Be careful with SDR's. One minute you're scrolling around the spectrum, and the next you'll find yourself ordering parts for a 36 element Yagi and AZ/EL rotator, and a $3k radio to do Earth Moon Earth bounce communication.
ews · 22h ago
Literally me right now, got my first SDR less than a month ago because I wanted to have an FM radio for emergencies and I am designing antennas and studying for my amateur radio license.
driggs · 13h ago
If you want an FM radio for emergencies, get a battery-powered analogue FM radio, not a computer running SDR!
diggan · 16h ago
> because I wanted to have an FM radio for emergencies
Just make sure you have batteries/a way to run it!
When we lost electricity for 1.5 day here last month (Spain), I thought I'd be clever and use my SDR too, but since we didn't have electricity at all, and none of my laptops were charged, I was out of luck. Wife's Macbook had battery available, but since I never used it with her Macbook, of course it didn't have the software/drivers needed, and the internet didn't work as all ISP equipment was also without electricity. Ended up listening to the radio in the car which was more than cumbersome :/
TLDR: get a shitty battery/hand-crank powered FM/AM radio for emergencies
varispeed · 15h ago
Remember schematics for radios powered just by radio waves. No need for battery or hand-crank. That was in some old books, but never managed to build one.
roelschroeven · 14h ago
I could be wrong but I think that only works for AM, not for FM.
cowboylowrez · 5h ago
supposedly you can demodulate FM with "slope detection", off tuning slightly so as the signal varies in and out of the resonance of the tuned circuit you can get an audio signal. Its gonna be mono lol. The "Q" of the tuned circuit needs to be pretty good and its interesting to see that they use copper tubing as the coil wire or more technically in the linked page, a resonator.
That's AM crystal radio but there aren't that many AM stations left these days, most have been torn down because (thanks to AM) they need insane amounts of power to be receivable across larger distances.
ggariepy · 11h ago
Not in the USA. We still have 50,000 watt clear channel stations. On a clear winter night, local lore has it that WJR-760AM Detroit could be heard in Mexico. Crystal radios still work...well, not fine, but as good as they ever did. AM frequencies are low enough they skip off the ionosphere.
DidYaWipe · 8h ago
I remember a family road trip from Chicago to South Carolina in our '77 Impala wagon, when my whole family was listening to a DePaul basketball game on WBBM Chicago. My dad was a big fan. It was late at night, and the game came down to the last shot in the last second or so. The station was barely coming in, so we pulled over and heard DePaul win on a buzzer-beater... then the station blinked out. It was perfect.
I always think about this when I see another story about AM's demise.
kanbankaren · 8h ago
> We still have 50,000 watt clear channel stations
On shortwave, we even have 250,000 W transmitters just blasting RF everywhere.
We call them flame throwers for a reason.
DidYaWipe · 8h ago
Mmm, I think you may have AM and FM reversed there. If I remember correctly, FM only goes 65 miles or so, but AM can go thousands of miles under the right conditions (at night, mostly).
_whiteCaps_ · 21h ago
Good luck with the license! There's lots of people on Mastodon that chat about radio stuff.
ews · 20h ago
Thanks ! What accounts should I follow ?
_whiteCaps_ · 14h ago
Anyone on mastodon.radio, and check out the #amateurRadio topic.
mycall · 7h ago
Packet radio, srsRAN, LoRA, Doppler Radar. So many fun things to do with SDR.
polishdude20 · 21h ago
If anyone wants ideas, try and get on the WISPR network!
All you need is like 20 ft of wire and an SDR and you can listen to signals from across the ocean easy.
Confirming this. Sounds like a joke but suddenly Ali knows just how how to snipe you with radio equipment offers...
tehlike · 23h ago
I was already building a homelab, and was eyeing SDR and Meshtastic gear.
chneu · 20h ago
Don't do it!! Next you'll be setting up a weather station. Then you'll be setting up a microphone to ID birds via Merlin. Then home Assistant. Oh gosh it never ends.
But it's so much fun.
bo0tzz · 18h ago
This comment is targeting me personally.
enterpriss · 11h ago
What weather station did you end up with? And if it’s already been set up, is it proving to be more useful than local weather stations?
JustSomePackets · 18h ago
Well now I'm looking at automatic bird id and logging so I can track local species and see what my attempts to turn my stretch of grass into a wildlife garden does... Thanks, I think?
chneu · 17h ago
I'm so sorry. Lol
zeristor · 18h ago
They are all ready on my to do list, but just those three things.
tehlike · 13h ago
So far. While at it consider storing all the Linux isos ever existed too
bitbckt · 16h ago
I feel attacked.
