[mmaimcal] the proper Tsys scale

[Bryan Butler]

hello all,

i'm trying to reconcile bob brown's Tsys numbers with those in
memo 170 (phil & jeff's treatment of the problem).  it turns out
that with the different assumptions in the two developments, the
numbers come out close to the same.  however, with a common set
of assumptions they are clearly different.  mostly, it comes down
to the definition of the scale for Tsys.  phil & jeff use the
TR* scale for Tsys, while bob effectively uses TA*, so there is a
difference of the forward spillover & scattering efficiency which
makes a difference of about 30% in the two estimates (with common
assumptions).  it is unclear to me which is the proper scale.
naively, it seems to me that for purposes of noise calculation,
the eta_fss factor should not be included, i.e., the TA* scale
is the proper one.  however, not being very familiar with these
scales, i am probably wrong about it :)...

	-bryan