Hi Markus,
yeah, that sounds right, but:
You'd probably want to use a PLL frequency detector (similarly
parameterized) to detect these and output a frequency estimate, and
then do some math on that estimate, and use it to correct the system.
Best regards,
Marcus
On Mon, 2019-10-28 at 16:41 +01
Hi Barry and Bill,
> I don't know how wide a spectrum the PLL can handle.
Generally, that's not really inherently limited by anything but the
loop bandwidth.
It's a really simple PLL, with a complex sample-argument phase
detector.
In other words: if you set the loop bandwidth too high, the PLL
To all who gave me good ideas and insights,
Thank you for your help. Based on all of your comments, I have a new and
improved AM receiver which automatically corrects small tuning errors.
Attached is a picture of the flowgraph.
Best regards,
---
Barry Duggan KV4FV
On 2019-10-28 12:21, Albin
Hi Markus,
From what I can tell, the PLL Carrier Tracking block does the
correction, but it doesn't tell you what it did, so I'm not sure you can
log the offsets. There are other PLL blocks I haven't looked at yet, so
I don't know about them. See
https://wiki.gnuradio.org/index.php/Category:B
The PLL Freq Det is the one I would like to figure out.
Bill Dailey
Negativity always wins the short game. But positivity wins the long game. -
Gary Vaynerchuk
Don’t be easy to understand,
Be impossible to misunderstand
- Steve Sims
> On Oct 28, 2019, at 11:01 AM, Barry Duggan wrote:
>
>
Dear OMs,
I guess this carrier tracking block would be useful to handle frequency
drift of cheap (unstabilized) devices, when working QO-100 satellite
connections. This block could be used to find the band end beacons and
derive the frequency shift and correct it accordingly. Right?
vy73
markus
d
Hi Bill,
Look at https://wiki.gnuradio.org/index.php/PLL_Carrier_Tracking. I
think I will add this formula to the Notes: radians per sample = 2 * pi
* freq / sample rate
I don't know how wide a spectrum the PLL can handle.
I am working on the documentation of blocks, so let me know if there
Can you give a little primer on using that PLL tracking?I would love to use
that to just track carriers random frequencies. For instance 10mhz.
Ultimately I want to track and periodically log and offset from true predicted
frequency. Like every 10 seconds.
Bill Dailey
Negativity always w
Hi Albin and Volker,
I added a PLL Carrier Tracking block to take care of the tuning problem.
See the revised https://wiki.gnuradio.org/index.php/File:FunCube_AM.png
Albin, that 'spike' is the carrier! This is AM ;)
Thank you both for your suggestions.
---
Barry Duggan KV4FV
On 2019-10-27 0
Hi Barry,
Some thoughts:
You have a large DC spike at the center, try using the frequency xlating
fir filter to tune an offset frequency.
Why don't you decimate at the channel filter?
Try observing the signal at various points using the frequency sink.
Good luck,
Albin SM6WJM
On Sat, Oct 26,
Hi Barry,
I have similar problem receiving and demodulating an rtty signal.
At the moment I do it in two steps:
First: set the fcdpp to the desired band, apply a lp with downsampling
to 48 Khz ( for rtty i even downsample to 8Khz) and add a
spectrumdisplay and this stage. Here you get a get readi
Hi,
I've been working on a gnuradio AM broadcast receiver, and have found
that the tuning is very critical to obtaining clear audio. My flowgraph
can be seen at https://wiki.gnuradio.org/index.php/File:FunCube_AM.png.
Are there any alternate demodulation methods which are not so sensitive
to
This, is a squelch, variable changes between 0 and positive gain value.
--
public PGP key
http://pastebin.com/dqZqgyVE
On Mon, Apr 28, 2014 at 1:24 PM, Activecat wrote:
> When I looked into the attached graphical flowgraph in the first email,
> the signal was multiplied by zero (constant multi
When I looked into the attached graphical flowgraph in the first email, the
signal was multiplied by zero (constant multiplier) before feeding into
file sink and audio sink. In this case what you get was probably amplified
noise.
Was it zero or something else?
On Fri, Apr 25, 2014 at 11:54 PM, M
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A shoot, I overlooked the 64 decimation rate... Sorry about that.
On 25.04.2014 17:36, Anton Komarov wrote:
> Marcus, w/o AGC audio sometimes is creapy. I have tested AGC2,
> tried to play with attack and decay, but at last when there is a
> plane in
Marcus, w/o AGC audio sometimes is creapy. I have tested AGC2, tried to
play with attack and decay, but at last when there is a plane in the
vicinity dongle overloads and sound become very loud. Then i tested FAGC
and it fits well! 1024M/64 gives 16k and 256 samples equals - 62 ms of
signal. Works
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Actually I'm a little confused - Is seeing an AGC in an AM demodulator
something you usually do?
Especially the feedforward AGC should be rather err jumpy with a scope
of but 256 samples, unless I'm missing something; f_sample seems to be
1024ksps, thu
An AM demodulator is a squaring function. It can only *ever* produce positive values. You can remove DC offset by using a high-pass filter after it.
on Apr 25, 2014, Anton Komarov wrote:
But when we have only positive values that means in fact we have 0.5 DC offset, and that is bad. More
Thanks a lot. It does work!
--
public PGP key
http://pastebin.com/dqZqgyVE
On Fri, Apr 25, 2014 at 5:41 PM, Michael Ossmann wrote:
> On Fri, Apr 25, 2014 at 05:25:54PM +0400, Anton Komarov wrote:
> >
> > But when we have only positive values that means in fact we have 0.5
> > DC offset, and th
On Fri, Apr 25, 2014 at 05:25:54PM +0400, Anton Komarov wrote:
>
> But when we have only positive values that means in fact we have 0.5
> DC offset, and that is bad. Moreover i've made test recording with
> GQRX - waveform is fine! Looking into the code, nothing special, am
> demod->low-pass->wav-s
But when we have only positive values that means in fact we have 0.5 DC
offset, and that is bad. Moreover i've made test recording with GQRX -
waveform is fine! Looking into the code, nothing special, am
demod->low-pass->wav-sink.
--
public PGP key
http://pastebin.com/dqZqgyVE
On Fri, Apr 25, 20
On Fri, Apr 25, 2014 at 04:14:30PM +0400, Anton Komarov wrote:
>
> Hi, you can find in attach AM demodulator grc file. Everything is
> straight forward with demod but audio file generated looks weird. Only
> positive values of amplitude.
The particular definition of "amplitude" adopted by GNU Radi
ilter_ccf blocks. I assume the sampling frequency is
> set to the sampling rate going in to the filter block before decimation.
> I am setting the center frequency to be again at half the desired
> frequency to shift by that amount.
>
> Any thoughts?
>
> Thanks much,
On Sun, 10 May 2009, davek wrote:
have you had success with your translating filters ?
dave
Dave-
thanks much for responding. I have not yet succeeded in making my
application work. Let me just review what I am trying to do. I want to
capture with the USRP2 two signals; one AM with a car
Hi all-
I have a USRP2 with a LFRX daughterboard. I'm trying to acquire two
channels each at a separate frequency where Ch0 is amplitude modulated and
Ch1 is not. As per suggestions made to me from this list, to capture two
channels at separate frequencies I was advised to tune the USRP2 to
Hello everyone. I am working on Amplitude demodulation. I am using the
attached python code. I have some doubts as to why particular frequencies
are chosen. Firstly, in the code
*channel_coeffs = gr.firdes.low_pass (1.0, if_rate, 8000, 1000,
gr.firdes.WIN_HANN)*
Why a cut off frequency of 80
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