Also known as: RSPdx, RSPdx-R2, SDRplay RSPdx, SDRplay RSPdx-R2
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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
Key takeaways Top-of-line single-tuner RSP: 14-bit, three antenna ports, HDR mode. The RSPdx wraps the Mirics tuner in the family’s richest preselection filter bank and adds an HDR dynamic-range mode below ~2 MHz — the pick for DXers fighting overload under strong broadcasters. GopherTrunk support is network only: it drives the RSPdx over a SoapySDR/rtl_tcp bridge, not as a direct USB device, because SDRplay’s closed API/service rules out the pure-Go USB path used for RTL-SDR, HackRF, and Airspy. Around $220. Like every receiver, it can’t decode AES encryption.
GopherTrunk support: network only. GopherTrunk drives the RSPdx over the network via SoapySDRServer/SoapyRemote (or an
rtl_tcp-style bridge), not as a direct USB device — you run SDRplay’s API service and a SoapySDR server on the machine it’s plugged into and mount it over TCP. GopherTrunk’s pure-Go USB drivers cover only RTL-SDR, HackRF, and Airspy. See the hardware guide and rtl_tcp notes.
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-R2 is the current-production revision (2023) and the one you will buy new today — it supersedes the original RSPdx with a refreshed front end and an upgraded processor for improved performance, while keeping the same three antenna ports, 14-bit converter, HDR mode, interface, and software. Treat “RSPdx” and “RSPdx-R2” as the same device for GopherTrunk purposes; prefer the R2 when buying. The line 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.
Where to buy
The RSPdx is sold by SDRplay and its distributors, and listed on Amazon. Note the integration path before buying it for GopherTrunk: it is supported over the network only, through a SoapySDR/rtl_tcp bridge rather than GopherTrunk’s direct USB drivers — see the hardware guide. If you want a plug-and-play scanner front end instead, a RTL-SDR or Airspy is the simpler choice; the RSPdx’s real edge is HF/below-UHF DXing.
As an Amazon Associate, GopherTrunk earns from qualifying purchases — at no extra cost to you. It never changes what we recommend.
Sources
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Software-defined radio — Wikipedia, background on receiver-class SDRs including the SDRplay RSP line. ↩
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RSPdx — SDRplay, official product page covering the 14-bit converter, filter banks, three antenna ports, and HDR mode. ↩
Frequently asked questions
Does GopherTrunk support the SDRplay RSPdx?
Yes, but network only. GopherTrunk’s pure-Go USB drivers cover RTL-SDR, HackRF, and Airspy — not the RSP’s closed API/service. You drive the RSPdx over the network via a SoapySDRServer/SoapyRemote (or rtl_tcp) bridge: run SDRplay’s service and the Soapy server on the machine the RSPdx is plugged into, then mount it over TCP. See the hardware guide.
What does the RSPdx add over the RSP1A?
A much larger bank of switchable preselection filters, three antenna ports (two SMA plus a dedicated HF/BNC path), and an HDR (high-dynamic-range) mode below about 2 MHz that trades span for cleaner dynamic range. For VHF/UHF trunking the two behave similarly; the RSPdx earns its price mainly on crowded HF and below.
Can I use the RSPdx's HDR mode with GopherTrunk?
GopherTrunk sees the RSPdx only as an IQ source over the SoapySDR/rtl_tcp bridge, so HDR mode and antenna-port selection are configured on the SDRplay service side, not from GopherTrunk. For VHF/UHF trunking you would typically run it as a plain wideband receiver anyway.
RSPdx or a directly-supported SDR for GopherTrunk?
For scanning simplicity, a plug-and-play RTL-SDR or Airspy needs no bridge. Reach for the RSPdx when you want its best-in-class front-end filtering and HDR dynamic range and are willing to run a SoapySDR server for it.