JPH1065746A - Radio telephone equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a radio telephone equipment preventing abnormal transmission. SOLUTION: A modulated signal oscillation monitoring circuit 35 operating as a window compactor is provided between a waveform correcting means 20 and an orthogonal modulator 21 to adjust the attenuation level of ATT on a returning side to control the transmission output on the returning side to be fixed when the modulated signals of axis I and Q exceed a previously decided amplitude level. This control prevents abnormal transmission in which a transmission output more than regulated one is generated when the loop gain of a means correcting distortion caused by the change of environmental temp. and secular change, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radio telephone device for preventing abnormal transmission.

[0002]

2. Description of the Related Art In recent years, various digital radio telephone apparatuses for performing burst transmission have been developed.
In many cases, a modulation method involving amplitude fluctuation represented by π / 4 shift QPSK or M16QAM is used. In these modulation schemes, amplitude fluctuations are repeated within a burst transmission slot. Therefore, even if the average transmission output is within a specified value, the maximum output per unit time may greatly exceed the specified value. A wave compensation circuit is provided.

FIG. 4 is a block diagram showing an example of a transmission wave distortion compensating circuit in such a wireless telephone device. Hereinafter, transmission wave distortion compensation will be described with reference to FIG. First, a high-frequency input signal supplied to the RF input terminal 1 is split into two by the splitter 2 and output to splitters 3 and 17 at the next stage. One high-frequency input signal split into two by the splitter 3 is an amplitude modulator 6 set to a phase of 0 °.
Is supplied to the local signal terminal of This amplitude modulator 6
Is constituted by a double balanced mixer. On the other hand, the other high-frequency input signal divided into two by the divider 3 is
After being set to -90 ° phase through the phase shifter 4, the phase
It is supplied to a local signal terminal of an amplitude modulator 5 comprising a double balanced mixer set at 90 °.

The output signals output from the respective high-frequency signal terminals of the amplitude modulators 5 and 6 are combined by a combiner 7, amplified by a power amplifier 8 and supplied to an RF output terminal 10. Part of the output of the power amplifier 8 is input to the high-frequency signal terminals of the double balanced mixers 13 and 15 via the coupler 9 and the distributor 14 with the same phase. The distributed output of the distributor 17 is directly input to the local signal terminal of the double balanced mixer 13, while the distributor 17 is coupled to the local signal terminal of the double balanced mixer 13.
Are applied via the -90 ° phase shifter 4.

Therefore, the double balanced mixer 1
Since the phases of the local signal terminals 3 and 15 are set to 0 ° and −90 °, respectively, the 0 ° direction component of the high-frequency signal vector applied to the high-frequency signal terminal side and −90 °
The component in the ゜ direction is detected and output from the intermediate frequency signal terminals of the double balanced mixers 13 and 15, respectively.

The detection signals output from the intermediate frequency signal terminals of the double balanced mixers 13 and 15 are supplied to the inverting input terminals of the comparators 11 and 12, respectively. Comparator 11
Terminal 19 (MODin-90 °)
, While a non-inverting input terminal of the comparator 12 is connected to a terminal 18 (MODin-0).
A modulation signal for 0 ° is supplied via ゜). The outputs of the comparators 11 and 12 are output from the amplitude modulators 5 and 6 respectively.
Is fed back to the intermediate frequency signal terminal.

According to the above configuration, the comparators 11 and 12 forming the feedback circuits control the amplitude modulators 5 and 6 so that the amplitudes of the modulation signal and the detection signal become the same. And the phase distortion can be automatically corrected.

[0008]

In the above-mentioned conventional radio telephone apparatus, the transmission output is kept at a specified value by a transmission wave distortion compensating circuit. If the compensating operation becomes uncertain due to a change in the electrical characteristics of the elements constituting the device or a problem such as deterioration of the components over time, abnormal transmission in which the transmission output exceeds a specified value occurs. If an abnormal transmission occurs,
In addition to the problem that the operation of the adjacent channel is hindered, there is also a problem in that the operation becomes a violation of laws and regulations.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a wireless telephone device capable of preventing abnormal transmission.

[0010]

According to the first aspect of the present invention, there is provided a distortion correcting means for correcting non-linear distortion of a modulated signal in accordance with a demodulated signal which has been subjected to quadrature demodulation. Determining means for determining whether or not the amplitude of the modulation signal output from the correction means exceeds a predetermined level; and determining that the modulation signal has exceeded a predetermined amplitude level by the determining means. And level adjusting means for controlling the amplitude level of the demodulated signal to suppress the amplitude of the modulated signal to a predetermined level.

According to the second aspect of the present invention, the discriminating means includes first and second comparing means for detecting a waveform amplitude with respect to a preset predetermined level; A logical sum generating means for generating a logical sum of outputs of the first and second comparing means.

According to the third aspect of the present invention, the determining means simultaneously and independently sets the plus side and the minus side of the waveform amplitude to a predetermined level. It is a window comparator for detecting by using this method.

