[HN Gopher] Fifty Things you can do with a Software Defined Radio
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Fifty Things you can do with a Software Defined Radio
Author : Timothee
Score : 228 points
Date : 2024-03-16 18:17 UTC (1 days ago)
(HTM) web link (blinry.org)
(TXT) w3m dump (blinry.org)
| mikewarot wrote:
| Well, it is truly amazing what you can do with a cheap RTLsdr
| dongle and some time and energy. I used GNU Radio to build a
| receiver flowgraph that decodes and displays the signal from a
| nearby VOR aircraft navigation transmitter. It was cool to drive
| around it, and see the pointer update in real time.
|
| The sensitivity of these things is on the order of a normal
| receiver, (0.1 microVolts) which surprised me, knowing the
| samples are 8 bits.
| CamperBob2 wrote:
| ADC sensitivity is influenced by quite a few things, some of
| them pretty unintuitive (e.g., some interference from unwanted
| signals in the RF passband can be a _good_ thing if it provides
| a source of dithering that allows weaker signals to cross bit
| boundaries).
|
| Bit depth is surprisingly far down the list in overall
| importance. To understand why, look up "FFT processing gain."
| Consider that sigma-delta converters are 1-bit ADCs, yet the
| S-D topology is used for many applications that require wide
| dynamic range.
| brcmthrowaway wrote:
| The interface between analog and digital signals is weird
| science
| nonrandomstring wrote:
| On hunting weather baloons:
|
| > And he was right: Someone had been faster than us! The status
| was changed. So in the end, I didn't find the sonde. But
| something that might be even better - a friend!
|
| Other than all the other fun packed into SDR this story just put
| me in a good mood today.
| isoprophlex wrote:
| Seems so idiotic that you're not allowed to _receive_ maritime
| traffic in Germany (item #49).
|
| Don't transmit any, if you don't want people to receive it.
| tostr wrote:
| I just wanted to post that I can't find anything about it being
| forbidden, but there is actually a link in the post[1]. So
| basically the situation is:
|
| Mit einer Funkanlage durfen nur solche Nachrichten abgehort
| oder in vergleichbarer Weise zur Kenntnis genommen werden, die
| fur den Betreiber der Funkanlage, fur Funkamateure im Sinne des
| SS 2 Nummer 1 des Amateurfunkgesetzes, fur die Allgemeinheit
| oder fur einen unbestimmten Personenkreis bestimmt sind.
|
| Which in English would read something like this:
|
| With radio equipment you are only allowed to listen to, or take
| note of in some other way, those messages that are addressed to
| the operator of the equipment, those messages that are
| addressed to ham radio operators in general, those messages
| that are addressed to the general public or for an undefined
| group of people.
|
| This is of course absolutely unenforceable, untraceable and
| generally ridicoulus, but it is what it is. Imagine your
| neighbours having very loud arguments (or very loud 'horizontal
| discussions') in a clairaudient flat, and then telling you that
| you cannot listen to it. And being correct legally ;)
|
| [1] https://www.buzer.de/5_TTDSG.htm
| isoprophlex wrote:
| > "Wir haben unsere Daten gesichert, indem wir nicht
| autorisierte Benutzer freundlich gebeten haben, nicht darauf
| zu schauen."
|
| :^)
| 082349872349872 wrote:
| You all may appreciate (a short browse away from TFA):
| Antragsformular fur den Passierschein A38
|
| https://blinry.org/passierschein-a38/
| newman8r wrote:
| There are also FCC regulations in the US that relate to
| receiving signals under certain circumstances:
| https://www.fcc.gov/consumers/guides/interception-and-divulg...
| yencabulator wrote:
| I recall Finland had a rule that you can listen (how else would
| you hear the next message meant for you on maritime VHF), but
| you can't repeat things publicly or act on knowledge gained
| from that. Now, why would that be? Well, it's mostly to
| minimize sensationalist news reporting of people's accidents,
| misfortunes and such, whether maritime or over old school
| police radio (before it was encrypted). Discourage ambulance
| chasing, that sort of thing. It's just another part of the
| European attitude toward privacy.
| Prcmaker wrote:
| I have a soft spot for SDR. I've only done a bit of it, but the
| mathematical techniques I learned from it helped kick start my
| career. While I worked in a different field, having made friends
| with frequency and phase analysis was hugely powerful.
| dgacmu wrote:
| SDR is great. I'm using an RTL-SDR dongle together with the
| rtlamr software to read my gas meter. It provides measurements
| about every 30 seconds, and my gas company doesn't give any real-
| time data. Quite handy.
|
| (and I run an adsb receiver, which incidentally provides free
| access to FlightAware and other services if you share with them.)
| demondemidi wrote:
| What frequency is your gas meter transmitting at?
| krallja wrote:
| Off-topic, web performance: compress your images, use caching
| headers, and/or serve them via a CDN (ideally one that supports
| HTTP/2). The current server is not powerful enough to handle the
| current set of images on this post in a reasonable time.
| paradox460 wrote:
| I set up one to pull readings from my utility meters. Now I've
| got the exact figures the power company uses to calculate my
| bill, and can track it throughout the month, entirely offline
| demondemidi wrote:
| Do you happen to have a write-up of this? I'd be interested in
| building the same capability, although I doubt we have the same
| provider.
| paradox460 wrote:
| I'll get one written up post haste
|
| I've been batting around a few blog posts on various home
| automation projects and will probably sit down and write this
| one this afternoon
|
| I'll reply with an link when it's up
| demondemidi wrote:
| Thanks! After I asked this I googled around and found on
| GitHub bemasher/rtlamr, but discovered it doesn't work on
| my meter's network (FlexNet/Icon/Census). Hopefully someone
| figures out FlexNet, I'd like to add my meters to my home
| data collection!
| pbnjeh wrote:
| Images still very slow, but:
|
| https://web.archive.org/web/20240316173921/https://blinry.or...
|
| (there are also two snapshots from today (2024-03-17), but
| yesterday's is the one I didn't give up on waiting to load)
|
| or
|
| https://archive.is/ZHnfV
|
| Saving with SinglePage, it's around 125 MB (original a bit less,
| archived copy a bit more).
| tamimio wrote:
| Here's more stuff to add I did before:
|
| - Scan for drones that are using RC link
|
| - Scan nearby cell operators and their metrics.
|
| - Scan and pentest cellular networks
|
| - Create your own LTE/5G tower.
|
| - Transmitting FM/AM radio
|
| - Communicate with other pilots by tuning on airband
|
| Among others, for this you need a full duplex SDR, so rtl or
| hackrf won't do, limeSDR or bladRF would.
|
| For the author: I did have a realtime voice over SDRangel, it
| allows you to have the sdr in a physical location away from you,
| if I got some time I will write how to do it.
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(page generated 2024-03-17 23:01 UTC)