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Welcome to the World of Software Defined Radio (2016)
- qubex 9y agoDVB-T type devices such as the one referred to in this article are indeed remarkably flexible but keep in mind that they are only able to receive. In my case, that quite rapidly exhausted my curiosity. I'm now eagerly awaiting delivery of a LimeSDR (https://www.crowdsupply.com/lime-micro/limesdr https://www.crowdsupply.com/lime-micro/limesdr), one of several hacker-friendly radio peripherals that can both receive and send (in the LimeSDR's case, in full duplex mode) because of course having a transceiver is a whole different ball-game. GnuRadio can serve as the logic of both receivers and transmitters. Of course depending on country, frequency and transmitted power you may require licences to operate.
- nextlevelwizard 9y agoSending capability (at least here) requires amateur radio license. It is technically illegal to even own transmit capable equipment without a license and you can operate it only under supervision of licensed person.
- payne92 9y agoThis is not at all true in the US: it is not "technically illegal" to own transmit-capable equipment without a license. It is true that transmissions are regulated by law in every country, and the particular license you need will be determined by frequency band and power. In the US, there are some cases ("Part 15") where no license is required.
- vvanders 9y agoYeah, GMRS band is actually pretty permissive as long as you stay under the power limit(5W?).
- platz 9y agoas noted above "part 15" rules actually allow low-power transmission along a multitude of bands. In some bands you are restricted to only a few mw of power, others like the scientific bands allow more.
- qubex 9y agoThat cannot literally be true... your cellphones and wifi devices are radio transmitters and I'm assuming owning either is not specifically illegal. I assume you mean unlicensed equipment?
- nextlevelwizard 9y agoYou are intentionally misinterpreting what I said, or maybe you do not know that some bands can be used by commercial devices. That doesn't mean you can do whatever you wish on any bandwidth you want. But even in something as common as WiFi you still have regulations, like channel 14, which as far as I know only works in Japan by default. Other common restriction is transmitting power.
- qubex 9y agoI’m not ”intentionally misrepresenting”, nor did I misunderstand — I was just being comically pedantic, because the absolute terms you couched your statement in are obviously not true, because a lot of personally-owned devices transmit radio and that doesn’t get you into any trouble whatsoever.
- nextlevelwizard 9y agor/iamverysmart
- robputt 9y agoYeah, I get that feeling too, but the problem is the licensing and stuff... The good news is I get my send and receive fix from LoRa and The Things Network, still has legislation you must abide by like duty cycle and power limits, but doesn't have the headache fo being a HAM.
- morganvachon 9y agoWhat is such a headache about amateur radio? The test is less expensive than two cups of coffee in most places and the license itself is free. I'd wager if you're a regular here, you'd have no problem learning the theory and rules to pass the test, especially if you're genuinely interested in radio communications.
- robputt 9y agoIs it still a requirement to be fluent in morse code? If so I personally feel this requirement is redundant in the current age with the tooling we have available which can easily encode and decode morse on our behalf... If not maybe I'll consider it, until then I would prefer to dedicate my time to learning something more current / relevant than memorising morse.
- detaro 9y agoIn the US morse hasn't been a requirement in the last decade or so (and I think basic classes without it even longer), and many other countries have dropped it as well.
- morganvachon 9y agoI got my "no-code Technician" class license in 1998, not long after they did away with the code requirement for Technician. At that time, Novice, General, Advanced, and Extra classes all still existed and all required Morse code. Later the FCC dropped Novice and Advanced and later still removed Morse code from all tests. Still, I wish I had started with Novice so I'd have learned Morse early on.
- superkuh 9y ago>In my case, that quite rapidly exhausted my curiosity. I've been exploring the world of radio emissions with rtlsdr since 2013 (http://superkuh.com/rtlsdr.html http://superkuh.com/rtlsdr.html) and I'm still finding plenty of new things to do. IMO, the newest cool stuff with rtlsdr are computational hacks to align multiple non-coherent receivers in time to do distributed direction finding and the like.
- ragix 9y agoThat sounds really interesting, have you got a url?
