Creating a global network of inexpensive remote SDRs

U_Twente_SDR

Many thanks to SWLing Post contributor, Mark Fahey, who replies to Ivan’s preliminary review of the V3 RTL-SDR dongle:

With Shortwave SDRs (the receiver dongle) now costing less than $20, the time has come for us to set up a global group of receivers that we can all log into at will!

RTL-SDR-RTL2832U-e1471375714199Have a look at SDR.hu – here you can put your SDR dongle on line and share it with anyone and they have full control of the receiver just as if it was in their own shack.

Imagine receivers scatted around the world – South America, Tropical Asia, Africa! The cost is now virtually nothing, all that is needed is the dongle, antenna (doesn’t have to be anything special – even a long wire or whip) and a small low cost CPU (Raspberry Pi for example).

Anyone else interested in this dream? Lets get together, get some receivers setup and then talk about our experience in a kick-ass presentation at the 2017 SWL WinterFest in PA!

Also… I am very soon to receive my KiwiSDR matched to a BeagleBone CPU. It will be online at SDR.hu and four remote listeners will be able to tune the full shortwave bands independently, its like my own Twente setup! Heaps of others are getting receivers online in the next few months with KiwiSDRs, this is going to be totally amazing!

I agree, Mark! While there is already quite a network of remote SDRs and receivers in the world, the barrier of entry keeps getting lower and lower. It’s hard to imagine that $25 can buy an SDR that natively covers the shortwave and mediumwave bands!

There’s only one other requirement for an online SDR that Mark didn’t mention: a decent Internet connection. Sadly, this is the only thing keeping me from hosting a remote SDR here at my home. I considered purchasing a KiwiSDR like Mark, but my upload speed (0.2-0.3 mbps) is so terrible and so unreliable that I could only host one listener at a time at best. You can bet that as soon as my ISP upgrades our service, I’ll launch a web SDR as well.

Of course, I’m willing to bet that most SWLing Post readers have more than enough bandwidth to host a $25 remote receiver! Let’s make Mark’s vision a reality!

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8 thoughts on “Creating a global network of inexpensive remote SDRs

  1. Mark Fahey

    Good stuff – thanks for the comments!

    The idea I had in my head was a growing hive of low cost SDRs scatted around the world.

    It’s kind on an conceptual leap or extension of something I already have set up as an idea. Because of my keen interest in North Korea I have my own satellite dish and receiver now installed in Taiwan which receives domestic Nth Korean Television and Radio circuits which are relatively difficult to receive in my home in Australia. I can tune the receivers, and operate the dish system remotely as if it was in my backyard in Sydney. The digital video and audio is delivered to me with no quality loss, so it feels kind of like I have a very, very, very long coax feed from Australia to the dish in Taiwan, of course the link is actually IP.

    So now not thinking about satellite microwave signals, but thinking about tropical band broadcasting. I would love to have receivers located in the equatorial regions to listen to the many shortwave domestic and regional services at good listening quality, I’m not actually thinking of typical DXer type interests. (What I mean by this is that often a DXer is usually quite happy to receive a weak signal make out a 30 second ID and be happy with chasing down the capture). My interest is more in being able to listen to the station and its exotic programming, so more towards the SWL interest rather than DXing.

    So a growing network of cheap to purchase, install and operate SDRs would be ideal for listeners to listen a very exotic distant station at local quality than they have little chance of hearing from their own location. Thinking this way the less than communications receiver quality of the stick SDRs doesn’t really matter. A few of them scatted around Indonesia, India or Africa would to my interests be amazing.

    Just like people have done in recent years for ADS B signals, hundreds of low cost stick receivers can be scatted around the globe, often even provided free-of-change (with a small pool of donation funding) to interested SWL’s in remote, exotic, and interesting locations. The ADS B free SDR dongle receiver distributions by outfits such as PlaneFinder, Flightradar 24, RadarBox have all found quite often acceptable broadband is found often in the most unlikely places and now allow for real time aircraft tracking in most parts of the planet. So same idea as what the ADS B fans have done – but this time for SWL interests.

