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GBT Operations & Commissioning Meeting

7 July 2006

AGENDA


Az Track, Antennae Report -- Bob


Observing News -- Ron

We supported 14 projects in 27 observing sessions, including one radar run and some polarization experiments. Average setup time was 13 min. The telescope was scheduled for 13.5 hrs of maintenance and 2 hrs of receiver checkouts.

Lost time was significant this week for many reasons that will need a bit more explaining than I've usually supplied over the past months. I'm not going to depress people with the percentage of time lost.

Of the 14 operator shifts, five had no problems and 2 had no-lost-time failures.

This rash of problems brings to mind a couple of suggestions:


Scheduling Status -- Carl


Microwave Electronics Status -- Roger

Operations

The K-band receiver has an intermittant problem with the dewar vacuum readout that caused some warning messages and e-mail, but no lost time. We spent some time searching for a 1421.xxx tone-like interference signal, but it appears to have turned itself off.

Development

High Frequency Receivers:

Q-band Receiver: We continue to test the Q-band receiver with the Lab Spectrometer. Detailed progress reports are on the wiki at:

http://wiki.gb.nrao.edu/bin/view/Projects/SpectralBaselinesKaQBand

Ka Receiver: The receiver is currently being dismantled to install the Zpectrometer signal taps and the upgraded phase switch control system. While that's being done the physical configuration is being changed so the differencing loops no longer have to be broken to install the receiver on the telescope. The primary support components are in the shop queue and reassembly is expected to start later next week.

In microcircuit assembly, started work on the following MMIC units:

Qty 3, 5040 amplifiers for Ka-band rx, approx 20% complete.

Qty 3, 5618/5040 LO freq doublers for Ka-band/zpect, approx 20% complete.

Qty 2, 2-28 Ghz amp with 44Ghz LPF for Ka-band, approx 90% complete.


Digital Electronics Status -- Randy

Digital Group Status 01-JUL-06 THRU 07-JUL-06

***Operations, Problem Summary***

Significant lost time (9.95 hours total) was reported with the Spectrometer. Of this lost time...

7.25 hours were due to "Configuration issues"... Ron Maddalena seems to have a handle on this as an operational issue.

2.00 hours were due to "DMA errors"... John Ford seems to think that these errors may be indirectly related to the LTA's; but specifically relate to an infrequent problem wherein the system-wide "Start" command is not being recognized by one or more of the uProcessors in the system.

0.70 hours were due to "Standard Spectrometer errors"... Most likely related to the LTA's...

QUESTION: Since the Spectrometer (and in particular the LTA's) seems to be increasingly problematic, should we focus less attention on the long-term solution (i.e., re-design of the LTA's) and explore some sort of near-term, band-aid fixes/improvements?

Summer maintenance continued with lots of work being done on the active surface.

***Development***

Cal-Tech Continuum Backend (CCB)...

The 2nd CCB has now been fully re-assembled; has successfully undergone bench testing; and awaits further testing with the Ka Band Receiver.

A large percentage of the circuit boards and sub-assemblies required for the 3rd CCB are complete and await bench testing. At this point, we feel that the 3rd CCB could be completed and readied for final testing in the course of two calendar weeks.

Spectrometer LTA Re-design...

Work has resumed on the LTA re-design project... A meeting with John Ford to discuss current and proposed new architectures, design approaches, and the implications thereof is planned for next week. Following this, a project schedule will be prepared and distributed.

Lab Spectrometer...

The Lab Spectrometer appears to have some remaining issues which result in 100MHz comb artifacts appearing in the spectra along with occasional ACF spikes and resultant ringing. Roger seems to think it's a manageable situation, so we'll most likely wait until John Ford returns after the 4th of July to tackle this issue (no change from last week's report).

ALMA...

John Ford's summer student, Manasseh Obi, continued work on a detailed, predictive noise analysis of the bias board with help and input from Randy and Jason.

***Plans***

- Begin construction of CCB #3...
- Evaluate Tektronix scope...
- Continue Active Surface maintenance...
- Continue ALMA support as needed...

Randy


Software Status -- Amy

This ends Week 1 of 6 in the fifth development cycle of 2006 which can be viewed at PlanOfRecordC52006.

Operational support included items in Ron's report above.

There is not a lot to report as it was a short week and we spent a lot of time this week reviewing and interviewing candidates for our open software position. Because the wiki is public, I will include no further details of our interview process in this report but we will be happy to answer any questions in person.


Pulsar Related -- Scott


MIT/LL 43m Project -- Glen

We have resumed normal tracking after the shutdown for upgrade of the MIT/LL electronics. Plan normal tracking next week as well.

We will start testing low frequency mapping with the 43m over the next month, using the up/down conversion unit built by Steve White. Right now we have a single polarization unit, but will have a second in a few weeks.

Still planning on further MIT/LL electronics upgrades in September.

Statement of work for 2007 and 2008 is being reviewed by George Clark in C'ville.


Any other Business

-- RichardPrestage - 06 Jul 2006

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