[HN Gopher] Universal Radio Hacker: Investigate Wireless Protoco...
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Universal Radio Hacker: Investigate Wireless Protocols Like a Boss
Author : mindcrime
Score : 225 points
Date : 2021-02-28 04:35 UTC (18 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| codetrotter wrote:
| > URH allows easy demodulation of signals combined with an
| automatic detection of modulation parameters making it a breeze
| to identify the bits and bytes that fly over the air
|
| Something I've been wanting to do for a long while is to figure
| out how to decode the time code audio signal of Serato Control
| Vinyl.
|
| I briefly looked at the audio signal of Serato Control Vinyl in
| Audacity and you can tell that it should be possible to reverse
| engineer what's going on. The signal if I remember correctly
| looks like a blend between a sine wave and a triangle wave, with
| a sort of "bend" that it looks like half of a banana kind of.
| Furthermore from memory the frequency of the signal changes over
| time, the shape changes, and there is a (possibly changing) phase
| difference between the left and right channels.
|
| Somehow, this encodes a time code. And I can tell that it makes
| sense that you'd be able to tell the time from looking at the
| changes in the signal. But I don't know how to actually decode it
| in order to determine the time code.
|
| Serato Control Vinyl is used for Digital Vinyl Systems (DVS) in
| DJing. It allows you to use the control vinyl on a vinyl player
| and hook it up to your computer in order to control the playback
| of audio on the computer.
|
| This way you can use physical control vinyl to do scratching and
| other DJing, and the software on the computer is able to very
| accurately manipulate the playback of digital audio based on the
| analog time code signal, so that speed and direction and time
| position is accurately tracked with high fidelity.
|
| For anyone else who also thinks this sounds interesting, download
| the control CD from https://serato.com/controlcd/downloads and
| look at the audio signal, it is similar (possibly even the same?)
| as the one on the control vinyl.
|
| In fact there is already some third-party software that supports
| using the Serato control vinyl. For example, the open source
| Mixxx.
| https://manual.mixxx.org/2.3/en/chapters/vinyl_control.html
|
| However, Mixxx is GPL v2 licensed, and I am hoping to implement
| interoperability with Serato control vinyl in software that is
| either ISC licensed or proprietary, so I don't want to even look
| at GPL licensed source code.
|
| If anyone is able to figure out how the time code signal of
| Serato control vinyl works, or knows of an existing description
| of it that can be used for implementing software for it, please
| let me know.
| sneakypete81 wrote:
| That brings back nice memories, I designed some of the early
| Serato scratch hardware. I didn't work for them directly
| though, so never did manage to find out how the vinyl timecode
| worked.
| lbotos wrote:
| Happy to see another DJ nerd here.
|
| Mixxx's timecode engine is powered by xwax:
|
| https://sourceforge.net/p/xwax/mailman/xwax-devel/ I'm pretty
| sure there was a thread on the mailing list where they talked
| about it.
|
| My understanding is that there are "directional" and
| "positional" signals on the timecode to give you "relative" and
| "absolute" positioning.
|
| You may be able to glean more from mspinkys as well:
| http://www.mspinky.com/SoftwareSpec_0.0.6.pdf (no code here,
| just function names and descriptions)
|
| Good luck!
| codetrotter wrote:
| Thank you :)
| molticrystal wrote:
| Wow this has come a decent way since I first tried it back in
| early 2017. I used to use the rtlsdr a lot as a hobby back then,
| and it inspired me to get a ham license after hearing the local
| chatter. I'll have to dig it back out and scan the airwaves again
| and see if I can decode anything interesting. Thanks for sharing
| this.
| PiotrVonKleve wrote:
| Nice hardware is the HackRF One [1], since you can record and re-
| transmit the recorded signal. Compatible with GNU Radio, SDR#,
| and more, 1 MHz to 6 GHz operating frequency. [1]
| https://greatscottgadgets.com/hackrf/one/
| WrtCdEvrydy wrote:
| Wow, I was looking at the Blade and Blade mini but this is
| cheaper.
| amelius wrote:
| > 1 MHz to 6 GHz operating frequency.
|
| But what is the maximum bandwidth?
| squarefoot wrote:
| Does having a 8-bit converter seriously affect in any way
| reception?
|
| I'm happy with my rtl-sdr v3 dongle, although living in a very
| noisy area would like to get something better for HF reception.
