8 ms·

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

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.

asdfman123 7y ago
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.
- AWildC182 7y ago
  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.
  - asdfman123 7y ago
    It was a physical device and I was setting it up to read the police scanners. I do have problems sitting too long with documentation, though, I'm sure if I more patiently worked through it I could have set it up.
- mlaretallack 7y ago
  Start with the spectrum analyser app, it is a nice way to see what transmissions are around. This leads to "what is that".....
larrywright 7y ago
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.
- larrywright 7y ago
  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). Source: https://www.fcc.gov/consumers/guides/interception-and-divulgence-radio-communications https://www.fcc.gov/consumers/guides/interception-and-divulg... via https://www.reddit.com/r/RTLSDR/comments/4nhg7h/legalities_of_intercepting_pager_signals/ 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.
- amatecha 7y ago
  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. [0] https://openprivacy.ca/blog/2019/09/09/open-privacy-discovers-vancouver-patient-medical-data-breach/ https://openprivacy.ca/blog/2019/09/09/open-privacy-discover... [1] https://www.ctvnews.ca/health/pager-systems-used-in-healthcare-could-be-exposing-patient-data-across-canada-1.4727129 https://www.ctvnews.ca/health/pager-systems-used-in-healthca... [2] https://openprivacy.ca/blog/2019/09/26/pager-breach-update/ https://openprivacy.ca/blog/2019/09/26/pager-breach-update/
  - 7y ago
MuffinFlavored 7y ago
Can't those only receive and not send?
- larrywright 7y ago
  That’s correct.
- AWildC182 7y ago
  There are some more expensive options that do but it's not recommended if you don't have a amateur radio license
- mokus 7y ago
  If you have no idea what you’re doing, then you should not be transmitting. There’s plenty of good clean fun to be had on the receive side, though.
- penagwin 7y ago
  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.
  - galangalalgol 7y ago
    Don't listen to the rule followers! There are no SDRs out there with enough power to be much of a nuisance to anyone. Do look up what the band is for. Do watch it for a few hours or days to confirm it is clear, but seriously if you don't interfere with anyone the FCC isnt paying you a visit. Even if you do insist on following the rules, just stick to ism bands. 315 ( key fobs) (2.5ghz wifi bluetooth) and one around 900. You can go full blast on any sdr and not get close to the half watt limit.
    - galangalalgol 7y ago
dariusj18 7y ago
Any recommendation for one to buy?
- fpgaminer 7y ago
  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.
- beanaroo 7y ago
  I recommend getting one from here: https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ Great hardware with driver/software compatibility
  - larrywright 7y ago
    My advice would be the same. These units are mostly built on the same parts, the big difference is build quality (metal dongle vs plastic) and what antenna comes bundled (antenna quality/size matters a lot for anything beyond just tinkering).
    - syedkarim 7y ago
      It's more than just build-quality. The actual RF design is very different. The RTL-SDR V3 dongle was purpose built to be an SDR device. Most of the generic plastic dongles were designed to watch broadcast television.
  - squarefoot 7y ago
    +1 on this one: well built, optimized for small signal reception (TV dongles are not) therefore lower noise etc. bias tee for active antennas, metal case. Still at a good price. I have two of them and never regretted the purchase. One day I'l probably get a HackRF or something similar, although I'm still good with the rtl-sdr.com dongles. If they made a small one with enclosed upconverter to be put in my laptop bag to be carried when I take a trip in the mountains I'd get one immediately. I've tried one of those no-name Chinese little boxes with HF and V-U inputs but performance is inferior compared to the above dongle.
nullwarp 7y ago
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!
- GuyPostington 7y ago
  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?
  - nullwarp 7y ago
    It was a bit hacky, i just had rtl_433 output the values as json, piped them into a mqtt topic and used node-red to inject the values in influxdb nothing fancy
    - sillysaurusx 7y ago
      If you set up a HackRF in Chicago, you can hear police dispatch. It's pretty nifty.
    - miohtama 7y ago
      Sir, you just received the most news.ycombinator.comish comment award of the year.
beanaroo 7y ago
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.
Rerarom 7y ago
In what country is a movie ticket $20? That seems unusually expensive to me.
- AkshatM 7y ago
  This is the price of a movie ticket in the United States, at least in California. Source: lived in LA and the Bay Area.
- addandsubtract 7y ago
  3D movies cost €15 and IMAX tickets cost €18 in Berlin
mysterydip 7y ago
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.
- kitd 7y ago
  AIUI, those websites are only hackers like you crowdsourcing that info anyway.
  - larrywright 7y ago
    I believe that’s correct. FlightRadar will actually give you a free pro membership if you run a receiver in your house (basically a Raspberry Pi, SDR dongle, and an antenna).
- larrywright 7y ago
  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/ 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.
JKCalhoun 7y ago
Hackaday (the other hacker news?) just posted a link to this ready-to-go Raspbian distro pre-packed with SDR software for the Raspberry Pi: https://pisdr.luigifreitas.me https://pisdr.luigifreitas.me
mindentropy 7y ago
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.
- Sanzig 7y ago
  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. [1] https://www.diamondantenna.net/d3000n.html https://www.diamondantenna.net/d3000n.html

asdfman123 7y ago

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.

