Chair: John Payne and Wolfgang Wild (not present)
Attendees: Robert Brown (NRAO), Viktor Belitsky (OSO), Matt Carter (IRAM), Charles Cunningham (HIA), Brian Ellison (Rutherford Appleton Laboratory), Mark Harman (RAL), James Lamb (OVRO), Bernard Lazareff (IRAM), John Payne (NRAO), Dick Plambeck (BIMA), Yutaro Sekimoto (NRO), John Webber (NRAO), and Carolyn White (NRAO)
John Payne confirmed that the accurate estimate of the heat loads on the various cryogenic stages report will be done.
Richard Plambeck has started work on calibration issue. He is researching Mangum memo. Plans to have this done.
John Webber has begun reviewing some old calculations and will review the memo. Plans to meet the deadline.
Has done report on ALMA Thermal link. Will send out to group. Please review and send questions, comments, etc., to Mark Harman. When it is in its final report, we will make this an ALMA Memo. John Payne, Mark Harman, and Brian Ellison will discuss this before it is posted as a memo.
Matt Carter talked with Mark Harman on the how the design of the cryostat was going and all seemed to be going well.
Payne questioned the purity of the polarization. Stafford Withington will have a person re-review the updated calculations. Napier is also calculating this effect.
The group has redesigned the thermal link and have returned the cartridge diameter back to 170 mm. Have also generated cartridge outline.
Cryogenics people are working on heat load from the cartridge itself. They have also generated a cartridge area outline.
Harman sent out a PDF file of the modified dewar (squashed dewar). Comments from the group included the modified dewar eases tolerances on the cartridges as well as creates a nice interface point.
Sekimoto deferred comments on the Japanese bands 8 and 10 until next teleconference.
The receiver subsystem does not include any local oscilltor package outside the cryostat. Some more of the LO pieces (drivers, etc.) that need to be mounted on the receiver frame should be included as the receiver subsystem.
We need to define interface to cartridge for cartridge builders. Also need to specify frequency range and cooled multiplier and state that as the final LO definition.
Correction from Webber on the Draft Receiver Specifications by Payne and Wild section 3.7 "in order to all . . . band shall be ready for operation at all times." The word band should be band 3.
Bernard Lazareff questioned using the wave guide hybrid mixer for higher frequencies. Webber believes we should adopt this as the ALMA specification.
Wolfgang is organizing various approaches to produce a 650 GHz waveguide hybrid.
Action Item to all include reviewing Wade's document on the testing for the ALMA Receivers.
It is time we should be able to start draft ICD's for the complete receiver package and the cartridges as well. The ICD template can be found at URL: http://www.tuc.nrao.edu/~demerson/icdtemplate.pdf. In the ICD's we will get down to the real components including types of connectors for the BIOS, power levels for unit output, etc.
The nature of the interface with the monitor and control systems needs to be reviewed: the two extremes of the options are: 1) the receiver should be smart (all monitor and control system does is tell it what frequency is required); or 2) the monitor and control system controls the receiver housekeeping.
Comments include:If we decide to have no intelligence in the receiver, we will have to control the software.
The engineer who builds it should make sure software works. The builder should be able to dial in and diagnose it remotely.
Using autonomous operation of the receiver should reduce overhead. It should be built to minimize the amount of tuning required.
Using autonomous systems, you can run into the danger of requiring a longer delay in tuning the system.
There is a maintenance headache for having a smart receiver. Software can be designed by a non-computer programmer, which is not going on the specified styles for the project.
We probably need to set up a list of specifications that names what we need to control and what we don't need to control.
The Project Book is a "living document" which defines the baseline design at any current time for the project. The specifications and time line detail what the subsystems comprises. What goes into the Project Book is the official baseline not just ideas. The receiver chapters are behind. Payne and Wild will write out a list of all sub-systems and place the responsibility on the person who is working on that aspect of the project.
There has been some interest in this in the UK. As well as at IRAM. Ellison and Lazareff will work on this together. Webber will send out technical report to them on the work that the CDL has done.
Rutherford needs an accurate estimate of the heat loads on the various cryogenic stages.
Calibration issues need to be addressed
Who: Richard Plambeck
When: June 30, 2000
HFET performance: An analysis and report on the suitability of the amplifiers
for ALMA.
Who: John Webber
When: June 30, 2000
Specifications on the what the receiver needs to control and what it
does not need to control
Who: Brian Ellison
When: July 30, 2000
Draft Receiver Cartridge ICD
Who: John Payne
When: July 30, 2000
Polarization Issue: Analysis about the impurity on the mirrors.
Who: Peter Napier, James Lamb, Stafford Withington
When: TBD
Minutes recorded and submitted by Carolyn White