Category: Airspy

Demod: An iOS/iPadOS Client for rtl_tcp, SpyServer and KiwiSDR

Thank you to Alphonse Romero for submitting news about the release of his new iOS and iPadOS SDR receiver app called Demod. Demod is a network client that connects to remote SDR servers, so it can be tried out immediately with no dongle needed at all. 

The app works as a client for rtl_tcp, SpyServer (Airspy and RTL-SDR), and KiwiSDR, all in a single app. It features a Metal-accelerated waterfall and spectrum display, AM/NFM/WFM/USB/LSB/CW demodulation, and adjustable bandwidth, gain, and squelch. Other features include frequency memories with CSV import and export, AirPlay and Lock Screen controls, and native layouts for both iPhone and iPad. It can also browse and connect to public SpyServers directly from within the app, which is how it can be used with no hardware of your own. The developer notes that it collects no data, with no ads or tracking.

Alphose writes that Demod is a solo project and is available on the US App Store for US$9.99. More information and screenshots can be found on the project website, and the app itself is available on the App Store.

The developer has also provided us with 15 free codes that we will be giving away in one week. To enter the giveaway, simply comment on this post (make sure to include your email address in the comment so that we can send you the code), the X post, or the Facebook post. (UPDATE: ALL CODES HAVE BEEN ALLOCATED NOW, THANKS!)

Demod iOS SDR App
Demod iOS SDR App

NyxScope: A Windows Multi-Protocol SDR Decoder Program with Multiple Digital Native Decoders

Recently, we've learned about NyxScope, a multi-protocol SDR receiver program for Windows that comes with multiple native decoders built right into the software. Their own description describes this all-in-one program best:

You get spectrum and waterfall, multiple concurrent VFOs, trunked-radio following, digital voice, aviation and marine tracking, paging, ISM sensors, HD Radio, and transcription, in one binary.

NyxScope includes decoders for P25 Phase 1 and Phase 2 voice, EDACS and NXDN control channels, ADS-B, AIS, ACARS, POCSAG, FLEX, LoRa CSS PHY + LoRaWAN MAC, Morse, RDS, CTCSS/DCS, Iridium decoding (with voice), and also includes a signal classification tool, Bluetooth LE scanner, and Whisper voice-to-text transcriber. It also outsources decoding of other protocols to mature decoding software such as multimon-ng, rtl_433, dsd-neo, nrsc5, direwolf, dumpvdl2, dump978, rs41mod where required, noting that the outsourced decoders are bundled with the software, meaning no extra installation work is required.

The software supports RTL-SDR, HackRF, Airpsy, bladeRF, SDRplay, Fobos and PlutoSDR. It also supports using multiple SDRs used in parallel.

The software does not appear to be open source, but it is provided for free with a limitation of 3 concurrent VFOs and a limitation on recording, transcribing, and pager messages. A perpetual per-machine license for $89.95 can be purchased to lift these restrictions and add access to their FCC frequency lookup database.

AI-Disclaimer: While the developers have not noted any use of AI tools, we suspect that AI was used in the creation of this software.

NyxScope Screenshot Scanning the 800 MHz Band
NyxScope Screenshot Scanning the 800 MHz Band

InmarScope: An Inmarsat AERO and STD-C Decoder with Multichannel Decoding and Automatic Call Following

Over on the SignalsEverywhere YouTube channel, Sarah Rose has released InmarScope, a multichannel L-band Inmarsat decoder that connects directly to an RTL-SDR, Airspy, or HackRF. The software can receive and decode both aeronautical (AERO) and maritime (STC-C / EGC) traffic at the same time. Decoders are dropped directly onto the aligned FFT and waterfall by holding CTRL and left-clicking, and the software lets you stack Aero MSK (600/1200 bps), high-rate OQPSK (10500 bps), AMBE voice (8400 bps), and Inmarsat-C BPSK decoders side by side.

One of the more interesting features is automatic voice-call following. By monitoring the 10500 baud forward-link channels, InmarScope can receive C channel voice assignments and automatically retune the SDR to the assigned frequency, lock the carrier, decode and record the AMBE call, and then hop back to where it was. There is also a two-SDR mode that dedicates a second radio to voice with a live split-view spectrum so one radio stays on the P control channel while the other tunes to voice calls. For assignments that never get broadcast, there is also a Call Hunter feature that uses a squelch threshold to automatically drop the decoder when a call appears. When a call is playing, the built in flight map also decodes the aircraft hex ICAO address and looks it up on airplanes.live, showing the plane's position and route in real time.

Recent updates have added a community-editable band plan, message search and filtering, an IQ recorder that also captures the seconds before you hit record, and a web dashboard for browsing decoded data from a phone.

The software is completely open source on GitHub, and the C++ code can be compiled from source, or a precompiled Windows build is available on sarasforge.dev for $15, with Sarah's Patreon patrons getting it free.

We note that Inmarsat signals such as AERO and STD-C/EGC can be received with our RTL-SDR Blog L-band Patch Antenna, which is available in our store.

Multi-Channel Voice Following Inmarsat Decoder for Windows!

Decoding Inmarsat in 2026

Airspy 2026 Summer Sale: 20% Off All Airspy Products

Airspy has just announced its annual summer sale, offering 20% off all Airspy products from June 27 to July 4, 2026. 

  • Airspy R2: US$169.00 US$135.20
  • Airspy Mini: US$99.00 US$79.20
  • Airspy HF+ Discovery: US$169.00 US$135.20
  • Airspy SpyVerter R2: US$49.00 US$39.20
  • YouLoop Antenna: US$39.95 US$31.96

The sale is active at all participating resellers, which includes our own store, where we have the YouLoop on sale for US$31.96, including free shipping to most countries worldwide (excluding tariffs!). 

