SDRplay as satellite downlink receiver?

Discussion in 'Satellite and Space Communications' started by WD9EWK, Aug 24, 2015.

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  1. W5SAT

    W5SAT Ham Member QRZ Page

    More random thoughts.

    Recently I posted about the elevated noise floor above 420 Mhz when orienting my Elk antenna horizontally. I noticed that when aimed towards the TV transmitters on South Mountain my noise floor would jump up 25 dB. I looked into this more today and what I found is A) this only happens when the LNA is turned on and B) only when I have a line of sight to the South Mountain transmitters. When my house was between the antenna and TV transmitters the problem did not manifest itself - presumably the house attenuation was enough to not cross the threshold to cause the problem. So, my conclusion is that in the presence of such strong signals - multiple 6 Mhz wide ATSC signals - the front end is getting overloaded and causing the dramatic rise in noise floor. It made no difference what sample rate or whether "Low If" or Zero IF" mode was used.

    SDR Sharp - I am not even a little surprised by this seeing how the website moved to and the fact that SDR Sharp and Airspy are in bed together. It's their right to do what they want. Fortunately, SDRPlay and SDR Console seem to have a relationship and are working together to integrate SDRPlay fully into SDR Console. I like SDR Console and think it decodes very well and has some great features but the interface is a bit clumsy to get around. We'll see how SDR Console V3 works whenever it gets released. So, in the end, like Patrick I am finding myself using HDSDR more than anything else.

    I have SDR Sharp v1.0.0.1361 with SDRPlay ExtIO installed zipped for archival purposes on my Google Drive if anybody needs it. It's portable so it requires no installation. This runs on Windows 10 and was the last build before they went to .NET 4.6. Luckily, I installed this the day before they made all the changes.

    Ok, that's it for now......
    WD9EWK likes this.
  2. WD9EWK

    WD9EWK Ham Member QRZ Page

    Interesting... more to play around with, this weekend.

    Some were reporting in other places that older versions of SDR Sharp worked with the SDRplay, without installing the SDRplay ExtIO driver into SDR Sharp. So it should be possible to make SDRplay and SDR Sharp play nice with each other, again. Hopefully the SDRplay guys are trying to address this, so they don't lose out on one selling point - compatibility with different SDR software packages.

    When I went to that link, it took me to the last SO-50 recording you posted. I should be able to do the same with my laptop and whatever older version of SDR Sharp I have on there, but it would be nice to have another copy set aside - until the SDRplay is able to work with the new versions of SDR Sharp.

  3. W5SAT

    W5SAT Ham Member QRZ Page

    Oops... I linked to a single file instead of the whole directory. My bad. Try this instead: This the whole folder.

    Agreed that not being SDR Sharp compatible is going to hurt sales..... But, I'm sure that SDR Sharp/AirSpy are VERY well aware of that.

    I'd like to see some ADS-B software that supports SDRplay as well......
  4. WD9EWK

    WD9EWK Ham Member QRZ Page

    Yes, SDRplay is very aware of that. I read on the SDRplay community forum that SDRplay used to work with SDR Sharp, without using an ExtIO DLL. Shouldn't be a major programming exercise to make the SDRplay work on the newer versions of SDR Sharp (but I'm not a programmer).

    That would be nice. I think only my RTL-SDR dongles have worked with some ADS-B software I tried a while back. Worked well at home with an RTL-SDR dongle and a Diamond telescoping whip, and really well at my office using the whip antenna supplied with the same dongle.
  5. WD9EWK

    WD9EWK Ham Member QRZ Page


    After a series of exchanges across Twitter and other places during the past day or so, the SDR Sharp group has posted a download with a version of SDR Sharp for those using the SDRplay receiver, until a new driver or API that works with the SDRplay and newer version of SDR Sharp is published. The download is available at:

    As of now, this download is not available on the Airspy/SDR Sharp download page. I downloaded a copy of it, and may give it a try this weekend. This was posted on the SDR SHarp Twitter feed last night:

  6. W5SAT

    W5SAT Ham Member QRZ Page

    That was nice of them. That's the same version i have archived - v....1361

    So, when you think about this, it's not THAT big of a deal unless SDR Sharp development races ahead and SDRplay cannot be integrated. As it stands right now, SDR Sharp - the Version ...1361 - is mature and stable and all the plugins, etc will work. So, worst case scenario is that SDRplay users are stuck with this version which supports all the plugins and works fine.
  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    As much as the SDR Sharp people say they work with the different receivers, it appears that the SDRplay group was not in the loop with the recent SDR Sharp upgrades using the .NET 4.6 framework that broke the SDRplay ExtIO DLL. Maybe it has to do with the SDRsharp developer being part of Airspy, and SDRplay is a competitor to Airspy in the marketplace. I'm OK with this SDR Sharp version, as I don't normally go out and grab lots of plugins. In fact, the way SDR Sharp/Airspy bundled this version is a lot better than the way SDR Sharp is normally installed. I think the normal installer is annoying, so being able to unzip this archive works OK for me.

    BTW I stopped by the Phoenix HRO this morning. Lots of SDRplay receivers in the display cabinet, each in a small box. :)
  8. W5SAT

    W5SAT Ham Member QRZ Page

    Well, I did my share in making that pile of small boxes disappear from the display cabinet. They have HDSDR running with a SDRplay back in the corner by all the demo radios too.
  9. WD9EWK

    WD9EWK Ham Member QRZ Page

    Brad (KG7NXH),

    Would you be able to share the settings you're using in HDSDR for the SDRplay that let you receive without that pesky center spike? I have tried to work passes with mine, and so far I either have the center spike or a very wide signal at the center of the passband unless I stay with settings like I illustrated early in this thread. Or if you can at least point me to places where your settings differed from mine, that would be great.

  10. W5SAT

    W5SAT Ham Member QRZ Page

    Patrick, Here are some examples from HDSDR and SDRplay using different methods to remove DC spike.

    One thing to play with is also the Bandwidth setting next to RX DC Removal Mode - I didn't get any screenshots of that but you can experiment and see the effects on center frequency spike removal.

    Below, ExtIO settings and RX DC Removal settings are changed and their affect on DC spike removal at LO frequency is shown

    This is the "normal" mode where ExtIO is set to Zero IF and Input Channel Calibration for RX is Off. HDSDR LO is set to 147.200 Mhz (local repeater). Large DC spike can be seen in this mode.

    FM voice carrier is active and you can see the DC spike well above carrier. FM modulated audio cannot be decoded.

    Here, ExtIO is still set to Zero IF and Input Channel Calibration for RX is now set to Auto. HDSDR LO is set to 147.200 Mhz (local repeater). DC spike is almost eliminated and I can decode FM voice now.

    Here, ExtIO is still set to now set to Low IF and Input Channel Calibration for RX is now set to Off. HDSDR LO is set to 147.100 Mhz (clear frequency). DC spike is very low and FM can be demodulated.

    Here, ExtIO is still set to Low IF and Input Channel Calibration for RX is now set to Auto. HDSDR LO is set to 147.100 Mhz (clear frequency). DC spike is completely eliminated.

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