# Re the spectrum estimation toolbox

**URL:** <https://www.ruby-forum.com/t/re-the-spectrum-estimation-toolbox/240368>\
**Category:** GNU Radio\
**Created:** [April 10, 2014, 12:14am UTC](https://www.ruby-forum.com/t/re-the-spectrum-estimation-toolbox/240368 "2014-04-10T00:14:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\
**Post date:** [April 10, 2014, 12:14am UTC](https://www.ruby-forum.com/t/re-the-spectrum-estimation-toolbox/240368/1 "2014-04-10T00:14:06Z")

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Hello GR,

I have multiple questions re the gr-specest toolbox:

1/ Is there any MTM estimator block for GRC

2/ Can anyone explain to me the figures in  
[https://www.cgran.org/wiki/SpecEst](https://www.cgran.org/wiki/SpecEst) related to Cyclostationarity-Based  
Modulation Classification. I am actually confused aren’t they inverted  
(QPSK  
and BPSK) because it is in the QPSK that you find components on the Im.  
axis  
not in the BPSK. Any explanations is well appreciated.

3/ The README file talks about how to tune the update rate (sample\_rate  
/  
block\_len) however I tried to decrease it to almost 15, sample rate =  
32k  
and block\_len = 2048 and even I tried to have an FFT size 256, I always  
get  
the plot stuck and is hardly updating. No zoom is possible after I run  
the  
estimator.  
And after I run that, I cannot Pause nor close. I just have to kill the  
process.  
Am I missing something or some tuning.

Best Regards,  
Ruecan

–  
View this message in context:  
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Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![naeo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/57b2e6/32.png) [@naeo](https://www.ruby-forum.com/u/naeo)\
**Post date:** [April 10, 2014, 9:56am UTC](https://www.ruby-forum.com/t/re-the-spectrum-estimation-toolbox/240368/2 "2014-04-10T09:56:01Z")

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On 04/10/2014 12:12 AM, Ruecan wrote:

> Hello GR,
> 
> I have multiple questions re the gr-specest toolbox:
> 
> 1/ Is there any MTM estimator block for GRC

Yes!

> 2/ Can anyone explain to me the figures in  
> [https://www.cgran.org/wiki/SpecEst](https://www.cgran.org/wiki/SpecEst) related to Cyclostationarity-Based  
> Modulation Classification. I am actually confused aren’t they inverted (QPSK  
> and BPSK) because it is in the QPSK that you find components on the Im. axis  
> not in the BPSK. Any explanations is well appreciated.

This is not IQ, it’s frequency and symbol rate on the axes.

> 3/ The README file talks about how to tune the update rate (sample\_rate /  
> block\_len) however I tried to decrease it to almost 15, sample rate = 32k  
> and block\_len = 2048 and even I tried to have an FFT size 256, I always get  
> the plot stuck and is hardly updating. No zoom is possible after I run the  
> estimator.  
> And after I run that, I cannot Pause nor close. I just have to kill the  
> process.  
> Am I missing something or some tuning.

Not sure here, but I know guys at CEL have been working to update the  
toolbox to 3.7, maybe that’ll fix it.

Martin

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<div class="post-metadata">

**Author:** ![naeo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/57b2e6/32.png) [@naeo](https://www.ruby-forum.com/u/naeo)\
**Post date:** [April 10, 2014, 9:17pm UTC](https://www.ruby-forum.com/t/re-the-spectrum-estimation-toolbox/240368/3 "2014-04-10T21:17:00Z")

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On 04/10/2014 05:54 PM, Martin B. wrote:

> Not sure here, but I know guys at CEL have been working to update the  
> toolbox to 3.7, maybe that’ll fix it.

When this gets updated to 3.7, it’s a good candidate for including on  
the GNU Radio DVD.

Johnathan