[mmaimcal] forwarded message from Ray Escoffier

[Al Wootten]

Folks--Ray wants to know some details for the MMA test array delays.
This is a throw away correlator, as I understand it.  I'm afraid I don't
know the plans for the test array as I should--what baseline is planned?
50m? 100m?  Presumably we don't want to resolve everything out.

From: Ray Escoffier <rescoffi at NRAO.EDU>
To: awootten at polaris.cv.nrao.edu (Al Wootten)
Cc: jwebber at polaris.cv.nrao.edu (John Webber), fowen at polaris.cv.nrao.edu,
        rescoffi at polaris.cv.nrao.edu (ray escoffier)
Subject: MMA test correlator
Date: Tue, 6 Oct 1998 17:57:38 -0400 (EDT)

To: Al Wootten

From: Ray Escoffier

Subject: Delay lines in the MMA test correlator (the GBT clone system)

We are planning to build a small version of the GBT spectrometer to use as a 
2-antenna correlator for the first and second MMA antennas. This system will 
be able to process the outputs of two 800 MHz wide baseband signals for each 
of the 2 antennas. 

One thing that is presently missing from this system is a set of delay lines. 

The GBT spectrometer can be modified to include delay lines but delay 
adjustment with full resolution capability would be somewhat difficult. The 
output of each 1.6 GHz sampler is split 16 ways on a system clock rate of 100 
MHz. It is relative easy to provide bulk delay with 16-sample resolution but 
to be able to adjust the delay to one sample accuracy would be much more 
difficult. 

Do you think the system needs any delay adjustment at all and if so, what 
maximum baseline should I plan for in the delay system? Is the 16-sample delay 
resolution sufficient?

Ray Escoffier

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