Re: [Discuss-gnuradio] Resampling audio using rational resampler doesn't work for multimon-ng

2019-05-18 Thread Kevin Reid 
On Sat, May 18, 2019 at 12:07 AM Albin Stigö  wrote:

> You need to use a low pass filter (taps) in you resampler. Look at the
> spectrum after the resampler and this will be obvious to you. A lowpass
> filter with a cutt off at 3-4kHz or so should do it.
>

This cannot be the problem, because rational_resampler automatically
calculates a filter if taps are not specified:
https://github.com/gnuradio/gnuradio/blob/4e4f44c726556496c420bceb87ccafe6843916f7/gr-filter/python/filter/rational_resampler.py#L107

(I also checked the GRC file, and the fractional bandwidth is also None
(auto-set) despite appearing as "0" in the screenshot.)

Unfortunately, I don't have any ideas what the problem *is*. For what it's
worth, I have successfully integrated multimon-ng into a flow graph (
https://github.com/kpreid/shinysdr/blob/master/shinysdr/plugins/multimon.py)
but the code is very differently structured so it would be hard to transfer
the knowledge into GRC.

As a next troubleshooting step I would recommend adding GUI sinks at
various parts of the flow graph so that you can check the signal integrity.
(For an example, consider adding after the float-to-short a short-to-float
and QT GUI Sink — to ensure the signal hasn't gotten lost in quantization
noise and just needs to be amplified before converting to short, as well as
checking that the bandwidth/resampling is good.)
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Re: [Discuss-gnuradio] query regarding store transmitted signal

2019-05-18 Thread Maitry Raval 
Hello,

Thanks for your reply.
I have successfully record one modulated signal transmitted from USRP into .txt 
file and done demodulation offline, i.e of that stored data and receive audio 
from that.
But, I have all this done with wav file which is 48k sampled. but my 
requiremnet is to do AM modulation of 600Hz audio file. for that, I have done 
the following.

signal source(600Hz,8K)- wav file sink

AM transmission of this wav file from USRP.

record AM modulated transmitted signal in .txt file.

and demodulate it in order to receive 600Hz, 8k wav file. during demodulation, 
I saw signal in scope sink and figure out frequency of that signal through FFT 
sink, biut when I record received 600Hz signal as wav file through wav file 
sink, then, that wav file's scope is blank, I get blank wva file, when am I 
doing wrong. I think, at transmitter side, amplitude of my original wav file 
source's amplitude is too low.
PLease guide.


With Best Regards,
Maitry Raval,

- Original Message -
From: "Marcus Müller, CEL" 
To: "maitry raval" 
Cc: "discuss-gnuradio" 
Sent: Friday, 17 May, 2019 11:57:45
Subject: Re: [Discuss-gnuradio] query regarding store transmitted signal

https://wiki.gnuradio.org/index.php/FAQ#What_is_the_file_format_of_a_file_sink.3F_How_can_I_read_files_produced_by_a_file_sink.3F
On Fri, 2019-05-17 at 17:06 +0530, Maitry Raval wrote:
> Hello,
> 
> Thanks for your reply.
> 
> I.e It is possible to store the transmitted modulated signal (for ex AM 
> modulated signal) through USRP as per below, 
> USRP source - file sink. but in which format, this data can be stored? (.txt, 
> .pdf)_ I have seen.DAT file in one of the example,but when I tried , it does 
> not give proper output.
> 
> Actually, my requirement is to receive the modulated signal through USRP 
> source, store it in a file. and later, I can be able to do demodulation 
> offline from that particular stored data. it will be grateful, if you provide 
> guidance.
> 
> 
> With Best Regards,
> Maitry Raval,
> 
> - Original Message -
> From: "Marcus Müller, CEL" 
> To: "discuss-gnuradio" , "maitry raval" 
> 
> Sent: Friday, 17 May, 2019 10:50:00
> Subject: Re: [Discuss-gnuradio] query regarding store transmitted signal
> 
> Hi Maitry,
> 
> sorry, we have no idea what lab you're referring to! However, yes, that
> sounds exactly what File Sinks are meant to do.
> 
> Best regards,
> Marcus
> 
> On Fri, 2019-05-17 at 12:01 +0530, Maitry Raval wrote:
> > Hello,
> > 
> > I want to store the modulated transmitted signal through USRP such as given 
> > in lab -3 receiving AM signal and store it as .DAT file. Is it possible to 
> > store transmitted signal as .DAT file through USRP source and file sink? 
> > and use that stored data from file source to do demodulation.
> > thanks for your support in advance.
> > 
> > 
> > With Best Regards,
> > Maitry Raval,
> > 
> > ___
> > Discuss-gnuradio mailing list
> > Discuss-gnuradio@gnu.org
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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