JP2859227B2 - Mobile radio telephone equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio telephone for transmitting and receiving a QAM (quadrature amplitude modulation) signal, and more particularly to a mobile radio telephone having a reception electric field strength detecting function.

[0002]

2. Description of the Related Art In general, a mobile radio telephone device has a function of detecting a received electric field strength in order to secure a communication quality.
Activation control is performed according to the received electric field strength. As shown in FIG. 4, the conventional mobile radio telephone apparatus employs a heterodyne reception method, in which a QAM (quadrature amplitude modulation) received signal is frequency-converted into an intermediate frequency signal by a mixer 11 and a quadrature demodulation unit 14 is provided. Is demodulated. Then, in order to detect the received electric field strength, a part of the intermediate frequency signal is detected by the detector 12 and this detected current is
And converted to a decibel value to obtain a received field strength output.

[0003]

As described above, in the conventional mobile radio telephone apparatus, the received electric field strength is detected by detecting the signal level of the intermediate frequency signal, and the detector used has a low allowable frequency. Things. Therefore, it is necessary to provide a mixer, an intermediate frequency filter, and the like for converting a received signal into an intermediate frequency signal, which causes a problem that the apparatus cannot be downsized. Further, the detection current is amplified by a logarithmic amplifier, but it is not easy to correct output fluctuations due to temperature changes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mobile radio telephone device capable of detecting a received electric field intensity without converting a received signal into an intermediate frequency signal and easily performing a temperature correction process of the detected electric field intensity value. To provide.

[0005]

SUMMARY OF THE INVENTION A mobile radio telephone apparatus according to the present invention directly demodulates a received signal without converting it into an intermediate frequency signal, and calculates a received field strength based on a quadrature demodulated output signal. Specifically, a high-frequency amplifier that amplifies the quadrature amplitude modulation signal received by the antenna, a quadrature demodulator that demodulates the signal amplified by the high-frequency amplifier and outputs demodulated signals orthogonal to each other, An A / D converter for converting a demodulated signal into a digital signal; an electric field intensity data storage unit in which data indicating a relationship between an amplitude value of the demodulated signal and a received electric field intensity is stored in advance; And an electric field intensity calculator for calculating a received electric field intensity based on the data stored in the electric field intensity data storage unit.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which an antenna 1 for transmitting and receiving radio waves and a transmitting unit 3 are shown.
(Quadrature Amplitude Modulation) signal transmitted from the antenna 1 and the QA signal received by the antenna 1
An antenna sharing unit 2 for transmitting an M signal to a band-pass filter (BPF) 4, a high-frequency amplifier 5 for amplifying a desired reception signal passing through the band-pass filter 4, and a local oscillation signal output from a local oscillation unit 7 A quadrature demodulator 6 for demodulating a received signal to output I and Q signals, an A / D converter 8 for converting the I and Q signals to digital signals, and processing the digitized I and Q signals for voice A communication data processing unit 9 for reproducing communication data such as a signal; an electric field intensity data storage unit 10 in which measurement data indicating a relationship between an amplitude value of a demodulated signal and a received electric field intensity is stored in advance; And an electric field strength calculator 11 for calculating a received electric field strength based on the data stored in the memory 10 and the digitized I and Q signals.

The quadrature demodulator 6 has two double-balanced mixers, and each of the two-branched received signals is supplied. In order to supply local signals having a phase difference of 90 ° to each of the double balance mixers,
° It has a phase delay circuit. Then, the reception signal and the local oscillation signal are mixed in the two double balance mixers, and an I signal and a Q signal having a phase difference of 90 ° from each other are output as demodulated signals.

The QAM signal is a signal in which carriers having a phase difference of 90 ° are amplitude-modulated, respectively. Therefore, the amplitudes of the I signal and the Q signal output from the quadrature demodulation unit 6 change according to the received electric field strength. For example, a relationship as shown in FIG. 2 is obtained. Therefore, the relationship between the received electric field strength and the amplitude level of the demodulated signal is measured in advance, and the measured data is stored in the electric field strength data storage unit 10, so that the received electric field strength can be obtained based on the amplitude level of the demodulated signal. Can be.

When measuring the relationship between the received electric field strength and the amplitude level of the demodulated signal, a standard signal generator for generating a predetermined QAM signal is used, and the output level of the standard signal generator corresponds to the received electric field strength. Adjust to the level and input to the antenna end of the mobile radiotelephone. Then, the amplitude level of the demodulated signal when the reception electric field intensity is changed is determined, and the amplitude level and the reception electric field intensity are stored in the electric field intensity data storage unit 10.

