NATIONAL RADIO ASTRONOMY OBSERVATORY

MEMORANDUM


DATE: October 7, 1998
TO: GBT Advisory Committee
FROM: Ronald J. Maddalena, Roger Norrod, and Jim Braatz
SUBJECT: Mockup testing

For over a year we have been hard at work testing GBT electronics. So far, tests have mostly concentrated on individual hardware components or hardware racks. Only a few tests have used simultaneously more than one hardware component or rack. Recently, we have decided to accelerate testing the GBT electronics from a complete system point of view. That is, we will conduct tests that simultaneously use as much of the GBT hardware as is practical.

Attached is a list of the tests we have conducted or need to conduct on the GBT hardware and software. We have indicated those tests that have been completed or are in progress. Note that one should consider this a simple check list -- the order and details of the tests are not given. Many tests and functional checks will be repeated routinely as software and hardware develops.

Sections one through five in the list are the tests for individual hardware racks or software components. Even though we are accelerating system testing we will not reduce our efforts in these important tests of components.

Section six shows the system tests that will test the continuum and spectral-line systems of the GBT. Soon we will augment the list with plans for testing the GBT pulsar and VLBI systems. The tests in this section are aimed to characterize the GBT hardware and software not only from an engineer's or operator's point of view but also from an astronomer's point of view. To this end, we hope, for example, to use and test the software that the operators and engineers will use as part of their jobs and that observers will routinely use for observing and data reduction.

The progress of the tests probably will be posted on the GBT world-wide-web pages.

 

List of GBT Mockup Tests

  1. Receivers -- Ku-Band
    1. Test M&C and user-interface software In progress
    2. Test for various switching signals In progress
    3. Test noise characteristics
  2. I.F. / LO System
    1. I.F. Rack
      1. Test M&C and user-interface software In progress
      2. Power detectors:
        1. Calibrate and record characteristics ----- Done
        2. Measure stability ---- In progress
      3. Test for proper I.F. Routing ----- Done
      4. Measure bandpass characteristics ----- Done
      5. Determine dynamic range of fiber optics system ---- In progress
    2. Converter Rack
      1. Test M&C and user-interface software In progress
      2. Measure bandpass characteristics
      3. Determine system stability ---- In progress
      4. Measure characteristics under various power levels and synthesizer frequencies
      5.  
    3. Analog Filter Rack
      1. Test M&C and user-interface software In progress
      2. Determine system stability ---- In progress
      3. Calibrate sampler detectors ----- Done
      4. Determine dynamic range of samplers
      5. Measure bandpass characteristics ----- Done
    4. LO1
      1. Test M&C and user-interface software In progress
      2. Check for proper L.O. Routing ----- Done
      3. Check for proper test-tone routing ----- Done
      4. Characterize phase-cal generator
      5. Measure characteristics of synthesizer for various power levels and frequencies
  3. Backends
    1. DCR
      1. Test M&C and user-interface software In progress
      2. Characterize detector dynamic range, stability and linearity ---- In progress
      3. Check V/F calibration ----- Done
      4. Test various switching, blanking, cal., and advance signals
      5. Test various data-taking modes In progress
      6. Determine limits on sampling time ----- Done
      7. Determine data integrity ---- In progress
      8. Verify data taking starts and stops at the proper times
      9. Measure noise levels for various combinations of bandwidth and sampling time
    2. Holography Backend
      1. Test M&C and user-interface software
      2. Characterize detector dynamic range, stability, and linearity
      3. Measure intrinsic phase errors
      4. Determine limits on sampling time
      5. Measure amplitude and phase noise levels
      6. Determine data integrity
      7. Verify data taking starts and stops at the proper times
    3. Spectral Processor
      1. Test M&C and user-interface software
      2. Test various switching, blanking, cal., and advance signals
      3. Determine accuracy of measured frequency
      4. Test data integrity
      5. Verify data taking starts and stops at the proper times
      6. Test various data-taking modes
    4. Spectrometer
      1. Test M&C and user-interface software
      2. Characterize detector dynamic range, stability, and linearity
      3. Measure sampler alias rejection.
      4. Determine accuracy of measured frequency
      5. Measure bandpass stability and spectral purity
      6. Measure gain stability
      7. Test various switching, blanking, cal., and advance signals
      8. Measure instrumental (channel) response
      9. Test data integrity
      10. Verify data taking starts and stops at the proper times
      11. Test various data-taking modes (spectral line and pulsar)

         

  4. Other Devices
    1. Motor Rack
      1. Test M&C and user-interface software In progress
    2. Weather Station
      1. Test M&C and user-interface software
      2. Test hardware and software reliability
    3. Switching-Signal Selector
      1. Test M&C and user-interface software In progress
      2. Test device selection & signal routing
      3. Determine timing characteristics of signals
  5. Software "Virtual" Devices
    1. Archivist
      1. Test M&C and user-interface software In progress
      2. Data Storage. Determine:
        1. Data write speed ---- In progress
        2. Data retrieval speed ---- In progress
        3. Data integrity ---- In progress
    2. Frequency Coordinator
      1. Test M&C and user-interface software
      2. Check for correct representation of the system under various hardware configurations.
    3. Scan Coordinator
      1. Test M&C and user-interface software In progress
      2. Check for proper device selection and coordination ---- In progress
      3. Test scan start/stop/abort ---- In progress
    4. Gateway
      1. Test M&C and user-interface software
      2. Test software reliability
      3. Determine whether adequate security is provided
  6. Systems
    1. Continuum -- for both DCR and IF Rack detectors
      1. Test observer's interface
      2. Verify routing of signals, L.O., and I.F.
      3. Determine accuracy of signal calibration
      4. Test various switching modes
      5. Measure 1/F noise characteristics, system stability, and dynamic range
      6. Measure noise level for various combinations of bandwidths and sampling times
      7. Test Aips++ software
      8. Evaluate effects of fiber optics
      9. Test the complete system on astronomical sources
    2. Spectral Line -- for both Spectral Processor and Spectrometer
      1. Test observer's interface
      2. Verify routing of signals, L.O., and I.F.
      3. Determine accuracy of signal calibration
      4. Test accuracy of frequency and Doppler tracking
      5. Test various switching and observing modes
      6. Measure bandpass shape and spectral purity for various I.F. and L.O. settings.
      7. Measure system dynamic range using various sampling modes
      8. Measure noise level for combinations of bandwidths and integration times
      9. Test Aips++ software for various observing modes
      10. Evaluate effects of fiber optics on bandpass
      11. Test the complete system on astronomical sources