Secondary radar system
First Claim
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1. A distance measuring system comprising a first measuring station which includes means for transmitting a first modulated carrier wave, means for receiving a second modulated carrier wave and means for comparing the phases of the modulations of the first and second waves to derive an indication of distance;
- and a second measuring station which comprises;
means for receiving the first modulated carrier wave;
means for retransmitting the second modulated carrier wave, the modulation of the second carrier wave being in phase with the modulation of the primary carrier wave; and
means for preserving the phase of the modulation of said first carrier wave for a longer period than the reception of that modulation by the second station, which preserving means comprises;
a zero crossing detector responsive to the primary carrier wave to derive time impulses;
a source of clock pulses;
a first digital counter for accumulating clock pulses under the control of the said time impulses;
a bi-directional counter which is arranged to increment and decrement alternately with a count corresponding to that accumulated in an interval between said time impulses by the first counter;
a bistable means which is arranged to change state at the times when the bi-directional counter reverses its direction of count so as to provide a signal in fixed phase relationship with the said zero crossings; and
,means for converting the latter signal into the modulation for the secondary carrier wave.
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Abstract
A distance measuring system in which a first station (FIG. 1) radiates a modulated carrier wave and a second station (FIG. 2) receives that wave, and retransmits the modulation on a carrier wave back to the first station, which compares the phases of the original and received modulations. The second station includes a digital counter (19) which accumulates clock pulses denoting the period of the modulation and a second counter is incremented and decremented to reproduce the modulation for retransmission thereof.
19 Citations
1 Claim
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1. A distance measuring system comprising a first measuring station which includes means for transmitting a first modulated carrier wave, means for receiving a second modulated carrier wave and means for comparing the phases of the modulations of the first and second waves to derive an indication of distance;
- and a second measuring station which comprises;
means for receiving the first modulated carrier wave; means for retransmitting the second modulated carrier wave, the modulation of the second carrier wave being in phase with the modulation of the primary carrier wave; and
means for preserving the phase of the modulation of said first carrier wave for a longer period than the reception of that modulation by the second station, which preserving means comprises;a zero crossing detector responsive to the primary carrier wave to derive time impulses; a source of clock pulses; a first digital counter for accumulating clock pulses under the control of the said time impulses; a bi-directional counter which is arranged to increment and decrement alternately with a count corresponding to that accumulated in an interval between said time impulses by the first counter; a bistable means which is arranged to change state at the times when the bi-directional counter reverses its direction of count so as to provide a signal in fixed phase relationship with the said zero crossings; and
,means for converting the latter signal into the modulation for the secondary carrier wave.
- and a second measuring station which comprises;
Specification
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Current AssigneeMichael Millett
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Original AssigneeMichael Millett
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InventorsMillett, Michael
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Primary Examiner(s)Wilbur, Maynard R.
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Assistant Examiner(s)Burk, Robert C.
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Application NumberUS06/233,608Time in Patent Office1,236 DaysField of Search343/7 PL, 343/5 DP, 343/6.8 R, 343/6.8 LC, 343/7 PL, 343/12 R, 343/6.5 R, 343/7.6, 324/83 RUS Class Current342/125CPC Class CodesG01S 13/36 with phase comparison betwe...G01S 13/84 for distance determination ...
