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US 3,946,337 AGranted
Phase modulator for phase shift key communications systems
AssigneeThe Bendix Corporation
InventorsWilliam D. Philips, William H. Franklin, Jr.
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Abstract
A carrier wave is directed through a voltage controlled phase shifter to a load. A sample of the signal at the output of the voltage controlled phase shifter is selectably applied, in accordance with modulation information, through one of a plurality of transmission line phase shifters to a phase detector which also receives a sample of the carrier wave. The resulting phase detector output signal is applied through a low pass filter to control the voltage controlled phase shifter.
Claims5
A phase modulator comprising
- means for generating a raw carrier frequency;
- means responsive to a control signal for shifting the phase of said raw carrier frequency to produce a phase shifted carrier frequency;
- at least first and second means, a signal applied to said first means being shifted a predetermined number of electrical degrees with respect to a signal applied to said second means;
- switch means for applying a sample of said phase shifted carrier frequency to one of said first and second means and subsequently to the other of said first and second means in accordance with information to be conveyed by said phase shifted carrier frequency;
- phase detector means for generating an output signal related to the phase difference between said raw carrier frequency and the signal from said first and second means;
- and,
- low pass filter means responsive to said output signal for generating the control signal for said means for shifting.
4 more elements
Dependencies are inferred from the claim text.