JPS6158334A - Automatic gain controlling system - Google Patents

Abstract

PURPOSE:To stabilize an automatic gain controlling system composed of an amplitude discriminating section, pattern discriminating section, AGC amplifier, etc., by bringing the output signal level nearer to a reference value only when an input signal is the same as or similar to a training pattern. CONSTITUTION:An adder circuit 5, inter-code interference quantity discriminating circuit 8, equalizing pulse generating circuit 9, and adder circuit input terminal 6 and output terminal 7 constitute a decision feedback type transversal equalizer. Signals outputted to the output terminal 7 are added to an amplitude discriminating section 10 and pattern discriminating section 15 and the output signal of each section 10 and 15 is supplied to the two input terminals 12 and 13 of a gain control discriminating section 11. The discriminating section 11 discriminates that the output signal of the amplitude discriminating section 10 is effective when the signal of the input terminal 13 is '1' and supplies the gain controlling signal of an AGC amplifier to a terminal 3 from the output terminal of the discriminating section 11. Therefore, only when the signal inputted in an input terminal 1 is the same as or similar to a training pattern, it is discriminated that whether the scale of the amplitude of the signal is larger than a reference value or not and the output signal level is controlled so as to bring the level close to the reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic gain control system for a digital subscriber traffic transmission device.

(Prior art) In the digital subscriber line automatic equalizer, for example, as shown in IEICE C383168R Digital subscriber line automatic equalization system study J, January 27, 1984, K. The procedures of automatic gain control (AGC) and nonlinear equalization control for bridge tags (IIT control) can be roughly divided into (1) ) laning pattern (periodic isolation) 4p -
/1.0,0,0,0.0. AGC (for convenience, referred to as rAGC-IJ) and BT control (for convenience, referred to as rBT-IJ) by receiving (repetition of O, O) (2) After the ring is ready in (1) above, information (random?
BT jli control (r13T-2J for convenience) and BT jli control (r13T-2J for convenience).

Both GC-1 and AGC-2 detect the peak value of the output signal of the automatic equalizer and control the gain based on the result.

Conventional AGC-1 and AGC-2 use exactly the same method to detect the peak of the output signal.The difference is that when updating the gain, for example, in AGC-1, the peak value of the output signal is The gain is updated every time the reference voltage is exceeded, or the gain is updated when the reference voltage value is exceeded by KM bit or more while receiving NI pits, or the gain is updated when the reference voltage value is exceeded by more than KM bits while receiving NI pits.Also, in AGC-2, the gain is updated when the reference voltage value is exceeded by more than N2 bits while receiving KN2 bits. When the voltage value is exceeded, the gain is updated. Generally, N+/M+ > N
2/M2 (Ml<N2). The purpose of this is to increase the average time during operation and prevent malfunctions due to noise.

Furthermore, BT-1 and BT-2 perform nonlinear equalization by adding equalization pulses of different magnitudes so as to reduce code amount interference at the time of code identification. 13T-1゜BT
-2, in BT-2, the input signal is random/4' turn, so the training f/4' p
When a pattern similar to -7 is received, the magnitude of code amount interference is detected, and the equalization coefficient is updated based on it.

The difference from the BT-1 is the means for determining whether a turn is determined during a crawl/dumb pattern or during a late training nozzle.

When moving from the operation described in (1) to (2) above, as described above, in BT-1, the code amount interference is zero at the time of code identification, so when moving to BT-2. At the time of code identification, the code amount interference is zero and the amplitude of the identification point is within the reference value. However, at points other than the point of code identification,
Since the magnitude of inter-signal interference is not monitored, when a random pattern is received, the amplitude of the output signal of the equalizer may become larger than the reference value of the code identification point due to code amount interference. An equalization layer output eye pattern showing this situation is shown in FIG. This is: Signal pit rate 320kbit/s Main line length 2
500 m Blinosotanope length 20OFFI 1 piece 600FM
This is a two-wire type 0.51jφ CCP cable, and this is the output eye-turn when a random pattern is input after the operation in item (1) is completed, the gain and the tag coefficient of the nonlinear equalizer are fixed, and a random pattern is input.

(Problems to be Solved by the Invention) As shown in FIG. 2, since the amplitude of the output signal of the equalizer exceeds the reference value, it is necessary to update the gain in AGC-2.

In 13T-2, the code 3 is applied to the gain control amplifier output signal.
Since equalization multiplied by a coefficient and p-rus are added so that the code amount interference becomes zero at the discrimination point, the ratio of the magnitude of the amplifier output signal and the equalization/p-rus changes for the above-mentioned reason. Therefore, since the code amount interference is no longer zero at the code identification point, it is necessary to update the nonlinear equalization coefficient.

As mentioned above, when moving from the operation described in item 1 (1) to the operation described in item (2), there is a drawback that an adaptive operation is required depending on the conditions of the transmission path.

(Means for Solving the Problems) The present invention relates to an automatic gain control method for a digital automatic equalizer that uses a periodic solitary wave as a training/l turn. a variable gain amplifier controlled by a variable gain control signal; a turn determination unit that detects an isolated pattern from an equalized output signal; An amplitude determining section is provided for determining the gain control signal.