According to the present invention, when the amplitude of the modulated signal output from the distortion correcting means for correcting the non-linear distortion of the modulated signal in accordance with the demodulated signal subjected to the quadrature demodulation exceeds a predetermined level, the determining means In response to the instruction, the level adjusting means controls the amplitude level of the demodulated signal to suppress the amplitude of the modulated signal to a predetermined level. This makes it possible to prevent abnormal transmission in which a transmission output exceeding a prescribed level is generated when the loop gain of the distortion correction means changes due to a change in environmental temperature or a change over time.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wireless telephone device according to the present invention can be applied to a portable telephone, an MCA business wireless device, and the like. Hereinafter, a wireless telephone device according to an embodiment of the present invention will be described as an example with reference to the drawings.

A. FIG. 1 is a block diagram showing a configuration of a wireless telephone device according to an embodiment of the present invention. In this figure, reference numeral 21 denotes a modulation signal in the 0 ° direction (I-axis component) and a −90 ° direction (Q-axis component).
Is a quadrature modulator that performs quadrature modulation on the modulated signal. Reference numeral 22 denotes a forward-side attenuator (hereinafter referred to as ATT), which variably controls the level of an RF signal output from the quadrature modulator 21.

Reference numeral 23 denotes a power amplifier for amplifying the power of the RF signal whose level has been adjusted via the forward-side ATT 22 and outputting the amplified signal. The transmission signal output from the power amplifier 23 is fed to the antenna, while being coupled to the couplers 26 and 2.
7 is partially extracted. 25 is a coupler 27
Is a forward side detecting means for detecting the level of the extracted transmission signal and generating a level detection signal.

An output control circuit 28 generates a level control signal for controlling the transmission output level of the power amplifier 23. Reference numeral 24 denotes a forward-side adjustment unit that compares a level detection signal supplied from the forward-side detection unit 25 with a level control signal supplied from the output control circuit 28,
The attenuation of the forward ATT 22 is adjusted according to the comparison result. That is, the components 22, 23, 27, 2
5, 28 form a feedback circuit and perform feedback control to stabilize the transmission output on the forward side.

Reference numeral 34 denotes a return-side attenuator (hereinafter, A
TT), and variably controls the level of the transmission signal extracted by the combiner 26. 29 is a local oscillator for generating a local signal. The local signal generated by the local oscillator 29 is supplied to the above-described quadrature modulator 21 and is supplied to the phase shifter 30. The phase shifter 30
Modulated signal input to quadrature modulator 21 and quadrature demodulator 31
The phase of the local signal output from the local oscillator 29 is variably controlled so that the phase of the modulated signal matches the phase of the output signal.

The orthogonal demodulator 31 has a return ATT 34
Are demodulated into a modulation signal of a 0-degree component (I-axis component) and a modulation signal of a -90-degree component (Q-axis component), and output. Numeral 32 denotes a return side detecting means for detecting and outputting each modulation signal level of the I-axis component and the Q-axis component. 33 is a return side detecting means 3
The return-side adjusting means adjusts the amount of attenuation of the return-side ATT in accordance with the detection signal output from the control signal 2 and the output of the modulation signal amplitude monitoring circuit 35 described later.

Reference numeral 20 denotes a waveform correcting means which compares the input reference modulation signal with the I-axis component and Q-axis component modulation signals output from the quadrature demodulator 31 and corrects the waveform according to the comparison result. The modulation signals of the I-axis component and the Q-axis component are supplied to a modulation signal amplitude monitoring circuit 35 at the next stage.

As shown in FIG. 2, the modulation signal amplitude monitoring circuit 35 constitutes a window comparator composed of comparators 38 and 39 and an OR circuit 40.
The amplitude of each modulation signal of the I-axis component and the Q-axis component corrected by 0 is monitored, and when the amplitude exceeds a predetermined amplitude level, a level control signal is generated. This level control signal is input to the above-described return-side adjusting means 33. The return-side adjusting unit 33 controls the return-side ATT 34 while the level control signal is supplied, that is, until the amplitudes of the modulation signals of the I-axis component and the Q-axis component fall within a predetermined specified value. It has become.

Here, the modulation signal amplitude monitoring circuit 35 will be described in detail with reference to FIG. In the comparators 38 and 39 constituting the window comparator, a bias voltage is applied to a non-inverting input terminal of the comparator 38 via a resistor R1, and a bias voltage is supplied to an inverting input terminal of the comparator 39 via a variable resistor 37. I do. The resistors R1 and R2 connected in series to the power supply have the same resistance value. Comparator 3
The inverting input terminal of the comparator 38 and the non-inverting input terminal of the comparator 39 are commonly connected to the modulation signal input 36. Comparator 3
8 and 39 are output from diodes 40a and 40
b, and the anodes of the diodes 40a and 40b are connected together to form an OR circuit 40. The output of the OR circuit 40 is pulled up via the resistor R3 and connected to the signal output 41.

