JP2868070B2 - Automatic gain control method in time division multiplex communication. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic gain control system in a time division multiplex radio system.

[0002]

2. Description of the Related Art An automatic gain control system aims at automatically controlling the gain of an amplifier circuit in accordance with an input signal in a radio receiving apparatus and keeping the input level of a demodulation circuit within a certain range.

FIG. 4 is a block diagram showing an example of a radio receiving apparatus using a conventional automatic gain control method.

The output of the variable gain amplifier 3 for amplifying the received signal input from the input terminal 101 is provided with a comparator 7 for detecting an envelope component. The output of the comparator 7 is supplied to the variable gain amplifier 3 so as to control the gain of the variable gain amplifier 3.

[0005] The operation of a radio receiving apparatus using this conventional automatic gain control method will be described.

When the received signal increases, the variable gain amplifier 3
Output also increases. The detector 6 outputs a voltage proportional to the output of the variable gain amplifier 3 to the comparator 7. The comparator 7 is
The output of the detector 6 is compared with a reference voltage, and a control voltage corresponding to the increase of the input is output to the variable gain amplifier 3. The variable gain amplifier 3 reduces the gain following the control voltage.

With this series of operations, the variable gain amplifier 3
Output level decreases, and the increase detected by the comparator 7 also decreases. Accordingly, the output level of the variable gain amplifier 3 and the gain are in a balanced state. If the gain of the comparator 7 is large, the output level of the variable gain amplifier 3 hardly changes.

[0008]

This conventional automatic gain control system is mainly composed of hardware such as the detector 6 and the comparator 7, so that the characteristic variation and the complexity of the configuration are reduced.
There were problems such as higher prices. Further, since the response to the input signal is affected by the response speed of the detector 6 and the comparator 7, it is difficult to follow a high-speed burst signal.
There were also performance issues.

SUMMARY OF THE INVENTION It is an object of the present invention to realize a faster and more accurate automatic gain control method in a time division multiplexing wireless communication system, and to simplify the configuration of a radio receiving apparatus by the automatic gain control method, thereby reducing the cost. An object of the present invention is to provide a wireless receiving device.

[0010]

According to the present invention, a variable gain amplifier for amplifying an input signal, an A / D converter for converting an output of the variable gain amplifier into a digital value, and the A / D converter Calculating an optimal gain control value of the maximum value of the input signal from the output of the input signal, and controlling the gain of the variable gain amplifier based on the calculation result. An automatic gain control method in time-division multiplex communication configured to calculate the optimum gain control value of the desired reception slot using a signal of a time slot immediately before a reception slot, wherein the control means is digitally converted. Means for reading an input level in a time slot immediately before the desired reception slot, means for storing the input level, means for calculating an absolute value of the input level, Means for determining a new input level by comparing the calculated maximum value of the input level, and, based on the new maximum value of the input level, a relative indication value between the optimum reception gain already supplied to the variable gain amplifier. Means for calculating;
Means for calculating a new optimum reception gain by adding the relative instruction value and the already optimum reception gain supplied to the variable gain amplifier, and means for supplying the new optimum reception gain to the variable gain amplifier An automatic gain control method in time division multiplex communication characterized by the following is obtained.

[0011]

Further, according to the present invention, the control means includes:
An automatic gain control method in time division multiplex communication characterized by being constituted by a control program which is software is obtained.

[0013]

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

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

In this embodiment, as shown in FIG. 1, a reception signal amplifying section 1 including a variable gain amplifier 3 controlled to keep the level of an output signal constant, and an analog / digital (A)
/ D) a demodulation unit 2 that includes a control circuit 5 for controlling the converter 4 and the variable gain amplifier 3 and performs demodulation by digital signal processing
It is constituted by.

FIG. 2 shows time slots of the time division multiplex system. In a receiving circuit for use in a time-division multiplex digital radio, a slot S (-
1), and calculates the maximum value and the optimum reception gain in the reception slot S (-1). The gain is set so that the reception gain in the section from the beginning to the end of the desired reception slot S0 becomes the above-mentioned optimum reception gain. The configuration is such that the variable amplifier 3 is controlled.

