Crystal oscillator synchronized digital very high frequency omni-range (VOR) instrumentation unit
First Claim
1. In a very high frequency omni-range (VOR) receiver of the type wherein an incoming VOR signal is comprised of both a reference signal and a variable signal, apparatus for producing navigation information in response to said reference and variable signals comprising:
- a crystal oscillator for producing a crystal oscillator signal;
first means for generating, in response to said reference signal and said crystal oscillator signal, a synchronized reference pulse stream being in substantially phase synchronized relationship with said crystal oscillator signal;
second means for generating a stream of timing pulses which are in a substantially phase synchronized relationship to said synchronized reference pulse stream;
means for producing, in response to said timing pulses and to said synchronized reference pulse stream, a stream of OBS pulses which are phase-shifted by an amount representative of a preselected radial emitted by a predetermined VOR station; and
third means for generating, in response to said variable signal and said crystal oscillator signal, a synchronized variable pulse stream being in substantially phase synchronized signal relationship with said crystal oscillator signal;
means, operative in response to said timing pulses, said OBS pulse stream, and said synchronized variable pulse stream, for producing a voltage indicative of course deviation between an actual course and said preselected radial.
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Accused Products
Abstract
A very high frequency omni-range (VOR) receiver for use in aircraft radio-navigation, which provides an indication of course deviation that is substantially immune to effects such as reflections in transmitted VOR signals, transients occurring in an aircraft'"'"'s electrical system and propeller and/or rotor modulations of an incoming VOR signal and the like which are all unrelated to actual course deviation, is disclosed. The receiver phase synchronizes a signal from a 1.08 MHz crystal oscillator to a 30 Hz reference signal and a 30 Hz variable signal; both the reference and variable signals are received from a VOR ground station. As a result of the phase synchronization, the receiver produces timing pulses which are accurately phase synchronized to a synchronized reference pulse stream derived from the 30 Hz reference signal. Additionally, the receiver produces a synchronized variable pulse stream that is derived from the 30 Hz variable signal. The receiver produces, in response to the synchronized reference pulse stream and the timing pulses, a signal (henceforth referred to as the "OBS" signal) which is phase shifted by an amount representative of a selected radial emitted by that station. To facilitate determining deviations from the selected radial, the receiver determines any phase difference between the "OBS" signal and the synchronized variable pulse stream. This phase difference is used to produce a deviation signal having a value that represents any course deviations existing between the selected radial and a present magnetic course of the aircraft with respect to the VOR station.
18 Citations
16 Claims
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1. In a very high frequency omni-range (VOR) receiver of the type wherein an incoming VOR signal is comprised of both a reference signal and a variable signal, apparatus for producing navigation information in response to said reference and variable signals comprising:
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a crystal oscillator for producing a crystal oscillator signal; first means for generating, in response to said reference signal and said crystal oscillator signal, a synchronized reference pulse stream being in substantially phase synchronized relationship with said crystal oscillator signal; second means for generating a stream of timing pulses which are in a substantially phase synchronized relationship to said synchronized reference pulse stream; means for producing, in response to said timing pulses and to said synchronized reference pulse stream, a stream of OBS pulses which are phase-shifted by an amount representative of a preselected radial emitted by a predetermined VOR station; and third means for generating, in response to said variable signal and said crystal oscillator signal, a synchronized variable pulse stream being in substantially phase synchronized signal relationship with said crystal oscillator signal; means, operative in response to said timing pulses, said OBS pulse stream, and said synchronized variable pulse stream, for producing a voltage indicative of course deviation between an actual course and said preselected radial. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a very high frequency omni-range (VOR) receiver of the type wherein an incoming VOR signal is comprised of both a reference signal and a variable signal, apparatus for producing navigation information in response to said reference and variable signals comprising:
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a crystal oscillator for producing a crystal oscillator signal; first means for generating, in response to said reference signal and said crystal oscillator signal, a synchronized reference pulse stream being in substantially phase synchronized relationship with said crystal oscillator signal; second means for generating a stream of timing pulses which are in a substantially phase synchronized relationship to said synchronized reference pulse stream and are maintained at a frequency which is substantially a pre-set multiple of the frequency of said synchronized reference pulse stream; means for providing digital information representative of a preselected radial; means for counting said digital information to a predetermined value in response to said timing pulses and for producing a pulse in an OBS pulse stream whenever said count reaches said predetermined value; means for initiating said counting at the occurrence of a pulse in said synchronized reference pulse stream; third means for generating, in response to said variable signal and said crystal oscillator signal, a synchronized variable pulse stream being in substantially phase synchronized signal relationship with said crystal oscillator signal; means, operative in response to said timing pulses, said OBS pulse stream and said synchronized variable pulse stream, for determining any phase difference existing between said OBS pulse stream and said synchronized variable pulse stream; and means, responsive to said phase difference for producing a voltage indicative of course deviation between an actual course and said preselected radial. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification