JPS5958922A - Automatic gain control system - Google Patents

Abstract

PURPOSE:To attain control with high accuracy without requiring a large input range for arithmetic processing, by obtaining an initial gain adjusting value at an arithmetic processing section in response to a level of a receiving signal. CONSTITUTION:A gain control section 6 is provided with a switch 6a. The switch 6a is operated to set a gain adjusting value outputted from a level converting section 5 to a gain tap register 6b at the initial state, i.e., signal acquisition. When the initial gain adjusting value is set to the tap register 6b, a received signal is multiplied by a gain adjusting value of said tap register 6b at a multiplication section 6c and outputted externally as the receiving signal value adjusted for the gain. A gain control section 6 switches the switch 6a when the initial gain adjusting value is set once to a tap register to connect the tape register 6b to a gain adjusting section 6d, which changes the tap register 6b while monitoring the fluctuation in the receiving signal adjusted with the know gain adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field: The present invention relates to an automatic gain control method for stabilizing the level of a received signal, and in particular to an automatic gain control method for stabilizing the level of a received signal.
Automatic gain control method that can optimally set the gain.

b. Prior art and problems A modem (quality recovery device) that reproduces data from the modulated signal of the line.l In this case, in order to stabilize the level of general CC9 trust, an automatic gain that can follow fluctuations in the line is used. Manipulating control methods.

In addition, these devices convert the received key signal into an analog signal.
After D conversion, gain control is performed using the AD converted digital value.

Furthermore, when digital '1t11 control is adopted, the gain adjustment value or control force for gain control can be changed instantaneously, so generally the received signal level is calculated from the received signal value. It has been considered to obtain an initial gain corresponding to level l at 1 o'clock, thereby shortening the so-called pull-in time.

However, with these conventional methods, the initial gain calculation uses the level value of the received signal as is, so it is difficult to obtain a gain adjustment value that can absorb from large fluctuations to small fluctuations. It has the disadvantage of requiring an input range.

Furthermore, in the conventional method, when the range is widened and the precision is reduced, the number of data bits increases7, and calculation of the initial gain requires extremely complex and large-scale calculation processing. It also has the disadvantage of

C. OBJECTS OF THE INVENTION The present invention overcomes the two drawbacks of the prior art and provides an automatic gain control method that does not require a large input range for arithmetic processing and is highly integrated.

d. Accomplishment of the Invention In order to achieve the above object 5, in the present invention, an initial gain (λ) adjustment value is obtained in an arithmetic processing unit corresponding to the level of a received signal.

This will be explained in detail below using examples.

e. Embodiment FIG. 1 is a block diagram showing the functions and algorithms of an embodiment of the present invention.

In the figure, the r&Z reception signal is the analog reception signal 1g, and the AD
Change f! This is an L digital value. Further, 1 is an input level calculating section, 2 (J input level determining section, 3 is a switch, 4.4', and 5 is a gain adjustment η section, each of which calculates a gain adjustment value from the input level by a known method. 6 is a gain control section which outputs a gain-adjusted received signal.

Explain the operation.

At the initial stage, the so-called retraction stage, the switch 10 is activated. The received and AD-converted received signal value is supplied to the input level calculation unit 2 via switch ]0.

In the input level calculation unit 11, an input signal value absolute value squaring unit 1a takes the absolute value of the input signal and outputs the squared signal value. The square value of the output absolute value is accumulated in the cumulative part lb. The cumulative total part lb determines the level of the input signal value (when the input signal values are cumulatively accumulated for a sufficient number n, the cumulative value is output to the multiplication unit 1d. The multiplication unit 1dl is a constant θ generation unit Inverse P of cumulative number from IC
The value of l- is supplied n, and the multiplier part is
and the corresponding cumulative value are multiplied.

This means that the average level value of the input signal has been calculated.

This average level value is supplied to the input level determining section 2 and the level converting section 3.

The input level determining unit 2 has foot cutting generating units 2g and 2c that generate different slice level values, in this case two slice levels 1ilfAi and A-kai.

The subtractors 2b and 2d calculate this slice level value A1 from the average input level value obtained as described above.

Subtract A2. The polarity determination units 2e and 2f determine the polarity of the subtracted value. This makes it possible to know in which range the average input level value exists. for example,
If the magnitude of the slice level value is given the relationship fkoA, >A, and the average input level is the value X, then the input range (according to , the following table of outputs will be obtained for each different combination.

The table switch 3 calculates the average input level value from the gain calculation units 4°4' and 5 based on the polarity determination data from the polarity determination units 2e and 2f (the logic of the data is indicated by 0 in the table above). It is supplied to one of the arithmetic units.

FIG. 2 is a diagram showing known gain adjustment values for received signal levels. In the figure, the same parts as those used in FIG. 1 are indicated with the same symbols. In Figure 1, when the amplitude of the received signal level is larger than the target amplitude, the gain adjustment value is less than 1, and conversely, when it is smaller than the target amplitude, the gain adjustment value is 1 or less according to this curve. It is set to take the value of .

Each of the above-mentioned gain calculation units 4.4' in FIG.

5, the gain calculation unit 4 calculates the gain adjustment value in the region x ) A , the gain calculation unit 4 / calculates the gain adjustment value in the candy area x The gain adjustment values of At are calculated and output respectively.Therefore, as described above, the switch 31
Therefore, only the gain calculation section to which the average input level value is supplied operates and outputs the calculation result to the gain control section 6I.

The gain control section 6 includes a switch 6a. Su・ychiroa
At the initial stage, that is, at the time of signal pull-in, the gain tag register 6b is operated to set the gain adjustment value of the bell converter 5 u1. (Thus, the initial gain 11J value obtained as described above can be set in the tag register 6bi. At this point in time, the switch 1o is restored and the process for initialization is completed.

When the initial gain adjustment value is set in the tap register 6b, the received signal value is multiplied by the corresponding gain 4? It is output externally as a value.

Once the initial gain adjustment value is set in the tag register, the eleventh gain control unit 6 first empties the switch 6a and J1
1 Press and hold the tag register 6b on the gain adjustment section 6d.

The gain adjustment unit 6d performs a known gain adjustment by monitoring fluctuations in the adjusted received signal value and then varying the value of the tag register 6b.

ff Effects of the Invention According to the present invention, as described above, the gain adjustment value can be calculated in the calculation section corresponding to the input level range, and the gain adjustment value can be calculated in the calculation section corresponding to the input level range. Calculations are performed more accurately than intermediate range calculations)
The gain calculation section can be configured to allow for high-speed retrieval.
Produces a powerful effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining functions and algorithms of an embodiment of the present invention, and FIG. 2 is a diagram showing input 1 level amplitude and gain adjustment hip value characteristics. 6 is a gain control section.

Claims (1)

[Claims] Received signal level x! In a gain control method that adjusts the gain of the received signal by a gain adjustment value that follows s,
Determine the level of the received signal, obtain a gain adjustment value by a gain calculation unit corresponding to the determined level, and use the gain adjustment value of the calculation unit as an initial gain adjustment value to adjust the gain of the reception signal. Automatic gain flt! control method.