SDRplay Release a Dual Tuner SDR called RSPduo

The RSPduo
The RSPduo

SDRplay have released a new product at this years Hamvention called the "RSPduo". The product uses the same technology as their previous RSP models, but this time includes a phase-coherent dual tuner architecture which allows you to tune to two completely separate 2 MHz bands of spectrum simultaneously. The RSPduo retails for US $279.95 + shipping. Their press release reads:

Today at the Dayton Hamvention, SDRplay is announcing the launch of a new Software Defined Radio product – the RSPduo.

The RSPduo is a radical new addition to the RSP line of SDR receivers from SDRplay. Architecturally, it is different from any previous RSP in that it features dual independent tuners, both piped through a single high-speed USB 2.0 interface.

The SDRplay RSPduo is a dual-tuner wideband full featured 14-bit SDR which covers the entire RF spectrum from 1kHz to 2GHz giving 10MHz of spectrum visibility. Initially using Windows based ‘SDRuno’ supplied by SDRplay, you can simultaneously monitor two completely separate 2MHz bands of spectrum anywhere between 1kHz and 2GHz.

Superficially the RSPduo looks identical to the highly popular RSP2pro and will be able to operate in a very similar way. However, it also allows a completely new and exciting set of usage scenarios such as:

1. Simultaneous monitoring of two widely spaced bands – e.g. 40m (HF) and 2m (VHF)
2. Mixing and matching applications simultaneously – e.g. ADS-B and ATC scanning
3. Phase and time coherent demodulation of two receivers

Scenario 3 is very difficult to achieve with two separate USB devices because of the uncertainty of USB latency. The RSPduo overcomes this limitation because all traffic goes through a single USB interface, thus enabling the possibility of the development of various types of diversity demodulation such as: spatial, frequency and polarisation which can bring huge benefits in terms of improved performance.

As well as adding a second independently controlled tuner, which in itself, offers a whole new set of exciting usage possibilities, the SDRduo features 14bit ADCs and a completely re-designed RF front end. These changes provide better RF selectivity and even more dynamic range, offering outstanding performance under extremely challenging reception conditions. The combination of performance and features makes the RSPduo our highest spec RSP yet and sets a new benchmark in the sub $300 SDR market.

Lots of great new videos are appearing on YouTube showing the Dual Tuner RSPduo in use. Just search for RSPduo in the YouTube Search bar.

So far several reviews have been released:

SWLing.com review: https://swling.com/blog/2018/05/a-review-of-the-sdrplay-rspduo-14-bit-dual-tuner-sdr/

Sevenfortyone video: https://youtu.be/8WNxtanfWIk

Tech Minds video 1: https://youtu.be/wxu0ZJUvATE

Tech Minds video 2 showing ATC and ADSB together: https://youtu.be/_842u1k8tQY

OG! Review: https://youtu.be/T-eXoNskDmA

While it appears that it will be a useful tool for multi-band monitoring, what we're looking forward to most are the phase coherent applications. Thanks to its phase coherence and predictable USB timing implementation, the unit should be very useful for passive radar and spatial filtering techniques, and we're hoping that SDRplay will be working on software for at least the latter. Multi-channel phase coherent applications are probably going to be one of the the next big developments in the SDR space so it's good to see low cost hardware with this potential coming out now.

We'll be reviewing the unit ourselves within the next month, so keep an eye out for that post!

RSPduo - introduction and software demonstration

17 comments

    • Gareth

      Two tuners. Operation down to 1 kHz on both 50 ohm ports. Better dynamic range. Improved notch filtering. Improved RF pre-selection. 14 bits vs 12 bits

    • Anonymous

      While there are quite a few radar bands from around 2.5 GHz to 36 GHz, I think the current crop of US police radar guns are either around 24 GHz, or in the 33 – 34 GHz range, so you do need to do some significant downconversion. Finding or building a downconnverter that works over 30 GHz might be a bit difficult.

      • Jeff

        Thanks for your reply.
        A passive radar is a radar system that relies on viewing existing transmitted signals from radio or tv stations bouncing off a target.
        You point one receiver at the (FM/TV) source and the other receiver at an area you want to view.
        The two receivers need to be locked. The software compares the two signals and their delays and can create a radar image from any signals bouncing back from the target area.
        So hoping these two receivers are locked.

  1. Bertran

    Shame it is not zoomed in enough to read the markings on the IC’s.
    https://i.imgur.com/llc1qep.jpg
    But at a guess the two tuners (MSI001 – 40 pin QFN) are on the right hand side of the board the chips near the screw holes at the top and bottom of the board. The ADC/DSP/USB chip (MSi2500 – 32 pin QFN) is in the middle close to the USB connector, and almost all the other IC on the board are RF switches or (SPI?) switching multiplexers. Not quite all the chips, there are LDO’s and I think the TCXO is in the top right hand corner, it is hard to see on the blurry image.

    I’m starting to wonder if they are using GPIO pin(s) from the MSi2500 to toggle between the two tuners.

    • Bertran

      Although since everything is clocked from the same 24MHz TCXO, probably no need to do that, scale down the clock and use more SPI switches to enable toggling.

  2. paul

    But where is the software for coherent beam steering, phase cancellation?
    Are there any plans or developments at SDRPlay?
    Or at SDR-Radio.com?
    Elsewhere?

    Without proper SW implementation, you could as well buy two dongles for two bands…

  3. Bertran

    Not a single image of the PCB (yet). I was wondering which RF switch(s) they were using for the “switch matrix” ( https://i.imgur.com/J0oFfET.jpg ), that toggles between the two MSI001’s baseband analogue IQ outputs at a multiple megahertz into the 8-bit ADC of the MSi2500 where DSP processing decimates it up to 14-bits samples. So every odd IQ sample pair is from the same tuner, and every even IQ sample pair would be from the other tuner.

    Overall it does appear to be a good hardware design to get the most out of the parts that were used. It should be phase coherent by design, but the devil is always in the details. I can see no measurements of phase noise or Jitter which would vary with frequency and is very much be depend on the TCXO used and the PLL jitter inside of the two tuners.

    • marketing

      Eeeek. The industry stopped multiplexing ADCs for radio since ages because of the cross-talk of the switches. You better not have strong signals in one tuner when listening to the other.

      • John

        I have no concerns aobut this if it is properly implemented. The switches only operate with signals at a few MHz as this is IF/Baseband. You can certainly achieve well over 100 dB of isolation at those frequencies when dealing with balanced signal paths so full scale in one path should give less than 1 LSB in the other.

  4. Nah

    Really excited for them to remotely block the features of this when they decide that they don’t like a certain vendor

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