Direct conversion receiver with wide band analog frequency conversion front end and digital demodulating and selecting back end
First Claim
Patent Images
1. A receiver adaptable to a plurality of radio communication systems comprising:
- a radio-frequency signal reception unit which collectively receives radio-frequency signals on a plurality of channels each of which is modulated with data;
a quadrature demodulator which multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal having a π
/2-phase differs from the first local signal to produce a second baseband signal having a π
/2-phase differs from the first baseband signal;
a first low-pass filter which outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter which outputs a second low-frequency component signal from the second baseband signal;
a quadrature modulator which multiplies the first low-frequency component signal by a third local signal to produce a first intermediate-frequency signal, multiplies the second low-frequency component signal by a fourth local signal having a π
/2-phase differs from the third local signal to produce a second intermediate-frequency signal, and combines the first intermediate-frequency signal and the second intermediate-frequency signal into an output signal;
an A/D converter which converts the outputs signal into a digital signal;
a digital downconverter which multiplies the digital signal by a first clock signal to produce a first digital baseband signal, multiplies the digital signal by a second clock signal having a π
/2-phase differs from the first clock signal to produce a second digital baseband signal having a π
/2-phase differs from the first baseband signal and selects a signal on at least one channel from the first digital baseband signal, selects a signal on at least one channel from the second digital baseband signal;
a digital signal processing unit which processes the first digital baseband signal and second digital baseband signal to recover the data.
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Abstract
A radio-frequency signal receive section, including an antenna, collectively receives radio-frequency signals on a plurality of channels each of which is modulated with data and outputs a received signal. In a quadrature demodulator, the received signal is multiplied by each of first quadrature local signals to produce quadrature baseband signals. In two low-pass filters, low-frequency component signals are extracted from the quadrature baseband signals. In a quadrature modulator, the low-frequency component signals are multiplied by second quadrature local signals and thereby converted into quadrature intermediate-frequency signals, which are in turn combined into an output signal. After converted into a digital signal, the output signal of the quadrature modulator is inputted to a digital signal processing unit where a signal on at least one channel is selected and the selected signal is processed to recover the original data.
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Citations
10 Claims
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1. A receiver adaptable to a plurality of radio communication systems comprising:
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a radio-frequency signal reception unit which collectively receives radio-frequency signals on a plurality of channels each of which is modulated with data;
a quadrature demodulator which multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal having a π
/2-phase differs from the first local signal to produce a second baseband signal having a π
/2-phase differs from the first baseband signal;
a first low-pass filter which outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter which outputs a second low-frequency component signal from the second baseband signal;
a quadrature modulator which multiplies the first low-frequency component signal by a third local signal to produce a first intermediate-frequency signal, multiplies the second low-frequency component signal by a fourth local signal having a π
/2-phase differs from the third local signal to produce a second intermediate-frequency signal, and combines the first intermediate-frequency signal and the second intermediate-frequency signal into an output signal;
an A/D converter which converts the outputs signal into a digital signal;
a digital downconverter which multiplies the digital signal by a first clock signal to produce a first digital baseband signal, multiplies the digital signal by a second clock signal having a π
/2-phase differs from the first clock signal to produce a second digital baseband signal having a π
/2-phase differs from the first baseband signal and selects a signal on at least one channel from the first digital baseband signal, selects a signal on at least one channel from the second digital baseband signal;
a digital signal processing unit which processes the first digital baseband signal and second digital baseband signal to recover the data. - View Dependent Claims (2, 3, 4)
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5. A receiver adaptable to a plurality of radio communication systems, comprising:
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a radio-frequency signal reception unit that collectively receives radio-frequency signals on a plurality of channels, each radio-frequency signal being modulated with data;
a quadrature demodulator unit that multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal, having a π
/2-phase difference from the first local signal, to produce a second baseband signal, having a π
/2-phase difference from the first baseband signal;
a first low-pass filter unit that outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter unit that outputs a second low-frequency component signal from the second baseband signal;
at least one A/D converter unit that converts the first low-frequency component signal and the second low-frequency component signal into a digital signal; and
a digital signal processing unit that selects a signal based on a desired one of the channels from the digital signal, and processes the signal to recover the data, wherein the digital signal processing unit includes, a quadrature modulator unit that multiplies the first low-frequency component signal by a third local signal to produce a first intermediate-frequency signal, multiplies the second low-frequency component signal by a fourth local signal, having a π
/2-phase difference from the third local signal, to produce a second intermediate-frequency signal, and combines the first intermediate-frequency signal and the second intermediate-frequency signal into an output signal,a digital downconverter unit that multiplies the output signal by a first clock signal to produce a first digital baseband signal, multiplies the output signal by a second clock signal, having a π
/2-phase difference from the first clock signal, to produce a second digital baseband signal, having π
/2-phase difference from the first baseband signal, and selects a signal on at least one channel from the first digital baseband signal and selects a signal on at least one channel from the second digital baseband signal, anda digital signal processor unit that processes the first digital baseband signal and second digital baseband signal to recover the data. - View Dependent Claims (6, 7)
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8. A receiver adaptable to a plurality of radio communication systems, comprising:
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a radio-frequency signal reception unit that collectively receives radio-frequency signals on a plurality of channels, each radio-frequency signal being modulated with data;
a quadrature demodulator unit that multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal, having a π
/2-phase difference from the first local signal, to produce a second baseband signal, having a π
/2-phase difference from the first baseband signal;
a first low-pass filter unit that outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter unit that outputs a second low-frequency component signal from the second baseband signal;
at least one A/D converter unit that converts the first low-frequency component signal and the second low-frequency component signal into a digital signal; and
a digital signal processing unit that selects a signal based on a desired one of the channels from the digital signal, and processes the signal to recover the data, wherein the digital signal processing unit includes, a digital downconverter unit that multiplies the first low-frequency component signal and the second low-frequency component signal from the A/D converter unit by a common clock signal to produce a first digital baseband signal and a second digital baseband signal, having a π
/2-phase difference from the first baseband signal, and selects a signal on at least one channel from the first digital baseband signal and selects a signal on at least one channel from the second digital baseband signal, anda digital signal processor unit that processes the first digital baseband signal and second digital baseband signal to recover the data. - View Dependent Claims (9, 10)
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Specification
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Current AssigneeFujitsu Mobile Communications Limited (Fujitsu Limited)
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Original AssigneeKabushiki Kaisha Toshiba (Toshiba Corporation)
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InventorsYoshida, Hiroshi, Tsurumi, Hiroshi
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Primary Examiner(s)Hunter, Daniel
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Assistant Examiner(s)Corsaro, Nick
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Application NumberUS09/262,104Time in Patent Office1,027 DaysField of Search455/310, 455/311, 455/324, 455/323, 375/316US Class Current455/324CPC Class CodesH03D 7/166 using two or more quadratur...H04B 1/0007 wherein the AD/DA conversio...H04B 1/28 the receiver comprising at ...H04B 1/30 for homodyne or synchrodyne...
