Pulse or digital communications – Receivers – Angle modulation
Reexamination Certificate
2000-12-01
2004-10-19
Chin, Stephen (Department: 2634)
Pulse or digital communications
Receivers
Angle modulation
C375S316000, C375S327000, C375S324000, C375S328000
Reexamination Certificate
active
06807237
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a radio apparatus used in a digital mobile communication system and the like, and more particularly, to a radio apparatus and transmission/reception method used in a CDMA (Code Division Multiple Access) mobile communication system.
BACKGROUND ART
FIG. 1
is a block diagram illustrating a configuration of a conventional radio apparatus. The conventional radio apparatus illustrated in
FIG. 1
is used in a radio system such that a reception frequency is only switched to another frequency at the time a transmission signal is transmitted so as to obtain a level measurement on a reception frequency channel that is different from an ordinary transmission/reception frequency combination and further obtain system control information.
Radio apparatus
10
is provided with D/A converters
11
and
12
to which I channel data and Q channel data (hereinafter, respectively referred to as I data and Q data) is respectively input, low-pass filters
13
and
14
, quadrature modulator
15
, gain control amplifier
16
, band-pass filter
17
, up-mixer
18
, band-pass filter
19
, and power amplifier
20
. Radio apparatus
10
is further provided with antenna duplexer
21
and antenna
22
. Radio apparatus
10
is furthermore provided with low noise amplifier
23
, band-pass filter
24
, down-mixer
25
, band-pass filter
26
, gain control amplifier
27
, quadrature demodulator
28
, low-pass filters
29
and
30
, and A/D converters
31
and
32
that respectively output I data and Q data. Still furthermore, radio apparatus
10
is provided with transmission IF (intermediate) frequency synthesizer
33
, transmission RF (radio) frequency synthesizer
34
, reception RF frequency synthesizer
35
, and reception IF synthesizer
36
.
The next explanation is given of the transmission processing operation in radio apparatus
10
.
I data and Q data to be transmitted is converted into respective analog signals in D/A converters
11
and
12
, subjected to low-pass filtering in low-pass filters
13
and
14
, and then converted in quadrature modulator
15
into a signal with a transmission IF frequency using a signal generated from transmission IF frequency synthesizer
33
, respectively.
The converted signal with the transmission IF frequency is amplified in gain control amplifier
16
corresponding to a control voltage, filtered in band-pass filter
17
to pass a signal with a predetermined frequency band, and then converted in up-mixer
18
into a signal with a transmission RF frequency using a signal generated from transmission RF frequency synthesizer
34
.
The converted signal with the transmission RF frequency is filtered in band-pass filter
19
to pass a signal with a predetermined frequency band, amplified in power amplifier
20
, and output to antenna duplexer
21
that separates a transmission frequency signal and reception frequency signal, whereby the radio signal is transmitted from antenna
22
.
The next explanation is given of the reception processing operation in radio apparatus
10
.
A quadrature modulated signal with a reception frequency received at antenna
22
is output to antenna duplexer
21
which separates a transmission frequency signal and reception frequency signal. The resultant signal is subjected to low noise amplification in low noise amplifier
23
, filtered in band-pass filter
24
to pass a signal with a predetermined frequency band, and then converted in down-mixer
25
into a signal with a reception IF frequency using a signal generated from reception RF frequency synthesizer
35
.
The converted signal with the reception IF frequency is filtered in band-pass filter
26
to pass a signal with a predetermined frequency band, amplified in gain control amplifier
27
corresponding to a control voltage, subjected to quadrature demodulation in quadrature demodulator
28
using a signal generated in reception IF frequency synthesizer
36
, and then demodulated to an I signal and Q signal.
The I signal and Q signal are subjected to low-pass filtering in low-pass filters
29
and
30
, and converted into respective digital signals in A/D converters
31
and
32
, respectively, whereby I data and Q data are output.
It is herein assumed that a transmission RF frequency is ft, a reception RF frequency is fr, and that the ft and fr have a relationship of fr>ft, the transmission RF frequency and reception RF frequency are specified so that fr minus ft (fr−ft) is constant.
Accordingly, assuming that a frequency of transmission IF frequency synthesizer
33
is f1, a frequency of transmission RF synthesizer
34
is f2, a frequency of reception RF synthesizer
35
is f3, and that a frequency of reception IF frequency synthesizer
36
is f4, the transmission RF frequency ft is expressed with f2−f1 or f2+f1, the reception RF frequency fr is expressed with f3−f4 or f3+f4, and f2 equals f3 (f2=f3) at the time of the ordinary operation where fr−ft is constant.
When a signal is received which has a reception RF frequency fr′ where fr-ft is not constant, i.e., when f2>f3 or f2<f3, the frequency of reception RF synthesizer
35
is switched corresponding to the reception frequency fr′ that is different from fr. In this case, a quadrature modulated signal with the reception frequency fr′ received at antenna
22
is output to antenna duplexer
21
while being separated from a signal with the transmission frequency, subjected to low noise amplification in low noise amplifier
23
, filtered in band-pass filter
24
to pass a signal with a predetermined frequency band, and subjected to frequency conversion in down-mixer
25
using a signal with a frequency generated in reception RF frequency synthesizer
35
corresponding to the reception frequency fr′ so that the reception frequency is the same as a case that the reception IF frequency is fr.
In the above-mentioned conventional apparatus, however, when a signal is received which has a frequency different from usually specified one in a communication, it is necessary to fast switch a frequency of reception RF frequency synthesizer
35
, and further to concurrently operate reception RF frequency synthesizer
35
and transmission RF frequency synthesizer
34
, thereby resulting in a problem that current consumption becomes great.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a radio apparatus and transmission/reception method capable of performing frequency switching fast and with low current consumption in the case of receiving a signal with a frequency different from ordinary specified one.
This object is achieved by generating in a common frequency synthesizer a first frequency signal with a transmission frequency and reception frequency combined, generating in a reception frequency synthesizer a second frequency signal with a frequency different from that of the first frequency signal, combining in a transmission mixer the first frequency signal and quadrature modulated transmission I and Q signals, and at the time of ordinary communications, combining in a reception mixer the first frequency signal and a received signal, while only at the time of receiving a signal with a frequency different from the first frequency, operating the reception frequency synthesizer to combine the received signal with the second frequency signal.
REFERENCES:
patent: 5327582 (1994-07-01), Wong
patent: 5953641 (1999-09-01), Auvray
patent: 5970053 (1999-10-01), Schick et al.
patent: 6075823 (2000-06-01), Sonoda
patent: 6154166 (2000-11-01), Sawada et al.
patent: 0878916 (1998-11-01), None
patent: 4021220 (1992-01-01), None
patent: 06164491 (1994-06-01), None
patent: 08139640 (1996-05-01), None
patent: 10322407 (1998-12-01), None
patent: 11004211 (1999-01-01), None
Korean Office Action dated Aug. 30, 2002.
English translation of Korean Office Action.
PCT International Search Report dated May 2, 2000.
Obara Toshio
Yamaguchi Manabu
Matsushita Electric - Industrial Co., Ltd.
Perilla Jason M.
Stevens Davis Miller & Mosher LLP
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