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GNU Radio

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Re: GNU Radio

#31

Post by galangalalgol »

n00p wrote: post #29
galangalalgol wrote: post #25

Earlier quoted context omitted.

that $25 dtv receiver only goes up to 2ghz so you can't get satellite tv without building a downconverter which isn't trivial or as cheap. Radar guns are even higher in frequency. It can only receive so you can emulate only the demodulation part of a modem. IR sounds like fun though. You could listen to tire pressure monitors too.

an LNB (the thing that goes in the focus of a parabolic antena) is really cheap and easy to power the probem would be that the cheap dtv (RTL-SDR) only gets up to 2.4MHz of spectrum bandwith, a typical DVB-S mux can be around 20MHz or the DVB-T terrestrial standard, 8MHz

The LNBs on ebay are pretty cheap but the intermediate frequency some of them use use is a bit too high. And as you say. You'd just be finding some slice of the signal without any hope of demodulation. I still think a microphone or rtl are a great way to play with gnuradio companion. Lime sdr is probably the next step up in price.

Re: GNU Radio

#32

Post by wavewalkerdsp »

cebert wrote: post #11

SDR and GNU radio has always sounded interesting to me ever since I heard it mentioned on the Security Now podcast years ago. Does anyone know of good resources on how to get started? This is something I’d love to tinker with one day. I also don’t know a great deal about RF communication in general.

I've put together new introductory tutorials here: https://wiki.gnuradio.org/index.php/NewTutorialReview

Using a virtual machine with Ubuntu 21.04 and installing using the PPA is a good way to test it out: https://wiki.gnuradio.org/index.php/InstallingGR#Ubuntu_PPA_...

More background information on the tutorials, future plans, etc. https://www.wavewalkerdsp.com/2022/01/13/gnu-radio-tutorials...

Re: GNU Radio

#33

Post by TheDesolate0 »

galangalalgol wrote: post #25
ggm wrote: post #2

Has always done a terrible job of selling itself. A $25 dtv receiver and a chickenwire antenna parabola and code your own satellite TV decoder, learn what radar guns emit, emulate a modem... maybe even shift to IR and do TV controls.. it's, latent in this stuff. But the frontpage doesn't take you there.

that $25 dtv receiver only goes up to 2ghz so you can't get satellite tv without building a downconverter which isn't trivial or as cheap. Radar guns are even higher in frequency. It can only receive so you can emulate only the demodulation part of a modem. IR sounds like fun though. You could listen to tire pressure monitors too.

No post body was provided.

Re: GNU Radio

#34

Post by lsllc »

geenew wrote: post #13
ggm wrote: post #2

Has always done a terrible job of selling itself. A $25 dtv receiver and a chickenwire antenna parabola and code your own satellite TV decoder, learn what radar guns emit, emulate a modem... maybe even shift to IR and do TV controls.. it's, latent in this stuff. But the frontpage doesn't take you there.

Is it possible to use a laptop's built-in wifi antenna / wifi card as the hardware side of a gnu radio setup? That seems like it would be a nice cheap one-two punch for getting started. AFAIR wifi uses the public (unregulated) bands so there should be lots of interesting stuff on those frequencies beyond wifi signals.

You can use a paperclip or a piece of wire if you have access to a GPIO port:

https://www.rtl-sdr.com/receiving-ads-b-jetliner-traffic-wit...

https://www.theverge.com/2019/11/26/20981630/raspberry-pi-pi...

Re: GNU Radio

#35

Post by mikewarot »

If you want to learn DSP, GNU Radio is the way to go. It has audio sources and sinks, so you can try out things and hear / see (using the scope sink) the results in real time.

It was really interesting to play with negative frequencies and get a better handle on it than the math alone would have ever given me.

Re: GNU Radio

#36

Post by beaugunderson »

minimilian wrote: post #4
mikewarot wrote: post #3

Have they fixed the incredible loss of features from the WX GUI yet, the QT widgets just didn't have anywhere near the same functionality last time I looked? [Edit]The WX versions of FFT and Oscilloscopes were far, FAR better than their QT replacements.

You're probably talking about something else, but it took me a while to realize that many features are hidden behind a right (or is it middle) click.

This is a big deal when running on e.g. a MacBook that has no middle click--it is very worthwhile to use software that emulates a middle click when a modifier key is held down to gain back this functionality.

Re: GNU Radio

#38

Post by wdfx »

n00p wrote: post #29
galangalalgol wrote: post #25

Earlier quoted context omitted.

that $25 dtv receiver only goes up to 2ghz so you can't get satellite tv without building a downconverter which isn't trivial or as cheap. Radar guns are even higher in frequency. It can only receive so you can emulate only the demodulation part of a modem. IR sounds like fun though. You could listen to tire pressure monitors too.

an LNB (the thing that goes in the focus of a parabolic antena) is really cheap and easy to power the probem would be that the cheap dtv (RTL-SDR) only gets up to 2.4MHz of spectrum bandwith, a typical DVB-S mux can be around 20MHz or the DVB-T terrestrial standard, 8MHz

How can the DVB-T signal bandwidth be larger than what the 'dtv' receiver is capable of if that device was actually originally designed to receive exactly that class of signal?

Re: GNU Radio

#39

Post by wdfx »

ganzuul wrote: post #26
ggm wrote: post #2

Has always done a terrible job of selling itself. A $25 dtv receiver and a chickenwire antenna parabola and code your own satellite TV decoder, learn what radar guns emit, emulate a modem... maybe even shift to IR and do TV controls.. it's, latent in this stuff. But the frontpage doesn't take you there.

For a little more investment you can get hacked version with a TCXO and it is able to receive almost 0 to IIRC 28MHz. It is a 2.8MHz spectrum analyzer although energy readings are not a feature. However cities are terribly noisy environments so loop antennas should work better for most people. Most amateur radio guides assume you are at least a homeowner but that is not realistic among people interested in a 20 eurod…

For about the same cost you can buy an sdrplay rsp clone which can receive from 0-2GHz with 10MHz bandwidth.

Re: GNU Radio

#40

Post by mimanning »

wdfx wrote: post #38
n00p wrote: post #29

Earlier quoted context omitted.

an LNB (the thing that goes in the focus of a parabolic antena) is really cheap and easy to power the probem would be that the cheap dtv (RTL-SDR) only gets up to 2.4MHz of spectrum bandwith, a typical DVB-S mux can be around 20MHz or the DVB-T terrestrial standard, 8MHz

How can the DVB-T signal bandwidth be larger than what the 'dtv' receiver is capable of if that device was actually originally designed to receive exactly that class of signal?

The 2.8 MHz limitation comes from shipping raw RF samples off the device over USB 2. When operating as a DVB-T receiver the device decodes the signals before sending them over USB so it uses less bandwidth.

The device was originally intended only as a dtv receiver and not a general purpose software defined radio. The hobbyist/ hacker community discovered the hidden debug mode that allows raw data acquisition and wrote drivers for it.

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