Cicada Topic

VEGAS Team Meeting

January 23, 2012

Attendees

• CASPER Team:
  • Dan Werthheimer
  • Glenn Jones
  • Mark Wagner
  • Andrew Siemion

• NRAO:
  • John Ford
  • Jason Ray
  • Randy McCullough
  • Mark Whitehead
  • Patrick Brandt
  • Galen Watts
  • Marty Bloss
  • Srikanth Bussa
  • Paul Demorest
  • Anish Roshi

Meeting Notes:

• March Testing Status
  • Mode 1 working and tested at high clock rate
    • Made a number of changes in Mode #1 design and are working but not yet at high clock rate. V2 of CASPER 10Ge driver. Expect to have the high speed ability fixed by later in Feb. then a significant level of testing is needed. Tests mainly at UC-B. Final tests before March observations.
  • IF/LO hardware
    • Still haven't identified cause of gain slope across band. Looking at freq equalizers combined with attenuators that will result in gain slope of ~1db from 100-1400 MHz.
    • Will need to make a revised PCB FR4 board.
    • Adding more attenuation in the noise source chain
    • Added I2C control capability.
    • Need 8 IF modules (16 channels) minimum for March testing (possible)
    • Should be stable in environmentally stable location
    • I2C drivers are working, parameters are in place, ready for testing
  • Config Tool/Balancing
    • Anish is working with Melinda to finish MR
      • Ability to do Galactic Center obs. will be in place for March Test (Config tool)
      • Balance is a more general but needed for March Obs.
  • ADC testing
    • Both ADCs tested for full bandwith. Spurs are about the same. Srikanth has circulated band shape here. Input power is constant across band so cable losses are negligible. There is a balun on input which may be the cause of what roll-off we have seen. Cross-coupling measurements are complete - results to be circulated. Currently spurs are similar between units (unadjusted).
    • GB to review test results and make recommendation for purchase. (due Jan 27)
  • Gathering of Roach and ADC hardware
    • Five roaches available for the test, eight needed - UC-B can make up the balance
    • Eight plus eight ADCs available (Nationals)
    • Spars from existing gear if needed
    • need a data acquisition PC w/ 10Ge NIC, 10Ge switch, cables
  • Approval of the following MR/PRs by the CCC (This section was updated after the meeting by NRAO)
    • VEGAS Manager
      • Ready for integration tests using system simulator generated data (test tone data through SDFITS). Measure highest sustained data speed capable. Populate switching table for use by FPGA.
    • IF Manager
      • Ready for integration tests in GBT system to support IF/LO I2C protocols above and populate the VEGAS FITS file with bandwidth and filter information
    • GBT status
      • (Not required for March test) Requirements received, SDD reviewing and will draft MR based on Reqs. Developer resource not yet identified
    • switching signal selector
      • Ready for integration tests using system generated data.
    • Antenna position reading at faster rate (Joe Brandt; needed for approved KFPA project)
      • Requirements are needed from Joe to write the MR (if needed). Mark and Joe to meet and discuss
    • Balance
      • MR drafting underway. Melinda and Anish refining requirements. NRAO scientific review of project-delivered information will gate the completion of this MR
    • Config tool
      • MR drafting underway. Melinda and Anish refining requirements. NRAO scientific review of project-delivered information will gate the completion of this MR
    • Connecting VEGAS to the GBT data storage system.
      • (Removed as a requirement for March)
    • Testing VEGAS Manager to write data at the required speed to the data storage system.
      • (Removed as a requirement for March) Under test for writing data, but not to data storage until the array is commissioned.
    • Integrated testing of VEGAS manager with other GBT software and checking the data with GBTIDL.
      • Remaining work requires testing of files generated in simulator for GBTIDL staff review
    • Testing the VEGAS Manager along with GBTIDL to see whether the state integration is done correctly.
      • Complete – requires testing of files generated in simulator for GBTIDL staff review
    • Testing VEGAS configuration for mode 1 (and 13) using config tool.
      • Goal for March, config tool availability contingent on MR approvals and completion of items above.
• Roach "disconnect" issues
  • Permanent address have been assigned to the Roaches and that should clear the problem.
• Sub-band specification in modes 13-17
  • Format of the user input: Eight sub-band center frequencies plus the mode (e.g. mode 13 + 8 frequencies).

• bandshape_adc5g_and_adc083000.pdf: Bandshape plot of SDC 5g and ADC 083000