In the modulation signal amplitude monitoring circuit 35 having such a configuration, a modulation signal having a bias voltage that is half of the power supply voltage is input to the modulation signal input 36 in advance. If the amplitude increases to the plus side, the output of the comparator 38 is inverted, and the signal output 41 is inverted via the OR circuit 40 to detect a state where the amplitude exceeds the allowable value. On the other hand, if the amplitude of the modulation signal becomes larger than the bias voltage on the minus side, the output of the comparator 39 is inverted, and the signal output 41 is inverted via the OR circuit 40 to detect a state where the amplitude exceeds the allowable value. By adjusting the variable resistor 37, the voltage width of the allowable value, that is, the window can be adjusted.

B. Operation of Embodiment As described above, the feedback control is performed so that the transmission output on the forward side is made constant by the feedback circuit formed by the components 22, 23, 27, 25, and 28. The feedback circuit composed of the components 30 to 35 is intended to be constant.

That is, the waveform correcting means 20 corrects the input I-axis and Q-axis modulated signals to match the I-axis and Q-axis demodulated signals demodulated by the quadrature demodulator 31 and modulates the signals at the next stage. When supplied to the signal amplitude monitoring circuit 35, the circuit 35 determines whether the I-axis and Q-axis modulation signals exceed a predetermined amplitude level, as described above.

If the I-axis and Q-axis modulation signals exceed a predetermined amplitude level, the circuit 35 supplies a level adjustment signal to the return-side adjustment means 33, and the return-side adjustment means In 33, the attenuation level of the return ATT is adjusted based on the level adjustment signal, and the transmission output on the return side is controlled to be constant. That is, the amplitudes of the I-axis and Q-axis modulated signals corrected by the waveform correcting means 20 are converged within a predetermined amplitude level.

By doing so, when the loop gain of the transmission wave distortion compensating circuit changes due to a change in environmental temperature or aging, in particular, the gain on the return side becomes smaller than the originally adjusted level, and When the control range of the adjusting means 33 is exceeded, the I-axis and Q-axis demodulated signals input to the waveform correcting means 20 become smaller than the level originally input, and as a result, the waveform correcting means 20 corrects the modulated signal. Therefore, it is possible to prevent abnormal transmission in which the transmission output of the data portion becomes larger than the original level and the transmission output exceeds the specified level.

C. Modification In the embodiment described above, the waveform correction means 20 and the quadrature modulator 2
A modulation signal amplitude monitoring circuit 35 acting as a window comparator is provided between the control signal 1 and the modulation signal amplitude monitoring circuit 35. When the I-axis and Q-axis modulation signals exceed a predetermined amplitude level, the return-side ATT attenuation level is adjusted. The abnormal transmission is prevented by controlling the transmission output on the return side to be constant. Alternatively, for example, as shown in FIG. The amplitude may be detected, and the detection result may be supplied to the modulation signal amplitude monitoring circuit 35 to monitor the amplitude of the modulation signal to prevent abnormal transmission.

[0029]

According to the present invention, the amplitude of the modulation signal output from the distortion correcting means for correcting the non-linear distortion of the modulation signal in accordance with the demodulated signal subjected to the quadrature demodulation exceeds a predetermined level. In this case, the level adjuster controls the amplitude level of the demodulated signal according to the instruction of the determiner to suppress the amplitude of the modulated signal to a predetermined level, so that the loop gain of the distortion corrector changes due to a change in environmental temperature or aging. In this case, it is possible to prevent abnormal transmission in which a transmission output exceeding a specified value is generated.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a configuration of a modulation signal amplitude monitoring circuit 35 in the embodiment.

FIG. 3 is a block diagram showing a modification.

FIG. 4 is a block diagram for explaining a conventional example.

[Explanation of symbols]

 Reference Signs List 20 waveform correcting means (distortion correcting means) 31 quadrature demodulator 32 return side detecting means (level adjusting means) 33 return side adjusting means (level adjusting means) 34 return ATT (level adjusting means) 35 modulation signal amplitude monitoring circuit (discrimination) means)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Naoki Taga 3-18-21 Shibaura, Minato-ku, Tokyo NEC Engineering Co., Ltd.

Claims (3)

[Claims] 1. A distortion correcting means for correcting non-linear distortion of a modulated signal according to a demodulated signal subjected to quadrature demodulation, and whether the amplitude of the modulated signal output from the distortion correcting means exceeds a predetermined level. Discriminating means for discriminating whether or not the modulating signal has exceeded a predetermined amplitude level by the discriminating means, controlling the amplitude level of the demodulated signal to set the amplitude of the modulated signal to a predetermined level. A wireless telephone device, comprising: a level adjusting unit for suppressing. 2. The method according to claim 1, wherein the determining means includes first and second comparing means for detecting a waveform amplitude with respect to a predetermined level set in advance, and a logic for generating a logical sum of outputs of the first and second comparing means. 2. The wireless telephone device according to claim 1, further comprising a sum generation unit. 3. The wireless communication system according to claim 2, wherein said discriminating means is a window comparator for simultaneously and independently detecting a plus side and a minus side of the waveform amplitude with respect to a predetermined level set in advance. Telephone equipment.