JPH033408A - Automatic digital gain control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 devices.

[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 107 by the multiplier 101 to become an output signal, which is output to the outside. At the same time, the square mean value of this output signal is calculated by the squarer 102 and the averager 103. 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, an arbitrary coefficient α in the multiplier 106 is added to this error.
Multiply by The output value of this multiplier 106 and the adder 107
The adder 107 adds the output value of the input value to the output value of the register 108 as a manual value, and supplies the result to the multiplier 101 to correct the gain for the next input signal so that the error is; As a result, the output signal was kept at a constant 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 time required to converge the 8-power signal to the desired level increases.

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
This may result in large fluctuations in the output signal level 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. It is an object of the present invention to provide a digital automatic gain control method that can sufficiently reduce fluctuations in output signal level.

(Means for Solving the Problems) In order to achieve this object, the present invention provides the above-mentioned method so that the level of an output signal obtained by multiplying an input signal whose level value fluctuates by a specified gain is always kept at a constant value. A digital automatic gain control method for controlling gain, comprising a first calculation means for calculating the root mean square value of the amplitude value of an input signal, and a predetermined set value divided by the root mean square value obtained from the first calculation means. The present invention is characterized in that it comprises a second calculation means for calculating the output value of the second calculation means, and a third calculation means for multiplying the input signal by using the output value of the second calculation means as a gain.

[Function] In the present invention, as in the above configuration, the root mean square value of the level value of the input signal is obtained, a predetermined set value is divided by this root mean square value, and the quotient of the division result is used as the gain to calculate the input signal. Since the level of the output signal is kept constant at a predetermined value by directly multiplying the amplitude value, it is possible to significantly shorten the time from when the input signal fluctuates until the output signal stabilizes to the predetermined level. As a result, fluctuations in the output signal with respect to fluctuations in the input signal level can be made sufficiently small.

〔Example〕

Embodiments of the present invention will be described in detail below 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 51 whose level value fluctuates is input from the outside to one input terminal of a multiplier 201, and an output value of a divider 204 is input to the other input terminal. This multiplier 20
The calculated value of 1 becomes the output signal S2 and is directly output to the outside.

At the same time, the above-mentioned input signal St is also input to the input terminal of the squarer 202, and the output value of the squarer 202 is outputted to the averager 203.
is input manually to the input terminal. Therefore, a root mean square value of the input signal Sl is outputted to the output terminal of the averager 203, and the root mean square value is inputted to one input terminal of the divider 204. A predetermined setting value is inputted to the other input terminal of the divider 204 from the outside.

The output terminal of the divider 204 is outputted as a result (quotient value) of dividing the above predetermined setting value by the root mean square value of the input signal Sl.

Since the output of the divider 204 is inputted to one input terminal of the multiplier 201 as the gain to be multiplied by the input signal S1, an appropriate gain can be obtained immediately when the root mean square value of the input signal S1 is obtained. It becomes possible to calculate.

Therefore, the time from when the first input signal S1 is input until the output signal level 52 stabilizes at 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.

(Effects of the Invention) As explained above, according to the present invention, a predetermined set value is divided by the root mean square value of the input signal, and the division result is used as the gain to be directly multiplied by the input signal. , an excellent effect can be obtained in that the time from when the input signal fluctuates until the output signal stabilizes at a predetermined level can be significantly shortened.

[Brief explanation of the drawing]

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. Figure 1: Multiplier, squarer, averager, divider. Figure 2

Claims (1)

[Claims] 1) A digital automatic gain control method that controls the gain so that the level of an output signal obtained by multiplying an input signal whose level value fluctuates by a specified gain is always maintained at a constant value. , a first calculation means for calculating the root mean square value of the amplitude value of the input signal; a second calculation means for dividing a predetermined set value by the root mean square value obtained from the first calculation means; A digital automatic gain control system, comprising: third calculation means for multiplying the input signal by the output value of the second calculation means as the gain.