JP2002319876A - Mobile station wireless equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital wireless receiver adopting linear demodulation system where maintenance of the linearity at a reception section is an important requirement that can keep the linearity even when an excess input especially arrives from an antenna. SOLUTION: The linearly at the reception section is maintained by switching an antenna changeover circuit having been switched to a receiver side at normal reception to a transmitter side when an excess input is received so that the antenna changeover circuit attenuates the received signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an antenna switching circuit when an excessive input is received from an antenna in a mobile station radio.

[0002]

2. Description of the Related Art A digital demodulation system generally employs a linear demodulation system. In the linear demodulation method, it is necessary to maintain signal linearity in a reception path in the wireless device.

A configuration of a conventional mobile station radio will be described with reference to FIG. In FIG. 1, antenna 1
And the received high-frequency signal is input to the receiving unit 3 via the antenna switching circuit 2 connected to the receiving side. The receiving unit 3 performs a demodulation operation from the input received high-frequency signal and outputs the demodulated signal to the control unit 5. In addition, a signal proportional to the input level of the input received high-frequency signal (hereinafter, referred to as
This is called an RSSI signal. ) Is output to the control unit 5.

Hereinafter, control of the antenna switching circuit 2 by the control unit 5 in the conventional mobile station radio will be described with reference to a flowchart shown in FIG. The control unit 5 switches the antenna switching circuit 2 between the transmitting side and the receiving side in accordance with ON / OFF of the press switch 6. When receiving,
The high-frequency signal received from the antenna 1 is input to the receiving unit 3 via the antenna switching circuit 2.

[0005]

FIG. 5 shows a relationship between a reception input level and an RSSI output and a relationship between a reception input level and a BER (bit error rate) during reception in a conventional digital radio system.

As shown in FIG. 5, the RSSI output has a predetermined dynamic range. For an input exceeding the dynamic range, the RSSI output does not change and the RSSI output of the signal in the reception path is not changed. Since the linearity cannot be maintained, there is a disadvantage that the BER rapidly deteriorates. The aim is to eliminate this drawback.

[0007]

SUMMARY OF THE INVENTION According to the present invention, in order to eliminate the above-mentioned drawbacks, a reception high-frequency signal input from an antenna is provided.
When the linearity of the signal is maintained and the RSSI output is equal to or higher than a predetermined level (set level), the antenna switching circuit is switched to the transmission side even in the reception state, so that an excessive reception high-frequency signal is output. Attenuate the input, RS
The dynamic range of the SI signal is widened.

As a result, the dynamic range of the RSSI signal is widened, and the input level of the received high-frequency signal that can maintain the linearity of the signal in the reception path is widened. Can be protected from deterioration.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a mobile station radio according to an embodiment of the present invention will be described below with reference to FIG. In FIG. 1, a received high-frequency signal input from an antenna 1 is input to a receiving unit 3 via an antenna switching circuit 2 connected to a receiving side. The receiving unit 3 performs a demodulation operation from the input received high-frequency signal and outputs the demodulated signal to the control unit 5. The control unit 5 also outputs a signal (hereinafter, referred to as an RSSI signal) proportional to the input level of the received high-frequency signal.

Hereinafter, the control of the antenna switching circuit by the control unit 5 in the mobile station radio of this embodiment will be described with reference to the flowchart shown in FIG. In the control unit 5,
When the press switch 6 is turned on and transmission is instructed, the antenna switching circuit 2 is switched to the transmission side. When the press switch is off and in the receiving state, the RSSI signal is observed. When the level is equal to or higher than the set level, the antenna switching circuit 2 is switched to the transmitting side even in the receiving state.

[0011]

According to the present invention, when there is an excessive input from the antenna, attenuation in the antenna switching circuit can be expected,
It is possible to realize a receiver that expands the dynamic range for performing the linear demodulation operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mobile station radio.

FIG. 2 is a flowchart illustrating a control operation of an antenna switching circuit performed by a control unit in the mobile station radio according to the embodiment of the present invention.

FIG. 3 is a diagram showing a reception input level versus RSSI output characteristic and a reception input level versus BER characteristic in a mobile station radio according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a control operation of an antenna switching circuit performed by a control unit in a mobile station radio as an example of the related art.

FIG. 5 is a diagram showing an example of a conventional mobile station radio, in which a received input level versus RSSI output characteristic and a received input level versus BER
The figure which shows a characteristic.

[Explanation of symbols]

1: antenna, 2: antenna switching circuit, 3: receiving unit,
4: Transmission unit, 5: Control unit, 6: Press switch, 7: Antenna switching circuit Control signal terminal, 8: Demodulation signal output terminal, 9: RSSI signal output terminal.

Claims (1)

[Claims] A receiving unit that demodulates a received signal; a transmitting unit that modulates a transmitted signal; an antenna switching circuit that is connected to the receiving unit and the transmitting unit to switch between transmission and reception; A mobile station radio including an antenna for receiving a signal and transmitting an output signal from the transmitting unit, wherein the antenna switching circuit is controlled to be in a receiving state and when the input level of the received signal is equal to or higher than a predetermined value. A mobile station radio, comprising: a control unit that connects an antenna to the transmission unit, and configured to attenuate the reception signal having an input level equal to or higher than a predetermined value.