JPH0951280A - Wireless transmitter - Google Patents

Abstract

(57) Abstract: A wireless transmission device used in a wireless communication system, and an object thereof is to change the transmission power to a specified value within a specified time and to keep the changed transmission power constant. . In a wireless transmission device, a variable low-pass filter for generating a first control signal from the comparison result is provided, and the variable low-pass filter is applied while a burst signal indicating a rising timing of a slot is being applied. The transmission bandwidth is increased, but the transmission bandwidth is reduced while the burst signal is not applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless transmitter used in a wireless communication system. For example,
In a mobile communication system, output signals transmitted from fixed stations, base stations, and wireless transmitters in mobile stations need to be maintained at average power so as not to affect other systems.

Further, in a system performing burst communication, it is necessary to reach the above specified average power within a specified time so as not to affect other channels.

However, there is a reciprocal relation between keeping the electric power at a specified value and reaching the specified average power within a specified time, but it is necessary to satisfy both requirements, so this is realized at the same time. Is desired.

[0004]

2. Description of the Related Art FIG. 6 is a configuration diagram of a conventional example, FIG. 7 is an operation explanatory diagram of FIG. 6, FIG. 8 is another operational explanatory diagram of FIG. 6, and (a) is an example of an attenuation characteristic diagram of a variable attenuator. , (B) is an explanatory diagram of the relationship between the voltage of the output control signal: attenuator control voltage: attenuation amount, (c) is an explanatory diagram of the attenuation characteristic variation of the variable attenuator, and FIG. 9 is another operational explanatory diagram of FIG. 6. is there.

The operation of FIG. 6 will be described below with reference to FIGS. First, when the output signal power is kept constant (APC)
Will be described. In FIG. 6, the input signal (the signal to be transmitted) that has passed through the variable attenuator 11 and the variable attenuator 12 is amplified by the power amplifier 13 to a predetermined power, and then transmitted as an output signal via the coupler 14. At the same time, a signal that is lower than the transmitted output signal by, for example, about 10 dB is added to the detector 32 via the variable attenuator 31.

Since the detector 32 detects this signal and extracts the envelope waveform as shown in FIG. 9 and adds it to the filter 33,
The DC component (voltage corresponding to average power) in the envelope waveform is applied to the comparator 42 as a filter output.

The comparator 42 receives the reference voltage from the reference voltage source 41.
Since (for example, 2.5V) is also added, the difference between the reference voltage and the DC component is added to the variable attenuator 11 as a control voltage through the integrator 43b. Therefore, the variable attenuator 11 makes the power of the output signal constant by giving the amount of attenuation corresponding to the control voltage to the input signal.

For example, the comparator 42 is a reference voltage and a filter.
It is assumed that when both 33 outputs are 2.5V, the control voltage of 2.5V is sent out. In such a state, when the output of the filter 33 becomes 3V, the control voltage of (2.5 + difference 0.5) = 3V is sent from the comparator to the variable attenuator 11. Since the variable attenuator 11 has the attenuation characteristic shown in FIG. 8 (a), the amount of attenuation increases as the control voltage increases, and the power of the output signal decreases. This operation is repeated until the filter output and the reference voltage match.

On the contrary, when the output of the filter is lowered, the operation reverse to the above is performed so as to maintain the specified power. next,
A case of switching the power of the output signal will be described.

Power switching is performed by the variable attenuator 12 and the variable attenuator.
Although the attenuation amount of 31 is controlled, the attenuation amount characteristics of these two attenuators are reversed because the inverting circuit 23 is provided.
For example, if the output control signal changes from 0V to 0.65V,
The variable attenuator 12 changes from 2 dB to 6 dB and +4 dB, while the variable attenuator 31 changes from 10 dB to 6 dB and -4 dB.

By thus reversing the attenuation characteristics of the two variable attenuators, the voltage applied to the detector does not change even when the power of the output signal is switched, and the detection efficiency remains constant. ing. Therefore, the condition of the APC loop does not change and it can be used for APC as it is (Fig. 8
(See (b)).

Further, the offset adjuster 21 and the gain adjuster 22 in FIG. 6 perform gain adjustment and offset adjustment even if the attenuation characteristics of the variable attenuators 12 and 31 deviate from the preset reference attenuation characteristics. By changing the inclination and position of the damping characteristic of the variable attenuator, the above-mentioned deviation can be minimized.

For example, the attenuation characteristic of the variable attenuator is shown in FIG.
If different as indicated by the dotted line, solid line, and dash-dotted line in (c), adjust the tilt with the gain adjuster 22 so that a variable width of 8 dB can be secured, and then operate the range ± 4 dB with the offset adjuster 21.
Adjust the offset so that

From a control unit (not shown), for example, 0.
When the output control signal of 65V is input, the attenuation amounts of the variable attenuators 12 and 31 are both set to 6 dB, so that the output signal power is set to -4 dB from the maximum power (0 dB) (Fig. 7).
reference). After that, the power of the output signal is controlled according to the input output control signal for each slot.

