ADALM PlutoSDR Spectrum Analyzer: Sweep from 100 MHz to 6 GHz

Thank you to RTL-SDR.COM reader Maka for sharing his latest software for the ADALM PlutoSDR, "ADALM PlutoSDR Spectrum Analyzer." The software is a sweeping spectrum analyzer that uses the 'lock-in amplifier techniques' and it allows you to view the entire 100 MHz to 6 GHz tuning range of the PlutoSDR.

The program is an open-source MIT-licensed Python script that can be run on Linux systems. Instructions to install and connect to the PlutoSDR are available on the program's GitHub page. Maka has also provided a YouTube video (embedded below) demonstrating the software and explaining the lock-in amplifier technique used in his software, as well as two other videos, one explaining the code, and another showing how to measure a filter with it.

Maka writes:

I built an open-source real-time spectrum analyzer using the ADALM Pluto SDR and Python. It allows you to sweep across wide frequency ranges (100 MHz to 6 GHz) and visualize RF signals like Wi-Fi, LTE, GSM, and Bluetooth in real-time.

It includes a custom PyQt GUI with:

  • Adjustable sweep parameters
  • Peak hold
  • Threshold alerts
  • Draggable markers
  • Highlighted known bands
  • Data export to CSV
See Invisible Electromagnetic Waves Around You with ADALM Pluto SDR Spectrum Analyzer + Code

Spectrum SDR: New Android App for RTL-SDR FM/AM Decoding and Spectrum Viewing

Thank you to James Mainwaring of Knowle Consultants for submitting news of the release of his latest Android app called "Spectrum SDR" for RTL-SDR. Knowle Consultants have previously released a range of RTL-SDR Android apps for FM, Airband, Ham FM and ADS-B reception. The new Spectrum SDR app has a spectrum viewer, as well as the ability to demodulate AM and FM signals.

James writes the following about Spectrum SDR:

This application is about having a bit of fun with those amazing little RTL-SDR dongles, whilst listening to AM/FM radio signals. It's nice and easy to use so why not give it a try?

- Covers the full frequency range of your RTL-SDR dongle
- AM and FM, wide and narrow
- FFT display
- Sample rates 240000 Hz to 2160000 Hz
- Bias tee control
- 75 presets over 5 pages
- Gain controls
- Squelch
- Built-in help

Spectrum SDR Android App Screenshot
Spectrum SDR Android App Screenshot

TechMinds: Testing out the SDRBerry Software on a Pi 4 with Touchscreen

Over on the TechMinds YouTube channel, Matt has posted a video demonstrating the SDRBerry software, which can be used with many SDR devices, including the RTL-SDR, on a Raspberry Pi with a touchscreen.

The SDRberry software is designed to be used on a touchscreen. As Matt points out, it has an aesthetically pleasing user interface and is compatible with almost any SDR software via the Soapy interface. Combining an SDR with a Pi 4 touchscreen and SDRberry results in an excellent hand-held SDR system.

In the video, Matt demonstrates the features of SDRberry, showing its RX features as well as some of its TX features, such as speech transmission and FT8, via a built-in WSjtx tab. He then shows the optional web interface, which is still in the early stages of development. Finally, he shows how to install the software and dependencies onto a fresh Raspbian image. 

SDRBERRY - This User Interface Is Just GORGEOUS! AND IT USES SOAPY TOO!

Khanfar Spectra-All: Combine Multiple SDRs into a Wideband Spectrum Analyzer Display

Over the past few weeks we've posted about the release of multiple Windows software programs from M. Khanfar an SDR hobbyist who has begun developing new software for the RTL-SDR and other SDR devices. He's released a Spectrum Analyzer and FM demodulator, directional antenna based radio direction finder, and a gr-phosphor based spectrum visualizer.

Recently, M. Khanfar has released a new Windows program called "Khanfar Spectra-All" which is a gr-phosphor based spectrum analyzer that can combine the bandwidths from multiple SDR devices, including RTL-SDR, Airspy and, HackRF SDRs into a wideband display.

Khanfar writes:

Control all connected SDR devices through a single unified interface. No manual alignment needed - devices automatically position frequency ranges to maintain continuity.

Seamless Spectrum Coverage: Create ultra-wideband monitoring setups that exceed capabilities of any single SDR. Ultra-fast frequency scanning with dwell times as low as 8ms for rapid spectrum sweeps.

Uninterrupted visualization across device boundaries. See all connected SDRs in a single, coherent display. Software automatically detects, initializes, and synchronizes all available SDR hardware on startup. All connected SDR devices function as a single block during scanning operations.

