DIGITAL PHASE SHIFTER
First Claim
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1. A digital phase shifter to generate first and second pulse trains having the same repetition rate and wherein said first and second pulse trains may be selectively phase-shifted a preselected number of clock pulses with respect to each other comprising:
- means to generate clock pulses;
a first counter adapted to receive each of said clock pulses and to advance in count with each of said received clock pulses;
means to provide an output pulse from said first counter each time said first counter is advanced to a first predetermined count level, a plurality of said output pulses from said first counter generating a first pulse train;
a second counter comprised of a plurality of flip-flops each having a set and reset input and each adapted to receive each of said clock pulses and to advance in count with each of said received clock pulses;
selection means for providing a combination of signals in binary form representative of a selected count level;
a plurality of gates, each having its output connected to one of said set or reset inputs of said flip-flops and each having one input responsive to one of said combination of signals and another input responsive to said output pulse from said first counter such that said second counter is at said selected count level; and
means to provide an output pulse from said second counter each time a total of said preset selected count level and the number of clock pulses received by said second counter is also equivalent to said predetermined count level, a plurality of said output pulses from said second counter generating a second pulse train which is shifted a preselected number of clock pulses from said first pulse train.
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Abstract
A digital phase shifter wherein pulses on one pulse train are advanced or delayed with respect to pulses on another pulse train in response to a digital command indicating the desired advance or delay. Two counters having a common clock input provide the pulse trains with the counter providing the one pulse train having means by which it may be preset by the command on occurrence of a pulse on the other pulse train. The phase shifter of this invention is particularly applicable for supplying sync commands in a system comprising a television camera and a matrix of displays on which the image generated by the camera may be selectively positioned is also shown.
24 Citations
6 Claims
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1. A digital phase shifter to generate first and second pulse trains having the same repetition rate and wherein said first and second pulse trains may be selectively phase-shifted a preselected number of clock pulses with respect to each other comprising:
- means to generate clock pulses;
a first counter adapted to receive each of said clock pulses and to advance in count with each of said received clock pulses;
means to provide an output pulse from said first counter each time said first counter is advanced to a first predetermined count level, a plurality of said output pulses from said first counter generating a first pulse train;
a second counter comprised of a plurality of flip-flops each having a set and reset input and each adapted to receive each of said clock pulses and to advance in count with each of said received clock pulses;
selection means for providing a combination of signals in binary form representative of a selected count level;
a plurality of gates, each having its output connected to one of said set or reset inputs of said flip-flops and each having one input responsive to one of said combination of signals and another input responsive to said output pulse from said first counter such that said second counter is at said selected count level; and
means to provide an output pulse from said second counter each time a total of said preset selected count level and the number of clock pulses received by said second counter is also equivalent to said predetermined count level, a plurality of said output pulses from said second counter generating a second pulse train which is shifted a preselected number of clock pulses from said first pulse train.
- means to generate clock pulses;
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2. The invention according to claim 1 wherein said plurality of gates comprises a first group of AND gates each having its output connected to said input of one of said flip-flops and a second group of AND gates each having its output connected to said reset input of one of said flip-flops, and further comprising a plurality of inverters, each located between one of said second group of AND gates and one of said combination of signals.
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3. The invention according to claim 1 wherein said first and second counters advance on the trailing edge of said clock pulses and said presetting means operates on the leading edge of said selected pulses.
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4. The invention according to claim 1 wherein said selection means comprises a plurAlity of switches.
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5. The invention according to claim 1 wherein said selection means comprises a general purpose digital computer programmed to provide said selected count level as a binary word.
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6. The invention according to claim 1 wherein said first counter is comprised of a plurality of flip-flops.
Specification
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Current AssigneeCae-Link Corporation
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Original AssigneeRobert W. Schonover
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InventorsSchonover, Robert W.
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Primary Examiner(s)Heyman, John S.
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Application NumberUS05/315,050Time in Patent Office628 DaysField of Search328/55,129,155,48,62US Class Current327/242CPC Class CodesH03H 17/08 Networks for phase shiftingH03K 5/135 by the use of time referenc...
