SDRplay as satellite downlink receiver?

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

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  1. WD9EWK

    WD9EWK Ham Member QRZ Page

    Great!

    Even though I use the SDRplay and FUNcube Dongle Pro+ when I work satellites, I have an assortment of the RTL-SDR types of dongles at home - and one at my office. They are a great way to get started with SDR, although with some drawbacks as KG7NXH mentioned. There's no front-end filtering in them, so having a transmitted signal nearby will swamp the cheap dongles. But for a receive-only need above 24-25 MHz, they can do the job. The RTL-SDR dongle at my office serves its purposes well - broadcast FM receiver, sometimes listening in on ham repeaters, and more. The dongle at my office is normally plugged into a PC running Linux, and I use GQRX as the software. I could take it and plug it into a Windows laptop or tablet, if I wanted to play with it on a Windows-based system, when at the office.

    Good luck!
     
  2. W5SAT

    W5SAT Ham Member QRZ Page

    Awesome, Robert. Darn cables and adapters will probably cost more than the dongle. :) For $20 you can have literally hundreds of hours of fun experimenting with all the things that you can receive with these dongles. You can't have that much fun for $20 anywhere that I can think of - not even in the Philippines or Thailand... :)
     
    WD9EWK likes this.
  3. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    I just saw a tweet on the @SDRplay Twitter feed, and on the SDRplay community forum, an announcement that Ham Radio Outlet will be the USA distributor for the SDRplay RSP. This item is already on the HRO web site, priced at US$ 149, and some locations already have this in stock. This is great news for those of us in the USA wanting to purchase the SDRplay, and not deal with potential delays if an SDRplay order from the UK is held up by US Customs.

    73!
     
    W5SAT likes this.
  4. W5SAT

    W5SAT Ham Member QRZ Page

    Hmmm... Looks like Phoenix has them in stock.... I may have to make a detour next time I'm in the neighborhood and pick one up. Thanks again, Patrick. You are a handy guy to have around!!!
     
    WD9EWK likes this.
  5. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    After all the testing I've done with the SDRplay over the past couple of weekends, I think I can scribble a list of the good points of this receiver versus the FUNcube Dongle Pro+. Keep in mind I still like both...

    SDRplay...
    • Cheaper than FUNcube Dongle Pro+
    • Now available through a stateside distributor (HRO), to avoid potential issues with international shipping & Customs clearance
    • Front-end filtering across its entire range
    • Receives at wider bandwidths than 192 kHz maximum bandwidth of FUNcube Dongle Pro+ (up to 8 MHz)
    • API updates can address certain issues with SDRplay (i.e., recent API update removed 380-420 MHz reception gap & fixed issues with Windows tablets)
    FUNcube Dongle Pro+...
    • A smaller and lighter receiver than the SDRplay
    • SAW filters for 2m & 70cm ham bands
    • FUNcube Dongle Pro+ can receive at even narrower bandwidths than 200 kHz minimum bandwidth in SDRplay
    • No drivers or APIs required for the dongle (ExtIO DLL download needed to control dongle from HDSDR, separate from OS support of the dongle)
    • Purchases support the FUNcube satellite project
    Both receivers are usable with the popular Windows SDR programs (HDSDR, SDR Sharp, SDR-Console), and also with recent versions of GQRX in Linux. I use HDSDR when I work satellites, but have SDR Sharp and SDR-Console installed on all of my Windows systems - including the tablets. I have to keep the SDRplay's receive bandwidth around 2 MHz or less with my Windows tablets, as they are not capable of handling larger bandwidths. I see the same issues with my tablets and larger bandwidths when using RTL-SDR dongles at 2.8 or 3.2 MHz bandwidths, and the HackRF devices with bandwidths around 2 MHz or higher (HackRF devices can work with bandwidths up to 20 MHz).

    From my experiences in working FO-29 with these receivers, I think the FUNcube Dongle Pro+ does slightly better at receiving that 70cm downlink when I'm transmitting on 2m. When I am not transmitting to FO-29, these receivers appear to be even in their abilities to hear the downlink. I think this has to do with the FUNcube Dongle Pro+ using SAW filters as its bandpass filters around the 2m and 70cm bands, compared to the passive front-end filtering in the SDRplay. I didn't see any real differences between these two receivers when working SO-50, which also uses a 2m uplink and 70cm downlink, since the single-channel SO-50 downlink is stronger than most signals being retransmitted by the FO-29 transponder. Other than making sure I didn't put my SDRplay too close to my FT-817ND and avoiding potential interference issues when transmitting from the 817, I have no issues at all working AO-73 with either of these receivers. I still want to try the SDRplay on AO-7, but I feel confident it will do at least as well as the FUNcube Dongle Pro+ as a downlink receiver.

    73!
     
  6. W5SAT

    W5SAT Ham Member QRZ Page

    I am definitely going to pick up an SDRplay at HRO. I like the dedicated SAW filters on FCDP+ but for me it's not enough to woo me away from the 8 Mhz B/W and wide/continuous frequency coverage of the RSP. I think the passive filters in RSP will be fine for me since I like to use my SDRs for a lot of different things. If it was 2M/70cm only use I'd probably sway more towards the FCDP+.

