Variable phase shifter
AssigneeCessna Aircraft Company
InventorAndrew M. Vesel
Life of this patent
Estimating the term…
Abstract
A variable phase shifter and comparator useable, for example, in a scalloping suppression system within a V.H.F. Omni Range (VOR) aircraft bearing determining system. The digital phase shifter-comparator network is employed to cause a phase of the reference signal to follow a phase of the variable phase signal. The phase shifter is comprised of two counters and the phase comparator is comprised of a bistable multivibrator. The delayed reference signal is the output of the system, and an analog rate controller is employed to limit the rate at which the reference signal can follow the variable phase signal.
Claims13
A variable phase digital phase shifter for shifting the phase of an input signal comprising:
- storage means for storing a signal indicative of the amount by which the phase of the input signal is to be shifted;
- a source of clock pulses;
- a first input signal terminal;
- counting means connected to said first input signal terminal, to said storage means and to said clock pulse source and responsive to receipt of an input signal at said first input signal terminal for counting a number of pulses, from said clock pulse source, determined by the signal stored in said storage means;
- output means coupled to said counting means for generating an output signal when said counting means has counted said number of pulses;
- and
- adjusting means for adjusting the signal stored in said storage means to adjust the phase difference between the output signal and the input signal.
A variable phase shift digital phase shifter for shifting the phase of an input signal comprising:
- an up-down digital counter;
- a second digital counter;
- means connecting the stages of said up-down digital counter in parallel with the stages of said second digital counter;
- input means connected to said second digital counter and responsive to receipt of an input signal for parallel loading a number stored in said up-down digital counter into said second digital counter, while retaining the number in said up-down digital counter, and starting said second digital counter counting downward;
- output means connected to said second digital counter for generating a phase shifted output signal when said second digital counter has counted downward from the number to zero;
- and
- control means connected to the up and down inputs of said up-down digital counter to incrementally change the number stored therein by counting up or counting down.
A phase comparator for comparing the phases of two signals comprising:
- first input means for receiving a first input signal;
- second input means for receiving a second input signal;
- switching means connected to said first and second input means and adapted to assume a first state upon receipt of the first input signal at said first input means and to assume a second state upon receipt of the second input signal at said second input means;
- and
- gating means connected to said switching means and to said second input means for generating a first phase comparison signal upon receipt of the second input signal while said switching means is in its first state and a second phase comparison signal upon receipt of the second input signal while said switching means is in its second state.
A phase comparison and following system for causing the phase of a second signal to follow the phase of a first signal comprising:
- first input means for receiving a first input signal;
- second input means for receiving a second input signal;
- switching means connected to said first and second input means and adapted to assume a first state upon receipt of the first input signal at said first input means and to assume a second state upon receipt of the second input signal at said second input means;
- gating means connected to said switching means and to said second input means for generating a first phase comparison signal upon receipt of the second input signal while said switching means is in its first state and a second phase comparison signal upon receipt of the second input signal while said switching means is in its second state;
- and
- control means connected to said gating means for adjusting the phase of one of said first and second input signals to decrease the delay of the phase of said second input signal with respect to said first input signal in response to a first phase comparison signal and to increase the delay of the phase of said second input signal with respect to said first input signal in response to a second phase comparison signal.
Dependencies are inferred from the claim text.