GNU Radio 3.9 | Hacker News Reader

GNU Radio 3.9

gnuradio.org

99 pointslukastyrychtr53 comments

OK, so anyone more familiar with this project, how possible would it be to make my own home network streaming service for OTA radio?

Like, I think it'd be fun to have something like an http server or whatever in my home that I could hit something like "streamer/99.9fm" and get an opus audio stream for that station.

You don't strictly need GNU Radio for something like that. A cheap RTL-SDR dongle and the `rtl_fm` command could work.

I played around with this a bit last year when I first got my HackRF. It's got quite the learning curve if you, like me, are not already knowledgeable about RF and SDR.

First step for your desired use case would be, I think, to acquire an SDR module that can receive broadcast FM and then it would simply be a matter of having your server command the SDR to tune to 99.9 MHz and then stream the result to the network.

Somewhat unrelated but does anyone have any good resources for learning GNU radio and SDR for someone who’s mostly and idiot. I took a single calc course in HS (which I hardly remember) and have some very limited digital communications knowledge from watching a few videos. I know what I want to eventually build and have a nice SDR, but I don’t know how to use GNU radio. Most of the blocks I see outside some rather specific modulation ones seem to be primitive operations.

You may find Michael Ossmann's SDR course [1] helpful - it builds the knowledge from the groud up and uses GRC for implementation.

[1] https://greatscottgadgets.com/sdr/

I quite like Marc Lichtmann's (who happens to be on the GNU Radio board) https://pysdr.org quite refreshing and good for beginners.

Unfortunately that's a guide for older GNU Radio versions. It will give new users quite a bit of trouble at this point with all the namespace changes since 3.6. But back in 2015 it was a great way to learn.

What is the current "easy" tooling/workup for GNU Radio ?

It used to be that you could download a GNU Radio livecd and that worked well - however it is no longer maintained. The latest release is from 2017 and I see it written that it is neither supported nor recommended.

Is loading the distro of my choice and then managing and installing GNU Radio, plus associated utilities/applications, and their dependencies my only choice in 2021 ?

PyBOMBS is probably the best way if you want to be able to handle out-of-tree modules. If you just want to play around with the built-in functions, using a prebuilt binary from a package repo is the easiest.

https://github.com/gnuradio/pybombs#pybombs

depends on your linux distro, but on current debian, ubuntu and co, you get 3.8.x.x using `apt install gnuradio`, fedora uses dnf, and so on.

On windoofs, `conda` got your back.

So, it's really gotten better. Yay!

I have nothing substantive to contribute here but it's always nice to see a GNU project with a decent website. Presentable, clean, modern. Good stuff. My only quibble is that it's very slightly low on contrast.

Make a bookmarklet with this:

javascript:var%20x%20=%20document.querySelectorAll("div,p,li,a,hr,em,font,strong,h1,h2,h3,td");var%20i;for%20(i%20=%200;%20i%20<%20x.length;%20i++)%20{%20%20%20%20x[i].style.backgroundColor%20=%20"white";x[i].style.color%20=%20"black";}undefined;//alert("Done");;

It changes the background to white and the text color to black. I use that on worse websites than the GNU Radio one.

Interesting trick. When I find that a website's design would be improved by removing it, I tend to go with Reader Mode.

A related note/question: why do projects like this choose github over gitlab? It's become a weird world to me, where a GNU project could ethically choose github.

To be clear, I use github often as well, but it seems odd to me that a GNU sponsored project would.

They should at least push it to both (maybe blocking issues/comments/etc on one of them).

gitlab is just another company; you probably mean a self-hosted gitlab server?

Hi: GNU Radio is not GNU-sponsored. Whatever that would be. Sure, we could put archives on Savannah, but I can have as many slow servers as I want...

They moved away from SWIG and to PyBind11. As they mention, this is going to be an annoying transition for my custom out-of-tree modules. Overall though, I'm excited for the changes.

Lots of new GUI blocks in this release. I'm especially glad to see the new eye diagram.

Also the ability to load non-WAV audio files will be nice. OGG/Vorbis and FLAC are now supported. Plus a slew of minor conveniences such as a freq shift block and scaling options in the IShort to Complex block (useful for loading recorded samples from hardware).

If only it would compile easily on my Mac. (https://github.com/ktemkin/gnuradio-for-mac-without-macports has a prebuilt 3.8 version)

I have a general question about these SDRs: what is the latency between when the radio wave "hits" the dongle, and when it is detected by the software framework?

Buffers, buffers everywhere... It depends on the sampling rate and technology (USB, ethernet, direct PCI), but in general 1msec is achievable, 10microsec is not achievable.

That's why BladeRF-wiphy ( https://news.ycombinator.com/item?id=25814237 ) implements the lower level phy on FPGA - there's no way to reply an IEEE 802.11 ACK frame within 10 microseconds of the end of the received frame, as required by the standard.

Depends on your buffer size, bandwidth, and what you're demodulating/decoding, but it's pretty fast. With a narrow bandwidth on a fast port and simple modulation/encoding, maybe a few milliseconds?

Counter-intuitively, it is often difficult to reach low latency with "narrow bandwidth" (you mean low sampling rate), because many SDR interfaces are designed to fill full packets with data, not send tiny packets (ex: Ethernet packets). This problem goes away above 1-10Msps.

A few ms as others have said, but it's also a non-deterministic delay.

This is a problem for applications like time-of-flight measurement, so one way to account for this is to send a known signal on TX and look for it on RX

For what it’s worth, I’m convinced that whoever can make this a $99 box with a great app interface is gonna make a fortune.

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