
WebSDR – Shortwave Radio on the Internet - bane
http://websdr.ewi.utwente.nl:8901/
======
waffle_ss
I found WebSDR a while back and was fascinated by it, however I was surprised
to find out the author, an EE/CS prof[1], has a very closed source view of
both the client-side JavaScript code as well as the server-side code. I wanted
to poke around the JavaScript and see what I could learn but that's explicitly
disallowed by the license[2]:

> _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/](http://wwwhome.ewi.utwente.nl/~ptdeboer/)

[2]: [http://websdr.ewi.utwente.nl:8901/websdr-
sound.js](http://websdr.ewi.utwente.nl:8901/websdr-sound.js)

[3]: [http://websdr.org/faq.html](http://websdr.org/faq.html)

~~~
tjohns
I've noticed that the amateur radio community tends to gravitate towards
developing closed source software.

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.

~~~
kawfey
From my experience, it's either

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.

[0] [https://n1mm.hamdocs.com/tiki-index.php](https://n1mm.hamdocs.com/tiki-
index.php)

[1] [http://www.wb8elk.com/](http://www.wb8elk.com/)

------
exabrial
Last time this was posted to HN I spent an entire 6 hours listening to Numbers
Stations, international broadcasts, and wrote a DTMF decoder in Java. I don't
recommend visiting this if you have actual work to get done.

~~~
rjplatte
Thanks for the idea. I ha(d)ve hours to bill...

------
escherplex
Cute. So now from your laptop with audio piped into a rec-room amplifier via
Bluetooth you can have a Euro-based SW receiver complete with 'waterfall'
display and U/LSB (moderate sensitivity) plus with the Google 'Radio Garden'
web site you can listen to American pop music in stereo live from
Petropavlovsk on the Russian Kamchatka peninsula, an area of significance
during the cold war.

------
mikece
This reminds me... I've been wanting to write two apps: one to scan SDR
looking for CW, RTTY, and other digital(ish) modes and then send an alert to
me (SMS, email, or push notification) that QSOs were found, along with a
separate alert type when it finds a CQ call. I don't suppose anyone has done
an app like that, have they?

~~~
jcims
SDRSharp has a bunch of plugins to scan bands and stroll through bands. You
could pipe that to CW Skimmer and figure out how to get the data out of CW
Skimmer (telnet server, log file, etc).

------
jakobegger
Could you use something similar to detect digital / data radio transmissions?

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.

~~~
vvanders
It's probably something on the VHF frequency which you can pick up via a cheap
$15-20 RTL-SDR. If it was installed that long ago there's a good chance it
runs on something really simple like DTMF tones.

Something like the 433Mhz ISM band parsing can give you an idea of what's
possible[1].

[1] [https://www.rtl-sdr.com/tag/rtl_433/](https://www.rtl-
sdr.com/tag/rtl_433/)

------
gorkish
This is a great project; unfortunately the guy who writes and maintains it
(regardless of his talent) is kind of a dick. Notice how there is only one
"wideband" receiver despite the simplicity of the hardware? There is a reason,
and it doesn't mesh well with the hacker ethos that we are all so fond of
around here.

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.

------
tlrobinson
FYI you can link directly to frequencies / modes like this:
[http://websdr.ewi.utwente.nl:8901/?tune=198am](http://websdr.ewi.utwente.nl:8901/?tune=198am)

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/](http://websdr.org/) are much narrower.

------
threeio
I'll also point out that [https://sdr.hu/](https://sdr.hu/) provides many many
other locations that you can listen from

~~~
xvf22
Thanks, I forgot about that one. I usually use
[http://www.websdr.org/](http://www.websdr.org/) and I find these sites quite
useful to check propagation.

------
LinuxBender
With enough of these set up around the world, it would be a great way to test
skip conditions and channel noise floor levels. The US military does this with
ChirpSounder. I would love to see a civilian version that just listens all
around the world.

~~~
vvanders
If it's propagation you're interested in then RBN[1] does a good job of that
by parsing morse code and callsigns. Sadly the map no longer exists due to the
changes in Google's Map API pricing.

[1]
[http://www.reversebeacon.net/main.php](http://www.reversebeacon.net/main.php)

~~~
LinuxBender
Nice, I had not seen that. Thankyou.

------
peetle
Russ Hanneman would be proud.

------
dang
From 2015:
[https://news.ycombinator.com/item?id=9574966](https://news.ycombinator.com/item?id=9574966)

------
wglb
Related:
[http://www.reversebeacon.net/main.php](http://www.reversebeacon.net/main.php)

------
russdpale
Shout out to the simple design! Made in '07, with the class of '97!

------
resters
Check out 1.8 to 1.9 MHz this weekend actually starting right now.

~~~
azinman2
I’m hearing Morse code... what’s being transmitted?

~~~
resters
Amateur radio Morse contest