    As for frequency range, my own interest is the tropical bands – 120MB, 90MB, 75MB etc. so my mind hadn’t actually thought of providing wide band 0 to 30 MHz etc. There are SDR sticks that can tune from 500 kHz to 1.7 GHz and has up to 3.2 MHz of instantaneous bandwidth, so that was what I was basing my thinking on.

    I’m going to put together a few (maybe 3) and give then to friends in India and hopefully Indonesia to install in their offices piggybacking on their business network. If we can find other cool places to drop them into in other parts of the world it would also be very cool! Anyone who is interested – come on join in!

    Cheers,
    Mark

    Reply
    1. Thomas Post author

      Rich, I think you’re right.

      Mark: perhaps we could set up an impromptu remote receiver at the fest to demonstrate? That could be seriously fun!

      And, Rich, those dongles would make excellent prizes.

      Reply
  2. Aaron Kuhn

    Here’s a rough price/parts list on what I think is probably the realistic minimum to do this. Older parts in many cases here will work, but I’m focusing on new implementations off the shelf from US suppliers. If you know of a cheaper off the shelf antenna solution that’s not a 6-hour long DIY project I’d love to hear it.

    * Raspberry Pi 3 Model B Starter Kit – $68 Shipped from MCM Electronics
    * RTL-SDR Blog Dongle only (China Shipping) – $20 shipped from RTL-SDR.COM
    * NooElec Balun One Nine – Antenna Balun – $20 shipped from Amazon
    * Random length of wire – Free from your junk bin or $3 for random wire you find at a thrift store.

    Total: ~$110

    Software configuration required:

    * Raspbian OS – Preloaded on the SD Card you bought in the Starter Kit, needs various configuration
    ** See https://www.howtoforge.com/tutorial/howto-install-raspbian-on-raspberry-pi/ or various other tutorials
    * RTL-SDR Hardware Setup – Various community documentation such as http://sdr.osmocom.org/trac/wiki/rtl-sdr
    * OpenWebRX Setup – See http://km4ood.net/creating-a-web-sdr-with-openwebrx-and-a-7-20-sdr-dongle/

    Internet connectivity required

    * Sufficient upstream to support your desired number of listeners – You’ll likely hit a practical usage wall on the (signal) bandwidth limit of the RTL-SDR as well for multiple listeners wanting to visualize more than a 2 MHz chunk of bandwidth at any given time.
    All told this requires around $110 in hardware, and some patience and many hours set aside to follow various tutorials. Your level of Linux familiarity and comfort on the command-line will determine your ease of setup.

    Reply
  3. Mike Westfall

    One frustration I have with these cheap dongles being put online, is that they cover only a small portion of the spectrum, and nearly always they are set to tune some ham band and rarely a broadcast band.

    Also, the 8-bit resolution doesn’t make for good S/N ratio, even when the antenna is properly installed away from man made noise.

    KiwiSDR looks promising, but from what I can tell, it looks like it’s $300 for the kit and you have to assemble it yourself, including soldering the tiny SMT parts.

    Reply
  4. Thomas Post author

    I think the way Mark and I see it, though, is that price is becoming less and less a barrier of entry. The new RTL-SDRs might not be the best for HF performance, but perhaps they’re good enough for newcomers to begin experimenting?

    I think it’s very cool, Ivan, that you have remotehams.com receiver online. Again…as soon as I have the bandwidth, I’ll join you! 🙂

    Reply
  5. Geir

    I am a little skeptical too. The poor HF coverage from 500 kHz to 24 MHz does not make this (new) dongle a good candidate for a global network. Minimum requirement for HF coverage is in my opinion from 150 kHz to 30 MHz.

    Reply
  6. Ivan Cholakov - NO2CW

    I think the network is a fact.
    1. SDR.hu
    2. websdr.org
    3.remotehams.com (shortwave listeners are welcome)

    I am a little skeptical about the abilities of the current $20 receivers – they need a little more work to make them a mainstream HF receiver. But I often browse the sites above and I also maintain a station on remotehams.com under my call NO2CW. SW listeners are always welcome and many times they connect to listen to local South Florida AM stations or to catch the Bahamas on 810 and 1540khz.

    Reply

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