JPH07254831A - Digital agc device - Google Patents

Abstract

PURPOSE:To attain high speed processing for an equipment to which the AGC device is applied by reducing the number of times of arithmetic processing for AGC processing so as to decrease the processing time. CONSTITUTION:An amplifier 11 and a squaring device 12 detect an input level and a smoothing section 13 smoothes an input level. Then a gain required to make an output level constant by an x<-1/2> generator 14 is calculated and it is inputted an adaptive LPF 15 to obtain a stable output. A coefficient obtained in this way is multiplied with an input sample to obtain an AGC output signal. Furthermore, an output switch of the smoothing section 13 is closed once for every input of 16-samples of input signals (1/m). Number of arithmetic operations of the x<-1/2> generator 14 and the LPF 15 is reduced by using the smoothing section 13 making the switching and the processing time is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital AGC device which is used in a digital radio telephone or the like to make the level fluctuation of an input digital signal constant.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional digital AGC (Automati).
FIG. 3 is a block diagram showing the configuration of a c Gain Control) device.
In FIG. 3, this example shows an amplifier 2 for frequency-converting a received signal in a digital wireless telephone or the like and amplifying an input signal obtained by digitizing an intermediate frequency signal, a squarer 3, and an x ^−1/2 generator. 4, adaptive LPF 5, and amplifier 6
And a multiplier 7.

Next, the operation of this conventional example will be described. Amplifier 2 for input signal (sampling data) level
And the squarer 3. The output signal of the ^squarer 3 is input to the x ^-1/2 generator 4, and a signal showing a gain corresponding to the input signal (sampling data) level is generated.
In this case, the x ^−1/2 generator 4 divides the input value into m sections and divides each section into a spline function (y
= A ₃ x ³ + a ₂ x ² + a ₁ x + a ₀ ). The spline coefficients (a ₃ , a ₂ , a ₁ , a ₀ ) are read from a spline coefficient table (not shown) provided in the x ^−1/2 generator 4. The output signal of the x ^-1/2 generator 4 is input to the adaptive LPF 5 to obtain a stable output level. The adaptive LPF 5 has a one-sample delay element, and compares the input value of this time and the output value of the previous time to change the filter coefficient dynamically. By changing this filter coefficient, it is possible to adjust the changing speed of the output level when the output signal level increases and when the output signal level decreases. Adaptive LPF5
The output signal from is input to the multiplier 7 through the amplifier 6, and the multiplier 7 multiplies the input sampling data to obtain the AGC output signal.

As described above, even in the conventional digital AGC device, an AGC output signal whose output level is kept constant can be obtained.

[0005]

By the way, in the conventional digital AGC device, all the input sampling data are used for control. Therefore, when the above AGC processing is performed using a digital signal processor (DSP), the processing time per data is 28 μs when converted by one command of 200 ns. That is, the spline function and the adaptive LPF are included in the entire AGC processing.
However, there is a drawback that the stabilization of an input signal in a digital wireless telephone equipped with the digital AGC device, for example, cannot be processed at high speed.

The present invention solves such a conventional problem, and can reduce the number of calculations of AGC processing, shorten processing time, and apply equipment to which the apparatus is applied, for example,
An object of the present invention is to provide an excellent digital AGC device that can process stabilization of an input signal in a digital wireless telephone at high speed.

[0007]

In order to achieve the above object, a digital AGC device according to claim 1 detects a level of an input signal, and an input signal based on the level detected by the detecting means. A smoothing means for smoothing the power, a function generating means for calculating a gain necessary for keeping the output level constant by using a spline function, an adaptive LPF for stably processing an output signal from the function generating means, The smoothing means includes delay means for matching the delay time when the input signal is processed by the adaptive LPF from the detecting means, and multiplying means for sending the AGC output signal obtained by multiplying the output signals from the adaptive LPF and the delay means. The conversion means transmits the processing signal to the function generation means and the adaptive LPF, or switches to stop the transmission.

According to another aspect of the digital AGC device of the present invention, the smoothing means amplifies the input signal and the delay circuit in which the delay elements are connected in series, and amplifies the signals from the respective delay elements of the delay circuit. Then, an amplifier circuit in which a plurality of amplifying elements are connected in series, and further, the input signal and the signal from the first stage of the amplifying element are added, and the signals from the amplifying elements of the previous stage and the next stage are added, An adder circuit in which the above adder elements are connected in series, and a switch for closing the signal from the adder circuit each time a sample is input and sending a processed signal to the function generating means and the adaptive LPF, or a switch for stopping the sending. It is configured to be equipped.

