Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
1998-07-28
2002-03-19
Chang, Vivian (Department: 2682)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S063300
Reexamination Certificate
active
06360077
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mobile radio communication device such as a portable telephone which performs communication with a base station using a downlink frequency and an uplink frequency which are assigned to the mobile radio communication device by the base station, and in particular, to a mobile radio communication device which is provided with functions for detecting occurrence of interference to the downlink frequency and/or the uplink frequency and informing the base station of the occurrence of the interference.
DESCRIPTION OF THE PRIOR ART
Post-detection selective space diversity systems provided with two reception systems are generally employed for ensuring stable radio wave reception and communication even when electric field intensity is decreased due to fading which is characteristic of mobile communication, in which a post-detection reception signal having higher post-detection field intensity is selected from two reception signals which have been received by the two reception systems.
FIG. 1
is a block diagram showing composition of a conventional mobile radio communication device (a mobile terminal
5
) which employs the post-detection selective space diversity system. The mobile terminal
5
is provided with two reception systems RA and RB each of which is composed of a double superheterodyne system in which demodulation of the reception signal is executed after two steps of frequency conversions. Along with the reception systems RA and RB, the mobile terminal
5
is provided with a transmission system TA. A first oscillator
35
and a second oscillator
36
are provided in order to generate a first local oscillation signal and a second local oscillation signal to be used for the first frequency conversion and the second frequency conversion (double superheterodyne) which are performed in each of the reception systems RA and RB. The first oscillator
35
is also used by the transmission system TA for converting the frequency of a modulated signal for being transmitted into a transmission frequency.
The reception system RA of the mobile terminal
5
is provided with an antenna ANT
1
for receiving a radio wave having a downlink frequency frx (a frequency transmitted by an unshown base station to the mobile terminal
5
). The reception system RB is provided with an antenna ANT
2
for receiving a radio wave having the downlink frequency frx and transmitting a radio wave having an uplink frequency ftx (a frequency transmitted by the mobile terminal
5
to an unshown base station).
The reception system RB is provided with an antenna switch
30
for switching the function of the antenna ANT
2
between reception and transmission. Hereafter, with respect to components which are common to both the reception systems RA and RB, explanation will be given on the reception system RA only, and reference numbers in round brackets ( ) represent components of the reception system RB which are equivalent to components of the reception system RA. In the example of
FIG. 1
, the reception system RA (RB) is provided with a band pass filter (BPF)
10
(
20
) for limiting the bandwidth of the reception signal (i.e. for rejecting unnecessary signals) supplied from the antenna ANT
1
, and a high frequency amplifier
11
(
21
) for amplifying the reception signal.
Further, the reception system RA (RB) of the mobile terminal
5
is provided with a BPF
12
(
22
) for further limiting the bandwidth of the reception signal supplied from the high frequency amplifier
11
(
21
), a first mixer
13
(
23
) for converting the reception signal into a first intermediate frequency signal (first IF signal) utilizing the first local oscillation signal supplied from the first oscillator
35
, a BPF
14
(
24
) for limiting the bandwidth of the first IF signal supplied from the first mixer
13
(
23
), and a first intermediate frequency amplifier
15
(
25
) for amplifying the first IF signal supplied from the BPF
14
(
24
).
Further, the reception system RA (RB) is provided with a second mixer
16
(
26
) for converting the first IF signal into a second intermediate frequency signal (second IF signal) utilizing the second local oscillation signal supplied from the second oscillator
36
, a BPF
17
(
27
) for limiting the bandwidth of the second IF signal supplied from the second mixer
16
(
26
), and a second intermediate frequency amplifier
18
(
28
) for amplifying the second IF signal supplied from the BPF
17
(
27
). After the second intermediate frequency amplifier
18
(
28
), the reception system RA (RB) is provided with an RSSI section
19
(
29
) for outputting an RSSI (Received Signal Strength Indicator) signal whose signal level varies according to the field intensity of the reception signal (the second IF signal), and a demodulator
19
a
(
29
a
) for demodulating the second IF signal and thereby outputting a demodulated signal such as a baseband signal.
The transmission system TA of the mobile terminal
5
is provided with a modulator
31
for modulating the baseband signal utilizing the first local oscillation signal supplied from the first oscillator
35
, a driver amplifier
32
as a preliminary amplifier for obtaining gain, and a power amplifier
31
for amplifying the modulated signal and supplying the amplified transmission signal to the antenna ANT
1
via the antenna switch
30
.
In the following, the operation of the conventional mobile radio communication device will be described. Incidentally, explanation of the operation of the transmission system TA is omitted for brevity.
In the reception system RA, a reception signal with the downlink frequency frx which has been received by the antenna ANT
1
and whose bandwidth has been limited by the BPF
10
is supplied to the high frequency amplifier
11
. Meanwhile, in the reception system RB, a reception signal with the downlink frequency frx which has been received by the antenna ANT
2
at the same time is supplied to the antenna switch
30
. When signal reception is performed, the antenna switch
30
is controlled by an unshown CPU etc. so as to connect the movable terminal c to the fixed terminal b, and thus the reception signal is supplied from the antenna switch
30
to the high frequency amplifier
21
via the bandwidth limiting BPF
20
.
Thereafter, the reception systems RA and RB operate in the same way, therefore, only the operation of the reception system RA will be described in the following. Incidentally, reference numbers in round brackets ( ) represent components of the reception system RB. The reception signal outputted by the high frequency amplifier
11
(
21
) is supplied to the first mixer
13
(
23
) via the bandwidth limiting BPF
12
(
22
). The first mixer
13
(
23
) is also supplied with the first local oscillation signal from the first oscillator
35
, and the reception signal is frequency converted by the first mixer
13
(
23
) into the first IF (intermediate frequency) signal having the first intermediate frequency which is lower than the downlink frequency frx.
The first IF signal is supplied to the second mixer
16
(
26
) via the BPF
14
(
24
) and the first intermediate frequency amplifier
15
(
25
). The second mixer
16
(
26
) is also supplied with the second local oscillation signal from the second oscillator
36
, and the first IF signal is frequency converted by the second mixer
16
(
26
) into the second IF (intermediate frequency) signal whose frequency is lower than the first IF signal. The second IF signal outputted by the second mixer
16
(
26
) is supplied to the RSSI section
19
(
29
) and the demodulator
19
a
(
29
a
).
The demodulator
19
a
(
29
a
) demodulates the second IF signal and thereby outputs a demodulated signal such as a baseband signal to the unshown CPU etc. Meanwhile, the RSSI section
19
(
29
) outputs the RSSI (Received Signal Strength Indicator) signal having a signal level corresponding to the field intensity of the reception signal (the second IF signal) into the CPU via an unshown A/D converter. Then, the CPU selec
Appiah Charles N.
Chang Vivian
McGinn & Gibb PLLC
NEC Corporation
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