Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Reexamination Certificate
2000-09-01
2003-12-30
Maung, Nay (Department: 2684)
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
C455S073000, C455S082000, C455S083000, C455S084000, C333S101000
Reexamination Certificate
active
06671496
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to communications apparatus such as a portable telephone set and a PHS (Personal Handyphone System) which is equipped with a first and a second antenna and performs communications via antenna switchover, and in particular, to communications apparatus which uses fewer signals to suppress a decrease in the transmission power and degradation in the receiving sensitivity.
Conventionally, communications apparatus to perform diversity reception for base stations and mobile stations is equipped with a plurality of antennas and selects an antenna which shows the highest signal level among those received by the plurality of antennas in order to perform reception by using the antenna, so that degradation in the receiving sensitivity caused by fading during travelling can be suppressed.
An example of the related art is shown in FIG.
5
.
FIG. 5
is a configuration diagram showing the conventional communications apparatus. In
FIG. 5
, the communications apparatus according to the related art is communications apparatus such as a PHS for performing communications via the TDMA (Time Division Multiple Access) system. The communications apparatus in
FIG. 5
is composed of a transmitter
11
, a receiver
13
, a transmission/reception selector switch
15
for switching to the transmitter
11
or the receiver
13
, antennas
17
a
and
17
b
, an antenna selector switch
19
for switching over the antennas
17
a
and
17
b
, and a controller
21
which generates a control signal C
11
for controlling the transmission/reception selector switch
15
and supplies the control signal C
11
to the transmission/reception selector switch
15
as well as generates a control signal C
12
for controlling the antenna selector switch
19
and supplies the control signal C
12
to the antenna selector switch
19
.
The control signal C
11
is composed of a transmission selecting signal C
11
a
for switching to the transmitter
11
and a reception selecting signal C
11
b
for switching to the receiver
13
. The control signal C
12
is composed of an antenna selecting signal C
12
a
for switching to the antenna
17
a
and an antenna selecting signal C
12
b
for switching to the antenna
17
b.
The transmission/reception selector switch
15
switches to the transmitter
11
when the transmission selecting signal C
11
a
is high and the reception selecting signal is low, and switches to the receiver
13
when the transmission selecting signal C
11
a
is low and the reception selecting signal C
11
b
is high. Meanwhile, the antenna selector switch
19
switches to the antenna
17
a
when the antenna selecting signal C
12
a
is high and the antenna selecting signal C
12
b
is low, and switches to the antenna
17
b
when the antenna selecting signal C
12
a
is low and the antenna selecting signal C
12
b
is high.
In the conventional communication apparatus, an antenna which received a signal having a higher signal level is identified by comparing signal levels of receive signals received via the antenna
17
a
and the antenna
17
b
, and uses the identified antenna which received a signal having a higher signal level to perform reception.
For example, as shown in
FIG. 6
, when transmission is performed at a transmitting slot T
1
by using the antenna
17
a
, the transmission selecting signal C
11
a
is driven high and the reception selecting signal C
11
b
is driven low, the antenna selecting signal C
12
a
is driven high, and the antenna selecting signal C
12
b
is driven low. Meanwhile, when reception is performed at a receiving slot R
1
by using the antenna
17
b
, the transmission selecting signal C
11
a
is driven low and the reception selecting signal C
11
b
is driven high, the antenna selecting signal C
12
a
is driven low, and the antenna selecting signal C
12
b
is driven high.
However, the conventional communications apparatus is equipped with a transmission/reception selector switch
15
and an antenna selector switch
19
serially connected between the transmitter
11
or receiver
13
and the antenna
17
a
or
17
b
. Thus transmission signals or reception signals pass through these two switches. Accordingly, transmission signals or reception signals suffer from a signal level loss each time they pass through the switches, thus generating a decrease in the transmission power and degradation in the receiving sensitivity corresponding to the two switches.
The conventional communications apparatus is equipped with separate switches for transmission/reception switching and antenna switching respectively, thus requiring individual control signals C
11
and C
13
. That is, in conventional apparatus in
FIG. 5
, the control signal C
11
for controlling the transmission/reception selector switch
15
is composed of a transmission selecting signal C
11
a
and a reception selecting signal C
11
b
, and the control signal C
12
for controlling the anntenna selector switch
19
is composed of an antenna selecting signal C
12
a
and an antenna selecting signal C
12
b
, thus requiring control via four control signals.
SUMMARY OF THE INVENTION
The invention is proposed in view of the conventional problems and aims at providing communications apparatus which suppresses a decrease in the transmission power and degradation in the receiving sensitivity via fewer control signals.
In order to solve the foregoing problems, communication apparatus according to the first aspect of the invention comprises a first antenna, a second antenna, a controller for generating first and second control signals based on the transmission or reception instruction and selection instruction from the first or second antenna, a transmitter switch for switching transmission signals to either the first or second antenna via connection switchover depending on the first and second control signals, and a receiver switch for receiving signals from either the first or second antenna via connection switchover depending on the first and second control signals, wherein the second antenna is connected via the receiver switch when the first antenna is connected via the transmitter switch and that the first antenna is connected via the receiver switch when the second antenna is connected via the transmitter switch.
Communication apparatus according to the second aspect of the invention comprises a first antenna, a second antenna, a transmitter, a receiver, a controller for generating a first control signal which is enabled when the first antenna is selected in transmission and a second control signal which is enabled when the second antenna is selected or generating a first control signal which is enabled when the second antenna is selected in reception and a second control signal which is enabled when the first antenna is selected, a first transmitter switch which is connected between the first antenna and the transmitter and is turned on/off based on the first control signal, a second transmitter switch which is connected between the second antenna and the transmitter and is turned on/off based on the second control signal, a first receiver switch which is connected between the first antenna and the receiver and is turned on/off based on the second control signal, and a second receiver switch which is connected between the second antenna and the receiver and is turned on/off based on the first control signal.
Communication apparatus according to the third aspect of the invention is communications apparatus according to the first aspect or second aspect of the invention, wherein the controller generates either the first control signal or the second control signal and that the other second control signal or first control signal is generated via signal inversion of the first control signal or the second control signal.
Communications apparatus according to the fourth aspect of the invention is communications apparatus according to either of the first, second or third aspect of the invention, wherein the apparatus comprises detecting means for detecting the signal level or signal field strength of th
Matsushita Electric - Industrial Co., Ltd.
Maung Nay
Pearne & Gordon LLP
Sharma Sujatha
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