Customize dwell time, frequency steps, and range to optimize for specific monitoring needs. Handles the complexity of coordinating multiple SDRs, presenting a unified interface.

Frequency Locking Across Multiple SDR Instances: Creates a continuous spectrum view by intelligently aligning frequency ranges of all connected devices.

One-Control Operation: Control all connected SDR devices through a single interface with synchronized parameter adjustments.

Turbo Scanning with 8ms Dwell Time: Ultra-fast frequency scanning capabilities for rapid signal discovery.

GPU-Accelerated Visualization: Uses Fosphor, a high-performance GPU-based spectrogram engine, for smooth real-time rendering.

The latest version 1.2 of Khanfar Spectra-All also adds a mobile web interface that can be used to control the settings of the SDRs remotely.

As mentioned in previous posts, antivirus software can flag M. Khanfar's software as suspicious. We suspect these are false positive results due to the PyInstaller system used to create the exe, but please take your own precautions just in case.

Khanfar Spectra-All

rtl_icecast: A Terminal Application for Streaming FM to an Icecast Server with RTL-SDR

Thank you to Jouni (OH3CUF) for submitting news about the recent release of his new Linux terminal based open-source software called 'rtl_icecast', which can be used with an RTL-SDR to stream FM audio to an Icecast server.

Icecast is an open-source streaming media server that broadcasts audio and video streams over the internet.

Jouni writes:

rtl_icecast is a shell native application that uses RTL-SDR to receive FM radio signals and stream them to an Icecast server in MP3 format.

The main target usage for this app is to stream your local HAM FM repeater audio to your public shoutcast/icecast server with just a RTL-SDR USB-receiver and for example Raspberry Pi. It can be used to stream broadcast FM too, of course.

The app is native app and uses the RTL-SDR on hardware level directly. No need to pipe or install anything extra. This works out of the box (well, I hope!)."

A block diagram of how the rtl_icecast streamer works
A block diagram of how the rtl_icecast streamer works

Saveitforparts: Snooping on the SatGus Selfie Satellite

SatGus is a recently launched cubesat owned by CrunchLabs/Mark Rober, an extremely popular science and engineering YouTuber. The satellite is designed to take selfies of CrunchLabs customers' own photos in space, using a screen and a selfie camera mounted on the satellite. It then broadcasts the selfie image back down to a CrunchLabs ground station, where it is eventually emailed to the customer. Customers then claim that they've had their selfie taken in space.

Over on the saveitforparts YouTube channel, Gabe has been attempting to listen in on the SatGus downlink using a HackRF and a motorized satellite dish setup. SatGus transmits telemetry at 400.2 MHz and the payload dump at 2,262.5 MHz. While he is able to receive the signal, Gabe notes that it is encrypted, so not much can be done with it.

Snooping On SatGus Again

Khanfar Phosphor: Real-time GPU Accelerated Spectrum Visualization for SDRs

We recently posted about new software programs from M. Khanfar on Feb 21 and Feb 4. So far, he has released spectrum analysis and FM demodulator software, as well as a power-based direction-finding program. Khanfar is continuing the pace and has just released a new program called "Fosphor Spectrum Visualization Windows Version" (scroll to the end of the page to find it).

This program is based on a GNU Radio backend and the Fosphor engine, a high-performance GPU-based spectrogram engine for real-time rendering. Kahnfar's software also adds frequency scanning capabilities. The software is for Windows only and consists of a single exe for ease of running. It supports RTL-SDR, Airspy and HackRF devices.

The software is free to download but is not open-source. As mentioned in the previous post, antivirus software can flag M. Khanfar's software as suspicious. We suspect these are false positive results due to the PyInstaller system used to create the exe, but please take your own precautions just in case.

Also, we just want to note that this program is based on the GPLv3 licensed https://github.com/osmocom/gr-fosphor. With this program not being open source, we are unsure if it violates the licensing. If any licensing experts are on here, please chime in on the comments.

UPDATE: Khanfar has released the code on GitHub under the GPLV3 licence, so all licensing concerns are alleviated.

Fosphor Spectrum Visualization Windows Version

TechMinds: Using your RTL-SDR Locally with Just a Web Browser

In the latest video on the TechMinds YouTube channel, Matt shows how an RTL-SDR can be used with a browser-based RTL-SDR web app at https://radio.ea1iti.es. We've featured EA1ITI's RTL-SDR web app a few times on the blog in the past, as it's a nice demonstration of what the HTML5 USB API is capable of.

In the video, Matt shows the software in action, receiving signals and he goes through the various settings available.

More information about the software can be found on the help page at https://radio.ea1iti.es/help.html, and the software is available on GitHub.

How To Use Your RTL-SDR Locally With Just A Web Browser