Building A Global Network Of Open Source SDR Receivers (jks.com)

hamster_nz writes: A fellow Kiwi is attempting to crowdfund a world-wide network of open-source, software-defined, radio receivers. Once in place, this will allow anybody anywhere in the world to scan the 0 to 30MHz RF spectrum from the comfort of their HTML-5 web browser. Built on top of the Beaglebone, the "KiwiSDR" RF board also includes a GPS receiver front-end, which will allow timing between receivers to be correlated, giving a lot of options for projects like long baseline interferometry and lightning detection. Prototypes are already deployed, and I've been RXing in Sweden, Australia and New Zealand. [The KiwiSDR design has been detailed on JKS.com, where there is a link to the project's Kickstarter page.]

Comments

Re:If the NSA did this, you'd think it was creepy.

[fyngyrz]

What is so significant in 0 to 30 MHz.

Shortwave stations from every continent. Longwave stations. The long established 160-, 80-, 40-, 20-, 15-, and 10-meter ham bands, as well as the newer (and lower bandwidth) WARC bands. Time and frequency reference stations. Weather fax. Lots of pirate radio. Various textual and other FSK encoded data transmissions. Beacons. Natural phenomena such as solar RF emissions. The AM radio bands. Maritime weather broadcasts. Citizen's band radio (both European and US band spans.) All manner of military and commercial and non-military government signals.

In addition, because of the way RF propagates through the atmosphere, signals at these frequencies are far better able to reach long distances than signals at higher frequencies; get much higher than 50 MHz, and reliable reception falls down into line-of-sight distance without the assistance of intermediate receive-and-re-transmit relay stations such as towers or satellites.

During the course of the day, the propagation characteristics of the atmosphere change, primarily due to varying exposure to solar radiation. This varies with solar output and events, terrestrial weather, and can even be affected to some degree by intentional energy delivery by technological means.

There are also signals at the low end that are electromagnetically sourced that have been found to presage events such as earthquakes.

If one goes to the (very minor) effort of converting from other types of signals, for instance from sound (air pressure variation) to electrical (IOW, use a microphone or a speaker-as-microphone), you can look into information realms normally out of perceptibility. For instance, I have a couple of old super-tweeters mounted in my attic and this enables me to check out the otherwise inaudible chirps and whistles of the bats that live up there (I have a bat habitat.)

There is more in the world than data packets. That doesn't mean these things will be of interest to everyone; but they are definitely of interest to some, and so that's what gives SDR hardware designed to work in this particular frequency range real value.

I write software for SDRs; it works with any frequency range the SDR is capable of, and because I do this, I have quite a few SDRs on the bench at any one time, and quite a range of frequency capabilities. I live in a fairly rural area, and for me, there is a lot more interesting going on from 0-30 Mhz than there is within 30 MHz and above. It's all in what tweaks your particular curiosities and leanings. :)