DesignSpark Electrical Logolinkedin

RSP2 — an affordable high performance SDR receiver

Second generation Radio Spectrum Processor provides a low-cost solution for receive applications, with improved specifications, new features and multi-platform software support.

The RSP2 (124-9619) from SDRplay bridges the gap between the popular RTL-SDR re-purposed TV tuner dongle that offers the very lowest cost SDR solution, and high-end platforms such as the LimeSDR and UmTRX which provide full-duplex transmit, MIMO and other more advanced capabilities.

Not to do the veritable RTL-SDR a disservice, since it represents truly incredible value for money and even with the limited performance of its 8-bit ADC is capable of receiving all manner of transmissions. However, as we’ll come to see, the RSP2 is a good step up from this.

Key Specifications

While the RSP1 provides continuous coverage from 10kHz to 2GHz, the next generation Radio Spectrum Processor extends this down to 1kHz. Other key features include:

  • 10MHz visible bandwidth
  • 12-bit ADC
  • 10x high-selectivity front-end pre selection filters
  • Software selectable multi-level low noise preamplifier
  • 2x software selectable SMA sockets
  • 1x high impedance balanced input for long wire antenna
  • Software selectable MW/FM notch filter
  • 0.5PPM TCXO
  • 24MHz reference clock I/O via MCX connectors
  • Open API

The RSP2 also improves on its predecessor by adding an RF shielding layer inside the plastic case. Alternatively, the slightly more expensive RSP2pro (125-7958) comes packaged in a metal enclosure.

With both variants, antenna connection is via SMA sockets and robust, pluggable terminals for connecting a long wire, with MCX connectors for the reference clock I/O, and USB Type B.

O/S Support

Software is provided for Windows, Linux x86 and ARM64, Raspberry Pi and Android. With all of which SDRplay supply at the least the driver/API, but much other software is provided also.

  • Windows. SDRuno, SDR Console, EXTIO plugins, SDR# plugin, HDSDR, dump1090, Mirics DVB-T & FM/DAB, and driver/API-only.
  • Mac. CubicSDR, driver/API-only.
  • Linux/x86. CubicSDR, driver/API-only.
  • Linux/ARM64. CubicSDR, driver/API-only.
  • Raspberry Pi. ADS-B, driver/API-only.
  • Android. Driver/API-only (developer use).

Thanks to support for the vendor and platform neutral SDR support library, SoapySDR, Linux users can also benefit from applications which use this API, and also the UHD API via the SoapySDR plug-in for this. SoapySDR also brings with it other benefits, such as the ability to transparently control/tune and stream samples over the network from remote RSP hardware.

It should be noted that a turnkey Raspberry Pi image is also provided.

Other SDR ecosystem software may well work or be made to work — in particular, that which uses the SoapySDR or UHD APIs — and the above is simply a list of software support that is provided directly by SDRplay. The SDRplay playground is also available for sharing ideas, tips and code.

Installing API support on Linux was as simple as downloading a single file, making this executable and running it.

$ chmod +x SDRplay_RSP_API-Linux-2.10.1.run

$ ./SDRplay_RSP_API-Linux-2.10.1.run

This appeared to install a library file to provide the driver/API, along with a header file so that applications can be built which link to this. Plus also udev rules to ensure that the USB device gets set up with the appropriate permissions when it is plugged in.

SDRuno

The SDRuno software from SDRplay was created specifically for RSP/RSP2 receiver hardware. A Windows-only application, this was easily installed on a Windows 7 laptop via the installer.

The main window allows you to create and enable/disable virtual receivers (VRX) and select different input devices, with other hardware supported provided there is an appropriate ExtIO DLL file for it. Plus also the ability to use sound card inputs and pre-recorded IQ files.

While multiple VRX can be created it is only the first one, the master, which can change the local oscillator (LO) frequency. Tuning can be achieved using direct entry, mouse control and via the spectrum display. There are also plentiful keyboard shortcuts.

Other notable features include:

  • Frequency and S-meter calibration
  • External converter offset
  • CAT control slave and master (via Omnirig)
  • Control via Tmate and Tmate2 hardware controllers
  • Memory banks with detailed information

For further details see the SDRuno User Manual.

Documentation

Other documentation provided includes handy application notes on:

  • AGC
  • RSP2 reference clock
  • High Z port
  • Panadapter use (e.g. with commercial amateur radio equipment)

The downloads section of the website also provides how-to and community contributed guides for systems such as ACARS, APRS and AIS, along with software including HDSDR and SDR Console.

Andrew Back

Open source (hardware and software!) advocate, Treasurer and Director of the Free and Open Source Silicon Foundation, organiser of Wuthering Bytes technology festival and founder of the Open Source Hardware User Group.