Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Reexamination Certificate
2001-01-31
2002-04-16
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
C342S362000, C342S427000
Reexamination Certificate
active
06373435
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a direction and position finding apparatus which receives an radio wave and determines a direction of arrival and a position of an emission source thereof with high accuracy.
DESCRIPTION OF THE PRIOR ART
One of the well-known basic direction finding apparatuses to detect a direction of arrival of radio wave is, for example, Yagi antenna which detects the direction of arrival of the radio wave using a directional antenna. Another direction finding apparatus is disclosed in the Japanese Patent Application No. H3-67789, which uses a non-directional antenna and two directional antennas to determine an approximate direction based on an output corresponding to a summing pattern of the two directional antenna patterns and another output from the non-directional antenna, and further to perform a direction finding based on the output corresponding to the summing pattern and another output corresponding to a differential pattern of the two directional antenna patterns.
Conventional direction finding apparatuses described above, however, can detect only a direction of arrival of radio wave. Further, because of a limited accuracy thereof in direction finding due to a beam width of the directional antenna, high accuracy of detection has not been obtained.
SUMMERY OF THE INVENTION
The present invention is made to solve the problems described above, and an object thereof is to provide a direction and position finding apparatus capable of not only detecting a direction of arrival of radio wave with high accuracy, but also performing a highly accurate position finding of an emission source thereof.
An invention defined in claim
1
of the present invention provides a direction and position finding apparatus comprising: a first directional antenna which rotates with a desired wave angle; a first phase sum and difference combining means for outputting a sum and a difference of outputs from said first directional antenna; a first differential gain control means for controlling a gain of the differential component of the output of said first directional antenna; a first receiving means for receiving the sum component from said first phase sum and difference combining means; a second receiving means for receiving an output from said first differential gain control means; a first subtraction means for subtracting one output from the other output of said first and said second receiving means; a first calculation means for determining a direction of arrival of radio wave based on an output from said first subtraction means; a second directional antenna which rotates with a desired wave angle; a second phase sum and difference combining means for outputting a sum and a difference of outputs of said second directional antenna; a second differential gain control means for controlling a gain of the differential component of the output from said second directional antenna; a third receiving means for receiving the sum component from said second phase sum and difference combining means; a fourth receiving means for receiving an output from said second differential gain control means; a second subtraction means for subtracting one output from the other output of said third and said fourth receiving means; a second calculation means for determining a direction of arrival of radio wave based on an output from said second subtraction means; and a position determining means for determining a position of an emission source of the radio wave based on the outputs from the first and the second calculation means; wherein said first directional antenna and said second directional antenna rotate interlockingly, and thereby, said apparatus constructed as described above provides an advantageous effect that it can determine the direction and the position of the emission source of the radio wave with high accuracy based on the summing output and the differential output of the outputs from the two directional antennas.
An invention defined in claim
2
of the present invention provides a direction and position finding apparatus in accordance with claim
1
, in which said directional antennas use at least two vertical polarized waves, and thereby, said apparatus constructed as described above also provides an advantageous effect that it can determine the direction and the position of the emission source of the radio wave based on the summing outputs and the differential outputs of the outputs from the two vertical polarized wave antennas.
An invention defined in claim
3
of the present invention provides a direction and position finding apparatus in accordance with claim
1
, in which said apparatus uses a vertical polarized wave directional antenna with acute horizontal directivity and a vertical polarized wave directional antenna with acute vertical directivity, and thereby, said apparatus constructed as described above also provides an advantageous effect that it can determine the direction and the position of the emission source of the radio wave based on the summing output and the differential output of the output from the vertical polarized wave directional antenna with acute vertical directivity and also by the summing output and the differential output of an antenna pattern of the vertical polarized wave directional antenna with acute horizontal directivity.
An invention defined in claim
4
of the present invention provides a direction and position finding apparatus in accordance with claim
1
, in which each of said first and said second phase sum and difference combining means can vary a phase difference in the output from each said directional antennas, and thereby, said apparatus constructed as described above also provides an advantageous effect that, since a setting of the phase difference can be varied, said apparatus can determine the direction and the position of the emission source of the radio wave based on the summing output and the differential output of the output from the directional antenna, which have been generated as a resultant formed by shifting a phase difference.
An invention defined in claim
5
of the present invention provides a direction and position finding apparatus in accordance with claim
1
, in which the position of the emission source of the radio wave is determined by controlling the gain of the differential component of the output from the directional antenna, and thereby, said apparatus constructed as described above also provides an advantageous effect that it can determine the direction of arrival of the radio wave by interlockingly rotating those two directional antennas to maximize the summing output and also determine the position of the emission source of the radio wave by controlling a wave angle while controlling a gain of the differential output.
REFERENCES:
patent: 5526001 (1996-06-01), Rose et al.
Akazawa Hayato
Kurihara Tsugihiro
Blum Theodore M.
Wenderoth , Lind & Ponack, L.L.P.
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