For example, as shown in FIG. 2, the horizontal axis represents the received electric field strength (dBμ), and the vertical axis represents the amplitude level of the demodulated signal (I, Q signal) (logarithmic conversion of the output value of the A / D converter 8). When the received electric field strength is 0 dBμ, the amplitude level of the demodulated signal is α, and when the received electric field strength is 50 dBμ, the amplitude level of the demodulated signal is β. If so, these two sets of data are stored in the electric field strength data storage unit 10 in advance. Then, in the electric field intensity calculator 11, the received electric field intensity Y may be calculated from the amplitude level X of the demodulated signal by the following equation (1). Received electric field intensity Y = {(X−α) / (β−α)} × 50 [dBμ] (1) In FIG. 1, a received signal from the antenna 1 is transmitted to the bandpass filter 4 by the antenna sharing unit 2. Then, the unnecessary signal component is removed, the signal is amplified to a predetermined level by the high-frequency amplifier 5, and then demodulated into I and Q signals by the quadrature demodulator 6. The I and Q signals are converted into digital signals by the A / D converter 8 respectively, and
And a DPS (Signal Processing Processor) 11.

The electric field intensity calculator 11 converts the amplitude values of the digitized I and Q signals into logarithmic values, refers to the data stored in the electric field intensity data storage unit 10, and calculates the received electric field based on equation (1). Calculate the intensity and output. A DPS (Signal Processor) 11 generates and outputs an audio signal from the digitized I and Q signals.

FIG. 3 is a block diagram showing another embodiment of the present invention, showing a case where temperature correction is performed on a received electric field strength calculation value.

Here, a temperature sensor 12 for detecting temperature is used.
And a temperature correction data storage unit 13 in which temperature correction data of the received electric field strength calculation value is stored in advance.

The temperature correction data is obtained by performing an environmental temperature test on the mobile radio telephone apparatus in advance. That is, the output (temperature) of the temperature sensor 12 and the calculated value of the received electric field strength are measured, and the difference between the calculated value of the received electric field strength and the normal value is obtained. Then, the temperature correction data for the temperature is stored in the temperature correction data storage unit 13 in advance. The electric field strength calculation unit 11
Temperature correction data storage unit 1 according to the output of temperature sensor 12
3 to read out the temperature correction data and correct the reception electric field strength calculation value. In this manner, the accuracy of the received electric field strength calculation value with respect to the temperature change can be improved.

[0016]

As described above, according to the present invention, a received signal is directly demodulated without being converted into an intermediate frequency signal.
By calculating the received electric field strength based on the quadrature demodulated output signal, the circuit related to the intermediate frequency can be eliminated to reduce the size of the device and at the same time improve the reliability. Further, the calculation of the received electric field strength and the temperature correction can be easily performed by digital data processing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a received electric field strength and an amplitude level of a demodulated signal.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional mobile radio telephone device.

[Explanation of symbols]

 Reference Signs List 5 high frequency amplification unit 6 quadrature demodulation unit 8 A / D converter 10 electric field intensity data storage unit 11 electric field intensity calculation unit 12 temperature sensor 13 temperature correction data storage unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/24-7/26 102 H04Q 7/00-7/38

Claims (3)

(57) [Claims] 1. A mobile radio telephone device for transmitting and receiving a quadrature amplitude modulated signal, comprising: a high-frequency amplifier for amplifying the quadrature amplitude modulated signal received by an antenna; and a demodulator for demodulating the signal amplified by the high-frequency amplifier. A mobile radio telephone apparatus comprising: a quadrature demodulation unit for outputting demodulated signals orthogonal to each other; and means for detecting a received electric field strength based on the amplitude of the demodulated signal. 2. The means for detecting a received electric field intensity includes an A / D converter for converting the demodulated signal into a digital signal, and data indicating a relationship between an amplitude value of the demodulated signal and the received electric field intensity are stored in advance. An electric field intensity data storage unit, and an electric field intensity calculation unit that calculates a reception electric field intensity based on the digitized demodulated signal and data stored in the electric field intensity data storage unit. Item 2. The mobile radio telephone device according to Item 1. 3. The apparatus according to claim 1, wherein the means for detecting the received electric field intensity includes a temperature sensor for detecting a temperature, and a temperature correction data storage unit in which temperature correction data of the calculated received electric field intensity is stored in advance. 3. The mobile radio telephone device according to claim 2, wherein the intensity calculation unit reads the temperature correction data from the temperature correction data storage unit based on an output of the temperature sensor and corrects a received electric field intensity calculation value.