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):
Total power for scan 5 (production OGP applied):
Total power for scan 6 (OGP applied, OG from external noise source):
Total power for scan 6 (OGP applied, OG from IF noise source):
Total power from scan 6 / total power from scan 7 for direct comparison:
Using random OG values in the OGP calibration (scan 8):
Using no OG values in the OGP calibration (i.e. phase only) (scan 9):
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).