According to a third aspect of the digital AGC device of the present invention, the function generating means divides the input value into a plurality of sections and obtains an approximate value obtained by processing each section with a cubic spline function,
The output gain corresponding to the input level, which is the average value of the powers of a plurality of samples, is obtained.

[0010]

The digital AGC according to claims 1 to 3 having this structure.
The device smoothes the power of the input signal based on the detected level. Furthermore, the gain required to keep the output level constant is calculated by a spline function, and the calculated signal is processed stably. At this time, whether or not the smoothing means performs the calculation in the function generating means and the adaptive LPF is switched for each of a plurality (m) of samples. As a result, the number of calculations of the spline function and the adaptive LPF is 1 / m.
Therefore, the AGC processing time is shortened.

[0011]

Embodiments of the digital AGC device of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a digital AGC device of the present invention. In FIG. 1, an amplifier 11 for frequency-converting a received signal in a digital wireless telephone or the like and amplifying sampling data of an input signal obtained by digitizing an intermediate frequency signal thereof, and a sampling data from the amplifier 11 are squared and sampled. A squarer 12 for obtaining the power of data and a smoothing unit 13 for smoothing the power obtained by the squarer 12 and having a detailed configuration shown in FIG. 2 below are provided. Further, this digital AGC device obtains an approximate value of x ^−1/2 from the output signal of the smoothing unit 13 and obtains an output gain corresponding to the input level, the x ^−1/2 generator 14
An adaptive LPF 15 for obtaining an output level that stabilizes the output signal of the x ^−1/2 generator 14, an amplifier 16 for amplifying the output signal from the adaptive LPF 15, and delay elements 17a, 1
7b, 17c ...
The sampling data from 7 is multiplied by the output signal from the amplifier 16 to control the gain of the sampling data.
It has a multiplier 18 for delivering the GC output signal. Figure 2
FIG. 3 is a block diagram showing a detailed configuration of the smoothing unit 13. In FIG. 2, this smoothing unit 13 is, for example, 15
A delay circuit 19 composed of delay elements 19a, 19b, 19c ... 19o in stages and an input signal is amplified, and the delay circuit 1
The signals from the respective delay elements 19a to 19o of 9 are
16 amplification elements 20a, 20b, 2 for amplifying each
0c, 20d ... 20q (amplification factor 1/16), and further the input signal and the amplification element 2 of the first stage
Adder element 2 for adding the signals from 0a and further adding the signals from the amplifying elements (20a to 20q) of the previous stage and the next stage
Adder circuit 21 having 1a, 21b, 21c ... 21q
And a switch 22 that outputs (turns on) or stops (turns off) the signal from the adder circuit 21.

Next, the operation of this embodiment will be described. The sampling data is input to the squarer 12 through the amplifier 11. The squarer 12 squares the sampling data to obtain the power of the sampling data. The output signal of the squarer 12 is input to the smoothing unit 13 shown in FIG. As shown in FIG. 2, the smoothing unit 13 includes, for example, a delay circuit 19 including 15 stages of delay elements 19a to 19o and an amplification circuit 20 including 16 amplification elements (20a to 20q) (amplification factor 1 / 16) and a switch 22. The amplification elements (20a to 20a) of the amplification circuit 20 here are provided.
By adding the output signals from 20q), the average value of the power of 16 samples from the data 15 samples before to the data of this time input can be obtained. In this case, the switch 22 is closed every 16 samples of the input signal. The switch 22 counts the sampling data by using a counter (not shown) and resets the count every 16 samples. That is, the smoothing unit 1
The output signal from 3 is input to the x-1 / 2 generator 14 every 16 sample inputs. Therefore, for every 16 samples input, the average value of the power of the 16 samples is input to the x ^−1/2 generator 14. In this example, the x ^−1/2 generator 1
4 divides the input value into 13 sections, the respective section cubic spline function ^{_{(y = a 3 x 3 +}} a 2 x 2 + a 1 x + a 0), to obtain an approximate value of x ^-1/2, input Find the output gain corresponding to the level. The output signal of the x ^−1/2 generator 14 is input to the adaptive LPF 15 to obtain a stable output level. The adaptive LPF 15 is equipped with a 1-sample delay element, and compares the magnitude relationship between the input value this time and the output value last time,
Dynamically change the filter coefficient. By changing this filter coefficient, it is possible to adjust the changing speed of the output level when the output signal level increases and when the output signal level decreases.
After the output signal from the adaptive LPF 15 is amplified by the amplifier 16, the input signal is held while 16 samples are input and has the same delay time as the delay circuit 19 of the smoothing unit 13, for example, the same number as the delay circuit 19 is provided. 15-stage delay element 1
The input sampling data that has passed through the delay unit 17 composed of 7a to 17o is multiplied by the multiplier 18. In this way, the AGC output signal is obtained.

