Communications: directive radio wave systems and devices (e.g. – Directive – Utilizing correlation techniques
Reexamination Certificate
2001-10-23
2003-06-03
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Utilizing correlation techniques
C342S174000, C342S368000
Reexamination Certificate
active
06573864
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a receiver, which includes a phased array antenna section and performs demodulation in accordance with the direct conversion method.
2. Description of the Related Art
In a conventional receiver including a phased array antenna, RF signals received by antenna elements are combined as they are, and demodulation is performed based on the combined signal.
Also, a conventional demodulator is, for example, of the direct conversion type using a mixer and a local signal.
Such a receiver including a phased array antenna, however, has a disadvantage in that since RF signals received by antenna elements are combined as they are, the amplitudes of the signals received by the antenna elements are uncertain and directivity control required in, e.g., the so-called beamformer, is difficult to perform.
Further, the demodulation method using a mixer has a difficulty in realizing a wider band and requires a high local level to be applied to the mixer. In addition, since the mixer is supplied with a high local power and is in a nonlinear operating state, a disadvantage occurs in that it is difficult to perform demodulation with a low distortion.
SUMMARY OF THE INVENTION
In view of the state of the art set forth above, it is an object of the present invention to provide a receiver, which can reliably recognize the amplitudes of signals received by antenna elements, can easily perform directivity control, and can realize demodulation over a wider band with a low distortion.
To achieve the above object, a receiver according to one aspect of the present invention comprises a phased array antenna section including a plurality of antenna elements each receiving a radio signal, a plurality of phase varying circuits for controlling phases of the respective signals received by the antenna elements to desired different phases, and a signal combiner for combining output signals of the plurality of phase varying circuits; a direct conversion demodulating section including a local signal generating circuit for generating a local signal of predetermined frequency, a generating unit for receiving a combined received signal, which is supplied from the signal combiner of the phased array antenna section, or a calibration signal and the local signal from the local signal generating circuit, for generating two signals having a phase difference therebetween based on at least one of the signals received by the generating unit, and for outputting at least one signal, at least one power detecting circuit for receiving the signal outputted from the generating unit and detecting a level of the signal received from the same, and a conversion circuit for, in a reception mode, converting the output signal of the power detecting circuit to a plurality of signal components, which are contained in the received signal or the local signal, based on set values of circuit parameters, and for, in a non-reception mode in which signals are not received, determining the values of the circuit parameters based on the output signal of the power detecting circuit and then correcting the circuit parameters to the determined values; and a switch circuit for, in the reception mode, applying the combined received signal outputted from the signal combiner of the phased array antenna section to the direct conversion demodulating section, and for, in the non-reception mode, applying the calibration signal to the direct conversion demodulating section instead of the combined received signal outputted from the signal combiner of the phased array antenna section.
Also, a receiver according to another aspect of the present invention comprises a phased array antenna section including a plurality of antenna elements for receiving a radio signal, a plurality of phase varying circuits for controlling phases of the respective signals received by the antenna elements to desired different phases, and a signal combiner for combining output signals of the plurality of phase varying circuits; a direct conversion demodulating section including a local signal generating circuit for generating a local signal of predetermined frequency, a generating unit for receiving a combined received signal, which is supplied from the signal combiner of the phased array antenna section, or a calibration signal and the local signal from the local signal generating circuit, for generating two signals having a phase difference therebetween based on at least one of the signals received by the generating unit, and for outputting at least one signal, at least one power detecting circuit for receiving the signal outputted from the generating unit and detecting a level of the signal received from the same, and a conversion circuit for, in a reception mode, converting the output signal of the power detecting circuit to a plurality of signal components, which are contained in the received signal or the local signal, based on set values of circuit parameters, and for, in a non-reception mode in which signals are not received, determining the values of the circuit parameters based on the output signal of the power detecting circuit and then correcting the circuit parameters to the determined values; and a switch control section for, in the non-reception mode, applying the local signal from the local signal generating circuit of the direct conversion demodulating section to one of the plurality of phase varying circuits of the phased array antenna section instead of the received signal from the antenna element corresponding to the one phase varying circuit, for setting a phase of the local signal, which is inputted to the one phase varying circuit, to a predetermined phase, and for applying the signal having been set to the predetermined phase, as the calibration signal, to the generating unit of the direct conversion demodulating section instead of the combined received signal outputted from the signal combiner of the phased array antenna section.
Preferably, the switch control section includes a control circuit for, at least in the non-reception mode, controlling the one phase varying circuit to set the phase of the local signal inputted thereto to be different from the phase of the local signal inputted to the generating unit.
Preferably, the switch control section comprises a first switch circuit having a first terminal connected to an output line of the antenna element corresponding to the one phase varying circuit, a second terminal connected to a local signal output terminal of the local signal generating circuit, and a third terminal connected to an input terminal of the one phase varying circuit, the first switch circuit selectively connecting the third terminal to the first terminal or the second terminal in response to a control signal; a second switch circuit having a first terminal connected to one input terminal of the signal combiner, a second terminal, and a third terminal connected to an output terminal of the one phase varying circuit, the second switch circuit selectively connecting the third terminal to the first terminal or the second terminal in response to the control signal; a third switch circuit having a first terminal connected to an output terminal of the signal combiner, a second terminal connected to the second terminal of the second switch circuit, and a third terminal connected to an input terminal of the generating unit, the third switch circuit selectively connecting the third terminal to the first terminal or the second terminal in response to the control signal; and a control circuit for, in the reception mode, controlling each of the first switch circuit, the second switch circuit and the third switch circuit by the control signal such that the third terminal is connected to the first terminal, and for, in the non-reception mode, controlling each of the first switch circuit, the second switch circuit and the third switch circuit by the control signal such that the third terminal is connected to the second terminal.
Preferably, at least in the non-reception mode, the
Abe Masayoshi
Kohno Ryuji
Sanada Yukitoshi
Blum Theodore M.
Frommer William S.
Frommer & Lawrence & Haug LLP
Sony Corporation
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