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.
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?
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
- the spectrum is not correct (look like a
modulated signal
- the received signal magnitude is not
constant
- 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.
I tried your grc and got the same
result.
See the waveform's envelope in this
oscilloscope capture. Note the timebase.
This isn't happening in SDRAngel.
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
the grc file in the original
email. Attaching it here as well.
(Don't know if the mailing list
allows attachments)
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
Hi,
To properly explain
the issue I'm facing,
I recorded a video
showing Oscilloscope
waveforms.
The gnuradio
flowgraph is here:
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
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