voice (P25, DMR, NXDN, D-STAR) with DSD+

Learn how to decode digital voice communications like APCO P25, DMR MotoTRBO, NXDN and D-STAR with DSD+ and an RTL-SDR dongle.

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Cheap AIS Ship Tracking

Large ships and passenger boats are required to broadcast an identification signal containing position, course, speed, destination, and vessel dimension information to help prevent sea collisions. This system is known as the “Automatic Identification System” or AIS for short. AIS can be decoded with an RTL-SDR dongle and right software.

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Review: Airspy vs. SDRplay RSP vs. HackRF

When people consider upgrading from the RTL-SDR, there are three mid priced software defined radios that come to most peoples minds: The Airspy, the SDRplay RSP and the HackRF.  These three are all in the price range of $150 to $300 USD. In this post we will review the three units and compare them against each other on various tests.


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Receiving NOAA Weather Satellite Images

Everyday multiple NOAA weather satellites pass above you. Each NOAA weather satellite broadcasts an Automatic Picture Transmission (APT) signal, which contains a live weather image of your area. The RTL-SDR dongle combined with a good antenna, SDRSharp and a decoding program can be used to download and display these live images several times a day.

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Decoding Meteor-M2 Weather Satellite Images in Real-Time

It is now possible to decode the Meteor M2 weather satellite images in real time on Windows using an RTL-SDR and a plugin for SDR#.

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Decoding Inmarsat STD-C EGC Messages

With an RTL-SDR dongle, a cheap $10 modified GPS antenna or 1-2 LNA’s and a patch, dish or helix antenna you can listen to Inmarsat satellite signals, and decode the STD-C NCS channel which contains information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports.

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RTL-SDR for Budget Radio Astronomy

With the right additional hardware, the RTL-SDR software defined radio can be used as a super cheap radio telescope for radio astronomy experiments such as observing the Hydrogen Line and meteor detection.

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Receiving Weather Balloon (Radiosonde) Data with RTL-SDR

Use your RTL-SDR to decode data from weather balloons (aka Radiosondes) that are launched twice daily by meteorological agencies all around the world.

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Analyzing GSM with Airprobe/GR-GSM and Wireshark

The RTL-SDR software defined radio can be used to analyze cellular phone GSM signals, using Linux based tools GR-GSM (or Airprobe) and Wireshark.

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New Command Line Utility: rtl_power

A new command line wideband spectrum monitor utility called ‘rtl_power’ has been released by keenerd on Reddit. See the original thread here. This tool let’s you gather signal data over a very wide area of the frequency spectrum, and then that data can be used to find active areas of the spectrum.

Rtl_power is a small CLI tool for logging wide swaths of bandwidth. You can specify any chunk of spectrum, with any FFT bin size and any logging rate. (For sane values of any.)

For example

rtl_power -f 150M:200M:2k -i 10 logfile.csv

will monitor everything between 150MHz and 200MHz. The resolution will be at least 2kHz fine. It will integrate for 10 seconds and dump those numbers to the logfile. The structure of the logfile is:

date, time, Hz low, Hz high, Hz step, samples, dbm, dbm, ...

So it is not quite the traditional CSV file. Each frequency hop gets its own line and the frequencies of each column are extrapolated.

Coupled with a python script, a heatmap can be generated from the excel data.

I’m scanning the region between 150MHz and 160MHz, where there is local emergency services chatter. Each pixel is 10kHz wide and 10 seconds long, over a period of seven hours

rtl_power heatmap

This is command line tool is somewhat similar to the Scanner Metrics SDRSharp plugin, which allows large areas of the frequency spectrum to be monitored from within SDRSharp.


  1. johndoe

    Would be fine have more configurable. For example labeling every x khz not only 2mhz hardcoded. Horizontal labeling for example every x mins. But ill give chance, its only alpha :)

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