GNURadio FM Receiver

[@MrDavidKingsland]

Fascinating John. I'd heard about people "writing" a receiver, but had no idea what that meant. You explained it perfectly. 73, de VE3MDX

[@foxtrot-Luv]

following alomg with anyones lesson is a challenge in itself. theres a few different versions. even when i actually have the right version to follow along with i find im missing certain blocks, like from the very beginning of lesson.

[@smnihal7440]

How You do modulation of that?

[@joepereira3421]

Very well presented thank you. I just built my first GNURadio FM receiver all thanks to you :)

[@VE6EY]

Like I say, it's the "Hello World" project to get you started. Have fun!

[@preuton]

Want to build with QT but there are no fft sinks.

[@WilliamHuster]

In QT, it's called "QT GUI Frequency Sink"

[@nguyenphamngockhoi6286]

Hello, I'm new in this field. Could you explain me how the low pass filter can select the FM station? I really don't understand. Thank you!

[@VE6EY]

100 kHz is wide enough to pick up the main FM signal including 92 kHz subcarriers. While FM modulation theoretically has infinite bandwidth, 100 kHz is enough to pick up one signal while attenuating others.

[@zgrafsoftware]

Thanks. Very helpful. How does one decide where to transition from complex (blue) to float (orange). Is that usually at the receiver stage?

[@AbuSous2000PR]

Many thx for the great introduction. I am very new to GRC. I didn't notice IF mixing to bring the signals to base band. I assume the down sampling did the trick? Many thx Salah

[@Salastil]

Excellent video, good presentation and you actually explain the reasoning behind your choices; something often missing in these kind of demonstrations. I learned more from your short video than I could from reading the terse Linux man pages for Gnu Radio for hours.

[@VE6EY]

Thanks, John. If you are not a Linux hacker (I am not) learning this stuff can be heavy lifting. Which was the motivation for these videos, because GNURadio is pretty neat once you get down the learning curve. Cheers.

[@MarkPentler]

Thanks - clearest tutorial yet on this. Finally understand the decimating and resampling. This would just be FM mono, right? Without doing any kind of decoding of the pilot tone or whatever the radio wouldn’t know what to do with it I guess?

[@MarkPentler]

Wait, getting an issue here on Windows: Latest version without those older WX widgets you're using that don't exist anymore. It doesn't like the connection between the WBFM Receive block and the resampler afterward: itemsize mismatch: wfm_rcv0:0 using 4, rational_resampler0:0 using 8 Any ideas?

[@VE6EY]

Yes, just mono Mark. Getting stereo decoding is a more complex scenario, but all the information you would need is being received in this circuit.

[@MarkPentler]

VE6EY i did get this working in stereo eventually. And TX as well! Got a hackrf on the way...

[@younesaitomar7272]

hi, can you show how to install the RTL-SDR Source on GNU Radio?

[@VE6EY]

Just use the RTL-SDR Source component. See here www.instructables.com/RTL-SDR-FM-radio-receiver-with-GNU-Radio-Companion/

[@king_d0ma1n41]

Let's say I wanted to take this project and apply the entire code into my python radio application. Is there a way to 'copy' the code and 'paste' it into my ide? And a further question, do you know how to create a set of buttons that changes the reciever frequency from said radio application, giving an easy-use access for a user. Essentially I am making a radio application and would like to know how to use the receiver in my project.

[@austindale3129]

I don't have WX GUI, just QT GUI. what do I do?

[@VE6EY]

Hi AUstin. You should be able to reconstruct the diagram with QT components.

[@cristianoliva3839]

Thanks so much for the tutorial!. I tried your source file to test my RTL-SDR dongle but at first, when I executed the flowgraph the program closed automatically with no errors. After some digging on the web I found out that I hat to specify the type of device I was using. I did this by writing "rtl=0" on the "Device Arguments" line in RTL-SDR Source properties. Problem solved!!

[@StoriesNMore]

Excellent tutorial! Thank you!!

[@yasiribm]

Liked and I will follow the coming video for the AM receiver

[@GetToHellOut]

Is there any way to do some kind of frequency scan? I mean in this video you fill GUI Chooser with already known frequencies, but is there a way to scan the frequencies to find the ones that carries something? As I see, the simple solution is to chech power (dB), but how to do it in GNU Radio? Thank you in advance and sorry for bad english.

[@VE6EY]

Hi. It is fairly easy to measure signal strength and set a threshold. The harder part is the scanning logic. I think you would have to write a scanner block. You can find examples on github and elsewhere. Just search "gnu scanner". Cheers.

[@bennguyen1313]

Is there any potential danger of setting the rf-gain on the source too high? Or not connecting an antenna, and/or using a wrong antenna? For example, I've had 2 wifi adapters die after a while when using a high-gain antenna. Also if transmitting (using a LimeSDR, HackRF, Blade, etc), what would be an example of the output power (db or mw) that it should be be set to if transmitting just a few inches?

[@VE6EY]

Hi Ben. Rohde and Schwarz has an excellent software "Field Strength and Power Estimator" that you can download free. This way you can check by frequency, distance and output power how much signal may be arriving at the receiver. Check it out. www.rohde-schwarz.com/ca/applications/field-strength-and-power-estimator-application-note_56280-15837.html?rusprivacypolicy=0

[@king_d0ma1n41]

Thankyou for this straight-forward explanaition!

[@waydav1s]

HALLELUJAH! FINALLY someone has post a FUNCTIONAL radio. Sweet Bro. NOW I can start to tinker. Muhahaha I can't tewll you how many HOURS I've wasted following bogus "tutorials". YOURS WORKS!

