Even if you have no idea what you're doing, I very much recommend buying one of the RTL-SDR dongles on amazon for ~$20-30 and playing around. For the cost of a movie ticket, an afternoon messing with one will teach you a MASSIVE amount of stuff about how RF works.
Seconded. I was playing with mine last week and had it set up to read pager messages. Turns out that hospitals still use pagers heavily, and pager data is completely unencrypted.
Oh yeah, this has actually been a bit of a controversy in Vancouver recently[0][1], including speculation that the problem may be national. Local hospitals have now removed diagnosis data from the transmissions, but apparently still broadcast everything else, including "patient name, age, gender marker, their attending doctor and room number" (as of Sept 2019)[2].
Vancouver Coastal Health claims they "have no information to suggest private patient information has been used in any malicious way", which is a very disingenuous statement to make, because there's no conceivable way for them to know who has received radio transmissions or made use of such data maliciously. To be frank, I find this pretty mind-blowing and it's disappointing that even in the face of press/public attention, it's not being remedied.
Adding, just in case anyone wants to do this on their own: IANAL, but my understanding is that in the US it is not against the law to capture and decode these plain-text messages, but it is probably against the law to publish that information elsewhere or act on it in some way (an example from the link below was intercepting taxi service text messages in order to gain a business advantage for your own taxi business).
The text messages that float about in the ether these days aren’t messages between individuals, they’re monitoring alerts (refrigeration systems, computers), and medical (doctors being paged, order to clean hospital rooms, calls for medical transport). That’s the case at least here in my medium-sized town in the US Midwest. It could be very different elsewhere.
yeah! I had picked one up a while ago to play with it and had some fun and stashed it away for a while. Well last week i was BBQing and the receiver end of my little remote temp monitor stopped working. Found rtl_433 that already is setup to read the output from the sender portion and in like 10 minutes had it graphed on grafana with alerts for temps!
Can you show this off? It sounds like something I need to have in my life. What TSDB did you use? What did your conversion from rtl_433 to a metric look like?
Agreed! I picked one up and learned about ADSB protocol and usage, and now have a live view of the air traffic in my vicinity. Sure, I could use one of the websites that tracks that info, but there's something about viewing it on your own equipment.
Fun fact: Most of those sites filter out a subset of air traffic, notably military and anyone that pays to have their flight data suppressed (typically celebrities or other high profile people). If you run your own equipment you’ll see everything within range of your antenna.
The one notable exception is https://www.adsbexchange.com/, which actually allows you to just show just military aircraft or just aircraft that have been tagged as interesting (typically planes owned by high profile people like Bill Gates, large corporations, or news and police helicopters).
It’s kind of fun to zoom their map out to the continental US and put on the military filter. At any given moment there are a surprising number of military aircraft over the US.
I tried to set up an SDR for my journalist girlfriend, and like the rest of you hackers, reading the manual, figuring stuff out and getting something working is usually pretty easy for me -- but there is a whole lot to software-defined radio.
What were you having issues with? Usually the RTL-SDR + SDR# (sdr sharp) works without any config. Once you start to look at more expensive devices like the Lime mini things get weird though.
I lost complete interest in SDR due to the fact that antenna's are very important. I am ok with the tools etc but the fact that I cannot do anything with the antennas and the interference put me off.
I mean... you could go buy or build an antenna appropriate for the signal you want to monitor? If you've got the space for it, a wideband discone like this one [1] out on the balcony and up on your roof paired with a wideband LNA from Mini-Circuits will give you acceptable reception from low VHF all the way up through S-band. Or, if you are looking for a specific frequency, build yourself a dipole of the correct length (it's really not hard).
You can't cheat physics, you do in fact need the right antenna. I don't know what else to tell you.
I either had a terrible antenna, interference or reception at my apartment and so my dongle gathered dust for a few years until I camr across an Android SDR Touch app. Using a USB-OTG I could easily listen in on the go for cheap.
For some values of "those" yes, for others No. Some are receivers that can only receive but you can also get transmitters or transceivers that will do both. Most of the cheap dongles are receive only. Disclaimer: Your local laws regarding the legality of transmitting (or even receiving) on a particular frequency at any given power may vary.
Receiving radio is perfectly fine and you aren't at risk of interfering with anyone.
Transmiting is very "dangerous" if you don't know what you're doing, and likely illegal unless you're licensed (you're only allowed to broadcast on certain frequencies below certain power limits without a license, but you can still cause trouble).
Tl;Dr Please do not experiment with transmitting if you don't know what you're doing.
