Stepped cardioid bearing system
First Claim
1. A system for determining bearing between a unit transmitting a signal and a signal receiving unit, comprising:
- a. an antenna array at one of said units having a central active antenna element and having a predetermined number of parasitic elements including at least three which are spaced in a ring around the active element, and including commutating means having discrete outputs respectively connected to sequentially activate said parasitic elements to provide the antenna array with a rotary stepped pattern having a fundamental sinusoid component;
b. means for generating a reference marker signal associated with each passing of the fundamental sinusoid of said stepped pattern through a predetermined bearing orientation;
c. means for synchronizing said reference marker generating means and said commutating means and operative to inititate the generation of each reference marker signal to coincide with said passing of the sinusoid component through said orientation;
d. means at the receiver unit responsive to amplitude samples of said transmitted signal corresponding with each commutation and providing therefrom a reconstituted sinusoid representing said fundamental sinusoid of the rotary stepped pattern but delayed by a constant delay which is a function of the number of parasitic elements commutated, and including means for determining said bearing with respect to said predetermined orientation from the phase relationship between a point on said reconstituted sinusoid and the occurrence of said reference marker signal; and
e. siad synchronizing means being coupled with a selected one of said discrete outputs which is activated prior to said component passing through said preselected orientation, and said synchronizing means being operative to delay said generation for a fixed interval including an interval compensating for said constant delay.
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Accused Products
Abstract
An antenna system having a central radiator element and one or more surrounding rings of parasitic elements which can be tuned or actuated separately in each ring by electrical commutation to provide a stepped cardioid radiation or receiving pattern. When the radiator element and a ring of parasitics are used to transmit a cardioid, its stepped pattern contains a fundamental sinusoidal component which can be extracted by a filter at a receiver and used to provide a TACAN/VORTAC bearing determination by comparing its phase with a reference signal transmitted once per revolution of the pattern to mark a predetermined position in its rotation, as is common in TACAN systems. When the cardioid pattern comprises transmitted squitter pulses, care is taken to ensure actual transmissions marking each stepping of the antenna pattern in order to provide optimum bearing information.
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Citations
11 Claims
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1. A system for determining bearing between a unit transmitting a signal and a signal receiving unit, comprising:
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a. an antenna array at one of said units having a central active antenna element and having a predetermined number of parasitic elements including at least three which are spaced in a ring around the active element, and including commutating means having discrete outputs respectively connected to sequentially activate said parasitic elements to provide the antenna array with a rotary stepped pattern having a fundamental sinusoid component; b. means for generating a reference marker signal associated with each passing of the fundamental sinusoid of said stepped pattern through a predetermined bearing orientation; c. means for synchronizing said reference marker generating means and said commutating means and operative to inititate the generation of each reference marker signal to coincide with said passing of the sinusoid component through said orientation; d. means at the receiver unit responsive to amplitude samples of said transmitted signal corresponding with each commutation and providing therefrom a reconstituted sinusoid representing said fundamental sinusoid of the rotary stepped pattern but delayed by a constant delay which is a function of the number of parasitic elements commutated, and including means for determining said bearing with respect to said predetermined orientation from the phase relationship between a point on said reconstituted sinusoid and the occurrence of said reference marker signal; and e. siad synchronizing means being coupled with a selected one of said discrete outputs which is activated prior to said component passing through said preselected orientation, and said synchronizing means being operative to delay said generation for a fixed interval including an interval compensating for said constant delay. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification