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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

    Of all the main windows SDR softwares I actually prefer SDR-Radio V2.3

    I know it supports the SDRPlay, RTL-SDR and others but not HackRF. It's interface is a bit quirky but it is very, very versatile. Not sure how it would run on a tablet. It can decode multiple VFOs at once - great for people that can listen to multiple things at one time. Can record and palyback like HDSDR and SDR Sharp.

    I like HDSDR second best. I just wish there was more recent development with it and the ability to do WFM.

    Either way, I am impressed with how well the SDRPlay seems to be performing for you. If/when I ever get back to work I need to buy one of those...
    WD9EWK likes this.
  2. WD9EWK

    WD9EWK Ham Member QRZ Page

    I also like the mouse wheel as a tuning "knob" in HDSDR. Make sure to set the tuning steps to the increment you like, and ensure the mouse wheel is set to adjust the TUNE frequency, not the LO frequency. Then you should be set. This is why I keep a mouse nearby when I use HDSDR to work satellites. Very easy to spin the mouse wheel, easier sometimes than clicking on the waterfall and then having to fine-tune to get the signal lined up.

    Good luck, and 73!
    KD8ATF likes this.
  3. WD9EWK

    WD9EWK Ham Member QRZ Page

    SDR-Radio supports the HackRF devices. I have used mine with it. The SDR-Radio web site has some information on how to make HackRF devices work with that program, or do a Google search to get that information.

    I don't use SDR-Radio on my tablets often, as I think it uses more memory and CPU than the other SDR programs I have tried. I have to really crank down the bandwidth in SDR-Radio on the tablets, so I don't overload them - and avoid options like multiple VFOs. These low-end Windows tablets can only handle so much. On my Win7 Pro laptop, SDR-Radio is a great piece of software. A lot more of a learning curve with SDR-Radio, compared to SDR Sharp or HDSDR. When I'm just listening to stuff, I like using SDR-Radio. For satellite work, the laptop stays indoors, and I go with HDSDR on either tablet (mostly using the smaller 8-inch tablet with a Bluetooth mouse when working satellite passes).

    HDSDR does wide FM, even though it isn't a mode selection like you have for AM, CW, USB, LSB, etc. on the screen. HDSDR considers FM of whatever bandwidth as "FM". You need to go to the Bandwidth menu (F7), and make sure the Output bandwidth is 192000 if you're looking to hear something like a broadcast FM station. This means the Input bandwidth needs to be at least 192000. With a FUNcube Dongle Pro+, make sure both Input and Output bandwidth on that menu are set at 192000. For RTL-type dongles, just pick an Input bandwidth bigger than 192000 and you're set. Same with HackRF devices. Since the minimum IF bandwidth for the SDRplay is 200 kHz (see my screenshot from an earlier post, for the ExtIO controller pop-up), you're all set there.

    As for recent development, I am OK with what HDSDR does. Relying on ExtIO drivers means it should be possible to make it work with anything else that comes on the market - as long as the manufacturer either writes the ExtIO driver (as SDRplay has done), or someone is able to write one based on information provided by the manufacturer (most other SDR devices). I'm not a fan of how SDR Sharp is installed, and - at times - its way-too-frequent updates. I have it on my tablets, as it has some functions that HDSDR lacks.

    W5SAT likes this.
  4. W5SAT

    W5SAT Ham Member QRZ Page

    Thanks for the HDSDR tip on WFM. Yea, they all have some features the others don't.

    I wanted to use an SDR as a panadapter on my TS-2000 but later found out the VHF and UHF IF chain is completely different than for HF and 6 meters and require a bit of SMT work to tap into. Not something I am willing to do - at least while I still have a warranty on it.

    Well, it sounds like your weekend experiments with the SDRPlay were successful. I hope you're happy - now I want one. :)
  5. WD9EWK

    WD9EWK Ham Member QRZ Page

    I'm glad that helps you out. I saw your comment in the other WEFAX thread. Good luck with trying HDSDR for that.

    Diving into the settings for the SDRplay made the difference, and a bit of RTFM (or, in the case of the SDRplay, reading through various PDF documents from their web site). What I did to get the SDRplay working on a Windows 10 tablet should transfer to other Windows PCs using the SDRplay API & ExtIO.

    I saw earlier this morning that SDRplay tweeted a link back to the post in this thread with my screenshots, and put this on their blog. I had been going back-and-forth with SDRplay when their device wouldn't work on my tablets - either under Windows 8.1, or after the upgrade to Windows 10 - until they released the latest version of their API. This device has a lot going for it, and it might be worth writing another article about using the SDRplay, or possibly a comparison between the FUNcube Dongle Pro+ & SDRplay as it relates to amateur satellite operators.

    Back to work, and at a normal hour again... :)

  6. W5SAT

    W5SAT Ham Member QRZ Page

    Well, you did a nice job detailing what you were doing and how you set up the SDRPlay to work - good info for others that may need it. It's really cool what an inexpensive SDR can do these days....
    K2NCC and WD9EWK like this.
  7. K2NCC

    K2NCC Ham Member QRZ Page

    Just bought the HackRF myself. Although it does transmit, doesn't seem I can do that in Windows. Still researching that, hope to not have to fire up Linux or GNURadio. :/

    I use the Airspy, looking forward to the "Spyverter" upconverter to go with it. Better receiver methinks. But I do like being able to see beyond 1.7GHz!