For various reasons (such as, it can cause interference), I do not want to transmit, and would rather have one that cannot transmit or that has a hardware switch to disable transmitting when you do not want to transmit.
I recently got a couple of the NooElec NESDR SMArt v4 dongles, and I've been quite happy with them. I also have a few no-name dongles, with one of them that has been running rtl_433 for years now to graph outdoor and basement temperature and humidity from off-the-shelf sensor units.
The NESDRs are much more accurate than the no-names and don't drift. I was flabbergasted when I plugged one in, tuned it to a nearby NOAA weather transmitter, fired up gqrx, and saw that it was spot-on without having to adjust the frequency error. Also, they have SMA connectors instead of the dodgy barrel connectors on the no-names.
Just hop on Amazon and search for rtl-sdr dongle. AFAIK they're all roughly the same since they're based off the same hardware; any with decent reviews should be fine. I think mine was a Nooelec brand or something; comes with the dongle and an telescoping antenna.
Man, this seems like such a great resource; wish I had found it when I first got into SDR. I wrote a blog post about controlling ceiling fans using SDR (https://blog.hmac.io/2019/10/25/making-dumb-fans-smart-using...), but I glossed over my initial struggles just getting up to speed with this stuff. All the concepts of SDR are straightforward and fairly intuitive, but it's the software stack and actually using the tools that's hard. The whole field is niche enough that you end up stubbing your toe with every step you take in that world.
Googling around and trying to figure out where to even begin comes up with so many fragmented, unhelpful pieces of information. You either end up being pointed at Gnu Radio, which amounts to an incomprehensible behemoth for a newbie, or you find the numerous lighter weight pieces of software which aren't very clear on what exactly they're good for and are often unmaintained.
Luckily my first project was rather simple; ceiling fan remotes don't exactly use the most advanced protocols. Once I found CubicSDR and fiddled around with it enough I was able to dump the radio signals to an audio file and just tease the rest out in Audacity. My blog post mostly covers the nightmare that was the TX side of things.
Plug for the “universal radio hacker” open source tool. It made it absolutely childs play to reverse engineer a wireless thermometer signal which i now feed into a dynamo db table and present as a graph via alexa. My kamado joe is at the bottom of the garden and when i’m smoking or bbq’ing i can bring up the meat and the grill temps on any screen in the house. Fantastic.
Rachel Kroll (wrote The Bozo Hour making fun of incompetent sysadmins and management) created a web portal for an SDR in C. I found her blog posts in the project very interesting.
This write up is a great introduction to what can be done and is nearly word for word what I have been through so far with SDR and amateur radio.
Another super interesting thing I have done with my RTL-SDR is track NOAA and Meteor weather satellites and decode the images in realtime as they fly by overhead
After playing with some examples I noticed the weird behaviour of the gnuplot windows that get focused and refreshed (including decorations) at every sample so that beside wasting cpu power for unneeded drawing, it takes away focus from the shell where the program was invoked, making impossible for example to press ctrl+c to stop the program. I was forced at every test to ctrl+alt+f1 to a full screen console to kill the process.
There's a nice Lua GUI project called TekUI which includes a basic graphing control that could be imported and extended to do the same without the need of an external dependency like gnuplot.
http://tekui.neoscientists.org/screenshots.html (look at about half of the page)
http://tekui.neoscientists.org/releases/
It's highly portable, a few years ago I managed to compile and use it on a A10 ARM processor board (Hackberry if memory serves).
Thanks, I'll take a look! New plotting sinks are easy to add and I really would like to migrate to something more stable. Gnuplot has been finicky with many people's setups, and it's been a real sore point. They seem to run best with the wxt output on Linux.
Thanks what a good link to SDR, the link feels like a Christmas present. SDRPlay is a good SDR receiver a step up from RTL-SDR for exploring the radio spectrum. Plus to exploring software defined radios there is a good community built around ham that one can join.
I got a SDRplay some time ago from a co-worker. I haven't used it yet because of the behemoth that is SDR, but with this source I feel I can finally do something with it.
I want to broadcast (unidirectional) UDP packets over the air on 2.4 GHz or 5 GHz at 3+ Mbit/s at maximum (legal) power. Is there a good way to do this with any current SDR hardware? Or is my best bet to ab(use) wifi cards for this purpose?
