Less than optimum SDR's online.

I find it somewhat frustrating to visit some of the online KiwiSDR only to find they are full of SMPS/RFI and unusable. Sadly it makes the experience poor, and often put people off using what in the main is an excellent resource. I know the + vote system is supposed to help, but I would really like to see the receivers ranked by performance. (maybe including a + and - button) If a receiver is poor or very poor, it really shouldn't be presented in the list as it distracts from the hard work, time and money some people have put into getting their SDR online.

Don't get me wrong, my SDR isn't perfect, but its a lot, lot better than some.

I guess its quality control, has anyone thought about how we can ensure its about the quality of receivers online, and not just the quantity..

Dave M0TAZ


  • I agree. One thing I suggested in a post awhile ago is to change your webpage settings so that your actual receiving capability is listed, not the default 0-30MHz. For example, when I had a AMBC HPF, I claimed 1.6-30, when I switched to notches, I claimed the 100 KHz to 30 MHz that my Pixel Loop spec is. Over time, I changed the 100 KHz to 10 KHz after logging stations down there. 
  • Hi,

    I also have this frustration. 

    I've tried to assist where I can by sending personal emails to admins where I think I can help improve things. 

    But unfortunately in some cases the Admins are more software orientated than having any real interest in the hardware or RF side of things. So it's very difficult to try to get them to improve things when either they aren't really that interested. Sometimes this is because they don't really know what sort of performance to expect, or alternatively they don't have a good enough understanding of RF to be able to understand the nature of the problem and how to go about fixing it. Just stuffing a random length of wire in to the KiWi antenna socket and hoping for the best shouldn't be the default position.

    I have offered to make up filters and send them free of charge to some  Admins (where I thought the SDR was otherwise OK apart from some local overloading or interference that could be filtered out), but so far there has not been any take up (I don't to make a wide announcement and then spend all my time sending free stuff where it's not going to make any difference).

    Maybe we could collectively write up some more detailed guidance notes for SDR Admins or folks considering buying a KiWi (as I notice that Farnell / Newark are now stocking the boards and kits) who are not well versed in the RF dark arts ?


    Martin - G8JNJ

  • I've written to Andr?s and suggested a different rating system for the receivers listed at sdr.hu . You never know, he might consider a usage based rather than a vote based rating system.
    Ron - KA7U
  • jksjks
    edited May 2017
    This has been frustrating for me also. Some of the free placement units I sent out have awful reception. I might need to buy better antennas for them.

    Antennas and filtering are one thing. But finding and curing noise problems is another level that some people may not be comfortable with. Plus it takes real effort sometimes (I still have major problems here!)

    Everyone needs to watch this video. It was a real revelation to me: EMC & Shack Noise: Filtering the mains supply

  • Hi All,

    Ron said "I've written to Andr?s and suggested a different rating system for the receivers listed at sdr.hu . You never know, he might consider a usage based rather than a vote based rating system."

    Ha ! and just as I've managed to get my SDR into the top four on SDR.hu too :-)


    Martin - G8JNJ
  • Don't worry Martin, Andr?s is busy with his PSK31 and other extensions, not to mention school, work, and life. I understood his last and gracious email, to be a NO! 
    Ron - KA7U
  • Hello,

    I'm the maker of http://rx.linkfanel.net/ so I've thought a bit about these issues. In my opinion the upvotes on sdr.hu stem from a good intent, although they're not a terribly great or effective idea. It tends to be skewed towards older receivers, or receivers that are already popular - the only way to upvote is from the rated listing itself. I've emailed Andr?s back in February regarding the use of his data, one of the things I asked was:

    "What would you think of using additional information to rank receivers, other than votes, for example visiter count or total listening time or rates of these? These would have to be reported by the receivers somehow. I guess more direct metrics like reception quality would be much harder to quantify."

    His reply: "That's a good idea." However it wasn't actually followed by any positive development.

    You also have to consider that a ranking "good" receivers at the top and "bad" receivers at the bottom is hardly an end by itself. There are many factors in which receiver one would pick, location would be a big one. Personally I look for a receiver in the area I'm interested in first, and then I try to pick one offering a quality reception, if there's more than one available. Of course this is tooting my own horn because I developped tools for that purpose.

    I'd love to add some representation of receiver quality to my map, but I'd need usable data to base it on. Andr?s even declined to allow me to use his data at sdr.hu for my map.

    Upvotes aren't terribly great. There could be more, possibly better metrics, like usage, that I mentioned to measure popularity. However just because a receiver is used at all times for some kind of monitoring doesn't mean it's actually popular. And popularity still does not equate quality.

    Actual quality metrics would be better, but shortwave is complicated and as I said it's difficult. Could there be some kind of metric built in KiwiSDR based on signal-to-noise ratio? If I look at a waterfall display and see strong signals standing out of weak noise, that's a good indication, especially if across all the spectrum; and that might be something possible to automatically calculate.

    The antenna field can be an indication of quality too, however not necessarily reliable or easily exploitable.

    I've developped https://github.com/priyom/pavlova and found that the best approach to pick and rank good receivers was still to try and test them one by one, compare and get a subjective appreciation of how well they receive, and curate a list by hand. Even then that's a partial rating for a very narrow purpose.

    Of course we should also help and make it easier to improve the setups and quality. Maybe filters could be bundled with the KiwiSDR when it's shipped, that might be the best way to be sure they make it to the people who should have them. Maybe there could be an interactive checklist in the admin page with items to tick to set up the receiver: registration, opening network access, proper antenna setup, installing filters, hunting for noise sources. It could calculate a score saying "your receiver is X % set up", like those online profiles do. Of course some people don't want to bother with that and have no advanced interest in making a great receiver; and that's okay too!
  • My efforts are always towards making my system better. Whether it be a good antenna, better shielding, addition of ferrites, or whatever, there's always something to do. Just when one thinks they are done, something changes, usually in the form of interference! I thought I had my MW filters all set and suddenly overload again. Turned out that the 50KW station 5 miles away, switched to their AUX 14 KW station that is only 1.5 miles away. I notched that out and watched until they switched it back and I took the notch back out.  RFI from neighbors is tougher to solve :-)

    I think that Radio Hobbyists have become more and more "appliance operators", as we hams found with the advent of cheap 2M radios. That is, they often have weak technical skills and often aren't even aware of problems let alone how to fix them.

    I wonder how many kiwiSDR owners are active on this forum, particularly those with public systems?

  • One peeve of mine are the receivers I see that use the default log, dx.json, as-is or add their own local stuff to it.  It takes a little effort, but it's far more meaning to have only entries that your receiver can actually receive!
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