JPH033409A - Automatic digital gain control system - Google Patents

Abstract

PURPOSE:To remarkably shorten a time until an output signal is stabilized at a prescribed level after an input signal is fluctuated by dividing a prescribed preset value by the mean value of the absolute value of the amplitude value of the input signal, and setting a division result as a gain for the input signal. CONSTITUTION:The system is equipped with first arithmetic means 202, 203 to calculate the mean value of the absolute value of the amplitude value of the input signal, a second arithmetic means 204 to divide the prescribed preset value by the mean value of the absolute value obtained from the first arithmetic means 202, 203, and a third arithmetic means 201 to multiply the input signal by the output value of the second arithmetic means 204 as the gain. Since the mean value of the absolute value of the amplitude value of the input signal is found, and the prescribed preset value is divided by the mean value, and a result is set as the gain to be multiplied on the amplitude value of the input signal, a proper gain obtained in several or more cycles in conventional feedback control can be found in one cycle. Thereby, it is possible to remarkably shorten the time until the output signal is stabilized at the prescribed level after the input signal is fluctuated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a digital automatic gain control system used in various digital signal processing headpieces.

[Conventional technology]

The second example of the circuit configuration of the conventional digital automatic gain control method is
The operation of the circuit will be described below. First, the input signal is multiplied by the output value of the adder/IA unit 107 by the multiplier 101 to become an output signal, which is output to the outside.

At the same time, this output signal is transmitted to the squarer 102 and the averager 103.
The root mean square value is calculated. Next, by subtracting this root mean square value from a predetermined set value in a subtracter 105, an error with respect to the set value is determined.

Furthermore, this error is multiplied by an arbitrary coefficient α in the multiplier 106. The output value of this multiplier 106 and the adder 1
Adder 107 adds the output value of register 108 which receives the output value of 07, and supplies the result to multiplier 101 to correct the gain for the next input signal so that the error is flat, As a result, I was able to keep Dekai No. 3 at one level.

(Problem to be Solved by the Invention) However, in the conventional digital automatic gain control method as described above, as the difference between the input signal level and the desired output signal level increases, the output signal is converged to the desired level. It takes longer to do so.

If the value of the coefficient α shown in Fig. 2 is increased, this convergence time will be shortened in almost inverse proportion to the value, but if the value of the coefficient α is increased beyond a certain level, the input signal level and the desired output signal level will be reduced. When the difference between
Therefore, fluctuations in the output signal level may become large, or even lead to oscillation of the output signal.

That is, in the conventional method, if an attempt is made to suppress the convergence time of the output signal within a certain period of time at all input signal levels, the dynamic range of the input signal level is restricted.

Therefore, the present invention eliminates the above-mentioned drawbacks, makes it possible to significantly shorten the time from when the input signal fluctuates until the output signal stabilizes at a predetermined level, and thereby reduces the practical input signal level. The object of the present invention is to provide a digital automatic gain control method that can greatly expand the dynamic range.

(Means for Solving the Problems) In order to achieve the above object, the present invention multiplies an input signal whose average value of amplitude varies by a specified gain to obtain an output signal, and calculates the average value of the amplitude of the output signal. is a digital automatic gain control method that controls the gain so as to maintain the amplitude at a predetermined value, the method includes: a first calculation means for calculating the average value of the absolute values of the amplitude values of the input signal; It is characterized by comprising a second calculation means that divides the absolute values obtained from the calculation means by the average value, and a third calculation means that multiplies the input signal by using the output value of the second calculation means as a gain.

(Function) In the tree invention, as in the above configuration, without performing feedback control as in the prior art, the average value of the absolute values of the amplitude values of the input signal is determined, and a predetermined set value is divided by the average value. However, since the quotient is used as the gain multiplied by the amplitude value of the input signal, it is possible to obtain an appropriate gain in one cycle, which was required to be obtained over several cycles using conventional feedback control. Therefore, according to the tree invention, it is possible to significantly shorten the time from when the input signal fluctuates until the output signal stabilizes at a predetermined level, and as a result, the allowable dynamic range of the input signal level in practical use. can be greatly expanded.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of a circuit implementing a digital automatic gain control method that best represents the features of the present invention. In the figure, an input signal S1 whose average value of amplitude fluctuates is input from the outside to one input terminal of a multiplier 201, and a pressure value from a divider 204 is input to the other input terminal. The calculated value of this multiplier 201 becomes an output signal S2 and is outputted to the outside as it is.

At the same time, the input signal 51 described above is also input to the input terminal of the absolute value generator 202, and the output value of the absolute value generator 202 is input to the input terminal of the averager 203. Therefore, averager 2
An average value obtained by averaging the absolute values of the amplitude values of the input signal Sl is output to the output terminal of the input signal Sl.
Manual input is input to one input terminal of 4. A predetermined setting value is manually input to the other input terminal of the divider 204 from the outside.

The output terminal of the divider 204 outputs the result (quotient value) of dividing the above predetermined setting value by the average value of the absolute values of the input signal S1.

Since the output of the divider 204 is input to one input terminal of the multiplier 201 as the gain to be multiplied by the input signal St, the appropriate value can be immediately calculated as soon as the average of the absolute values of the input signal S1 is calculated. It becomes possible to calculate the gain.

Therefore, the time from when the first input signal Sl is manually input until the level 52 of the output signal stabilizes to a predetermined value can be significantly shortened compared to the conventional method described above.
Fluctuations in the output signal level with respect to fluctuations in the input signal level can also be made sufficiently small.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an example of the configuration of a circuit implementing the digital automatic gain control method of the present invention, and FIG. 2 is a block configuration diagram showing the circuit configuration of a conventional digital automatic gain control method. (Effects of the Invention) As explained above, according to the present invention, a predetermined set value is divided by the average value of the absolute values of the amplitude values of the input signal, and the division result is used as the gain for the input signal. Therefore, it is possible to obtain an appropriate gain in one cycle, which takes several cycles or more in conventional feedback control.Therefore, according to the present invention, it is possible to obtain an appropriate gain in one cycle after the input signal fluctuates until the output signal stabilizes at a predetermined level. 201... Multiplier, 202... Absolute value generator, 203... Averager, 204... Divider. Fig. 1 Fig. 2

Claims (1)

[Claims] 1) An input signal whose average value of amplitude fluctuates is multiplied by a specified gain to produce an output signal, and the gain is adjusted so as to maintain the average value of the amplitude of the output signal at a predetermined value. A first digital automatic gain control method for calculating an average value of absolute values of amplitude values of the input signal.
a second arithmetic means for dividing a predetermined set value by an average value of the absolute values obtained from the first arithmetic means; and an output value of the second arithmetic means as the gain. A digital automatic gain control system characterized by comprising a third calculation means for multiplying a signal.