Here, the change in the attenuation amount of the attenuators 12 and 31 can sufficiently follow the output control signal. However, since the time constant of the integrator 43b provided in the preceding stage of the variable attenuator 11 is such that the output signal power does not fluctuate within the slot, the control voltage of the variable attenuator 11 does not rise at the rising edge of the slot. Round.

To improve this, it is necessary to reduce the time constant of the integrator, but this changes the power of the output signal within the slot. This is because when the time constant is reduced
This is because the band of the APC loop (integrator 43b → variable attenuator 11 → combiner 14 → detector 32 → integrator 43b) widens and follows a rapid change in the output signal.

[0017]

As described above, in order to reduce the influence of the instantaneous power fluctuation caused by some cause, the fluctuation amount over a long time is integrated by the integrator.
This makes it possible to keep the power of the output signal constant, but there is a problem that it cannot be changed to a specified value within a specified time.

It is an object of the present invention to change the power of an output signal to a specified value within a specified time so that the changed transmission power can be kept constant.

[0019]

According to a first aspect of the present invention, a variable low pass filter for generating a first control signal from a comparison result is provided, and while a burst signal indicating the rising timing of a slot is being applied, Widen the transmission bandwidth of the variable low-pass filter.

However, the transmission bandwidth is narrowed while the burst signal is not applied. In the second aspect of the present invention, when the transmission bandwidth switching of the variable low pass filter counts the time corresponding to the burst signal interval, a carry is transmitted and the counting operation is repeated from the initial state. Provide a counter that can be cleared by.

The carry is sent from this counter to perform band switching. In the third aspect of the present invention, a signal obtained by integrating input envelope information is used as the reference voltage.

That is, in the digital mobile radio system, the power of the output signal is reduced within a specified time (for example, 4 bits as a burst transient response guard time of 1 burst 280 bits) from the rising edge of the time slot. It is stipulated to rise to the specified value.

Therefore, the time of 4 bits (for example, 95.2 μ
sec), the time constant of the variable low-pass filter is made smaller and the bandwidth of the loop is made wider to speed up the rise of the power of the output signal, but after the lapse of the specified time, the time constant of the variable low-pass filter is made large. Then, the bandwidth of the loop is narrowed so that the power of the output signal is not affected by extraneous disturbances.

As a result, the power of the output signal after rising can be kept constant, and the above problems can be solved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is an operation explanatory diagram of FIG. 1, (a) is an output control explanatory diagram, and (b) is a diagram in FIG. It is a variable low-pass filter principal part block diagram. FIG. 3 is a block diagram of an embodiment of the second invention, and FIG. 4 is FIG.
And FIG. 5 is a block diagram of the third embodiment of the present invention.

Here, the same reference numerals denote the same objects throughout the drawings. Further, the variable attenuators 11 and 12, the power amplifier 13 and the coupler 14 are included in the amplifier section in the claims, and the variable attenuator 3 and
1, the detector 32, the filter 33, the reference voltage source 41,
The comparator 42 corresponds to the comparison unit 4.

Further, the variable attenuator 11 is a first variable attenuator,
The variable attenuator 12 is the second variable attenuator, and the variable attenuator 31 is the third variable attenuator.
Corresponding to the variable attenuators of. 1 to 5, the parts described in detail above will be briefly described, and the parts of the present invention will be described in detail.

First, as shown in FIG. 1, the variable low-pass filter 51 is constructed by an RC type using an analog switch as shown in FIG. 2 (b)-. In addition, a burst signal indicating the rising time of each slot 1, 2, 3 is applied from the control unit (not shown) to the gate of the FET Q ₁ which performs on / off operation in the variable low pass filter.

Therefore, in the configuration shown in FIG. 2B, when the burst signal is "H", the FET Q ₁ is in the off state and the time constant is C ₁ .R ₁ . On the other hand, when the burst signal is "L", FET
Q ₁ is turned on, resistors R ₁ and R ₂ are connected in parallel, and the time constant is smaller than when R ₁ alone is used.

Therefore, the bandwidth of the loop widens near the rising edge of the time slot, so that the power of the output signal rises to a specified value within the guard time for burst transient response, but after the guard time for burst transient response elapses. Since the time constant becomes large, the power of the specified value can be maintained.

The configuration shown in FIG. 2 (b) -uses an electronic variable resistor (Rv) in place of the fixed resistor shown in FIG. 2 (b)-. The resistance value changes according to the value.