UtahDave · 1d ago
$3k is barely getting started. Literally barely getting started.
But you love it anyway
wglb · 23h ago
My buddy is one of the top station builders and contesters. He says it is a about $10,000 per tower. And one tower won't do.
Keyframe · 19h ago
The hell are those guys doing? I always had the itch, but never pulled the trigger on getting my feet wet into SDR. Radio astronomy?
drmpeg · 18h ago
It's a ham radio contest station. Doesn't really have to do with SDR.
One of the few hobbies in my adhd/ult life that has sucked me in and spat me out precisely as described
travisjungroth · 22h ago
What’s ult?
ews · 22h ago
adult with adhd I assume?
travisjungroth · 18h ago
That makes sense, thanks. Ad[hd/ult].
agiacalone · 1d ago
And then there's the license upgrades!
zoklet-enjoyer · 10h ago
I will avoid it for now because I don't think my wallet can handle it. I got really into home brewing for a while. Then synthesizers and drum machines. I need to stick to cheaper hobbies
tecleandor · 17h ago
Admiral Ackbar says... "It's a trap!"
mschuster91 · 14h ago
... and time and money for acquiring a ham license!
Followed by more thousands of dollars for HF and 2m/70cm rigs, followed by more thousands of dollars for Hamnet links, a QO-100 sat dish for the Europeans...
73
_whiteCaps_ · 6h ago
I'm so jealous of the people that can see QO-100. Here I am in Canada checking my app for the birds to fly over, and people on the other side of the world can just point their antenna at it any time. :-/
ggariepy · 11h ago
You can do it on the cheap with CCRs and estate sales. My Kenwood HF unit was bought for $250, I made wire dipole antennas. I'm surrounded by Baofeng equipment as I type this. Total outlay for all of it probably on the order of $1000.
I do so want an Icom 7300, though.
dheera · 22h ago
Only 3K to bounce shit off the moon?
giantg2 · 16h ago
Can be cheaper than that. I picked up 2 used icoms for about $500. I haven't tried to moon bounce with it yet, but the one should be able to (and do satellites too). So the radio by itself would have been about $300 and the antennas are self built.
_whiteCaps_ · 21h ago
No... 3k just for the radio - actually, an IC-9700 is about $2k now.
Then add the yagi antenna, az/el moon tracker, amplifier, coax, etc. It really starts to add up.
I've never done this but I've worked a bunch of satellites and the ISS repeater. It's generally the same stuff, just a bit more powerful and precise.
RF_Savage · 21h ago
Can be done more cheaply if tou are good at reusing things and building.
There's a lot of garbage equipment out there and it's easy to buy something that does not work or creates spurious emissions or other weird interference and incompatibilities. Unless you know how to mitigate these issues with a deeper understanding of electronics and RF, you're going to struggle to get good results.
That site is easily the most comprehensive starting point for beginners, but read through it carefully before purchasing a dongle.
drweevil · 14h ago
I second the rtl-sdr.com site.
There's a lot of cheap (as in not very good) stuff out there. I have 3 goto SDRs in my collection. The RTL-SDR.com Blog V4 dongle is a great--and affordable--starting point. You're only out ~$40 if you decide this isn't for you, but if it is, the 27 MHz to 1.6 GHz coverage will keep you busy. If you are a ham, or enjoy short wave listening, go with the Airspy HF+. Covers 0.5 KHz (I've seen reports of ultrasound experiments with this!) through HF, and VHF bands. For the price, this is the highest quality SDR I have. Great sensitivity, low noise. Rounding out my small collection is the Great Scott Gadgets HackRF One, which is pretty much a radio lab in a box. 1 MHz to 6 GHz, 20 MS/s (albeit at only 8-bit quadrature sampling), and can transmit. (As an added bonus their teaching videos are very good.)
BTW, I have no problems with running these 3 SDR devices on Linux, if that is a consideration.
net01 · 18h ago
I love SDRs, I use mine to record the microphone signal of my professors.
much better than using a phone or a dedicated recorder!
HWR_14 · 13h ago
I take it they are using a lavalier microphone during lectures that broadcasts the recording in an unencrypted format? If so, that's a great solution.
net01 · 6h ago
Yeah, they are using Sennheiser transmitters (some are lavs some are full XLR mics )
Basically, I am using an SDR(RTL-SDR V4 with a small antenna) and SDR++
they have set frequencies that I have bookmarked and saved.
Funny thing, this allows me to listen to courses in other rooms, its quite fun to tune in and guess the class xD
This is not a python module, but a guide to learn the basic of digital signal processing using python in the context of using a SDR. It also goes into the specific of using the most popular SDR HW.
ash-ali · 1d ago
Table of contents & the books description seem a little gloomy to anyone else?
