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Date: Wed, 03 Sep 2003 17:43:40 -0400 From: Jeff HagenTo: rbrown@astro.cornell.edu, goldsmit@astrosun.astro.cornell.edu, desh@naic.edu, satorchi@naic.edu Subject: GALFA software spectrometer Hi Bob, You asked me to give a short status report on the GALFA software spectrometer. Paul Goldsmith gave me the Heiles signal processing document and I have implemented those changes. This includes the ability to do fft overlaps and Welch weighting. Current performance status: - 2.4GHz dual xenon motherboard - 8192 spectral channels - Welch weighting - overlap factor of 3 (this is up from olap=2 that I reported to Paul several weeks ago.) - 40 MB/second (16 bit I and 16 bit Q). This refers to one polarization at 10MHz or dual pol at 5MHz bandwidth. - The digitizers run at 80 MHz and are digitally filtered and down converted (from 30 MHz) in the graychip. The next step is to do a practical test taking a standard on/off on the telescope. I am going to finish the WAPP spectral line project first as I can easily use the same software to produce the single dish FITS data format. With a working WAPP spectral line mode, a software spectrometer mode is an easy step. Jeff