For this reason, the level converting portion 511 is provided on the input side so that "H" and "L" of the burst signal are converted into corresponding predetermined voltages and are applied to the control terminal of the electronic variable resistor.
This makes it possible to switch the resistance value of the electronic variable resistor when "H" is input and when "L" is input.

In FIG. 3, the time constant of the variable low-pass filter is switched by using a frame synchronization signal input every 3 slots instead of the burst signal. When the counter 52 in the figure counts clocks for one slot from the initial value, it carries out a carry and repeats the counting operation from the initial value.

On the other hand, since the counter is reset when the frame signal is input, the counter performs the counting operation once every three slots in synchronization with the frame signal, and the other two times are self-running (FIG. 4). reference).

However, since the cycle of the clock applied to the counter hardly changes, there is no problem in practical use even if the frame synchronization signal is applied only once every three times. Here, as described in detail above, the comparator 42 shown in FIGS. 1 and 3 compares the reference voltage supplied by the reference voltage source 41 with the DC component in the envelope waveform sent by the detector, and compares them. The result is output.

However, in FIG. 5, the envelope information is used as the reference voltage. This indicates that the envelope curve shows the change of the transmission signal for each symbol, and by using this, it becomes possible to control the power of the output signal on a symbol-by-symbol basis.

Therefore, since the signal input to the variable attenuator 11 is a modulation signal, this signal is detected by a detector (not shown) having the same configuration as the detector 32, and the envelope waveform as described above. Is taken out and added to the integrator 43a having the same function as the filter.

As a result, a DC component (a voltage corresponding to the average power) in symbol units is applied to the comparator 42. On the other hand, since the detector 32 and the output of the low-pass filter 33 are also added to the comparator, a comparison result in symbol units is obtained,
The attenuation amount of the variable attenuator 11 is controlled in symbol units as a control voltage via the variable low-pass filter 51.

As a result, the transmission power can be changed to the specified value within the specified time, and the changed transmission power can be kept constant.

[0040]

As described in detail above, according to the present invention, there is an effect that the transmission power is changed to a specified value within a specified time and the changed transmission power is kept constant.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1, (a) is an output control explanatory diagram,
(b) is a configuration diagram of a main part of a variable low-pass filter in FIG. 1.

FIG. 3 is a configuration diagram of an embodiment of the second present invention.

FIG. 4 is an operation explanatory diagram of FIG. 3;

FIG. 5 is a configuration diagram of a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional example.

FIG. 7 is an operation explanatory diagram of FIG. 6;

8 is another explanatory diagram of the operation of FIG. 6, (a) is an attenuation characteristic diagram of the variable attenuator, (b) is an explanatory diagram of the relationship between the voltage of the output control signal: the attenuator control voltage: the attenuation amount, FIG. 3C is an explanatory view of the variation of the attenuation characteristic of the variable attenuator.

FIG. 9 is a diagram explaining still another operation of FIG. 6;

[Explanation of symbols]

1 amplification section 3 detection section 4 comparison section 11 first variable attenuator 12 second variable attenuator 13 power amplifier 14 combiner 21 offset adjuster 22 gain adjuster 23 inverting circuit 31 third variable attenuator 32 detector 33 Filter 51 Variable low-pass filter

Claims (3)

[Claims] 1. An amplification unit for amplifying the power of an input signal that has passed through the first and second variable attenuators and transmitting the power signal as an output signal, and for branching and outputting a part of the input signal, and a branch output from the amplification unit. Through a third variable attenuator whose attenuation changes so as to compensate for the change in the amount of attenuation of the second variable attenuator, and then outputs a mean voltage obtained by detecting and averaging. A comparison unit that compares the output of the detection unit and the applied reference voltage and sends a comparison result is provided, and the attenuation amount of the first variable attenuator is controlled by a first control signal to output the output signal. In a wireless transmission device for performing burst communication by keeping power constant and changing power of an output signal according to an input output control signal, a variable low-pass filter for generating a first control signal from the comparison result is provided, and a slot is provided. The burst signal indicating the rising timing of The wireless transmission device is configured such that the transmission bandwidth of the variable low-pass filter is widened while the burst low-pass filter is not applied, and the transmission bandwidth is narrowed while no burst signal is applied. 2. A frame signal to be input, wherein when the transmission band of the variable low pass filter is switched, a carry is transmitted when the time corresponding to the interval of the burst signal is counted and the counting operation is repeated from the initial state. 2. The wireless transmission device according to claim 1, wherein a counter that is cleared in step 1 is provided, and the transmission band is switched using a carry sent by the counter. 3. The wireless transmission device according to claim 1, wherein a signal obtained by integrating input envelope information is used as the reference voltage.