Method of and apparatus for position location and tracking of a vehicle or the like by the reception at the vehicle of pulsed radio navigation signals as of the Loran-OC type and the like, with an autonomous loop antenna-receiver
First Claim
1. A method of vehicle location by a pair of orthogonally crossed loop antennas for receiving radio-frequency navigation signals from navigation transmitters, that comprises, acquiring the signals in the individual loop antennas of the pair of loop antennas;
- along separate channels, separately phase-shifting the acquired signals respectively + and -45° and
then adding together the signals acquired by the individual loop antennas of the pair to render the loop antenna pattern omnidirectional;
selecting the stronger of the transmitted channel signals and using its polarity as the received signal reference;
determining from signal time delays a rough estimate of relative bearing angles to the transmitters; and
using said relative bearing angles together with measured bearing angle to determine the orientation of the loop antenna with respect to the transmitter.
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Abstract
This disclosure deals with processing radio-frequency navigation signals, particularly Loran-C signals, from crossed loop antennas (H-field antennas) by shifting the signal phase from two loops to be in quadrature with respect to each other and adding them together to achieve omnidirectivity of the antenna pattern during the acquisition mode; using the stronger signal of the two during the cycle selection mode to determine the polarity of the received signals; and calculating the relative bearing angles on transmitting stations to determine, with measured bearing, the orientation of the loop antenna with respect to these stations.
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Citations
14 Claims
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1. A method of vehicle location by a pair of orthogonally crossed loop antennas for receiving radio-frequency navigation signals from navigation transmitters, that comprises, acquiring the signals in the individual loop antennas of the pair of loop antennas;
- along separate channels, separately phase-shifting the acquired signals respectively + and -45° and
then adding together the signals acquired by the individual loop antennas of the pair to render the loop antenna pattern omnidirectional;
selecting the stronger of the transmitted channel signals and using its polarity as the received signal reference;
determining from signal time delays a rough estimate of relative bearing angles to the transmitters; and
using said relative bearing angles together with measured bearing angle to determine the orientation of the loop antenna with respect to the transmitter. - View Dependent Claims (2, 3, 4, 5)
- along separate channels, separately phase-shifting the acquired signals respectively + and -45° and
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6. Apparatus for radio navigation signal vehicle location having, in combination, a pair of orthogonally crossed loop antennas for receiving radio-frequency navigation signals from navigation transmitters;
- a corresponding pair of radio-frequency receiver channels, one for each of the pair of loop antennas;
+ and -45°
phase-shifters respectively inserted into the channels and connected to an adder to combine the phase-shifted signals, thereby to render the loop antenna pattern omnidirectional. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
- a corresponding pair of radio-frequency receiver channels, one for each of the pair of loop antennas;
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14. In apparatus for receiving radio-frequency navigational signals emanating from Loran-C master and slave station transmitters, and acquired by a pair of crossed loop antennas, a receiver system having, in combination, a pair of radio-frequency receiving receiver channels to be respectively connected to the pair of antennas, each channel receiver provided with a bandpass filter connected to a corresponding phase shifter and to a Loran-C signal envelope deriver in turn connected to a channel signal selector also inputted from the corresponding bandpass filter and an adder connected to the phase shifter of each channel;
- each channel signal selector being connected to a hard limiter and thence to a microprocessor for performing digital analyses on the signals, including correlations to determine the stronger channel signal and to provide selection control of the signal selectors.
Specification