[evlatests] 3-bit state counts, input power levels, & GSE settings
Michael Rupen
mrupen at nrao.edu
Thu Apr 7 22:51:07 EDT 2011
Herewith the promised, more detailed report on 3-bit power levels and
gain-slope equalizer (GSE) settings.
We were able to set the attenuators so that the sampler rms was 1.6-1.7 in
all cases. The resulting state counts looked remarkably similar for
all the samplers, especially A1 (RCP) -- see attached plots (data path 0
[upper] is LCP; data path 1 [lower] is RCP).
However, this required a wide range of input powers to the samplers,
as detailed below. After setting those power levels we tweaked
the gain slope equalizers to flatten the bandpass; again this required a
range of settings. A quick look showed no obvious spectral differences
when the GSE setting was changed -- the slope across the band changed, but
the smaller-scale features were constant.
Quick summary of GSE results:
- GSE needed for a given sampler was generally similar for all
tunings
- Most samplers required GSE settings within a couple "steps" of the
default (10). The clearest exceptions were ea12-A1 (even a GSE
setting of 0 left 12-15 dB residual slope across the band) and
ea22-A1 (GSE settings of 3-7).
Here are the required settings for each sampler, for a number of
different tunings, chosen by Keith as particularly difficult places in
the bands -- the goal was to see whether the GSEs could indeed flatten
the bandpass for even the most difficult tunings (Keith can provide details
as to how "difficult" is defined).
Key:
RMS --> sampler RMS
Ch1Power --> power out of T304, into the sampler
GSE setting --> setting which produced flat bandpass (0-31; 10
is the default), or residual slope across the 2 GHz band if
this failed (ea12-A1 only)
Frequency covered --> frequency range covered by that tuning
Sampler RMS Ch1Power GSE setting Frequency covered
------- --- -------- ----------- -----------------
ea12-A1 1.7 -21.5 dBm 12dB res.slope 5- 7 GHz (C band)
1.7 -22.2 dBm 12dB res.slope 19-21 GHz (K band)
1.7 -22.2 dBm 15dB res.slope 44-46 GHz (Q band)
1.7 -24.6 dBm 15dB res.slope 35-37 GHz (Ka band)
1.7 -22.1 dBm 13dB res.slope 38-40 GHz (Ka band)
ea12-C1 1.7 -41.9 dBm 9 5- 7 GHz (C band)
1.7 -41.1 dBm 9 19-21 GHz (K band)
1.7 -41.4 dBm 8 44-46 GHz (Q band)
1.7 -41.4 dBm 7 35-37 GHz (Ka band)
1.7 -41.3 dBm 9 38-40 GHz (Ka band)
ea15-A1 1.7 -38.3 dBm 10 5- 7 GHz (C band)
1.7 -38.2 dBm 9 19-21 GHz (K band)
1.6 -38.8 dBm 10 44-46 GHz (Q band)
1.7 -38.6 dBm 9 35-37 GHz (Ka band)
1.6 -38.9 dBm 11 38-40 GHz (Ka band)
ea15-C1 1.7 -39.7 dBm 10 5- 7 GHz (C band)
1.7 -39.5 dBm 10 19-21 GHz (K band)
1.6 -40.0 dBm 10 44-46 GHz (Q band)
1.7 -39.5 dBm 8 35-37 GHz (Ka band)
1.6 -40.4 dBm 10 38-40 GHz (Ka band)
ea22-A1 1.6 -32.6 dBm 7 5- 7 GHz (C band)
1.7 -32.3 dBm 3 19-21 GHz (K band)
1.7 -30.2 dBm 6 44-46 GHz (Q band)
1.7 -32.2 dBm 4 35-37 GHz (Ka band)
1.7 -30.2 dBm 7 38-40 GHz (Ka band)
ea22-C1 1.7 -35.0 dBm 9 5- 7 GHz (C band)
1.7 -35.5 dBm 7 19-21 GHz (K band)
1.7 -35.4 dBm 8 44-46 GHz (Q band)
1.7 -36.6 dBm 6 35-37 GHz (Ka band)
1.7 -35.7 dBm 9 38-40 GHz (Ka band)
ea28-A1 1.7 -39.1 dBm 10 5- 7 GHz (C band)
1.8 -38.9 dBm 8 19-21 GHz (K band)
1.6 -39.5 dBm 10 44-46 GHz (Q band)
1.7 -39.6 dBm 7 35-37 GHz (Ka band)
1.7 -39.3 dBm 9 38-40 GHz (Ka band)
ea28-C1 1.7 -34.6 dBm 11 5- 7 GHz (C band)
1.7 -34.1 dBm 10 19-21 GHz (K band)
1.7 -35.0 dBm 11 44-46 GHz (Q band)
1.6 -34.4 dBm 9 35-37 GHz (Ka band)
1.6 -35.5 dBm 11 38-40 GHz (Ka band)
-- Michael
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