
The day when starting a receiver fixed the transmitter - ingve
https://rachelbythebay.com/w/2019/11/13/sdrlag/
======
sneak
> _I recorded about 10 seconds of the ENTIRE FM band to a ramdisk, then turned
> around and pushed it back out in the unlicensed band on a continuous loop._

> _Now I had a second problem on my hands: was it the recording itself? To
> answer that question, I took the file and washed it through a bunch more SDR
> gunk to isolate a single station, demodulate it to audio, and pushed it to
> my machine 's speakers. The song sounded fine. Other stations were also
> okay._

Rachel, I would pay double-digit dollars per month for a screencast per week
of you doing some serious hacker shit like this. (I've used Gnuradio et al and
it's always a screaming pain, at least for a novice like me.) Watching someone
hack away at it in a while(!functioning) would be pure pleasure, and I'm sure
quite educational too.

~~~
Jenda_
I'm not Rachel and this is not a podcast, but I have wanted to write a similar
tutorial for a while. So I finally did it:
[https://www.abclinuxu.cz/blog/jenda/2019/11/gnu-radio-
first-...](https://www.abclinuxu.cz/blog/jenda/2019/11/gnu-radio-first-steps-
a-fm-receiver)

------
tpmx
I really enjoy reading these posts from Rachel. I think I have read like 10+
of them by now.

Can I be so bold as to suggest something for improved readability? [Edit:
turns out I cannot. Immediate downvote!]

Breaking that wall-of-text into 2-3 sections with headlines would probably
improve readability greatly. Honestly, it doesn't matter that much what the
headlines say - the important thing is breaking up that wall of text into
separate pieces.

------
dfox
> I recorded about 10 seconds of the ENTIRE FM band to a ramdisk

We live in wonderful age of SDR where this is not only possible but apparently
also the way how even entry-level car infotainment's FM receiver works. And it
still amazes me.

------
Snoozus
Was there really a time where HDDs were to slow for 40MB/s but we still had
400MB of RAM? Did I miss a factor of 2 because of the I/Q?

~~~
rachelbythebay
20 MHz --> 40M samples per second (Nyquist). 16 bits per channel, and two
channels (I, Q).

40000000 x 2 x 2, so... about 160 MB/sec?

It's a lot of data. It wasn't happening with the disk I had on hand, so I went
for the ramdisk thing. 1.6 GB of memory? That I _did_ have.

~~~
jcims
Would be nice if you could use flowgraphs to program any fpgas on the radio.

~~~
madengr
You can with RFNoc blocks in GNU Radio, but that’s specific to Ettus hardware.

