Frequency converter and radio communications system employing the same
First Claim
1. A radio frequency converter for converting a signal in a first frequency band to a signal in a second frequency band by successively mixing the signal in the first frequency band with a plurality of local-oscillation signals having different frequencies, the frequency converter comprising an oscillator for providing a first one of the local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;
- and a phase-locked loop, wherein the phase-locked loop generates at least a second one of the local-oscillation signals having a lowest frequency among the plurality of local-oscillation signals, based on an intermediate frequency beacon signal, which is generated by mixing a predetermined radio frequency beacon signal generated from the signal in a first frequency band with the first local-oscillation signals, and wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth of 20-30 GHz or a millimeter bandwidth 30-300 GHz.
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Accused Products
Abstract
In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.
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Citations
22 Claims
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1. A radio frequency converter for converting a signal in a first frequency band to a signal in a second frequency band by successively mixing the signal in the first frequency band with a plurality of local-oscillation signals having different frequencies, the frequency converter comprising an oscillator for providing a first one of the local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;
- and a phase-locked loop,
wherein the phase-locked loop generates at least a second one of the local-oscillation signals having a lowest frequency among the plurality of local-oscillation signals, based on an intermediate frequency beacon signal, which is generated by mixing a predetermined radio frequency beacon signal generated from the signal in a first frequency band with the first local-oscillation signals, and wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth of 20-30 GHz or a millimeter bandwidth 30-300 GHz. - View Dependent Claims (2, 3, 4, 5, 6)
- and a phase-locked loop,
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7. A radio communications system comprising a hub station and at least one subscriber station radio linked to the hub station, wherein
the subscriber station communicates with the hub station by converting a signal in a first frequency band to a signal in a second frequency by successively mixing the signal in the first frequency band with a plurality of subscriber station local-oscillation signals having different frequencies, the hub station transmits, to the subscriber station, a beacon signal having a radio frequency that is generated by mixing a signal having a hub station local-oscillation frequency with a beacon signal having a predetermined hub station intermediate frequency, and the subscriber station comprises an oscillator for providing a first one of the subscriber station local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth; - and a phase-locked loop,
wherein the phase-locked loop generates at least one of the subscriber station local-oscillation signals having a lowest among the plurality of local-oscillation signals, based on an intermediate frequency beacon signal, which is generated by mixing the radio frequency beacon signal with another one of the subscriber station local-oscillation signals, and wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth of 20-30 GHz or a millimeter bandwidth of 30-300 GHz. - View Dependent Claims (8, 9, 10, 11, 12, 13)
- and a phase-locked loop,
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14. A radio frequency converter for converting a signal in a first frequency band which is above a predetermined radio frequency to a signal in a second frequency band which is above the predetermined radio frequency by successively mixing the signal in the first frequency band with a plurality of local-oscillation signals having different frequencies, the frequency converter comprising an oscillator for providing a first one of the local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;
- and a phase-locked loop,
wherein a spread spectrum reference signal having a predetermined frequency and the first local-oscillation frequency signal are mixed into an intermediate frequency signal which is despread to result in a reference signal, wherein based on the reference signal, the phase-locked loop generates at least a second one of the local-oscillation signals having a lowest frequency among the plurality of local-oscillation signals having the different frequencies is generated, and wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth of 20-30 GHz or a millimeter bandwidth of 30-300 GHz. - View Dependent Claims (15, 16, 17)
- and a phase-locked loop,
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18. A radio communications system comprising a hub station and at least one subscriber station radio linked to the hub station, wherein the subscriber station communicates with the hub station by converting a signal in a first frequency band which is above a predetermined radio frequency to a signal in a second frequency band which is above the predetermined radio frequency by successively mixing the signal in the first frequency band with a plurality of subscriber station local-oscillation signals having different frequencies,
the hub station transmits, to the subscriber station, a spread spectrum signal that is generated by spreading a predetermined reference signal and then by mixing a hub station local-oscillation frequency signal with the spread spectrum reference signal, and the subscriber station comprises an oscillator for providing a first one of the subscriber station local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth; - and a phase-locked loop,
wherein the phase-locked loop generates at least a second one of the subscriber station local-oscillation signal having a lowest frequency among the plurality of subscriber station local-oscillation signals used in the subscriber station from a reference signal that is obtained by despreading a subscriber station intermediate frequency signal which results from mixing the spread spectrum signal transmitted from the hub station and the first subscriber station local-oscillation frequency signal, and wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth of 20-30 GHz or a millimeter bandwidth of 30-300 GHz. - View Dependent Claims (19, 20, 21, 22)
- and a phase-locked loop,
Specification