[evlatests] Level settings

[Walter Brisken]

Ken and I have been working on various bits needed for the attenuator 
parameters for LUT.  Ken made a plot of sync detector voltage and 
correlation coefficient amplitude as a function of attenuation (or 
equivalently the 8bit sampler RMS).  Both the SD voltage and the CC 
amplitudes have broad maxima where the sampler RMS ranges between 8 and 
15.  This is seen on antenna 14 IFs A, B, C.  IF D was not talking 
yesterday and produces anomolously low output power today.  We believe 
that setting the default attenuators such that in good weather at the 
zenith a sampler RMS of 8 is achieved.  Yesterday morning was clear and I 
was able to get enough measurements to populate the attenuator table for 
ant 14, IFs A,B,C at bands C,X,K,Q.  Today I got data for L band.  RFI is 
really quite an issue here with occasional spikes (at least once per 
minute) that double the sampled voltage.  Thus I used the lowest 
repeatable RMS output value in determining appropriate coefs.

As for a script to populate the parameter database, I propose a slightly 
more general solution -- one that takes as input a text file with lines 
consisting of:

<entity> <band> <parameter> <value>

for example:

14	1.5GHz	IFARFA	8
14	1.5GHz	IFAOUTA	18
14	1.5GHz	IFBRFA	8
14	1.5GHz	IFBOUTA	13
14	1.5GHz	IFCRFA	8
14	1.5GHz	IFCOUTA	19
.
.
.

which exactly matches the values shown in parmstool.  Thus we can maintain 
a human readable/editable table of values and this tool could be used for 
other purposes.

Before I get to doing that, I'll list the values I think we should be 
using for the time being for antenna 14:


Band	IF	RF_Atten	Output_Atten
L	A	8		18
L	B	8		13
L	C	8		19
C	A	8		15
C	B	8		15
C	C	8		18
X	A	0		13
X	B	0		10
X	C	0		18
K	A	8		15
K	B	8		13
K	C	8		17
Q	A	0		21
Q	B	0		19
Q	C	0		27