- superkuh 9y agohttps://www.rtl-sdr.com/tracking-wildlife-with-tdoa-direction-finding-and-rtl-sdr-dongles/ https://www.rtl-sdr.com/tracking-wildlife-with-tdoa-directio... See also, https://ptrkrysik.github.io/ https://ptrkrysik.github.io/
- superkuh 9y agoAlso, http://www.panoradio-sdr.de/tdoa-transmitter-localization-with-rtl-sdrs/ http://www.panoradio-sdr.de/tdoa-transmitter-localization-wi...
- ptero 9y agoI recently read here that a Raspberry Pi can be turned into an SDR transmitter by attaching a wire to a pin. On paper, the specs look impressive (for a $20-$30 device), but I would love to know the RF quality of the resulting waveform. I cannot find the discussion, but the info is here: http://www.rtl-sdr.com/tag/rpitx/ http://www.rtl-sdr.com/tag/rpitx/
- grawlinson 9y ago>but I would love to know the RF quality of the resulting waveform. Technically it works, but it's very noisy and the transmission range isn't far enough for anything too serious. A full duplex SDR would be a better investment.
- ptero 9y agoOn noise, this is what I suspect, too; thus I am not trading in a couple of HackRF One-s that I am currently playing with. Still would be useful to know the numbers. On the range, I did not pay much attention (but maybe I should have): the power of HackRF one is low, too; one needs an amplifier to transmit in the open air anyway. Do you think that the rpitx TX power is not suitable for table-top sized prototypes?
- planteen 9y agoThere are some details here: http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll.html http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll... It says a dynamic range of only 13 dB on the levels.
- th0ma5 9y agoAs an Amateur Extra I've used a Pi to transmit WSPR 24/7 and was once heard in New Zealand from Ohio. No amplifiers even...
- j_s 9y agoJust to triple-confirm, there was no additional hardware besides the Pi? I'm assuming at least some sort of antenna was involved... Any links to write-ups/HOWTO's would be tremendously appreciated!
- technofiend 9y agoWhat exhausted mine is the fact broadcast digital FM radio in the US is protected by patent and license encumbered encoding schemes, so there are no open-source decoders for GNU Radio and derivatives.
- drmpeg 9y agoIt's been cracked. Here's a receiver for RTL-SDR. https://github.com/theori-io/nrsc5 https://github.com/theori-io/nrsc5 And a transmitter for GNU Radio. https://github.com/argilo/gr-nrsc5 https://github.com/argilo/gr-nrsc5
- technofiend 9y agoThank you! I'm happy to be corrected. :-)
- captainmuon 9y agoInteresting! A conspiracy theory of mine is that one factor in the push to digital TV and radio was to prevent widespread pirate transmissions, as much more people got access to "studio" equipment aka multimedia devices. Of course if that was one motivation it is moot now, since the internet has become more relevant than traditional media. Still, this might be cool for subversive actions in countries with censored media, in an "Arab spring" like situation. Just a laptop, SDR and antenna on a driving truck and your on air (ofc I think there is not much overlap in places with widespread digital radio and places where you'd need to do this anyway)
- drmpeg 9y agoSDR has completely changed the landscape. I'm the developer for the digital television component of GNU Radio. There are transmitters for ATSC, DVB-T, DVB-T2, DVB-S, DVB-S2 and cable QAM. Here's a video of DVB-S2 being transmitted with a LimeSDR. https://www.youtube.com/watch?v=Ed7iy0gVywo https://www.youtube.com/watch?v=Ed7iy0gVywo
- anfractuosity 9y agoThat micro limesdr looks very tempting. Also someone on /r/rtlsdr mentioned PlutoSDR which is also in a similar price range. I need to start to save up!
- jeffdubin 9y agoLime's policies on free and open source software and hardware (https://www.crowdsupply.com/lime-micro/limesdr#free-and-open-source https://www.crowdsupply.com/lime-micro/limesdr#free-and-open...) pushed me over the edge. The LimeSDR Mini project (https://www.crowdsupply.com/lime-micro/limesdr-mini https://www.crowdsupply.com/lime-micro/limesdr-mini) has my money.
