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From: | George Edwards |
Subject: | Re: How to display a part of the GRC spectrum? |
Date: | Fri, 3 Feb 2023 10:52:21 -0700 |
On 03/02/2023 12:07, George Edwards wrote:
Yeah, you can just use the UI controls to "zoom in" if that's all you care about.Thank you Marcus, thank you everyone!
A more fundamental question I have is: Let's assume I was working at a low sample rate, say 32 kHz. Both the QT Freq GUI and the webgui would display a spectrum between -16 kHz +16 kHz. Suppose, I would like the displays to pop-up over the range 5-12 kHz, is there a way to instruct either the QT or webgui block to plot what I consider my range of interest at a sample rate of 32 kHz?
Thanks for all your inputs.
Regards,George
If you want it (the GUI block) to be only "seeing" that spectrum, then the frequency-xlating FIR/FFT filter does what you want.
On Fri, Feb 3, 2023, 9:12 AM Marcus Müller <mmueller@gnuradio.org> wrote:
First of all, that's a high sampling rate!
You would want to shift the signal (e.g using the "Rotator" block, or
just by using a signal source at the shift frequency and a (conjugate)
multiplication), then decimate it by a factor of 3 GHz / 8 MHz = 375.
From a point of view of designing the decimator, decimation by 375 is
quite a mouthful - it requires a filter transition width of
significantly less than 1/375 of the input Nyquist rate. So, it would
seem advisable to do this decimation in a cascade of decimators – in the
extreme case, decimation by 3, by 5, by 5, by 5.
Best regards,
Marcus
On 2/3/23 16:52, George Edwards wrote:
> Dear GNURadio Community,
>
> Let's say I build a GRC flowgraph operating at a sample rate of 3 GHz
> and wish to display the spectrum over the fixed range of 1GHz +/-
> 4MHz, how do I get the QT GUI Frequency sink to plot over this range?
>
> Thank you!
>
> George
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