Field Guide · hardware

Also known as: RSPduo, SDRplay RSPduo

SDRplay RSPduo is a dual-tuner receive-only software-defined radio covering 1 kHz to 2 GHz with 14-bit sampling on each tuner.1 Its distinguishing feature is two independent receiver chains that can operate at once — as two separate ~2 MHz streams on different frequencies, or as a coherent pair for antenna diversity.2

Ant AAnt B Tuner 1 (14-bit) Tuner 2 (14-bit) USB Host
Two independent 14-bit tuners share one USB link — usable as two receivers or as a coherent diversity pair.

Overview

The RSPduo effectively packs two RSP-class receivers into one box, sharing a single USB connection and the SDRplay API. That opens uses no single-tuner SDR can manage: watch two widely separated bands simultaneously — say an HF net and a VHF control channel — or point two antennas at the same signal and combine them. It retains the family’s continuous 1 kHz–2 GHz tuning and 14-bit converters, but each tuner’s instantaneous bandwidth is capped around 2 MHz when both run together (a single tuner alone can go wider).

What it is

Each chain is a Mirics tuner and ADC; both stream raw IQ to the host over USB, where all demodulation and decoding happen. Two modes matter:

  • Dual independent — the tuners sit on different centre frequencies, giving two unrelated ~2 MHz windows for parallel monitoring.
  • Diversity / coherent — both tuners share a common clock and can be phase-referenced, enabling antenna diversity to fight multipath and fading, or experiments in coherent processing and direction finding.

The shared reference clock is what makes the coherent mode meaningful: without a common timebase, two receivers cannot be combined sample-for-sample.

Variants

The RSPduo is the only dual-tuner model in the RSP line; the single-tuner alternatives trade its second receiver for other strengths:

  • RSP1A — the low-cost single-tuner baseline.
  • RSPdx — a single tuner with the richest front-end filtering and an HDR mode for LF/MW/HF.

All three use SDRplay’s proprietary API/service and the shared SoapySDR module.

Relevance to SDR

The RSPduo’s niche is anything that benefits from two simultaneous, frequency-agile receivers: diversity reception, spectrum comparison across bands, and multilateration or direction-finding experiments that need phase-coherent captures. For trunking, the dual tuners could in principle follow a control channel on one receiver while a voice channel is tracked on the other, though the ~2 MHz per-tuner limit is narrower than an Airspy’s single wide capture.

As with every RSP, GopherTrunk has no native RSPduo driver — the hardware needs SDRplay’s closed API/service, reachable only through a SoapySDR bridge rather than GopherTrunk’s direct USB backends for RTL-SDR, HackRF, and Airspy. The receiver is capable; integration is the open question, so confirm current support before designing around it.

Sources

  1. Software-defined radio — Wikipedia, background on receiver-class and diversity-capable SDRs. ↩

  2. RSPduo — SDRplay, official product page describing the dual 14-bit tuners, shared clock, and diversity operation. ↩

See also