Telescope ASPH 611 Term Project
A University of Calgary Department of Physics and Astronomy
Graduate Course in Radio Astronomy

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ASPH 611 Team

Update 1

Jeff Dever, December 24, 2005

A little Christmas present came in for us last week, the 1420MHz filter. It doesn't make all the problems go away, but the band is WAY cleaner. The following profile shows the entire band across CygX, 10s integration, raw data:

Wow, you can see the three arms of our Galaxy!

There are still some problems with RFI that were not occuring in the above spectra. The case where the entire band is trashed with high energy stuff still occurs, but not all the time. The other case is where there is apparently some strong signal just at the top end of our band, which appears to causes gain compression in the LNA, which is not protected by the filter.

There are some things that can be done to try and make these problems go away:

  1. The broad band stuff doesn't look like a radio transmission to me, it looks more like a generator or motor or somthing like that. Perhaps a proper ground would help with this.
  2. The high energy stuff that is at the top of the band might be helped with some radio shielding of the electronics. Russ suggested a metal can on the front end electronics, and another metal box for the mixers.
  3. There is always a move to Rothney (and a 12' dish as a bonus to the expected quiter RFI environment).

I took several days of data with the filter on, on the same 41 degree DEC line that used for the observation, but over several days. Here is a selection of that data, again complete raw and unprocessed, that scans through the galactic plane and then back out again:

The gentle time variations are probablly Tsys and temperature related. The dark bands are gain compression from that strong RFI.

Last modified: 10:22 am July 17, 2014

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