WebSDR – Shortwave Radio on the Internet
websdr.ewi.utwente.nl
websdr.ewi.utwente.nl
> Since the intended use of this code involves sending a copy to the client computer, I (PA3FWM) hereby allow making it available unmodified, via my original WebSDR server software, to original WebSDR clients. Other use, including distribution in part or entirety or as part of other software, or reverse engineering, is not allowed without my explicit prior permission.
The server-side code is only available if you email him with plausible reasons you will use it[3]:
> Q: Where can I download the server software?
> A: Nowhere. However, I distribute it (without cost) via e-mail to people who are setting up a publicly accessible server ...
He's well within his rights of course to share his code however he pleases. But it did kill off a fun little idea I had for a Twitter bot pretty quickly since I can't touch the code.
[1]: http://wwwhome.ewi.utwente.nl/~ptdeboer/
It really confuses me, given both the FCC rules about keeping the airwaves open and unobfuscated, as well as amateur radio being exclusively a community of hobbyists.
There are exceptions of course... The MD-380 firmware, FreeDV, and GNU Radio all being some good examples of open source projects. But it's far from universal, and less common than I'd expect.
1. People who make profit and don't want to lose it to the FOSS crowd 2. People who are ashamed of their code 3. It's status symbol and they 4. They don't realize open source exists 5. They're a corporation which reuses hardware/software/IP from their commercial line of gear (such as D-STAR, Yaesu System Fusion, etc)
N1MM logger [0] fits 3.) - it's the most popular contest logger, it's totally free, absolutely packed with features, and worked on by volunteers, but it's closed source because Tom (N1MM) doesn't want to lose control, but it really seems he enjoys the limelight.
WB8ELK fits into 1.) with regards to his round-the-world high altitude balloon tracker packages [1] He sells his kit for $150, with a BOM cost of $20 and no more than 1000 SLOC. I spoke to him and all he had to say was "he has no plans of open sourcing." I assume it's because it's a good income.
I'm not sure where the WebSDR fits in, but I feel like there's a good reason.
I think in general it's because the ham community sees software more like hardware and less like information - it's something that you work on and make a working thing, not something you share. So closed source, and often non-free, software is common.
It's written down in the Auteurswet (Dutch): https://wetten.overheid.nl/BWBR0001886/2009-01-01#HoofdstukV...
People have tried scraping broadcasts from his service without permission, and most of the places running software don't have the best internet. Scraping data from the station depends on who is running it at that side, although he did tell me he can't imagine why people wouldn't be okay with it (given it's for a university and not a private corporation).
Creating an open sourced API, although would increase popularity and satisfy use cases, would saturate the host internet and tap the physical limits of the hardware. I would really want some SDR network to exist that is open sourced, but physical limits would be reached pretty soon.
Binary only, but not obfuscated or anything like that, so reverse engineering it isn't too onerous.
http://www.sm5bsz.com/linuxdsp/linrad.htm
https://www.youtube.com/channel/UClmNy6VRE1YqOeBHwb3o0Yg/vid...
I use this to see if my antenna is effectively transmitting any kind of signl: http://www.reversebeacon.net/main.php
The devices, which are spread all over the world, watch the whole cw band.
http://www.dxatlas.com/cwskimmer/ is the primary one, however its pay and windows only
Motivation: here in Linz we have electronic signs at bus and tram stops that display how many minutes until the next bus/tram arrives. I believe those signs somehow get their data via radio (they have antennas). I know nothing about the technology used, but since they were installed more than 15 years ago they probably don't use the cellular network.
The company also offers an API with live data, but for some reason the estimates from the API are not as precise as those on the signs. So I'd love to somehow intercept the data sent to the signs.
Does anybody have an idea how to go about that? I know nothing about how radio works.
Something like the 433Mhz ISM band parsing can give you an idea of what's possible[1].
Anyway as a basic rundown, the implementation does a very large FFT on the high samplerate data coming in from the ADC and then individual receivers can be constructed by filtering and decimating in the frequency domain followed by doing an IFFT which makes the prospect of running many hundreds of receivers achievable on commodity hardware without having to process the full ~1+gbps dataset for each Rx. The specifics are a bit more complicated, but that is the general idea.
I would encourage anyone who is deeply interested in this technique to please follow the work of Phil Harman VK6PH and Warren Pratt NR0V who are implementing the same type of processing which they term "Direct Fourier Conversion Receivers" on top of the OpenHPSDR hardware platforms. The code including the software and verilog is all open, and there are open OpenHPSDR hardware designs as well.
Also, the neat thing about this particular instance of WebSDR is has a custom SDR receiver that covers ~30MHz of spectrum, whereas most of the ones listed on http://websdr.org/ are much narrower.