Method and system for locating direction of transmission source based on wave therefrom
AssigneeTokyo Keiki Co., Ltd.
InventorNoriyuki Akaba
Life of this patent
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Abstract
A direction finding method and system for locating the direction of a transmission source based on an electromagnetic wave which is transmitted from the transmission source and is received by an antenna means at a receiving end apparatus. The transmission source transmits an angle-modulated wave. Meanwhile, the receiving end apparatus receives the transmitted wave, converts into electrical signals a beat frequency signal which is caused by direct and reflected waves contained in the received wave, and time-averaging the electrical signals, thus minimizing a angle error due to a multipass interference.
Claims12
A direction finding method for locating the direction of a transmission source based on an electromagnetic wave which is transmitted from the transmission source and is received by an antenna means at a receiving end apparatus, said method comprising:
- (a) at the transmission source, transmitting an angle-modulated wave which is a communication wave selected from a group consisting of a frequency modulated wave, a phase modulated wave, a chirp modulated wave, a frequency hopping wave, and a wave modulated by a phase shift keying;
- and
- (b) at the receiving end apparatus receiving the transmitted wave, converting a beat frequency signal formed from a combination consisting of a direct wave and a reflected wave contained in the received wave, into intermediate signals, and time-averaging the intermediate signals, whereby an angle error due to a multipath interference is minimized by substantially eliminating multipath signal components so that the direction of the transmission source can be determined by using a monopulse method at the receiving end apparatus,
- wherein a time averaged of the signals converted from the beat frequency signal is substantially 0 and modulation is unaltered by the direction of the transmission source with respect to the receiving end apparatus.
A direction finding system for locating the direction of a transmission source based on an electromagnetic wave which is transmitted from the transmission source and is received by an antenna means at a receiving end apparatus, said system comprising:
- (a) said transmission source including means for transmitting an angle-modulated electromagnetic wave which is a wave selected from a group consisting of a frequency modulated wave, a phase modulated communication wave, a chirp modulated wave, a frequency hopping wave, and a wave modulated by a phase shift keying, said angle-modulated electromagnetic wave being constituted to carry directional information and communication information;
- (b) said antenna means disposed at the receiving end apparatus for receiving the transmitted wave arranged so that the direction of the transmission source can be determined by using a monopulse method at the receiving end apparatus;
- (c) a signal conversion means disposed at the receiving end apparatus for converting into intermediate signals a beat frequency signal formed from a combination consisting of a direct wave and a reflected wave contained in the wave received by said antenna means;
- and
- (d) an averaging circuit for time-averaging the intermediate signals, whereby an angle error due to a multipath interference is minimized based on an output from said averaging circuit so as to substantially eliminate multipath signal components wherein a time averaged value of the signals converted from the beat frequency signal is substantially 0.
Dependencies are inferred from the claim text.