Field Guide · hardware

Also known as: RSP1A, SDRplay RSP1A

SDRplay RSP1A is a low-cost, receive-only software-defined radio that tunes continuously from 1 kHz to 2 GHz with a 14-bit ADC and up to about 10 MHz of visible bandwidth.1 Built around the Mirics MSi001 tuner and MSi2500 sampling chip, it offers markedly more dynamic range and preselection than an RTL-SDR while staying in a similar price class.2

02 GHz4 GHz6 GHz RSP1A (1 kHz–2 GHz) continuous coverage
The RSP1A covers everything from VLF through UHF with one antenna port and a 14-bit converter.

Overview

The RSP1A is SDRplay’s entry-level model and the reference design the rest of the RSP line builds on. Its appeal for scanning and general monitoring is the combination of an uninterrupted tuning range — no LF/HF/VHF gap — with real front-end filtering: a bank of switchable preselection filters, an MW/broadcast-FM notch, and a software-controlled bias tee for powering an active antenna or LNA. Sampling at 14 bits gives it far better dynamic range and resistance to intermodulation than the 8-bit RTL-SDR, so strong nearby signals are less likely to desensitise the receiver or spray spurs across the band.

What it is

Internally the RSP1A is a Mirics chipset: the MSi001 is a broadband zero-IF tuner, and the MSi2500 handles the ADC and USB interface. The device streams raw IQ samples over USB 2.0; all channelisation, demodulation, and decoding happen on the host. The maximum displayed spectrum span is around 10 MHz, though the ADC actually samples faster and decimates internally. Unlike the RTL-SDR, the RSP family is not libusb-generic — SDRplay ships a closed API/service (the RSP driver daemon) that applications talk to, and a SoapySDR module (SoapySDRPlay) that exposes the RSP through the common Soapy interface used by GNU Radio, SDRangel, CubicSDR, and others.

Variants

The RSP1A sits at the base of a family that trades up in front-end sophistication:

  • RSP1 / RSP1B — the original RSP1 was simpler (fewer filters, no bias tee); the RSP1B refreshes the RSP1A with improved LF/MW performance and remains single-tuner.
  • RSPdx — adds more preselection filters, three antenna ports, and a high-dynamic-range (HDR) mode optimised for LF/MW/HF.
  • RSPduo — a dual-tuner design that can run two 2 MHz streams at once for diversity or simultaneous monitoring of separated bands.

All share the same underlying Mirics silicon and the same SDRplay API, so software support carries across the range.

Relevance to SDR

The RSP1A is a popular choice for HF through UHF listening: shortwave and amateur bands, ADS-B at 1090 MHz, VHF/UHF land-mobile, and broadcast monitoring. Its 14-bit converter and preselector make it a step up for crowded RF environments where an RTL-SDR would overload.

For trunking specifically, the ~10 MHz span lets it cover a system’s control and voice channels from a single capture, much like an Airspy. The practical caveat is the driver model: GopherTrunk drives RTL-SDR, HackRF, and Airspy hardware directly, whereas the RSP line depends on SDRplay’s proprietary API/service. Using an RSP1A with GopherTrunk therefore hinges on a SoapySDR/RSP bridge rather than a native backend — check the project status before assuming turn-key support. As a receiver the hardware is well suited to the task; the integration path, not the RF, is the limiting factor.

Sources

  1. Software-defined radio — Wikipedia, background on receiver-class SDRs including the SDRplay RSP line. ↩

  2. RSP1A — SDRplay, official product page with tuning range, ADC resolution, filtering, and bias-tee specifications. ↩

See also