| I don't have a HAM license and no need for the HackRF transmit
| capabilities, though it may turn out useful for testing
| remotes, filters, aligning RF stages in diy receivers etc, but
| the SDRPlay RSPdx or the AirSpy + Spyverter seem better
| alternatives for receiving only with their 14 and 12 bit ADCs.
|
| Here's a comparison of the three; I'd be interested in reading
| from other owners as well. https://www.rtl-sdr.com/review-
| airspy-vs-sdrplay-rsp-vs-hack...
| aftbit wrote:
| I have a bunch of RTL-SDRs, the HackRF, and the AirSpy. I
| have only done VHF -> UHF work with them, never HF. In my
| experience, the HackRF receive frontend is pretty poor, at
| least in comparison. I'd use it if I needed transmit or for
| local strong signals only. The AirSpy has the best receiver
| of the bunch, but worse software support. I've had quite a
| challenging time getting it to work with GNU Radio and GQRX.
| It works great in SDR Sharp but that is no longer FOSS and
| must be run on Windows IIRC. The RTL-SDR is cheap and has a
| receiver at least on par with the HackRF and by far the best
| compatibility.
| penagwin wrote:
| Do you have any experience with the limesdr? I've been eyeing
| those for a bit
| the_only_law wrote:
| I bought one several months ago, albeit haven't used it much
| yet. My one concern is how hot it ran when I first plugged it
| in, you may want to get a case for it.
| they4kman wrote:
| I purchased the aluminum case along with my LimeSDR. A few
| months ago, I figured out how to use trunk-recorder, and
| the Lime has been my police/EMS radio scanner ever since.
| It's been running almost nonstop for months, and I haven't
| noticed any issues -- even as it remained hot to the touch
| for all those months.
| sponaugle wrote:
| Oh yea, it does run pretty hot! I made a case for it from
| an electronics project case I had laying around, and even
| with that it is toasty. If I was building something that
| was going to be running of for a long time a 3d printed
| case with support for a small fan would be helpful.
| sponaugle wrote:
| I have a limesdr and a hackrf. Both work really well, but it
| does seem like there are more people/projects for the hackrf.
| Once you learn the ins and outs of GNUradio, it is pretty
| amazing what you can do.
| motohagiography wrote:
| Super valuable. I remember specing out Ettus radios for a
| security research project and they were in the thousands of
| dollars, whereas today it's a $20 dongle with gnuradio.
| the_only_law wrote:
| Well, the Ettus radios are still probably superior if you're
| working with higher frequencies, but there are still cheaper
| alternatives.
|
| Last time I was at the Ettus site I was dumbfounded more with
| how much they're trying to sell software for.
| motohagiography wrote:
| My comment was a fragment of something I thought I didn't
| post, it's there in error. It was in reference to some RF
| security work I did almost 10 years ago. Ettus seems super
| cool, and they were more cost effective than that, and this
| was just before people popularly discovered that TV tuners
| could be used as SDRs.
| CraigJPerry wrote:
| This made it really easy to figure out how to interpret the
| packets from my wireless barbeque thermometer. Previously i used
| some monstrous excel for this kind of pattern finding, e.g.
| https://github.com/cleanflight/cleanflight/issues/1125#issue...
|
| In the end the bbq temp sensor turned out to be trivial, using
| rtl433 on a raspberry pi I just log the packets to a dynamo table
| and alexa (using google charts from a lambda) plots the last 20
| points on screen.
| methyl wrote:
| Is there anything like this, but for serial (ie. UART)?
| wedowhatwedo wrote:
| https://www.saleae.com/
| methyl wrote:
| That looks great, although I thought about something more
| high level, a software which works with USB-UART converters.
| Like minicom or HyperTerminal, with built in protocol
| debugging capabilities.
| ris wrote:
| https://sigrok.org/
| donquichotte wrote:
| Also check out the Pulseview GUI front-end for sigrock,
| it is excellent.
| biosed wrote:
| What would be a very good starter software defined radio?
| newhouseb wrote:
| Hands down the PlutoSDR (a.k.a ADALM-PLUTO) has the best
| price/performance & support I've seen (and I've owned a
| BladeRF, LimeSDR and various RTL dongles as well).