The operation of this embodiment will be described. The slot S (-1) preceding the desired receiving slot S0 of the time division multiplexing TDMA frame is received, and a signal is input to the variable gain amplifier 3 and amplified. Then the output is A
The digital signal is converted by the / D converter 4 and output to the control circuit 5. The control circuit 5 calculates the maximum value of the input level in the slot S (-1) preceding the digitally converted desired reception slot S0, and calculates the optimum reception gain in the reception slot S (-1) from the value. Then, by supplying the signal to the variable gain amplifier 3, control is performed such that an optimum reception gain is obtained in the desired reception slot S0.

Here, a flow in which the control circuit 5 calculates the optimum reception gain will be described with reference to FIG.

The control circuit 5 first takes in the input level in the slot S (-1) preceding the digitally converted desired reception slot S0, that is, reads and stores the input level (S1). Next, the absolute value of the input level is calculated (S2). The calculated absolute value is compared with the maximum value of the previously calculated input level, and the larger of the calculated absolute value and the maximum value of the previously calculated input level is determined as the maximum of the new input level. It is determined as a value (S3). continue,
The control circuit 5 calculates the input level from the maximum value of the input level obtained in S3.
A relative instruction value with the optimum reception gain already supplied to the variable gain amplifier 3 is calculated (S4). Further, a new optimum reception gain is calculated by adding the already-specified optimum reception gain supplied to the variable gain amplifier 3 and the relative instruction value (S5). And
The optimum reception gain is output to the variable gain amplifier 3 (S
6). Through the above steps, an optimum reception gain is obtained for the desired reception slot S0.

[0021]

As described above, according to the automatic gain control method in the time division multiplex communication of the present invention, since the gain is controlled by digital signal processing, the characteristics can always be kept constant. , Control hysteresis can be eliminated.

Further, the addition or change of the function can be easily made without changing the existing circuit, since only a part of the software needs to be changed.

Further, by controlling the reception gain, A
The dynamic range of the / D converter and the wireless receiving device is expanded, and as a result, an inexpensive receiving circuit can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an automatic gain control method in time division multiplex communication according to one embodiment of the present invention.

FIG. 2 is a diagram showing a time slot configuration of time division multiplex communication in the automatic gain control system shown in FIG.

FIG. 3 is a flowchart showing a method for calculating an optimum reception gain in the automatic gain control method shown in FIG.

FIG. 4 is a block diagram showing a conventional automatic gain control method in time division multiplex communication.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Received signal amplification part 2 Demodulation part 3 Variable gain amplifier 4 A / D converter 5 Control circuit

Claims (2)

(57) [Claims] A variable gain amplifier for amplifying an input signal;
A / D for converting the output of the variable gain amplifier into a digital value
A time-division multiplexing unit that calculates an optimum gain control value of a maximum value of the input signal from an output of the A / D converter, and controls a gain of the variable gain amplifier based on the calculation result. An automatic gain control method in time division multiplex communication configured to calculate the optimum gain control value of the desired reception slot using the signal of the time slot immediately before the desired reception slot when receiving the signal of Wherein the control means is means for reading an input level in a time slot immediately before the digitally converted desired reception slot, means for storing the input level, means for calculating an absolute value of the input level, Means for comparing the absolute value and the maximum value of the previously calculated input level to determine the maximum value of the new input level, and from the maximum value of the new input level,
Means for calculating a relative indication value with the optimum reception gain already supplied to the variable gain amplifier, and adding the relative indication value and the already optimum reception gain supplied to the variable gain amplifier to obtain a new optimum reception gain. An automatic gain control method in time-division multiplex communication, comprising: means for calculating; and means for supplying the new optimal reception gain to the variable gain amplifier. 2. The automatic gain control method according to claim 1, wherein said control means is constituted by a control program which is software. method.