Fox SDR (or FoxSDR) – Software or Hardware?

| October 15, 2026 | Amateur Radio (Ham Radio) | No Comments

The name Fox SDR (or FoxSDR) currently refers to two distinct and notable projects within the amateur radio and SDR communities:

1. FoxSDR Standalone Transceiver by VU3ZOF

This is a modern, homebrew standalone SDR transceiver project built entirely around a single ESP32-S3 microcontroller. It is designed to provide a high-performance SDR experience without requiring an expensive FPGA or a connected PC.

  • Hardware Architecture:It utilizes the ESP32-S3 to handle all the heavy DSP math, touchscreen user interface, and a real-time, high-speed waterfall display natively.The RF front-end employs a Tayloe mixer paired with a WM8731 audio codec for high-fidelity 24-bit I2S audio processing.
  • Features: The core build supports full SSB and CW transceiver operation, featuring a 3-band graphical EQ and variable DSP filtering (adjustable from 500Hz to 6kHz). It also includes Wi-Fi and USB CAT control support to interface easily with logging applications.
  • Availability: Compiled firmware, complete circuit schematics, and PCB Gerber files are distributed via the project’s website (rdvibes.com). A related branch of this development also integrates Radioberry hardware with a Raspberry Pi and a custom Android app for remote network operation.

2. FoxSDR Software Application (by Steven Fox)

Alternatively, FoxSDR is also the name of a standalone SDR software suite for Windows, Linux, and Android. It is written entirely from scratch with a strict clean-room design (zero GPL-linked dependencies).

  • Capabilities: It features 8 native demodulation modes, 28 catalogue plugins, and native drivers for hardware like RTL-SDR, HackRF, Airspy, and SDRplay.
  • Interface & Integration: The software includes a highly customizable “patch-canvas” interface for wiring virtual radios, demodulators, and decoders together simultaneously. It features built-in map plotting for aircraft (ADS-B) or vessel tracking. It also supports transmitting when paired with an ADALM-Pluto. Several of the features are yet to be tested on real hardware.
  • Availability: It is currently in open beta and is permanently free for hobbyists, SWLs, and non-commercial users (foxsdr.com).

Note: I have used neither of these, though I am thinking of homebrewing the hardware item and has initiated discussions with VU3ZOF. I am also considering whether I can use the second one for my RTL-SDR dongle for which I am currently using SDR#.

If you are looking to homebrew a compact, hardware-based rig, the schematic and Gerber files from the ESP32-S3 project provide a very capable standalone foundation. On the other hand, the PC/Android software suite offers an incredibly versatile and visual interface for driving existing USB SDR dongles.