Hi Anish - I would argue the flowgraph is a potentially a model for a
broken audio device :).
That is, the input signal to the WBFM block is not a 48 kHz signal -
it's a null source, but you're telling the WBFM block to expect an input
frequency of 48 kHz.
If you were to add a signal source of 48 kHz, you would need to add a
rational sampler in front of the WBFM block for a quadrature rate of 480
kHz.
And the typical bandwidth for a WBFM signal is roughly 200 kHz.
A mismatch in sampling rates in a flowgraph is a common problem.
And there are other resamplers.
What I did previously was kludge so I could see the sine wave better
without any hardware. If the other devices are actually using a null
source, then they must be clipping the side bands.
-- Cinaed
On 5/15/21 5:34 AM, Anish Mangal wrote:
Hi. I performed some more tests and report the results on this thread.
https://discourse.myriadrf.org/t/glitchy-behavior-gr-limesdr-limesdr-usb-sinewave-test/7022/10?u=vu2tve
<https://discourse.myriadrf.org/t/glitchy-behavior-gr-limesdr-limesdr-usb-sinewave-test/7022/10?u=vu2tve>
I'd love some advice with which I can produce a simple FM modulated
sinewave with gnuradio and limesdr. If someone on this mailing list
has a limesdr, and some bandwidth to test this out, I'll be more than
happy to provide my flowgraphs.
Thanks!
On Mon, Mar 22, 2021 at 10:10 AM Anish Mangal <anis...@umich.edu
<mailto:anis...@umich.edu>> wrote:
So far as I am able to tell with my limited knowledge of limesdr
and gnuradio, it seems like some kind of issue with the right
settings to me.
The gr-limesdr provides a sink block that allows one to use an
.ini file instead of the settings done via the block's settings. I
will have access to the radio in a few days' time and am thinking
i'll copy over the .ini file that was used in sdrangel and use the
exact same one in gnuradio and see what happens.
On Mon, Mar 22, 2021 at 8:22 AM Cinaed Simson
<cinaed.sim...@gmail.com <mailto:cinaed.sim...@gmail.com>> wrote:
Hi Anish - yes, I removed the LImeSDR block from the flow graph.
I inserted a throttle instead since I didn't have any front
end hardware available at the time.
I do have a WBFM receiver using gnuradio running on a HackRF
which works great.
But I'm using low pass filter taps in the complex rational
resampler which leads the WBFM receiver.
-- CInaed
On 3/20/21 7:52 PM, Anish Mangal wrote:
Hi Cinaed,
But this is without the actual LimeSDR sink block? Or with it?
Because, I can produce a clean sinewave with a HackRF, but
not the LimeSDR.
On Sun, Mar 21, 2021 at 1:07 AM Cinaed Simson
<cinaed.sim...@gmail.com <mailto:cinaed.sim...@gmail.com>> wrote:
Hi Anish - I think I may have found the problem.
When the complex rational resampler is on the out put of
the WBFM, it bothered me later that I couldn't see the
top of the signal.
The scale on QT GUI SINK was clipping the signal but not
the computational noise.
In the QT GUI SINK, if I set the Y-min to be -99 and
Y-max to be 0, the signal looks perfect.
And if the receiving RTL dongle has noise while
listening, it may be a DC offset problem.
-- Cinaed
On 3/18/21 6:58 AM, Anish Mangal wrote:
Here are two debug logs from LimeSuite GUI. In one, I
load the settings that gnuradio does to the limesdr and
see the debug log. The other is the settings file which
the sdrangel writes.
If I diff them, among other differences, this is what I
see in the end of the sdrangel-debug-log
DEBUG: Selected: VCOL
DEBUG: csw 169; interval [166, 172]
DEBUG: M=195, N=3, Fvco=1300.000 MHz
And this is what I see in the gnuradio-debug-log
DEBUG: Selected: VCOM
DEBUG: csw 174; interval [171, 177]
Now, I'm *very* new to this.. but could it mean that
different VCOs are used in both cases, and in the case
of gnuradio, it maybe has some issues to stabilize to
some freq?
On Thu, Mar 18, 2021 at 7:12 PM Christophe Seguinot
<christophe.segui...@orange.fr
<mailto:christophe.segui...@orange.fr>> wrote:
Hi all
There is something wrong in this simulation.
Attached is a flowgraph with a selectable Lime SDR
Source, and a RTL-SDR dongle as receiver. I tested
this with a Lime SDR Mini.
* I was suspecting a Lime SDR issue, however this
is not so clear.
* As Anish I also tested a const source.
