[alma_na] [Fwd: Time Synchronization In ALMA]

[Dick Sramek]

Dear Friends,

FYI here is a new document on ALMA EDM for your inspection, pleasure 
and delight.  Forward as necessary to your group.

..DS..


-------- Original Message --------
Subject: Time Synchronization In ALMA
Date: Wed, 24 Dec 2003 14:14:51 -0700
From: "Larry D'Addario" <ldaddario at nrao.edu>
Organization: National Radio Astronomy Observatory
To: dsramek at nrao.edu, rmarson at nrao.edu, clangely at nrao.edu,
zbarnes at nrao.edu,Marc Torres <torres at iram.fr>, rescoffier at nrao.edu
CC: bglendenning at nrao.edu, Baudry Alain
<baudry at obs.u-bordeaux1.fr>,cjanes at nrao.edu

Hello all.

As requested by Dick, I have prepared a new document describing in more
detail than before the methods and design rules for achieving the
necessary synchronization in timing among the widely distributed devices
in the ALMA telescope.  It can be found on ALMAEDM under

/IPTs/ System Engineering/ Documentation

as document number 80.04.00.00-003-A, "Time Synchronization Design
Rules."

In addition, I have re-written the 'Synchronization' part (sec 4.5) of
the System Design Description, document 80.04.00.00-002-B, available in
the same folder on ALMAEDM, in the hope of making it more clear.  This
covers the design at a higher level and in less detail, but it provides
some of the background needed for a full understanding of the new
document.

In the present design, these timing considerations affect the following
devices:  Correlator, First LO Offset Generator, Second LO Synthesizer,
DTS Transmitter, and Digitizer Clock.  Also affected are many modules of
the control software, including but not limited to drivers for these
devices.

This is not intended to impose any new requirements or to force any
design changes.  It is done merely to clarify and provide documentation
of things that should already be incorporated into the design.

Please forward this message to anyone you think would be interested. 
Comments and questions on these documents and the points raised in them
are welcome.

--Larry 

============================================================
Larry R. D'Addario
Research Engineer
National Radio Astronomy Observatory, Tucson, Arizona, USA

949 N Cherry Ave, Campus Bldg 65           7711 E Linden St
University of Arizona                      Tucson, AZ  85715
Tucson, AZ  85721-0655
tel:  +1/520/882-8250 x123                 +1/520/885-8240
fax:  +1/520/882-7955
Email:   ldaddario at nrao.edu
============================================================