- platz 9y agoLime has the best hardware/specs at their price points, but their software toolchain is atrocious; just trying to do simple tasks in GNURadio is so flaky/error prone. I wish I'd gone with ahackrf (michael ossmann products) rather than the lime.
- jeffdubin 9y agoI've met Mike a couple of times, and he's a great guy, a great teacher, and super passionate about open source. The HackRF is a revolutionary little board, but it seems to be getting a little outdated compared these newer projects. I'm hoping he'll have something new soon!
- platz 9y agoRight, HackRF is not going to cut it if your building a cell phone repeater. But for home/hobby projects it's pretty good. I own a LimeSDR. It's not just the hardware, you also have have good software drivers. Everything open source in RF pretty much uses GNUradio, and there are endless problems trying to get LimeSDR working with GNUradio. Just read the message boards for LimeSDR. The first thing lime tells you do so is install Pothos which has zero support in open source community, so good luck. I wish it were otherwise as I said I've spent a lot of time fiddling with my limesdr
- brian-armstrong 9y agoI got a Lime and I've not really had a great experience with it. You can't actually receieve HF with it unless you desolder an inductor. Also mine has a HUGE DC bias which introduces a ton of noise and basically cuts the usable bandwidth in half, if not more. Sadly I think these things were overhyped and/or ran into design issues that keep them from living up to the promise
- platz 9y agosame experience, sadly.
- qubex 9y agoThis is very upsetting, I have been really looking forward to getting my LimeSDR. I’ve already opted for having it delivered with the offending inductor removed, but reading of high DC biases and (elsewhere in the thread) bad drivers and poor interoperability with GnuRadio has kind of spoiled my excitement.
- brian-armstrong 9y agoWell, I wish you the best. It's possible they're just having QC issues. Yours might be perfect!
- payne92 9y agoFor a device that can transmit as well as receive, consider HackRF: https://github.com/mossmann/hackrf/wiki https://github.com/mossmann/hackrf/wiki It's been out for a while. The newer option is LimeSDR, which just shipped: https://www.crowdsupply.com/lime-micro/limesdr https://www.crowdsupply.com/lime-micro/limesdr (Note that you need to comply with all local laws regarding transmitting).
- jballanc 9y ago...wrong thread...
- lima 9y agoWrong thread :)
- jballanc 9y agoWow...no idea how that happened...
- mnarayan01 9y agoIf anyone's confused, parent is presumably intended for https://news.ycombinator.com/item?id=15302267 https://news.ycombinator.com/item?id=15302267.
- trishmapow2 9y agoSDR and RF in general has always felt like black magic for me, but the availability of cheap hardware and wife software selection makes this accessible to everyone. For newcomers I recommend the RTL-SDR subreddit, plenty of great resources. My latest venture is a jam and replay attack on keyless entry systems eg vehicles, project page is here: https://github.com/trishmapow/CC1101-FSK https://github.com/trishmapow/CC1101-FSK
- mberger 9y agoavailability of cheap hardware and wife software selection If only that was true... ;)
- acidburnNSA 9y agoThe rtl-sdr dongles are like $15. They're usually recieve only, and you need more like $300 to get a HackRF One for serious work.
- iamatworknow 9y agoYes, but which wife software do you use?
- qubex 9y agoA socially-conservative Tinder clone that books you both into a church on the first mutual right swipe.
- iamatworknow 9y agoPewter?
- bjt2n3904 9y agoNot gonna lie. As a radio guy, our terminology is messed up. My favorite though is using superlatives. Low Frequency (LF), Medium Frequency (MF), High Frequency (HF). You'd think that maybe HF is WiFi, but you gotta remember these terms were invented back in the early days of radio. HF is between 3 and 30 MHz. You have Very High Frequency and Ultra High Frequency, but that only takes us to 3 GHz. 5 GHz Wifi is technically SHF -- or Silly High Frequency. But we also refer to these frequency bands in terms of MHz, or if we feel like it, wavelengths. Since radio signals travel (effectively) at the speed of light (m/s), we can multiply Hz (1/s) by a distance and get wavelength. (c = f * l). 144 MHz then is the 2 meter band, or VHF as we call it. Confused yet? Wait until we start talking about baseband and I/Q signals!
