Field Guide · hardware

Also known as: RSPdx, SDRplay RSPdx

SDRplay RSPdx is a top-of-line receive-only software-defined radio that covers 1 kHz to 2 GHz with a 14-bit ADC, three selectable antenna ports, and an extensive bank of front-end filters.1 It extends the RSP1A with more preselection and a dedicated HDR (high-dynamic-range) mode that sharpens performance below about 2 MHz.2

02 GHz4 GHz6 GHz RSPdx (1 kHz–2 GHz); dark band = HDR mode (LF/MW/HF)
The RSPdx spans VLF to UHF; below ~2 MHz its HDR mode trades span for cleaner dynamic range.

Overview

The RSPdx is aimed at listeners who need the best possible front end in a single-tuner RSP: DXers chasing weak signals under strong broadcast neighbours, and monitors working crowded bands where intermodulation and overload are the real enemy. It keeps the RSP family’s continuous 1 kHz–2 GHz tuning and up to ~10 MHz of visible bandwidth, but wraps the Mirics tuner in a much larger set of switchable preselection filters and adds three antenna inputs (two SMA plus a dedicated HF/BNC path) so different antennas can serve different bands without a patch panel.

What it is

Like the rest of the line, the RSPdx is a Mirics-based receiver that streams raw IQ over USB while the host does all demodulation and decoding. Its defining feature is HDR mode, available on the lower bands (LF, MW, and the HF broadcast/amateur segments). In HDR mode the receiver reconfigures its signal path to widen usable dynamic range and improve spurious-free dynamic range at the cost of instantaneous span — a deliberate trade that pays off when a nearby MW blowtorch would otherwise swamp a distant HF signal. Above those bands the RSPdx behaves as a wideband receiver with the fuller filter bank switched in as you tune.

Variants

The RSPdx anchors the high end of the single-tuner RSP family; the closely related RSPdx-R2 is a hardware refresh with the same interface and feature set. It contrasts with:

  • RSP1A — the entry model: one antenna port, fewer filters, no HDR mode.
  • RSPduo — dual-tuner, trading the RSPdx’s rich single front end for two independent 2 MHz receivers usable in diversity.

All models share SDRplay’s proprietary API/service and its SoapySDR module, so applications see them through a common interface.

Relevance to SDR

The RSPdx is most valued below UHF, where its filtering and HDR mode let it pull weak signals out from under strong ones — a scenario RTL-SDR-class hardware handles poorly. For VHF/UHF trunking it works like any wideband RSP: capture a system’s control and voice channels in one ~10 MHz window and channelise on the host.

As with every RSP, GopherTrunk has no native RSPdx backend — the device requires SDRplay’s closed API/service, so any use goes through a SoapySDR bridge rather than GopherTrunk’s direct USB drivers for RTL-SDR, HackRF, and Airspy. The RF hardware is more than capable; the practical question is driver integration, so verify current project support before relying on it.

Sources

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

  2. RSPdx — SDRplay, official product page covering the 14-bit converter, filter banks, three antenna ports, and HDR mode. ↩

See also