A New SDR# Panadapter Plugin

Thank you to Marco Argilli (IU4HMY) for writing in and sharing with us the release of a new SDR# Panadapter plugin that turns the popular RTL-SDR- and Airspy-compatible program SDR# into a panadapter for your transceiver. A panadapter gives you a live spectrum and waterfall view of the band around your radio's tuned frequency, which makes it much easier to spot activity, find clear frequencies, and visually navigate a busy band. Synchronization between the radio and SDR# is handled by OmniRig, so as you tune your transceiver, the panadapter display follows along.

To use the plugin, you connect your SDR to your transceiver's IF or antenna output, then set the receiver IF frequency and a per-mode offset in the plugin settings, with changes saved to a JSON config file. The plugin also has band presets, where a right-click on a preset button stores a snapshot of frequency, demodulation mode, and zoom level, so you can recall a favorite spot instantly. SDR# version 1921 or newer and the .NET 9 framework are required, and it runs on Windows 8, 10, and 11.

There are a couple of limitations worth noting. Marco recommends using Center Frequency mode for the best performance, and because OmniRig exposes the frequency as a 32 bit COM value, frequencies above around 2.1 GHz are not supported. The plugin does not appear to be open-source, but it is free for personal and non-commercial use.

SDR# Panadapter Plugin Screenshot
SDR# Panadapter Plugin Screenshot

iq_tool: A Command Line Tool for Resampling, Filtering, Shifting and Correcting IQ Data Streams

Thank you to Eric Inloes for submitting to the blog his new tool called "iq_tool". This is a tool designed to "provide an easy, fast, and lightweight command-line utility for converting I/Q data from files or SDRs to a specific sample rate and format, and then either piping it to other programs or writing it to a file". Or in other words have a "neutral ffmpeg like converter tool but for IQ data".

Many SDR software tools are written for specific SDR hardware, such as RTL-SDRs, and may only accept a specific sample rate, type, or bit depth, meaning other SDRs cannot use these tools. The goal of iq_tool is to easily allow the IQ data stream from any SDR to be converted into a compatible format. 

Eric gives some examples. For example, if you wanted to use rtl_433 with an Airspy you could run the command:

iq_tool --input airspy  --airspy-gain-mode linearity --airspy-gain-value 15 --output stdout  --sdr-rf-freq 433.92e6 --output-sample-rate 250e3 --output-sample-format cu8 --output-agc | rtl_433 -r -

Similarly, for an SDRplay, you could run:

iq_tool --input sdrplay   --sdrplay-lna-state 15 --sdrplay-antenna b --sdrplay-if-gain -50 --output stdout  --sdr-rf-freq 433.92e6 --output-sample-rate 250e3 --output-sample-format cu8 --output-agc | rtl_433 -r -

We note that Eric released this tool with the caveat that it is experimental and was written with heavy AI assistance.

iq_tool example converting from a networked Airspy and piping into rtl_433
iq_tool example converting from a networked Airspy and piping into rtl_433

OpenWXSDR: A Streamlined Automated Multi-Sonde Decoder for Raspberry Pi with RTL-SDR or Airspy

Thank you to Mike (DL2MF) for writing in about the release of OpenWXSDR, a new open-source Python framework that turns one or more RTL-SDR dongles or Airspy SDRs into a fully automated radiosonde ground station running on a Raspberry Pi 4/5 or Linux x86 machine.

If you are unaware, a radiosonde is a lightweight instrument package typically carried by a weather balloon to collect atmospheric data, including temperature, humidity, pressure, and GPS position. It transmits this data back to the ground via radio signals. Using an RTL-SDR or another software-defined radio (SDR) along with appropriate decoding software, hobbyists or researchers can receive, decode, and visualize these signals. Radiosondes are typically launched by local meteorological agencies in many cities worldwide at least twice per day.

OpenWXSDR continuously scans the 400-406 MHz meteorological band, automatically identifies balloon transmissions using DFT correlation analysis, and spawns dedicated rs1729 decoder subprocesses. Supported sonde types include RS41, RS92, DFM06/09/17, M10, M20, iMet-54, LMS6, and MRZ.

The software also supports multi-sonde and multi-SDR. While one dongle scans for new signals, others simultaneously handle active decoding sessions. Decoded telemetry can be submitted in parallel to SondeHub v2 and to OpenWX.de via MQTT (with optional TLS), and as Horus-compatible UDP JSON datagrams for local tools like SondeMonitor. A built-in Flask and Leaflet web interface shows live positions, flight tracks up to 20,000 points, PTU sensor readings, and signal metrics, with most settings editable from the WebUI during operation.

OpenWXSDR Web Interface
OpenWXSDR Web Interface

P25-Survey: A Tool for Scanning and Logging P25 Control Channels with an SDR

Over on GitHub, programmer blantonl has released p25-survey, a Python tool that scans a frequency range with an RTL-SDR, Airspy or HackRF and identifies any P25 control channels present. For each one found, it logs the WACN, System ID, NAC, RFSS ID and Site ID, the full IDEN_UP band plan, neighbor sites with resolved frequencies, and signal quality metrics including RSSI, BER and decode rate.

The tool also has an optional RadioReference cross-reference mode that annotates results with the RR system name and site description, flags frequency offsets versus the database, and generates a Markdown submission report for data not yet in RadioReference. An auto-gain feature sweeps gain values on each confirmed control channel and recommends the optimal setting for your SDR and location based on BER.

P25 Survey Tool
P25 Survey Tool