| タイトル | Automatic oscillator frequency control system |
| 本文（外部サイト） | http://hdl.handle.net/2060/19860011197 |
| 著者（英） | Smith, S. F. |
| 著者所属（英） | NASA Goddard Space Flight Center|Smith (Stephen F.) |
| 発行日 | 1985-10-29 |
| 言語 | eng |
| 内容記述 | A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder. |
| NASA分類 | ELECTRONICS AND ELECTRICAL ENGINEERING |
| レポートNO | 86N20668 |
| 権利 | No Copyright |
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