AWildC182 7y ago
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.
- asdfman123 7y ago
  It was a physical device and I was setting it up to read the police scanners. I do have problems sitting too long with documentation, though, I'm sure if I more patiently worked through it I could have set it up.
mlaretallack 7y ago
Start with the spectrum analyser app, it is a nice way to see what transmissions are around. This leads to "what is that".....

larrywright 7y ago

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.

larrywright 7y ago
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). Source: https://www.fcc.gov/consumers/guides/interception-and-divulgence-radio-communications https://www.fcc.gov/consumers/guides/interception-and-divulg... via https://www.reddit.com/r/RTLSDR/comments/4nhg7h/legalities_of_intercepting_pager_signals/ 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.
amatecha 7y ago
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. [0] https://openprivacy.ca/blog/2019/09/09/open-privacy-discovers-vancouver-patient-medical-data-breach/ https://openprivacy.ca/blog/2019/09/09/open-privacy-discover... [1] https://www.ctvnews.ca/health/pager-systems-used-in-healthcare-could-be-exposing-patient-data-across-canada-1.4727129 https://www.ctvnews.ca/health/pager-systems-used-in-healthca... [2] https://openprivacy.ca/blog/2019/09/26/pager-breach-update/ https://openprivacy.ca/blog/2019/09/26/pager-breach-update/
- 7y ago

MuffinFlavored 7y ago

Can't those only receive and not send?

larrywright 7y ago
That’s correct.
AWildC182 7y ago
There are some more expensive options that do but it's not recommended if you don't have a amateur radio license
mokus 7y ago
If you have no idea what you’re doing, then you should not be transmitting. There’s plenty of good clean fun to be had on the receive side, though.
penagwin 7y ago
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.
- galangalalgol 7y ago
  Don't listen to the rule followers! There are no SDRs out there with enough power to be much of a nuisance to anyone. Do look up what the band is for. Do watch it for a few hours or days to confirm it is clear, but seriously if you don't interfere with anyone the FCC isnt paying you a visit. Even if you do insist on following the rules, just stick to ism bands. 315 ( key fobs) (2.5ghz wifi bluetooth) and one around 900. You can go full blast on any sdr and not get close to the half watt limit.
  - galangalalgol 7y ago

dariusj18 7y ago

Any recommendation for one to buy?

fpgaminer 7y ago
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.
beanaroo 7y ago
I recommend getting one from here: https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ Great hardware with driver/software compatibility
- larrywright 7y ago
  My advice would be the same. These units are mostly built on the same parts, the big difference is build quality (metal dongle vs plastic) and what antenna comes bundled (antenna quality/size matters a lot for anything beyond just tinkering).
  - syedkarim 7y ago
    It's more than just build-quality. The actual RF design is very different. The RTL-SDR V3 dongle was purpose built to be an SDR device. Most of the generic plastic dongles were designed to watch broadcast television.
- squarefoot 7y ago
  +1 on this one: well built, optimized for small signal reception (TV dongles are not) therefore lower noise etc. bias tee for active antennas, metal case. Still at a good price. I have two of them and never regretted the purchase. One day I'l probably get a HackRF or something similar, although I'm still good with the rtl-sdr.com dongles. If they made a small one with enclosed upconverter to be put in my laptop bag to be carried when I take a trip in the mountains I'd get one immediately. I've tried one of those no-name Chinese little boxes with HF and V-U inputs but performance is inferior compared to the above dongle.

nullwarp 7y ago

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!

GuyPostington 7y ago
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?
- nullwarp 7y ago
  It was a bit hacky, i just had rtl_433 output the values as json, piped them into a mqtt topic and used node-red to inject the values in influxdb nothing fancy
  - sillysaurusx 7y ago
    If you set up a HackRF in Chicago, you can hear police dispatch. It's pretty nifty.
  - miohtama 7y ago
    Sir, you just received the most news.ycombinator.comish comment award of the year.

beanaroo 7y ago

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.

Rerarom 7y ago

In what country is a movie ticket $20? That seems unusually expensive to me.

AkshatM 7y ago
This is the price of a movie ticket in the United States, at least in California. Source: lived in LA and the Bay Area.
addandsubtract 7y ago
3D movies cost €15 and IMAX tickets cost €18 in Berlin

mysterydip 7y ago

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.

kitd 7y ago
AIUI, those websites are only hackers like you crowdsourcing that info anyway.
- larrywright 7y ago
  I believe that’s correct. FlightRadar will actually give you a free pro membership if you run a receiver in your house (basically a Raspberry Pi, SDR dongle, and an antenna).
larrywright 7y ago
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/ 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.

JKCalhoun 7y ago

Hackaday (the other hacker news?) just posted a link to this ready-to-go Raspbian distro pre-packed with SDR software for the Raspberry Pi: https://pisdr.luigifreitas.me https://pisdr.luigifreitas.me

mindentropy 7y ago

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.

Sanzig 7y ago
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. [1] https://www.diamondantenna.net/d3000n.html https://www.diamondantenna.net/d3000n.html