* The flowgraph is running fluently and I dont'
see any error message about transmission to Lime
SDR
Conclusion of my simulations :
* with a const source (=1) at Lime input :
everything is OK, the received signal is
frequency shifted (normal) and the SNR is
correct if LimeSDR Gain is sufficient
* Using ratioanal resampler followed by WBFM
Transmit Same reslt, everything is OK
* First source+ WBFM + Rational resampler (this is
a sample file found on LimeSDR website
o the spectrum is not correct (look like a
modulated signal
o the received signal magnitude is not constant
o *BUT the send signal on the Time Sink look
like correct. ( I.E =1+j0 as for others
sources, whitout any glicht)
*
How can we further investigate this?
On 18/03/2021 13:13, Anish Mangal wrote:
And, if I try the attach gnuradio file, which is
just a constant source of value '1' going to the
limesdr sink block, I actually see a sine-ish wave
without the glitchy behavior.
On Thu, Mar 18, 2021 at 5:31 PM Anish Mangal
<anis...@umich.edu <mailto:anis...@umich.edu>> wrote:
I tried your grc and got the same result.
See the waveform's envelope in this
oscilloscope capture. Note the timebase.
https://drive.google.com/file/d/1b7PnpmvFfdQTDIwALuOzb22AzeffzR2w/view?usp=sharing
<https://drive.google.com/file/d/1b7PnpmvFfdQTDIwALuOzb22AzeffzR2w/view?usp=sharing>
This isn't happening in SDRAngel.
On Thu, Mar 18, 2021 at 3:49 AM Cinaed Simson
<cinaed.sim...@gmail.com
<mailto:cinaed.sim...@gmail.com>> wrote:
I moved the rational resampler block from
the output side to the input side of the WBFM.
The output of WBFM block needs to match the
input of your LimeSDR.
I don't have the LimeSDR software installed
so I couldn't look inside the sink block.
-- Cinaed
P.S - yes, you can post GRC's on the
mailing list - they're text based.
On 3/17/21 4:14 AM, Anish Mangal wrote:
I linked
<https://drive.google.com/file/d/1xQz1Kp_feAO1YrZRXXnMF25XEGgqVPSw/view?usp=sharing>
the grc file in the original email.
Attaching it here as well. (Don't know if
the mailing list allows attachments)
On Wed, Mar 17, 2021 at 1:40 PM Cinaed
Simson <cinaed.sim...@gmail.com
<mailto:cinaed.sim...@gmail.com>> wrote:
Hi Anish - since this is a gnuradio
mailing list, the starting point would
be to post your GRC - which is an yaml
or text file.
-- Cinaed
On 3/16/21 11:19 PM, Anish Mangal wrote:
Hi! Any pointers to where I can start
debugging this?
Maybe run gnuradio-companion in debug
mode?
Do more simpler tests?
Any other suggestions?
I have a HackRF One and will try the
exact same comparison there too ...
SDRAngel & grc
On Mon, Mar 15, 2021 at 7:32 PM Anish
Mangal <anis...@umich.edu
<mailto:anis...@umich.edu>> wrote:
Hi,
To properly explain the issue I'm
facing, I recorded a video
showing Oscilloscope waveforms.
https://drive.google.com/file/d/11anGShu-I3NhL9Jet6YAiyBprvwP4kDc/view?usp=sharing
<https://drive.google.com/file/d/11anGShu-I3NhL9Jet6YAiyBprvwP4kDc/view?usp=sharing>
The gnuradio flowgraph is here:
https://drive.google.com/file/d/1xQz1Kp_feAO1YrZRXXnMF25XEGgqVPSw/view?usp=sharing
<https://drive.google.com/file/d/1xQz1Kp_feAO1YrZRXXnMF25XEGgqVPSw/view?usp=sharing>
The various versions of the
software/hardware involved are
the following.
gnuradio-companion: 3.8.2.0
(Python 3.6.9)
gr-limesdr: branch gr-3.8 (last
commit
47511dd58de1695b70e1028366411bada85eb60f)
sdrangel: 4.12.1
OS: Linux Mint 19.1
CPU: Intel© Core™ i7-4900MQ CPU @
2.80GHz × 4
RAM: 16GB
H/w: Thinkpad T440p
tl;dr
I'm trying a simple test to
create a sinewave output from a
WFM modulator block. If there is
no audio input, its WFM modulated
signal should be a simple
sinewave. If I test this with
SDRAngel, I see a clean-ish
actual sinewave in time domain on
the oscilloscope. But if I try to
do the same with gnuradio, it
seems to produce a glitchy signal.
Could I have any advice on what I
might be doing wrong?
Thanks,
Anish // VU2TVE
