[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Galileo Frequency Shifting and Filtering
From: |
Daniel Estévez |
Subject: |
Re: Galileo Frequency Shifting and Filtering |
Date: |
Mon, 27 Feb 2023 19:10:59 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 |
On 27/02/2023 18:59, David Dima wrote:
Hi guys,
I am trying to simultaneously record Galileo's E5a and E5b signals as
follows:
imagen.png
I have tried to record them separately by tuning the local oscillator in
the middle of the signals bandwidths and sampling at 25MHz and it
worked. But when I try to shift and filter to get the signals in a
different file, it does not work. I have no idea what am i doing wrong.
Galileo's Signal Plan is as follows:
Hi David,
I see the following problems:
1. The "Sample Rate" parameter in the Frequency Xlating FIR Filter is
the input sample rate. Hence it should be 50 Msps in your case, not 25 Msps.
2. An anti-alias lowpass filter to decimate from 50 Msps to 25 Msps
should have a cut-off frequency of around 12.5 MHz, not 25 MHz.
3. The band plan you posted is slightly wrong. The distance between the
AltBOC sidebands and the centre frequency is 15 * 1.023 MHz. See
https://gssc.esa.int/navipedia/index.php/Galileo_Signal_Plan (the
difference between this and what you used is a few MHz, so it may or may
not matter depending on what you're trying to do with these recordings).
Best,
Daniel.
OpenPGP_signature
Description: OpenPGP digital signature
Re: Galileo Frequency Shifting and Filtering,
Daniel Estévez <=