2014 November 7 VEGAS testing

Overview

Testing the new OGP calibration method to compare against the current (production) method

Method

Same method as in the previous tests by Adam, Paul and Jason. Using VEGAS mode 2.

Data in TGBT14A _912_45, using Astrid script TGBT14A_912/ogp_tests
  • Scan 2 was a quick 60 second test to check we were switching the noise source successfully
  • Scan 3 - 600 second scan, with no OGP calibration
  • Scan 5 - 600 second scan, with production OGP
  • Scan 6 - 600 seconds, new OGP, OG values derived from external noise source
  • Scan 7 - 600 seconds, new OGP, OG values derived from IF noise source
  • Scan 8 - 600 seconds, random OG number used
  • Scan 9 - 600 seconds, zero OG numbers used

Data in scans 6 and 7 were compared directly by dividing through as follows in GBTIDL;

GBTIDL -> gettp,6
GBTIDL -> copy,0,6
GBTIDL -> gettp,7
GBTIDL -> copy,0,7
GBTIDL -> divide,6,7,8 # saves the output from divide in buffer 8
GBTIDL -> show,8

Results

All total power plots use same y axis range for direct comparison. Total power for scan 3 (no OGP applied):
gettp 3.png

Total power for scan 5 (production OGP applied):
gettp 5.png

Total power for scan 6 (OGP applied, OG from external noise source):
gettp 6.png

Total power for scan 6 (OGP applied, OG from IF noise source):
gettp 7.png

Total power from scan 6 / total power from scan 7 for direct comparison:
divide 6 7.png

Using random OG values in the OGP calibration (scan 8):
gettp 8.png

Using no OG values in the OGP calibration (i.e. phase only) (scan 9):
gettp 9.png

Conclusions

By comparing scans 6 or 7 to scan 5, it seems that the new OGs as calculated by the new method do not seem to produce better results then our current production method.

The comparison of scans 6 and 7 show that there does not seem to be a major difference between using the new method with an external noise source or the one in the IF.

Scan 8 shows that both methods for determining the OGs are better then generating random numbers for the offsets and gains.

Comparing Scan 3 to Scan 9 shows the affect of just applying phase corrections (the offsets and gains are all zero in both scans).

Topic attachments
I Attachment Action Size Date Who Comment
divide_6_7.pngpng divide_6_7.png manage 15 K 2014-11-07 - 13:15 SamBates Total power from scan 6 / total power from scan 7 for direct comparison
gettp_3.pngpng gettp_3.png manage 16 K 2014-11-07 - 13:12 SamBates Total power for scan 3 (no OGP applied)
gettp_5.pngpng gettp_5.png manage 14 K 2014-11-07 - 13:13 SamBates Total power for scan 5 (production OGP applied)
gettp_6.pngpng gettp_6.png manage 14 K 2014-11-07 - 13:13 SamBates Total power for scan 6 (OGP applied, OG from external noise source)
gettp_7.pngpng gettp_7.png manage 15 K 2014-11-07 - 13:14 SamBates Total power for scan 6 (OGP applied, OG from IF noise source)
gettp_8.pngpng gettp_8.png manage 14 K 2014-11-07 - 13:15 SamBates Using random OG values in the OGP calibration
gettp_9.pngpng gettp_9.png manage 14 K 2014-11-07 - 13:16 SamBates Using no OG values in the OGP calibration (i.e. phase only)
Topic revision: r4 - 2015-01-27, RichardPrestage
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