[@winsucker7755]

Thanks! If by any chance nothing happens when you run it, just add rtl=0 in RTL-SDR Source's Device Arguments. Also windows route of installing if you want WX GUI: - Install Python 2.7.x 32bit (Yes it's deprecated) - Install pygtk-all-in-one-2.24.2.win32-py2.7.msi - Install gnuradio_3.7.13.5_win64.msi (Yes it's deprecated) Cheers

[@farhadv5781]

Thanks for the rtl=0 pointer; that made a difference. At least it compiles and runs now (on Raspberry Pi 3). I get the two FFT spectrum plots to open and update (i.e., see a live signal), but I get no audio. Seems to be tuned to the wrong frequency and different from the default frequency. Also although the GUI controls are there, they do not react to my requested changes. So I can't change the RF gain, volume or the stations. No error on the GUI. jut getting a bunch of UaUoa... on the screen. I have also done a "rtl_test -t " test and the tuner seems to be online. Any ideas? Thanks in advance.

[@farhadv5781]

The only other clue I see is the message below: [R82XX] PLL not locked! So I would not expect an audio output. Probably unrelated to the unresponsive controls issue.

[@umairraza5972]

Hey, I do have an issue while I run it, the FM Receiver window does not appear and nothing is shown as output, what might be the issue?

[@crookedtool]

Try reading through the console output for errors.

[@rustcohle9134]

download sdr drivers. it will fix

[@djolic94]

Does it works for some other recievers as Hack-RF one, LimeSDR or USRP B210 (Ettus/NI)? Thanks

[@VE6EY]

Yes. But a good way to start is with the RTL-SDR to see if you really want to make investment in something better.

[@djolic94]

yes yes, i see, but i can borrow some of those just to try. Thank you!

[@UjanTalukdar30]

Hi there, I was using these blocks in an attempt to create an FM receiver but I was unable to get the GUI to pop up when I pressed play. I have no errors. Could you tell me why this is the case?

[@VE6EY]

Hi Ujan. No idea I am afraid. Any errors showing in the log? Could the GUI be there but minimized?

[@cristianoliva3839]

Hi man! maybe you have to write "rtl=0" o whatever your model of RTL-SDR is on the "Device Arguments" line in RTL-SDR Source properties. Worked just fine for me. Search for your model on the "Documentations" tag into RTL-SDR Source properties.

[@wyattzinc6636]

@@cristianoliva3839 That solves the problem! Thank you!

[@douglarue8485]

Very nice walk-through. Thank you.

[@adon2424]

Oh the humanity! on with the show, please!

[@davidbrooks8621]

Excellent tutorial!!!

[@cesaraugusto3554]

Hello friend, how are you ?, Greetings from Colombia, can you make a video explaining Dsss modulation on Gnu radio?

[@VE6EY]

Sorry, Cesar, that's beyond what I can do. If I every figure it out, I will try. Thanks.

[@handbanana6205]

Great video, exactly what I was looking for, just need to add a generic band selector and decoder selector and will be sweet.

[@VE6EY]

Great. Have fun!

[@fmiranda]

Do you need some special hardware for this?

[@VE6EY]

You need to connect to a receiver. Really easy with the RTL-SDR stick which is cheap and GNURadio supports well.

[@adrianh42r]

awesome!! thanks, Saludos from Ecuador!!

[@berkayylmaz6574]

Hi. I have a gnu radio project. I wanna make fm modulation without receiver? Can ı do that? İf yes how? And how can ı do like fm demod block without fm demod block? Thank you :)

[@VE6EY]

Hello Berkay. You can use either tone generator or audio recording as source material, and create an FM signal with the VCO (voltage controlled oscillator). You can find ideas for demodulation schemes at www.radio-electronics.com/info/rf-technology-design/fm-reception/fm-demodulation-detection-overview.php . You might try quadrature detection.

[@sathishkumar-xt1zm]

i need that .grc file sir!

[@tav9755]

Great work. Appreciate

[@imzack27]

Good work!

[@sanderverweij]

giving up! 30 minutes trying to find a simple download of the GnuRadio Live SDR iso... there isnt even a download section on gnuradio.org as of 24 sept 2019... there really is not a single link so i can download gnuradio... so the program must be better then their website, but i never will know.. crap

[@VE6EY]

You can download from www.gcndevelopment.com/gnuradio/downloads.htm . I agree that GNURadio consideration of Windows users is pretty minimal.

[@JamesEdwards780]

Your Google-foo is weak ,,, and it will already be in your package manager

[@sanderverweij]

@@VE6EY Thank you

[@sanderverweij]

@@JamesEdwards780 Well i it i guess, i just wondered why the original website did not have a download link/section... and tnx

[@7xr1e20ln8]

It's crap because they dont want to develop code for crap os like windows. If you want to be dumb forever use Windows. Or be a mature person and use Linux

[@sanjaybhatikar]

Awesome 🎉

[@TheGmr140]

nice video, well done

[@paulfrancis8836]

Just buy a cheap FM receiver, how about doing a NBFM receiver for HackRF in the UHF Band.

[@jl5051]

Thank you for the video but i received only UaUaUa after following this tutorial

[@VE6EY]

That means some sort of audio output under-run on your PC. Try a different sample rate for output.

[@jl5051]

@@VE6EY thank you, it works after I change the output sample rate to 500k. :)

[@Omygod47]

Can you please explain what you changed?, i got the same UaUa thing, Thank You!

[@stefanrunkel9013]

that was quite helpful !