    Posted this thread on Facebook in one of the SDR groups.

    While you're there, most of my posts are about amateur radio, particularly digital modes and SDRs.

    Plus I'm a generally interesting read anyway! :)
  8. WD9EWK

    WD9EWK Ham Member QRZ Page

    Yup. I haven't found anything that enables transmit with a HackRF and a Windows PC, unless I try installing GNU Radio on a Windows PC and go down that path. I have a Linux workstation at home with GNU Radio and other SDR-related stuff on it, but haven't really looked too closely at the HackRF's transmit capabilities. No front-end receive filtering, so I won't use it as a downlink receiver when working satellites. Even if I'm not using the HackRF devices in my portable all-mode satellite station, they are still interesting devices.

    I see a couple of advantages in the SDRplay over the Airspy:
    1. Coverage above and below what you get with the Airspy (down to 100 kHz without needing an upconverter, up to 2 GHz)
    2. The SDRplay's MSRP is US$ 50 less than the Airspy.
    Add in the front-end filters across the entire range of the SDRplay, and you see my reasons for going with the SDRplay instead of the Airspy as another SDR receiver for working satellites. Being able to receive more of the HF bands below 24 MHz without needing additional hardware (other than a different antenna) is a nice bonus.

    Another thing I can't clearly tell with the Airspy... does it have any sort of front-end filtering like the SDRplay or the FUNcube Dongle Pro+? A normal RTL-SDR type of dongle has no front-end filtering, and I can't use those dongles when I work satellites. My 5W FT-817ND will shut those dongles down while I transmit. When I unkey the transmitter, the RTL-SDR dongles return to normal. I also saw this with the original FUNcube Dongle Pro. The SDRplay and FUNcube Dongle Pro+ both have front-end filtering that work for my satellite operating (the FUNcube Dongle Pro+ has SAW filters for the 2m and 70cm bands). The Airspy has some sort of tracking filters for image rejection, according to the specifications on the Airspy web pages. I don't know if this would also allow the Airspy to function while transmitting from a nearby radio. The Airspy folks appear to have done a lot to take an RTL-SDR dongle and improve on it, but I'll pass on getting one right now. Maybe in the future, or - like with the SDRplay - if the price comes down.

    I see the comparisons posted on the Airspy web site, claiming how that receiver's dynamic range measures better than many other SDR devices on the market. That may be the case, but the intersection of price and functionality in the SDRplay was more compelling for me. Now that I'm able to use the SDRplay as a downlink receiver (with a Windows tablet) for working satellites, I'm happy with it. Seeing how a $150-$200 SDR receiver and an inexpensive Windows tablet with free SDR software makes for a decent satellite downlink receiver that is also portable... I like that!

    Last edited: Sep 1, 2015
    K2NCC likes this.
  9. W5SAT

    W5SAT Ham Member QRZ Page

    So after feeling a little inadequate after reading about Patrick's successes with the SDRPlay, I decided I'd do something with my RTL-SDR dongle. I tapped the 10.7 Mhz IF out of my TS-2000 and am feeding that through a Ham it Up Converter to my RTL-SDR dongle. This gives me about 24 Khz of bandwith centered on whatever my main VFO is tuned to and works on all bands the radio supports. I did not use a buffer amp between the IF tap and the Ham It Up Converter as is commonly suggested when doing this mod but from what I can see there is no perceptible loading of the IF or apparent loss of sensitivity. There certainly is some loading of the IF path but it's not noticeable.

    What does this get me? It lets me do low bandwidth IQ recordings of whatever the radio happens to be tuned to. So, if recording a satellite pass for example, the computer is doing tuning of the main VFO so the recordings are already doppler corrected. Nice thing is it basically uses a good radio as the front end for a cheap SDR so with fairly narrow bandwidth being fed to the RTL the problem of no front end filtering on the RTL is greatly reduced. I also get a nice panadapter out of it. So, I would have liked more bandwidth but for the ease fo doing this mod it was worth it to me.

    Patrick, your IQ recordings is what finally pushed me to do this mod to my radio. I also found out that HDSDR can do IF recordings (instead of full BW selected for SDR) so I set my output bandwdith to 24 Khz (which nicely matches the BW of my IF) and I can get reasonable sized recordings.

    I wanted to be able to tap the first IF (70 Mhz-ish) with it's wide bandwidth and therefore would be no need for Ham it Up Converter but it's not easy to get to that path in the radio for the VHF and UHF bands nad it requires SMT work.
    WD9EWK likes this.
  10. WD9EWK

    WD9EWK Ham Member QRZ Page

    Don't feel inadequate. It's great that the RTL dongle can be put to good use like you described. I know of others who have tapped the IF in a radio, and then use a small SDR receiver/dongle that way. You get the "real" radio, but you also get the benefits of SDR at your station.

    I'll have to take a closer look at the recording options in HDSDR, especially with the SDRplay. It wasn't a huge issue when using the FUNcube dongle with its smaller bandwidth, but when I'm starting at 200 kHz with the SDRplay the disk space (or space on my tablets' micro-SD cards) can vaporize quickly. With the holiday weekend, I should have some time to play around with that. I definitely want to use the SDRplay to work more passes, especially FO-29 and SO-50, to see how well it handles the downlinks from those satellites.

    Last edited: Sep 4, 2015

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