GNU Radio, filters, AM/FM, IQ demod ... I remember working through all these topics on GNU Radio Tutorials wiki [0] but I don't know if the book offers anything more of value?
Also, if the authors focus on GNU Radio as their software stack why would they not include a chapter on creating your own Python Blocks which is the biggest upside (imo) to GNU Radio. I love SDRs and think anyone interested in electrical engineering should play around with them. I dont know if I'd recommend this book based off what the sample chapter 4 provided.
I think sending people directly to GNU Radio is a bit of a risk. Sending folks that just learned how to spell SDR deep into the bowels of DSP is a bit steep of a learning curve that many might equate with a brick wall.
A little over ten years ago (!) I got started with a windows box, sdrsharp and a cheap RTL-based SDR. Just cruising around the spectrum, clicking on signals that were interesting, cobbling together decoding pipelines and getting real results was a way better way for me. Getting started with software that works and interesting use cases you can get into with cheap hardware got me hooked and THEN I had something that I was genuinely craving an understanding of to drive me into GNU Radio.
perrygeo · 6h ago
Agreed, GNU Radio exists in this weird no-mans land where it works on low-level concepts wired up with high-level guis. Do not want. I want to playing with CubicSDR to zoom around the spectrum, then if I I need to do anything fancy with the data, switch over to signal processing and start writing code.
focusedone · 13h ago
Handy map of online web SDRs if you'd like to play with one while waiting for yours to ship :-)
Tried playing with SDR a while back. Back then, biggest challenge was to find an appropriate hardware that can receive at various frequencies and also compatible with my Linux box.
Pawka · 20h ago
Hermes Lite is not _so_ expensive and decent open source project: http://hermeslite.com/
noman-land · 12h ago
The HackRF has a super wide range and works great. Highly recommended.
Rtlsdr are extremely cheap to start with. Then maybe Hackrf one? They're all (?) trivial to use on Linux these days.
joker99 · 21h ago
If you want to go even a step up in the trvial to use ladder, there's the Portapack H4m project. It builds on the HackRF One and adds a screen, custom firmware (open source, extensible) into an handheld factor and lets you do a bunch of... _stuff_ without needing a computer :) Also not _that_ expensive, I got mine for about 400€ from lab401.
azernik · 16h ago
Things have improved a lot. These days GNU Radio (via OsmoSDR) supports all the big hobbyist-price-point SDR vendors, and most of them go from ~50MHz to ~6GHz.
Havoc · 17h ago
Is there any sort of automatical signal detection tech out there. i.e. something that identifies part of spectrum that aren't noise automatically?
The cheap SDRs have pretty narrow receive windows so would be helpful
zhengyi13 · 13h ago
The way I read your question, anything that will display a waterfall is what you want; you'll see crystal clear that there are signals wherever they might be, and you can just click/tune over to that frequency. You typically can zoom in or out on that waterfall to cover broader or narrower ranges.
You can get this with either full on (expensive!) radios, or with a cheap RTLSDR dongle paired w/ appropriate software on your computer. And to what you said about cheap SDRs... 24 to 1766 MHz isn't a particularly narrow range from my point of view, but if you're willing to spend some more money, the HackRF One will cover 1MHz (160m band) all the way on up to 6GHz (wifi). Going lower or higher than that probably needs more specialized stuff.
(And of course, appropriately tuned antennae hooked to the radios/dongles)
Havoc · 10h ago
I do have a hack rf one just not unboxed (for a while it sounded like UK might ban SDR sales so preemptive buy).
I was under the impression that the spectrum is quite large relative to what you can look at with a waterfall and thus would take forever. Based on your comment sounds like I might need to take another look!
ThrowawayR2 · 12h ago
Specialized hardware exists for that. Google for "spectrum monitoring".
sorenjan · 17h ago
If you want another use for SDR, the KrakenRF kan be used to find radio transmitters.
No one asked, but, if you're here:
check out this (new-ish) Python library for SDR that is really well designed and developed (IMHO)
https://mhostetter.github.io/sdr/latest/
Jimmc414 · 1d ago
Thats how Russ Hanneman made his money.
ianschmitz · 23h ago
ROI?
rsync · 22h ago
There used to be an all-in-one boot image for the raspberry pi:
Just make sure you have batteries/a way to run it!
When we lost electricity for 1.5 day here last month (Spain), I thought I'd be clever and use my SDR too, but since we didn't have electricity at all, and none of my laptops were charged, I was out of luck. Wife's Macbook had battery available, but since I never used it with her Macbook, of course it didn't have the software/drivers needed, and the internet didn't work as all ISP equipment was also without electricity. Ended up listening to the radio in the car which was more than cumbersome :/
TLDR: get a shitty battery/hand-crank powered FM/AM radio for emergencies
https://electronbunker.ca/eb/FMCrystalSet.html
I always think about this when I see another story about AM's demise.