You can use SDR to transmit any I/Q stream you want. I/Q is just a stream of two numbers for the strength of two phase-shifted carrier waves. How you encode your data (UDP packets) in the I/Q stream is up to you. SDRs like the LimeSDR Mini support sample rates of up to 30 MS/s, therefore it should be perfectly possible to achieve high throughput rates. On the receiver side you will also get an I/Q stream. The problem though is that it is not going to be the same of the transmitted I/Q stream. There might be a lot of noise, the carrier may be slightly shifted, the phase is not the same. Therefore you have to use some modulation to encode and decode the data. It is really up to you what kind of modulation to use. Some traditional ones are OOK (on-off keying), and some of the more complicated ones are APSK. LimeSDR Mini comes with example Python code to transmit raw I/Q. RTL-SDR should be enough for a passive receiver, but it is limited to 3.2 MS/s.
What does "broadcast UDP packets" mean? They'll need some sort of physical encoding; if wifi, why not use a wifi card? If not wifi...what are you trying to do by broadcasting UDP packets?
Readit News
Vancouver Coastal Health claims they "have no information to suggest private patient information has been used in any malicious way", which is a very disingenuous statement to make, because there's no conceivable way for them to know who has received radio transmissions or made use of such data maliciously. To be frank, I find this pretty mind-blowing and it's disappointing that even in the face of press/public attention, it's not being remedied.
[0] https://openprivacy.ca/blog/2019/09/09/open-privacy-discover...
[1] https://www.ctvnews.ca/health/pager-systems-used-in-healthca...
[2] https://openprivacy.ca/blog/2019/09/26/pager-breach-update/
Source: https://www.fcc.gov/consumers/guides/interception-and-divulg... via https://www.reddit.com/r/RTLSDR/comments/4nhg7h/legalities_o...
The text messages that float about in the ether these days aren’t messages between individuals, they’re monitoring alerts (refrigeration systems, computers), and medical (doctors being paged, order to clean hospital rooms, calls for medical transport). That’s the case at least here in my medium-sized town in the US Midwest. It could be very different elsewhere.
https://pisdr.luigifreitas.me
The one notable exception is https://www.adsbexchange.com/, which actually allows you to just show just military aircraft or just aircraft that have been tagged as interesting (typically planes owned by high profile people like Bill Gates, large corporations, or news and police helicopters).
It’s kind of fun to zoom their map out to the continental US and put on the military filter. At any given moment there are a surprising number of military aircraft over the US.
Source: lived in LA and the Bay Area.
You can't cheat physics, you do in fact need the right antenna. I don't know what else to tell you.
[1] https://www.diamondantenna.net/d3000n.html
Transmiting is very "dangerous" if you don't know what you're doing, and likely illegal unless you're licensed (you're only allowed to broadcast on certain frequencies below certain power limits without a license, but you can still cause trouble).
Tl;Dr Please do not experiment with transmitting if you don't know what you're doing.
Great hardware with driver/software compatibility
The NESDRs are much more accurate than the no-names and don't drift. I was flabbergasted when I plugged one in, tuned it to a nearby NOAA weather transmitter, fired up gqrx, and saw that it was spot-on without having to adjust the frequency error. Also, they have SMA connectors instead of the dodgy barrel connectors on the no-names.
Googling around and trying to figure out where to even begin comes up with so many fragmented, unhelpful pieces of information. You either end up being pointed at Gnu Radio, which amounts to an incomprehensible behemoth for a newbie, or you find the numerous lighter weight pieces of software which aren't very clear on what exactly they're good for and are often unmaintained.
Luckily my first project was rather simple; ceiling fan remotes don't exactly use the most advanced protocols. Once I found CubicSDR and fiddled around with it enough I was able to dump the radio signals to an audio file and just tease the rest out in Audacity. My blog post mostly covers the nightmare that was the TX side of things.
> http://scanner.rachelbythebay.com/
Another super interesting thing I have done with my RTL-SDR is track NOAA and Meteor weather satellites and decode the images in realtime as they fly by overhead
After playing with some examples I noticed the weird behaviour of the gnuplot windows that get focused and refreshed (including decorations) at every sample so that beside wasting cpu power for unneeded drawing, it takes away focus from the shell where the program was invoked, making impossible for example to press ctrl+c to stop the program. I was forced at every test to ctrl+alt+f1 to a full screen console to kill the process.
There's a nice Lua GUI project called TekUI which includes a basic graphing control that could be imported and extended to do the same without the need of an external dependency like gnuplot.
It's highly portable, a few years ago I managed to compile and use it on a A10 ARM processor board (Hackberry if memory serves).https://befinitiv.wordpress.com/wifibroadcast-analog-like-tr...
Correct me if I'm wrong, but I don't believe there is a "broadcast mode" for wifi.
So I'm asking if there is some SDR software/hardware combo that works well for this purpose, or if re-purposing wifi is the best option.