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Re: [Discuss-gnuradio] Testing crystal accuracy
From: |
Jason Matusiak |
Subject: |
Re: [Discuss-gnuradio] Testing crystal accuracy |
Date: |
Tue, 12 Jan 2016 10:43:07 -0700 |
User-agent: |
Workspace Webmail 5.16.0 |
Thanks for the quick response Marcus!!!!
Since my Latex isn't very good (as in pretty much non-existent). Let me
see if I can rewrite what you recommended in my dumbed down language and
see if I am close.:
*I have two dongles, dongle 1 will be my modified dongle, dongle 2 will
be my un-modified dongle.
*Put a a known reference tone into each of the dongles where Ftune =
Fref - Foffset
** Foffset should be roughly a third of the sample rate
**An example at a sample rate of 1.024Msps would be a reference tone at
98MHz, and then tune the dongles to 97.659MHz
*I'll now see a baseband signal for both dongles whose offsets won't be
exactly the same.
*Multiple the resulting signals found above against each other (offset,1
* offset,2)
*Pass that through a LPF with a cutoff of Fsample/4, or 256khZ in this
case
**This will give the difference between the frequencies at frequency at
Foffset,1 +/- Foffset,2
*perform a QT freq sync or a quad demod into a QT time sink to compare.
Is that close? I think I am missing something in there, and I have a
feeling that it has to do with the multiplication step as that makes the
least amount of sense to me. Any way to enlighten me on what I am
missing above? Thanks!