Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Reexamination Certificate
1998-06-16
2001-06-05
Maung, Nay (Department: 2681)
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
C455S082000, C455S277100
Reexamination Certificate
active
06243563
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a wireless device for high power transmission radio signal, which is for use in a TDMA (time division multiple access) system and a diversity reception system. Herein, it is to be noted that the wireless device can prevent any deterioration of local oscillator characteristics or transmission characteristics, and more prevent any breakage of parts such as transistors, filters or the like of receiver, due to occurrence of high power transmission radio signals.
Conventionally, the wireless device for use in the TDMA system is liable to undesirably cross or turn transmission signals from a transmitting portion into a receiving portion and into even a local oscillator through an antenna common switch, which is used in common to both reception and transmission signal paths. Such crossed transmission signals will be called cross components. In most of such the wireless devices, the high power transmission signal deteriorates not only local oscillator characteristics due to the cross components but also transmission characteristics. Furthermore, it often happens that a high power level of transmission signal breaks transistors, filters and the like which construct the receiving portion due to the cross components of the high power transmission radio signals.
In order to remove an interference of such cross components or interference, the wireless device has a BPF (band pass filter) which allows only the receiving signal frequency to pass therethrough. With this structure, the BPF can attenuate the transmission signal with a high level and then prevent the cross components of the transmission signal.
Another wireless device has been described in a Japanese Unexamined Patent Publication No. Hei 6-6275, namely, 6275/1994. The wireless device described in this publication can prevent such the transmission signal from being crossed into the receiving portion.
Referring to
FIG. 1
, the wireless device comprises a plurality of antennas
101
and
101
N, a plurality of antenna common switches
102
and
102
N, a receiving portion, a transmitting portion and a switch controller
111
. Each of the antenna common switches
102
and
102
N switches connections between the antenna
101
or
101
N and the receiving portion and between the antenna
101
or
101
N and a hybrid
110
of the transmitting portion for radio signals from one to another. The receiving portion performs a reception diversity for the antennas
101
and
101
N, while the transmitting portion performs a transmission diversity by the use of the antenna
101
or
101
N selected by the reception diversity.
The receiving portion comprises RF/IF (radio frequency/intermediate frequency) receivers
103
and
103
N, demodulators
104
and
104
N, a level comparator
105
, and a selector
106
. The RF/IF receiver
103
and the demodulator
104
are provided for each of the antenna common switches
102
and
102
N. The level comparator
105
compares signal levels measured by the demodulators
104
and
104
N with each other and decides one of the RF/IF receivers
103
and
103
N by reception diversity. And the selector
106
selects one of the outputs sent from the demodulators
104
and
104
N in accordance with the information from the level comparator
105
.
On the other hand, the transmission portion comprises a burst generator
107
, a modulator
108
, and an IF/RF transmitter
109
. The burst generator
107
produces burst signals from carrier signals. The modulator
108
modulates the burst signals by the IF (intermediate frequency). The IF/RF transmitter
109
converts the IF modulated signals into the RF (radio frequency) which is send to a hybrid
110
as radio signals.
The hybrid
110
distributes the RF signals or the radio signals to all of the antennas
101
and
101
N, respectively. The switch controller
111
controls the antenna common switches
102
and
102
N each of which connects between the antenna
101
or
101
N and each reception portion correspondingly for the reception diversity. Then, by the switch controller
111
, the antenna common switch
102
or
102
N connects the RF/IF receiver
103
or
103
N with an antenna
101
or
101
N selected by the information from the level comparator
105
, under control of the switch controller
111
when the radio signal is received. On transmission, the switch controller
111
controls the antenna common switch
102
or
102
N to connect the transmission portion to the same antenna
101
or
101
N used in the reception of the radio signal. Thus, the diversity transmission is carried out.
The local oscillator
112
generates local oscillation signals for use in frequency conversion of signals supplied to the RF/IF receivers
103
and the IF/RF transmitter
109
. However, in the above-described publication, an oscillator switch
113
is located between the local oscillator
112
and the IF/RF transmitter
109
. As a result, the local oscillator
112
is connected with the IF/RF transmitter
109
only on the transmission of radio signals to the antenna
101
or
101
N.
In the case where the radio signal is transmitted by the use of the above-described construction, the local oscillation signals are given from the local oscillator
112
to the transmitting portion, and are rendered into the transmission radio signals which are sent out from the antenna
101
or
101
N selected by the reception diversity.
On the other hand, during the signal reception, the transmission of the radio signals from the transmitting portion to the antenna, is stopped. Accordingly, during the reception of the radio signals, even if isolation among the antennas, the receiving portion, and the transmitting portion is not sufficient, it is possible to protect the transmission radio signals from being crossed into the signal reception side. And with this structure, good diversity can be accomplished on signal reception.
However, during the transmission of the radio signal, it is difficult to prevent the transmission radio signal from being crossed into the receiving portion, if the isolation is insufficient.
In the wireless device described above, the high power transmission radio signal is inevitably given to the local oscillator through the signal receiving portion. Therefore, the BPF is provided for attenuating the transmission signal within the predetermined frequency band. However, such a BPF is difficult to be designed and complicated in structure. Accordingly, the wireless device is complicated in structure and expensive.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a wireless device, which is used for a high power transmission radio signal, and which can prevent any breakage of structure elements due a high power transmission radio signal and which is inexpensive and small in size.
According to an aspect of this invention, a wireless device for high power transmission radio signal comprises a plurality of antennas, transmitting portion, receiving portion, switching portion, and switch controller. Especially, the first point is the switching portion which has a common switch and a reception dedicated switch.
The common switch is provided between the antennas and the transmitting portion, connects between the transmitting portion and one of the antennas which is designated on signal transmission. The common switch further connects between each of the antennas and the receiving portion on signal reception. The reception dedicated switch is provided between the common switch and the receiving portion and connects between the common switch and the receiving portion on signal reception.
The switch controller controls the common switch to connect between the transmitting portion and one of the antennas which is selected and further controls the reception dedicated switch to separate the receiving portion from the common switch on signal transmission. The switch controller further controls both the common switch and the reception dedicated switch to connect between the receiving portion and one of the antennas whi
Maung Nay
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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