Voyager LECP Pages
A special test set is available which allows fast verification of the accuracy and resolution of the PHA in a semi-automated manner. A digital servo loop is used to measure each major bit of the A to D converter. Precision of each bit may readily be observed with a standard digital voltmeter while monotonic progression of the calibration is displayed on an oscilloscope in the region of each major bit. Thereby, one photograph and ten recorded numbers (using a 4 1/2 place or better DVM) completely characterizes the flight hardware for accuracy and resolution. The unit also provides visual decimal readout for all four channels and may be continuously operated at any desired point (using its internal adjustable drive voltage or eternal precision supplies) for test or trouble-shooting.
The PHA Test Set performs the following functions:
The tester is illustrated by the two block diagrams, Figure A-1, "PHA Test Set Timing and Data Presentation" and Figure A-2, "PHA Test Set Digital Servo Control Loop." The timing and Data sections of the circuitry can stand alone and may be used to build a PHA readout device if desired. The Digital Servo Control Loop requires inputs from the Timing and Data sections for closed loop operation, but may be used as a simple precision variable power supply in the open loop case. Signals within both sections are made available for DVM and oscilloscope interface. The design is for minimum operator effort during PHA checkout. Schematics and timing diagrams are included herein; for further information contact the author.
A3, PHA Test Set Timing Diagram
A4, MJS-PHA Test Set Data Store, Error Sense and BCD Conversion
A5, PHA Test Set Display & Control Logic
A6, PHA Test - Misc. Schematics
A7, PHA Test Set - Panel Detail
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Last modified 6/20/03, Tizby Hunt-Ward