|
| The core radio chip itself (the AD9363) appears to be identical
| and/or a binned version of the AD9364 chip used in things like
| USRP Radios (i.e. the high-end standard bearer brand for SDR)
| and can be configurated to behave like it [1]. The unit price
| for the AD9364 chip (in low volumes) is around $200. The ENTIRE
| PlutoSDR is $150 and that includes a Zynq-7010 FPGA (which
| itself is not cheap)!
|
| Because it's built by Analog Devices, it's generally well
| supported. It's designed as an educational tool so there are a
| lot of tutorials for beginners like PySDR. I really like the
| interfacing libraries (pyadi) that allow me to easily configure
| the SDR from a python notebook and pull an RX buffer into numpy
| and process away.
|
| [1]
| https://wiki.analog.com/university/tools/pluto/users/customi...
| [2] https://pysdr.org/index.html
| aftbit wrote:
| $250 from Analog directly, $200 from Amazon right now. Where
| can I find it for $150?
| roamingryan wrote:
| Most of the major component distributors:
| https://www.findchips.com/search/Adalm-pluto
| sva_ wrote:
| You can sometimes find a good deal on a HackRF as well. It has
| a freq range of 1mhz to 6ghz (rx/tx). The popular RTL-SDR only
| has 0.5mhz to 1.7ghz freq range (rx), but costs only about 1/4.
| nucleardog wrote:
| If you're okay with (1) not supporting the guy that designed
| it in the first place and (2) taking a risk on a Chinese
| knock-off (reviews generally seem good), you can often find
| the Hackrf One on the usual suspect sites straight from China
| relatively cheaply.
|
| There's a listing right now for just the hackrf one board at
| $125USD (versus a legit one at $350USD).
|
| Hate to say it but I ordered one from there (with a metal
| case, high stability clock, assortment of antennas and other
| useful stuff) for $160.
|
| I've had my eye on one for years, but it's just never going
| to be something I'm willing to drop $350+ on as part of the
| hobby.
| sva_ wrote:
| I don't think you can really call them a knockoff. As far
| as I know, the HackRF has been designed as an opensource
| hardware[0], so I'd guess the designer intended it to be
| built by different entities.
|
| [0] https://github.com/mossmann/hackrf/tree/master/hardware
| "This is a free hardware design; you can redistribute it
| and/or modify it under the terms of the GNU General Public
| License[..]"
| mhh__ wrote:
| The SDR you actually own is the best one - the cheap Chinese
| ones are rubbish, don't get me wrong, but you can still do a
| hell of a lot with a little RTL-SDR
|
| Analog Devices have some good offerings well up the price scale
| but I forgot if they start at DC
| mindcrime wrote:
| I've only used the RTL-SDR ones, so I can't offer any first-
| hand comparison. But for receive-only operations, the RTL-SDR
| dongles are cheap, readily available, compatible with many or
| most SDR related software packages, and basically "just work".
| YMMV, but one of those is probably where I'd suggest starting.
|
| I've heard good things about the HackRF devices as well. The
| nice thing about those is that they're programmable
| transmitters as well, not just receivers. But they're a bit
| pricier as well, which is the downside. If I buy another SDR
| anytime soon, that will probably be the direction I go.
| hatsunearu wrote:
| Depends on what you wanna do with it, but a Red Pitaya is
| pretty good. Wish I had that instead of the hackRF
| tosteris wrote:
| https://www.redpitaya.com/f135/spectrum-analyzer
|
| > Frequency span is from DC up to 62.5MHz
|
| This seems rather limiting.
| theodric wrote:
| Get an upconverter
| Gracana wrote:
| That covers all of the amateur HF bands, so you'll have
| lots of signals of known types that you can try to decode.
| nucleardog wrote:
| If you just want to _look_ at signals, a RTL-SDR kit with a
| basic dipole antenna (rabbit ears) and the USB dongle is like
| $35USD and readily available.
|
| I would 100% recommend starting there. If you actually find
| yourself using it and/or enjoying it, then look at spending
| some more money.
|
| If you do enjoy playing with SDR stuff, could also recommend
| getting an amateur radio license. Basic license is ridiculously
| easy to get and gives you access to legally transmit on a whole
| bunch of different frequency ranges and put you in contact with
| some other RF geeks.
| CapricornNoble wrote:
| I'm a big fan of my LimeSDR Minis:
| https://www.crowdsupply.com/lime-micro/limesdr-mini/
|
| The SDR comparison table on that page above is useful too.
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