| 摘要 |
1,227,829. Digital to frequency converters. ROSEMOUNT ENG. CO. Ltd. 10 July, 1969 [17 July, 1968], No. 34028/68. Heading G4H. An apparatus for providing a pulse train having a mean frequency in accordance with a digital input comprises a pulse generator 11, 13, a recycling store 16, and a gate 17 controlling the feeding of pulses from the generator to an output, the gate being controlled by the digit at the output of the store, shifting of the digits in the store being controlled by the circuit 46 which presents each digit at the store output for a number of periods in a given time interval which correspond to its significance. The shift controlling circuit 46 comprises a binary divider 19 producing non-coincident outputs at submultiples of the input frequency on lines 20 to 24 and a counter 25 having outputs 26-30 gated with the divider outputs. The pulses from the generator 31 cause the counter 25 to step round until an output occurs at the " AND " gate corresponding to the divider output whereupon the shift pulses from the high frequency generator 31 are inhibited by the " AND " gate 42. When the next output from the divider occurs the " AND " gates 35-39 are blocked and the gate 42 passes pulses from the generator 31 which shift the data in the store and operate the counter as above. The data in the store is shifted so that the most significant digit is presented at the output for each alternate 100Hz pulse, the next most significant digit each alternate one of the remaining pulses &c. In an embodiment, Fig. 5 (not shown), a delay line replaces the shift register. The data may be stored in pure binary or binary coded decimal and the store output may be monitored, modified and rewritten as desired. |