- TKinNC 9y agoThere is a glaring error at the beginning of this article under the "things you cannot do with SDR." "Listening in on the conversations of Ham operators." In the US at least, there are many VHF/UHF Ham bands easily received by SDR. I use an Airspy on Mac OS X, and although the software is terrible, there is plenty to listen to.
- codazoda 9y agoI was thinking / wondering the same. Many new HAM operators get handheld radios that use the 144MHz (2 meter) and 440MHz (70 cm) bands. Both of these seem to be within range of this device. You can also build a dipole antenna for these frequencies for a few dollars. That would allow many of us to listen to repeaters in our local area. RepeaterBook.com (or the mobile app) is a good resource for listing repeaters near you. I haven't had time to write much detail about this but here's an antenna I built recently. A quick google search will bring up dozens of other designs. https://www.joeldare.com/topics/amateur-radio/#gift-card-dipole https://www.joeldare.com/topics/amateur-radio/#gift-card-dip...
- mikestew 9y agoMaybe they were thinking HF (High Frequency), which is what's used for long distance/international contacts and what many people think when they think "ham radio". AFAIK the USB stick receivers can't receive HF. But that's a hardware limitation, not SDR limitation. There exist SDRs that can do HF, they just don't cost $15.
- BenjiWiebe 9y agoActually the latest RTL-SDR has a software switch for direct sampling. Which isn't great quality, but with an indoor wire antenna in the basement (!) I received JT65 transmissions from 47 states in the course of a few evenings. Hawaii, Vermont, and Alaska are the ones I missed. However, I did hear Hawaii... On SSB!!
- coin 9y ago> mhz Should be written using the proper SI prefix, MHz. There's a huge difference between the milli (m) prefix and mega (M).
- codazoda 9y agoIs there a similarly priced and sized SDR that can both receive and transmit? Having received my ticket recently, I'd love to try some digital ham radio modes without spending a fortune.
- rwmj 9y agoNot that I've seen. There exists SDR hardware for transmitting, but all seemed to start at multiple $100's. In any case note that you will almost certainly need a license to transmit on most interesting frequencies and power levels. Edit: "ticket" = license?
- billh 9y agoYou are correct, ticket is ham nomenclature for license.
- billh 9y agoThere is the LimeSDR Mini that is currently being croudfunded[1]. For $140 USD you would be hard pressed to find anything like it that would give you full duplex across that frequency range. I own the full size LimeSDR device and it has been a great piece of hardware for playing around with. 1. https://www.crowdsupply.com/lime-micro/limesdr-mini https://www.crowdsupply.com/lime-micro/limesdr-mini
- platz 9y agoLime has the best hardware/specs at their price points, but their software toolchain is atrocious; just trying to do simple tasks in GNURadio is so flaky/error prone
- senatorobama 9y agoWhy are SDRs for TX when you can get a SoTA radio in a smartphone for < $10?
- KGIII 9y agoThis thread could use this link: http://websdr.ewi.utwente.nl:8901/ http://websdr.ewi.utwente.nl:8901/ Basically, it is an SDR for multiple users and an online interface. It's RX only, of course. More options are available at websdr.org but the above is my favorite. Caution, it can be a huge time sink.
- dogruck 9y agoReminds me of this ye old project at MIT http://www.sds.lcs.mit.edu/SpectrumWare/home.html http://www.sds.lcs.mit.edu/SpectrumWare/home.html
- bosky101 9y agoRelevant... Listen to Radio from around the globe http://radio.garden/live/ http://radio.garden/live/ (drag the map to tune in)
- lioeters 9y agoThis is really wonderful, thank you for the link. I'm enjoying now a radio broadcast from..Malawi. The diversity of voices around the world, the ease of moving and focusing on stations - one of the best things I've seen on the web.