Ah cool! Thanks for clarifying :) This sounds to be a rather nice setup,
analog-wise!
Yeah, then just dumping the raw 32bit unsigned to SD Card is probably easiest.
(by the way, this is << 1Mb/s, so just dumping the raw data over a UART or SPI interface
to some serial-to-USB converter might work as well to get the data into your PC. If your
ARM does have USB2 built-in, then that would also be a rather cool thing, but knowing the
varying quality of chip vendor USB hardware abstractions, that might or might not be easy
to implement :) In both cases, UART/SPI serial output converted to USB, or native USB,
you'd probably have to afterwards write a schmall C/C++ driver, so that SoapySDR or GNU
Radio directly can talk to it.)
Cheers,
Marcus
On 18.03.22 19:26, david vanhorn wrote:
I'm using a PCB that I designed with an ARM chip, codec, and SD card for logging, as my
data capture platform.
Feeding that is a QSD (Tayloe) front end that I designed, specifically for the 630m ham
band, converting down to 1kHz differential I and Q signals to the codec, which has a 105dB
SNR.
The front end appears to have a 90dB linear dynamic range so far as I can measure with my
equipment. I'll improve that if I can.
Once I capture to SD, then I can pull the SD and process on the PC to develop weak signal
detection.
On Fri, Mar 18, 2022 at 12:12 PM Marcus Müller <mmuel...@gnuradio.org
<mailto:mmuel...@gnuradio.org>> wrote:
Hey :)
CSV might or might not be convenient, but if C or assembler is your tool:
The things that
the GNU Radio file source reads or the file sink writes is exactly what you
get when you
take a buffer of samples and do an `fwrite` on that :) Just a dump of the
raw memory to a
file. 32 bit unsigned should be directly digestible by GNU Radio (even if
there were
endianness issues – you can just read as bytes and reshuffle as needed :)).
I didn't fully get how you're currently interfacing your hardware. Care to
explain in a
bit more breadth? What are the components of your system, and how does the
computer
running GNU Radio relate?
Best and slightly excited regards,
Marcus
On 18.03.22 18:37, david vanhorn wrote:
> Hi!
>
> I'm trying to interface some radio hardware I built to GnuRadio by way
of data
captured to
> SD cards.
> I have two channels (I and Q) of 32 bit unsigned data internally, and I
originally
assumed
> CSV would be the easy path, but now I see it's not.
> Coming in through the PC sound card is not an option for me, I'm using a
particular
codec
> selected for the application, and my goal is to develop signal processing
algorithms to
> then be implemented back on my processor in C or ASM.
>
> I suppose it would be easiest if I rework my hardware to log data as if
it were the
> "Signal Source" block with complex output.
> Where can I see what that looks like at the level of raw data?
>
>
>
>
> On Fri, Mar 18, 2022 at 4:59 AM Marcus Müller <mmuel...@gnuradio.org
<mailto:mmuel...@gnuradio.org>
> <mailto:mmuel...@gnuradio.org <mailto:mmuel...@gnuradio.org>>> wrote:
>
> Hi David,
>
> you could write a quick python block that just reads values from the
CSV file
and outputs
> them. That'd be a very nice, basic exercise, and I think our freshly
overhauled
> tutorials[1] should bring you there very quickly!
> If you want help with that, hit us up in this mailing list (ideally
after
reading the
> tutorials up to the point of roughly understanding how to write
(embedded) Python
> blocks),
> and tell us more about the data in your CSV files.
>
> Alternatively, you could also write a converter of CSV to a format
that GNU
Radio by
> itself already has a reader for – and the main candidate here would
probably
just be
> plain
> raw data files (as e.g. numpy's `ndarray.tofile("filename")` does) –
the File
Source
> could
> directly read that. But with our freshly rewrite Wavfile sink and
source
blocks, we can
> write and read most audio files, just as well.
>
> Then your flow graph could do the signal processing you want – e.g
frequency
translation,
> low-pass filtering… and finally output it to any device that you
have a GNU Radio
> interface to (e.g., your sound card). The hardware runs at a sample
rate – GNU
Radio
> itself just tries to feed it as fast as possible. So, the signal
processing in
GNU Radio
> itself isn't concerned with rate at all!
>
> Hope this helps,
> Marcus
>
> [1] https://tutorials.gnuradio.org <https://tutorials.gnuradio.org>
<https://tutorials.gnuradio.org <https://tutorials.gnuradio.org>>
>
> PS: you'll often find me online, recommending not to use CSV as a
sample
storage format.
> I'll do the same to you here, but not because I think it's in any
way invalid
to have
> data
> in CSV files; I just want to point out it might be worth thinking
about using
something
> else. So take this with a "I think it's pretty cool you're doing
this!".
>
> That has the reasons that
> a) unless you're more restricted than "CSV" says, you don't know how
many bits
are there
> per sample, as numbers might be represented in different lengths, so
seeking
exactly only
> works by reading and understanding the whole file up to the point
you seek to,
> b) conversion of floating point numbers to human-readable form
incurs rounding
errors,
> and
> that can really wreck your day if you need to rerun *exactly* the
same
experiment twice,
> c) printing numbers as text is really inefficient, both storage-wise
as well as
compute
> wise (which will only matter at higher sampling rates) and
sometimes, but only
sometimes,
> ( d) people say that CSV is good because it's human-readable, but I
challenge
anyone to
> read a text file with only 10000 values and be happier about that
than if he
used a tool
> that displayed the values graphically, zoomably, and then allows for
inspection
of single
> values once zoomed sufficiently in.)
>
>
> On 18.03.22 04:55, david vanhorn wrote:
> > I've done a little with Gnuradio a couple years ago, but I'd now
like to
apply it to a
> > serious problem.
> >
> > I have a design I'm working on that will output raw data that
could be
interpreted
> as an
> > audio stream centered on 1kHz. I'd like to work on extracting CW
signals
that are
> rather
> > slow, from a rather narrow bandwidth, and see how far down into
the noise I can
> actually
> > extract the signals.
> >
> > Is there a block that can bring in CSV data from a file at a
specific rate, and
> serve as
> > the input to my CW detection system?
> >
> >
> > --
> > K1FZY (WA4TPW) SK 9/29/37-4/13/15
>
>
>
> --
> K1FZY (WA4TPW) SK 9/29/37-4/13/15
--
K1FZY (WA4TPW) SK 9/29/37-4/13/15