On shortwave, we even have 250,000 W transmitters just blasting RF everywhere.
We call them flame throwers for a reason.
https://www.rtl-sdr.com/a-tutorial-on-receiving-wspr-with-an...
But it's so much fun.
But you love it anyway
https://www.youtube.com/watch?v=Dd4NWyFq-dM
Some stations do use SDRs to feed the reverse beacon site. https://beta.reversebeacon.net/main.php
Followed by more thousands of dollars for HF and 2m/70cm rigs, followed by more thousands of dollars for Hamnet links, a QO-100 sat dish for the Europeans...
73
I do so want an Icom 7300, though.
Then add the yagi antenna, az/el moon tracker, amplifier, coax, etc. It really starts to add up.
I've never done this but I've worked a bunch of satellites and the ISS repeater. It's generally the same stuff, just a bit more powerful and precise.
There's a lot of garbage equipment out there and it's easy to buy something that does not work or creates spurious emissions or other weird interference and incompatibilities. Unless you know how to mitigate these issues with a deeper understanding of electronics and RF, you're going to struggle to get good results.
That site is easily the most comprehensive starting point for beginners, but read through it carefully before purchasing a dongle.
There's a lot of cheap (as in not very good) stuff out there. I have 3 goto SDRs in my collection. The RTL-SDR.com Blog V4 dongle is a great--and affordable--starting point. You're only out ~$40 if you decide this isn't for you, but if it is, the 27 MHz to 1.6 GHz coverage will keep you busy. If you are a ham, or enjoy short wave listening, go with the Airspy HF+. Covers 0.5 KHz (I've seen reports of ultrasound experiments with this!) through HF, and VHF bands. For the price, this is the highest quality SDR I have. Great sensitivity, low noise. Rounding out my small collection is the Great Scott Gadgets HackRF One, which is pretty much a radio lab in a box. 1 MHz to 6 GHz, 20 MS/s (albeit at only 8-bit quadrature sampling), and can transmit. (As an added bonus their teaching videos are very good.)
BTW, I have no problems with running these 3 SDR devices on Linux, if that is a consideration.
Funny thing, this allows me to listen to courses in other rooms, its quite fun to tune in and guess the class xD
This is not a python module, but a guide to learn the basic of digital signal processing using python in the context of using a SDR. It also goes into the specific of using the most popular SDR HW.
GNU Radio, filters, AM/FM, IQ demod ... I remember working through all these topics on GNU Radio Tutorials wiki [0] but I don't know if the book offers anything more of value?
Also, if the authors focus on GNU Radio as their software stack why would they not include a chapter on creating your own Python Blocks which is the biggest upside (imo) to GNU Radio. I love SDRs and think anyone interested in electrical engineering should play around with them. I dont know if I'd recommend this book based off what the sample chapter 4 provided.
[0] https://wiki.gnuradio.org/index.php/Tutorials
A little over ten years ago (!) I got started with a windows box, sdrsharp and a cheap RTL-based SDR. Just cruising around the spectrum, clicking on signals that were interesting, cobbling together decoding pipelines and getting real results was a way better way for me. Getting started with software that works and interesting use cases you can get into with cheap hardware got me hooked and THEN I had something that I was genuinely craving an understanding of to drive me into GNU Radio.
https://www.receiverbook.de/map
https://greatscottgadgets.com/hackrf/
The cheap SDRs have pretty narrow receive windows so would be helpful
You can get this with either full on (expensive!) radios, or with a cheap RTLSDR dongle paired w/ appropriate software on your computer. And to what you said about cheap SDRs... 24 to 1766 MHz isn't a particularly narrow range from my point of view, but if you're willing to spend some more money, the HackRF One will cover 1MHz (160m band) all the way on up to 6GHz (wifi). Going lower or higher than that probably needs more specialized stuff.
(And of course, appropriately tuned antennae hooked to the radios/dongles)
I was under the impression that the spectrum is quite large relative to what you can look at with a waterfall and thus would take forever. Based on your comment sounds like I might need to take another look!
https://www.krakenrf.com/
https://github.com/luigifcruz/pisdr-image
Unfortunately it appears to have been abandoned ...
https://sourceforge.net/projects/dragonos-pi64/
Communication Systems Engineering with GNU Radio: A Hands-on Approach Jean-Michel Friedt, Herve Boeglen
https://www.wiley.com/en-fr/Communication+Systems+Engineerin...