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Entry  Thu Mar 13 02:52:06 2008, Lisa, Configuration, LSC, Locking with 3f 
    Reply  Thu Jul 24 01:04:01 2008, rob, Configuration, LSC, IFR2023A (aka MARCONI) settings 
Message ID: 729     Entry time: Thu Jul 24 01:04:01 2008     In reply to: 373
Author: rob 
Type: Configuration 
Category: LSC 
Subject: IFR2023A (aka MARCONI) settings 

Quote:


P.S.: We made a test by changing the frequency of the local oscillator by a little bit and then coming back to the original value. We observed that the phase of the signal can change, so every time this frequency is moved the 3f demod phase need to be retuned.



We discovered this little tidbit in March, and remembered it tonight. Basically we found that whenever you change the frequency on one of these signal generators (and maybe any other setting as well), the phase of the signal can change (it's probably just the sign, but still...), meaning that you when you return settings to their intial value, not everything is exactly as it once was. For most applications, this doesn't matter. For us, where we use one Marconi to demodulate the product of two other Marconis, it means we can easily cause a great deal of grief for ourselves, as the demod phase for the double demod signals can appear to change.

Programmatically, what this means is that every time you touch a Marconi you must elog it. Especially if you change a setting and then put it back.
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