[evlatests] [evla-sw-discuss] parameter simplification for the VHF receivers

[Chuck Kutz]

Bryan, et. all

The new low band receiver provides for four separate channels in each
polarization. Currently there are two of the four channels used, for the
4-band and the P-band. These two channels are combined and routed to the
T301. This is what was done in the EVLA, though they were combined in the
T301 instead of the receiver. 

Chuck

-----Original Message-----
From: evlatests-bounces at nrao.edu [mailto:evlatests-bounces at nrao.edu] On
Behalf Of Bryan Butler
Sent: Thursday, June 28, 2012 11:11 AM
To: Ken Sowinski
Cc: evlatests at aoc.nrao.edu; evla-sw-discuss at aoc.nrao.edu
Subject: Re: [evlatests] [evla-sw-discuss] parameter simplification for the
VHF receivers


do they come through different receivers within the box?

i'm concerned about being able to distinguish between them in the SDM.

	-bryan


Ken Sowinski wrote, On 6/27/12 9:30 AM:
> Currently parmainator distinguishes between 75 MHz and 300 MHz for 
> band related paramters.  The parameters of interest are subreflector 
> rotation and focus and band-dependent delays.  Also there are T_cals, 
> which are now obsolete in the paramters DB, and tables of attenuator 
> settings, also obsolete.
>
> I suggest that we have only one band code "VHF" to select the low 
> frequency receivers.  Receiver.java will transform any reference to 
> "75MHz" or "300MHz" to "VHF".  This allows us to keep only one set of 
> parameters in the DB, rather than two identical sets; prevents 
> possible mistakes when two sets are maintains; more accurately 
> reflects the current hardware; and, eliminates the confusing necessity 
> of having to know whether the script selected "75MHz" or "300MHz".
>
> The rational is that there is one receiver box containing all 
> receivers.  Its single output (dual polarization) is conneted to one 
> T301 input.  Regardless of which band is selected, the hardware 
> configuration is the same and the same wideband signal is presented to 
> the T304.
>
> Would doing this prevent anything that would be practical and useful 
> with the current scheme?
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