[0013] calculation of the x ^-1/2 generator 14 and adaptive LPF15 is performed only when the switch 22 is closed (on), in the case of off-x ^-1/2 generator 14 and adaptive LPF15
Is not performed, and the input sampling data that has passed through the delay unit 17 is multiplied by the coefficient held at that time.
The delay unit 17 operates so that the sample group used for the calculation of the x ^−1/2 generator 14 and the adaptive LPF 15 and the sample group multiplied by the coefficient obtained by the calculation have the same time axis. That is, the deterioration of the dynamic characteristics is prevented.

In this case, the static characteristic and the dynamic characteristic are, as compared with those in the conventional example, almost the same as the audibility of a received call when the digital AGC device is installed in a digital radio telephone.

As described above, in this embodiment, the number of calculations of the x ^−1/2 generator 14 and the adaptive LPF 15 is reduced and the processing time is reduced, so that, for example, the stability of the input signal in the digital radio telephone is stabilized. (AGC) is processed at high speed, enabling high-quality calls.

[0016]

As is apparent from the above description, the digital AGC device according to claims 1 to 3 smoothes the power of the input signal based on the detected level and keeps the output level constant. The required gain is calculated by the spline function. Further, whether or not the calculated signal is stably processed and whether the smoothing means performs the operation in the function generating means and the adaptive LPF is switched for each of a plurality of (m) samples, so that the spline function and The number of operations of the adaptive LPF is reduced to 1 / m, the AGC processing time is shortened, and, for example, the stabilization of the input signal in the digital wireless telephone can be processed at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration in an embodiment of a digital AGC device of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a smoothing unit in FIG.

FIG. 3 is a block diagram showing a configuration of a conventional digital AGC device.

[Explanation of symbols]

12 squarer 13 smoothing part 14 x ^-1/2 generator 15 adaptive LPF 17 delay device 18 multiplier 19 delay circuit 20 amplification circuit 21 addition circuit 22 switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04B 7/26 H04L 27/00

Claims (3)

[Claims] 1. A detection means for detecting the level of an input signal, a smoothing means for smoothing the power of the input signal based on the level detected by the detection means, and a gain necessary for keeping the output level constant. With a spline function, an adaptive LPF for stably processing an output signal from the function generating means, and a delay time when the input signal is processed by the adaptive LPF from the detecting means. For delaying the output signal from the adaptive LPF and the delay unit, and the smoothing unit sends the processed signal to the function generating unit and the adaptive LPF. Or a digital AGC device characterized by performing switching to stop transmission. 2. The smoothing means amplifies the input signal with a delay circuit in which delay elements are connected in series, and amplifies the signals from the respective delay elements of the delay circuit, thereby forming a plurality of amplification elements. An amplifier circuit connected in series, and further adding an input signal and a signal from the first stage of the amplifying element, and adding signals from the amplifying elements of the previous stage and the next stage, and connecting a plurality of adding elements in series And a switch for closing the signal from the adder circuit each time a sample is input and sending a processing signal to the function generating means and the adaptive LPF, or a switch for stopping the sending. The digital AGC device according to claim 1. 3. The function generating means divides an input value into a plurality of sections, obtains an approximate value obtained by processing each section with a cubic spline function, and outputs the approximate value to an input level which is an average value of powers of a plurality of samples. The digital AGC device according to claim 1, wherein a corresponding output gain is obtained.