List of Receiver and Optics Specs Required
List of Receiver and Optics Specs Required
Deadline: 3 April 2000
o What are the implications of the 1% cal spec, as regards
to the performance of the WVR (should it be cooled?) and
the need for a cold load?
o What are the scientific and calibration requirements of the
polarization performance, both interferometrically and
in total-power (single-dish) mode? (Larry asks for maximum
cross-polarization and polarization mismatch between antennas.)
o What are the scientific and calibration stability requirements
for the gain fluctuations in total power modes for each band?
(The current spec is 1E-4 at 1Hz, but we should have some specs
over a wider frequency range as per Larry's request.)
o What are the specific specs for Band 1, which may have to have
non-optimum optics (eg. mirror size, off-axis placement) and
poorer total-power stability? (We should have some fallback
relaxed specs in this band.)
It would also be a good idea to revisit and firm up the specs on:
o What are the limits for minimum image sideband rejection (in dB)
for the expected worst-case continuum and more critically narrow
band signals in the image sideband? (The feeling is that 10dB
is enough in hybrid schemes and some QO schemes claim on 7dB.)
o What are the limits on optical aberrations (I and polarization)
that are tolerable from the scientific and calibration
standpoints?
o What are the implications of adopting DSB front-ends and thus
performing the sideband separation or rejection in the back-end
and correlator? (The phase switching will require some minimum
time to cycle through the Walsh functions and thus we may have
to limit the number of antennas in the subarray doing this when
fast switching or scanning is desired.)
o Are there any unacceptable tuning limitations of Larry's LO
scheme (as modeled by Barry's handy C program)? (I am not sure
that anyone has actually done this fully.)