    BTW, I got my new RTL SDR in the mail today (with the TCXO, SMA and R820T2 tuner) and it is actually a bit better than my other RTL SDR. Same front end overload and intermods but frequency is right on and receiver is more sensitive in my quick tests. This is the one that Robert, KA2CZU has ordered as well. I need to sneak over to HRO to get the SDRplay now....
     
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  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    Make sure to stop by a store like Fry's Electronics for a USB cable if you don't have a cable to spare (I use a 3-foot/1m cable for mine), and - if needed - adapters if your coax or antenna doesn't use an SMA connector.

    I like both of these receivers for different reasons, but the 8 MHz bandwidth of the SDRplay is a great thing. Your comment about the SAW filters confirmed what I've gathered from reading about those filters. Thanks!

    I ordered a couple of those new RTL-SDR dongles you referenced a couple of weeks ago. What I've seen with them is 100% in line with your comments, Brad. I use all of these devices for different purposes, other than the SDRplay and FUNcube Dongle Pro+ are both suitable for my portable satellite work with their front-end filters.

    73!
     
  8. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    Regarding front-end filtering... I was trying to read over information on the FUNcube Dongle Pro+ and its front-end filtering. Besides the SAW filters for the 2m and 70cm ham bands, I saw a block diagram in a presentation Howard Long G6LVB - the creator of that dongle - that shows bandpass filtering across the entire range that the dongle covers.

    http://mstl.atl.calpoly.edu/~bklofa...ymposium2012/Long_FUNcube_Dongle_Pro_Plus.pdf

    With this in mind, my list above should expand the "SAW filters for 2m & 70cm ham bands" to be more like the SDRplay's mention of filtering. For the FUNcube Dongle Pro+, I'd now say "Front-end filtering across its entire range, including SAW filters for the 2m and 70cm ham bands":

    SDRplay...
    • Cheaper than FUNcube Dongle Pro+
    • Now available through a stateside distributor (HRO), to avoid potential issues with international shipping & Customs clearance
    • Front-end filtering across its entire range
    • Receives at wider bandwidths than 192 kHz maximum bandwidth of FUNcube Dongle Pro+ (up to 8 MHz)
    • API updates can address certain issues with SDRplay (i.e., recent API update removed 380-420 MHz reception gap & fixed issues with Windows tablets)
    FUNcube Dongle Pro+...
    • A smaller and lighter receiver than the SDRplay
    • Front-end filtering across its entire range, including SAW filters for the 2m & 70cm ham bands
    • FUNcube Dongle Pro+ can receive at even narrower bandwidths than 200 kHz minimum bandwidth in SDRplay
    • No drivers or APIs required for the dongle (ExtIO DLL download needed to control dongle from HDSDR, separate from OS support of the dongle)
    • Purchases support the FUNcube satellite project

    While I was at the ARRL Southwest Division Convention last weekend in California, I saw the Ham Radio Outlet booth was selling the SDRplay. I had mine with me, and gave a quick demonstration of the SDRplay with my 10-inch WinBook TW100 to an interested ham. He was impressed, and was talking about getting an SDRplay himself. I didn't use my SDRplay for the FO-29 demonstrations I gave outside the convention hotel, as I didn't want to deal with the bright surroundings and trying to see the tablet's display outside in the mid- to late-afternoon.

    73!
     
  9. W5SAT

    W5SAT Ham Member QRZ Page

    I picked up my SDRPlay from HRO today and have been playing with it quite a bit. Certainly a step up from the RTL SDR dongles. A LOT less "junk" in the spectrum from intermods than the RTL. Still easy to create IMD issues if the gain is too high but some filtering for different chunks of bandwidth clearly helps. Sensitivity on HF is quite good and being able to see such a huge chunk of bandwidth is cool. Speaking of bandwidth I think calling it 8 Mhz is a bit of a stretch - I think 7-ish is more accurate due to the roll-off on either end of the spectrum.

    Monitored an SO-50 pass and an AO-73 pass. Reception on both was OK but I can't really compare to my TS-2000 or TM-V71a as I have no coax switches setup to do quick A/B comparisons. Gut feeling is that the TS-2000 is somewhat better on VHF and UHF but surprisingly close on HF reception sensitivity compared to the SDRPlay. I'll need to do more testing and set up a splitter so I can feed the Kenwoods and the SDRPlay at the same time.

    Tomorrow, I'll connect my Elk antenna to the SDRPlay and run it off my laptop to see how it really hears. My reception in my shack is marginal due to cable runs and obstructions.

    Also, I haven't done any TX tests to check for desense but will do that soon as well. I don't expect to get different results than Patrick, but it never hurts to compare notes.

    So, overall I am quite happy with the SDRPlay. More to come...
     
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  10. WD9EWK

    WD9EWK Ham Member QRZ Page

    Yes, 8 MHz might be stretching it a little, but it's still better than 192 kHz from the FUNcube Dongle Pro+ or 2-3 MHz from the RTL-type dongles.

    I'm looking forward to seeing what you have to say as you test yours. I'm liking what I've seen so far.

    73!
     

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