(Function) The variable gain amplification section is for adjusting the level of the equalizer system, and controls the gain of the input signal using a variable gain control signal and outputs it to the equalizer. The output signal pattern determination section selects a training non-turn (00
000001 repetitions) and turns similar to the training pattern (e.g. tbaooo±1 and 0000±1・
......oooooooo±1) is detected. The amplitude determination section determines whether the amplitude of the output signal appearing at the equalizer output is larger or smaller than a reference value, and based on the determination, sends a variable gain control signal to the variable gain amplification section for control. At this time, the amplitude determination section sends out a variable gain control signal by detecting 74 turns similar to the ``yaturn determination section'', ``cut training'' and ``turn'', or ``pigeon training'' and ``gutter''. Furthermore, by treating only the amplitude of "±1'" when a pattern similar to a training turn or training turn is detected as information for updating the gain, step (1) to step ( Eliminate unnecessary update operations that occur when moving to 2) to stabilize the system.

(Example) FIG. 1 is a configuration diagram showing an embodiment of the present invention.

The received signal is passed through the input terminal I to an automatic gain control amplifier (A
GC amplifier) 4. The AGC amplifier 4 variably amplifies the gain based on the gain control signal applied to the gain control terminal 3 and outputs an output signal to the terminal 2. The output signal of the AGC amplifier 4 is applied to one input terminal of an adder circuit 5.

The addition circuit 5, the code amount interference determination circuit 8, the equalization/Grus generation circuit 9, the addition circuit input terminal 6, and the output terminal 7 constitute a conventionally well-known decision feedback type transparsal equalizer. are doing.

On the other hand, the equalizer output signal appearing at the output terminal 7 of the equalizer is transmitted to the amplitude determining section IO and...! The respective output signals are applied to the two input terminals 12 and 7.7 of the gain control determining section 11. A signal output from the output terminal 14 of the gain control determination section 1 is applied to the gain control terminal 3 of the AGC amplifier 4.

The amplitude determining section 10 generates different control signals depending on whether the amplitude of the output signal appearing at the output terminal 7 of the equalizer is larger or smaller than a reference value (both positive and negative). In addition, the turn determination unit I5 outputs a training turn or a turn (000
Determines that a nog turn that is the same as or similar to a 00001 nogashi return (periodic isolation) P turn (for example, a set turn in which there is a 1" after 4 or more bits of "0") is received. When the same or similar pattern (solitary wave) is received, "1" is output to terminal No. 3, and "O" is output at other times.

The control determination unit II validates the output signal of the amplitude determination unit '10 when the signal at the terminal 13 becomes l'', and i1+lI.
l111 judgment unit 11 (7) output terminal 14 Yori AGC
This is a dart circuit that is applied to terminal 3 as a gain control signal for amplifier 4. Therefore, the automatic gain control system composed of the amplitude determining section IQ, /4'turn determining section/, i, the output terminal I4, and the AGC amplifier 4 is configured such that the signal applied to the input terminal IK is the same as the training pattern 7, or Only when similar
It is determined whether the magnitude of the amplitude of the signal is larger or smaller than the reference value, and based on this, the level of one output signal is controlled so as to approach the reference value.

Therefore, even if the training pattern changes from random color to turf, the information used for gain control is the same, so the new gain update and the equalization A pulse of the nonlinear equalization section There is no size update.

(Effects of the Invention) As explained above, there is no deterioration in equalization performance due to the re-updating of the gain that occurs when changing from a training pattern or turf to a random pattern, and the associated updating of the tag coefficient of the nonlinear equalizer, and the system Since it is possible to stabilize the situation, the original purpose of using the training turn can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a circuit port of an embodiment of the present invention, and FIG. 2 is a diagram showing an output eye and a turn. 1. Input terminal, 4. Automatic gain control system amplification 2J17.
...Output terminal, IO...Amplitude judgment section, I5...Rig turn judgment section. Figure 1 Figure 2 - Support 1 Procedural amendment (Shark) 1 Indication of the case 1982 Patent Application No. 179457 2 Name of the invention Automatic gain control system 3 Relationship with the person making the amendment Patent application Address (〒105) 1-7-12 Toranomon, Minato-ku, Tokyo Address (〒105) 1-7m2, Toranomon, Minato-ku, Tokyo
Subject of amendment No. 5: 4t of “Detailed Description of the Invention” in the specification
146. Contents of the amendment In the first line of page 3 of the specification, the phrase "Ru, Mata" is amended to read "Ru. Mata."

Claims (1)

[Claims] An automatic gain control method for a digital automatic equalizer using a periodic solitary wave as a training pattern includes a variable gain amplifier, an amplitude determination section, and a pattern determination section, and the pattern determination section detects an isolated pattern from an equalized output signal. and a determination value of the deviation of the amplitude of the isolated pattern from a reference value determined by the amplitude determining section at the time of the detection as a gain control signal of the variable gain amplifier.