FUNcube Dongle

Also known as: FUNcube Dongle, FCD, FUNcube Dongle Pro Plus

FUNcube Dongle is an early UK USB software-defined radio receiver, created by Howard Long under the AMSAT-UK amateur-satellite banner and named after the FUNcube educational cubesat whose telemetry it was built to receive.¹ Launched in 2010 — before hobbyists discovered that cheap DVB-T dongles could stream raw IQ — it was one of the first affordable, self-contained SDRs aimed squarely at ordinary computer users, and it helped seed the SDR hobby that the RTL-SDR would later make ubiquitous.

The Pro+ reaches from LF up to 240 MHz and again from 420 MHz to 1.9 GHz, with a gap in between — receive only.

Overview

The FUNcube Dongle was designed for a concrete mission: giving schools and radio amateurs an easy way to receive satellite telemetry from AMSAT-UK’s FUNcube spacecraft (FUNcube-1 / AO-73). Unlike the repurposed TV tuners that came after it, the FCD was purpose-built as a receiver — a small USB stick presenting itself as a USB audio device, so its demodulated IQ arrived through the operating system’s standard sound interface at up to ~192 kHz, needing no special driver. That plug-and-play simplicity, at a time when SDR otherwise meant expensive or DIY hardware, was its appeal.

Variants

FUNcube Dongle Pro (2010). The original. It targeted the VHF/UHF amateur-satellite bands, covering roughly 64 MHz – 1.7 GHz, and established the USB-audio-device design.
FUNcube Dongle Pro+ (2012). The improved and better-known model. It widened coverage dramatically — about 150 kHz – 240 MHz and 420 MHz – 1.9 GHz, with a gap between the two segments — added input filtering and a TCXO for better frequency stability, and kept the ~192 kHz capture width. The lower-frequency reach let it work HF and the GNSS and satellite bands the hobby cared about.

Both are receive-only, drew their power from the USB port, and used an SMA-style antenna connector on later revisions.

In practice

By modern standards the FUNcube Dongle’s ~192 kHz of bandwidth is narrow — an RTL-SDR captures more than ten times as much, and an Airspy far more — but for its intended job of demodulating a single satellite’s narrowband telemetry that width is ample, and the dedicated receiver design gave it cleaner performance and better stability than the earliest RTL-SDR dongles. It was priced around £125, well above a later RTL-SDR but reasonable for a purpose-built receiver of its era. Its main historical significance is as a bridge device: it proved there was a real amateur market for a cheap, simple, computer-connected SDR just before the RTL-SDR discovery made such a thing nearly free.

Relevance to GopherTrunk

The FUNcube Dongle predates and is largely superseded by the RTL-SDR generation GopherTrunk targets, and its narrow ~192 kHz capture is far too small to channelise the multiple wideband control channels a trunking system spreads across a band — so it is not a practical front end for GopherTrunk. It matters here as context: it is an early milestone in the story of affordable SDR, the receiver niche the cheaper, wider RTL-SDR soon filled for scanning and trunk-tracking. For decoding, use a modern RTL-SDR or Airspy instead.

Sources

Funcube Dongle — Wikipedia, on the FUNcube Dongle’s origin, variants and coverage. ↩