MINUTES OF JOINT RECEIVER DESIGN GROUP (JRDG) MONTHLY TELECONFERENCE
16:00 UTC, 2001-Mar-29
Chair: John Payne
Attendees: Brown (NRAO), Carter (IRAM), Guesten (MPifR), Lamb (OVRO),
Lazareff (IRAM), Payne (NRAO), Plambeck (BIMA), Rafal (NRAO), Webber (NRAO),
White (NRAO), Wild (RUG)
SIS Receiver Stability Specification
After a few moments of discussion, the members present agreed it would
be a good idea to delay discussion on this issue. Members agreed
that Holdaway should be brought into these discussions. Webber states Wootten
did express this was what the ASAC desired. No details of this have
come out from the recent ASAC meeting. Wright has put out a memo which
claims this is not an easy specification to achieve. Members would
like to bring in ASAC members to further discuss this item. Payne
agreed to set up some type of meeting to clarify this issue.
Rafal suggested that before going to the ASAC, the JRDG should have
a specific number that they believe will give optimum performance and be
realistic. Also the ASAC needs to provide justification for their specifications.
Lamb suggested that we state we can have a limited number of receivers
with total power stability. Payne will clarify these issues.
TBDs
Simultaneous Operation of Bands
Agreed to delete "but at least with bands 2 to 10" out of the specifications.
This is because it can be done with WVP at all bands.
Selection of a pre-set Observing Band
Members can now be done by re-pointing the antenna. We need to appropriate
this for the appropriate observing bands. Webber confirms that this
will be fine. No problem to meet this specification. Agreed
to leave it in the specification because we are able to satisfy it.
Keep limits for future items. Front end will be compatible with the
system specification of 1.5 seconds.
New Observing Band
Do we want to switch the warmup time? There is no pressure to change
this. Agreed to leave as is.
Receiver Calibration
This still cannot be totally answered. The issue is still under discussion
with the ASAC. Guilloteau has requested testing the vane scheme.
After this is complete, some definite answers can be given.
There needs to be space above the receivers for an ATL, but no real
numbers can be provided. Discussion continued on the need to add
specific receiver optic specifications for different widgets that may need
to be added at some future time. Carter will circulate sketches of
his concepts. Lamb stressed that we do not want to hamper current
observations while preparing for future widgets that may need to be added.
It was agreed to add a receiver optic specification.
WVR
Lamb suggested that Hills/Belitsky write up these specifications with the
current information available. Lamb has not listed the additional
+/- 1 1/2 db. There should be no specification on any 2 GHz band
yet. Webber would like to have more lab testing before providing
any specification; claims this does not affect sensitivity.
Miscellany
Payne suggested that we add a specification to state we will not change
out cartridges while receiver is on the antenna. Group agreed this
should be done. Current turnaround time for changing cartridges is
about 5 days. Brown stated these specifications are also spelled
out in the operations spec.
Group should review ALMA Memo 357.
Action Items
New
Payne to clarify the SIS Receiver Stability and set up outside meeting
to discuss this issue.
Carter to provide Receiver Optics Specification
Wild/Payne to write up remaining TBDs
ASAC to provide definite answers on radiometry - Marc Rafal: Due Date:
2001-Apr-02
Old
Brown/Rafal will discuss with AEC JRDG issues (fall back plans, technology
freeze, etc.) - Due Date: 2001-Mar-09
Brown/Rafal/Kurz will ask ASAC to designate preferred frequency range
for Band 7 - Due Date: 2001-Apr-02
Next meeting will be 2001-Apr-18 at 1500 UT.
Minutes recorded and submitted by Carolyn White