Two Antenna Diversity For the SDRPlay RSPDuo now Available in SDRUno

The SDRplay RSPDuo is a 14-bit dual tuner software defined radio capable of tuning between 1 kHz - 2 GHz. It's defining feature is that it has two receivers in one radio, which should allow for interesting phase coherent applications such as diversity.

In the latest v1.32 release of SDRUno a diversity feature has been added. Diversity reception was demo'd back in May at Hamvention, and we have a previous post with video about that. Diversity works by subtracting or adding two signals from the two receivers running independent antennas. The result is an up to 3 dB increase in SNR, and better performance with fading signals. They write:

From V1.32 onwards, MRC (Maximal Ratio Combining) Diversity is supported using the RSPduo. MRC Diversity can be used to combine the 2 tuner input streams together to potentially improved the SNR (signal to noise ratio). The same frequency is used for both tuners in the RSPduo and the gain can be adjusted either on each tuner independently or locked together (the default method).

Diversity mode is enabled by clicking on the RSPduo MODE dropdown and select DIVERSITY. Make sure both the 50 ohm ports are connected to the correct input source and note that the HiZ port is not available for Diversity mode. Trying to use the HiZ port will result in an error message being displayed.

Diversity Controls in SDRUno
Diversity Controls in SDRUno

13 comments

  1. JTC

    This seems like an interesting and potential useful feature, although I’m not familiar with the SDRUno software, I primarily use GQRX on Ubuntu with either an RTL-SDR, Kerberos or an Airspy. Anyone know if the SDRUno can be used in fashion with other phase coherent devices such as the Kerberos? Or does it only work with the SDRPlay? If the latter, does anyone know of any other software (other than GNU Radio GRC) that might implement this diversity feature?

  2. Martin

    Ahh, the curse of the inexplicable SDR Uno user interface strikes again 🙁

    It doesn’t say you can vary the phase in the brief press release, only the gain.

    The control panel has two sliders for gain adjustment, but no slider for phase.

    The ‘radar’ display and vector line window shows no obvious method of adjustment it just looks like some form of indicator.

    It’s this sort of thing that makes SDR Uno so difficult to use.

    A bit like the hard to find volume control, which just looks like an indicator bar rather than a properly defined slider control.

    Nothing is intuitive and common controls that would be used together are spread across multiple control panels, so you have to keep lots of them open which obscures the receiver waterfall and spectrum panels.

    If you can adjust gain and phase, you should be able to null out single instances of local interference, is this possible ? I can see no reference to this potentially useful function, other than a comment regarding diversity reception and a 3dB boost in signals, which isn’t quite the same thing.

    Regards,

    Martin – G8JNJ

  3. SDR User

    The phase can be adjusted That is exactly what the vector line does. Length is magnitude and position on the circle is the relative angle from 0-360 degrees

  4. Martin Ehrenfried

    “The same frequency is used for both tuners in the RSPduo and the gain can be adjusted either on each tuner independently or locked together”

    Pity they didn’t include a phase adjustment too, as it’s still not offering enough to entice me to use SDR Uno.

    Although the ‘radar’ display seems to be ready for it, so maybe they will at some point in the future ?

    Regards,

    Martin – G8JNJ

    • SDR User

      The phase can be adjusted That is exactly what the vector line does. Length is magnitude and position on the circle is the relative angle from 0-360 degrees

        • SDR user

          Relative phase of the two diversity channels. The ‘auto’ feature adjusts the phase and amplitude to maximise the SNR. You can turn off the auto feature and manually adjust both the amplitude and phase if you want to try noise cancelling

            • SDR User

              In this current version of the S/W that appears to be the case. I guess other applications such as direction finding and passive radar as possible in the future? Only time will tell. In the meantime, SNR improvement can be a big advantage in fading or marginal reception conditions

              • wanaopoly

                exactly, i will wait those days (Directions finding/passive radar) to come, it is interesting things to play with.

                thanks.

Leave a Reply to SDR User Cancel reply

You may use the following HTML:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.