JPS61102831A - Waveform equalization system pull-in control method - 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 Application of the Invention] The present invention relates to a demodulator with a built-in automatic equalizer that performs synchronous pull-in using a training signal, and in particular to a demodulator with a built-in automatic equalizer that performs synchronous pull-in using a training signal. This invention relates to a pull-in control method for an automatic equalizer that can shorten the time.

[Background of the invention]

In the conventional waveform equalization system, as described in Japanese Patent Publication No. 55-33203, in the automatic equalization method that corrects the correction signal based on the equalized residual signal, the training signal is used to establish the adjustment coefficient at the initial pull-in. is used. For this reason, a certain amount of time is required for synchronization, making it difficult to apply a system that requires a quick start-up.

That is, the training signal is generally placed before the waveform of the information data is equalized, that is, immediately before the data, and the demodulator is initialized and pulled in. Figure 1 (
α) and fbl are diagrams for explaining initialization of a training signal, and FIG. 2 is a block diagram of a conventional automatic equalization system. Fig. 1 (α) shows the phase plane of the received signal, and A, B, . . . show data, and Fig. 1 (b)
The training signal that would correspond to each data A B CD is the non-signal period NOX M T .

1st figure) A period in which the illustrated data A and B are regularly repeated alternately (hereinafter AB period: ALT), a period in which data CD is arithmetic with a certain imago polynomial and randomly repeated (hereinafter CD period: AE) , and all the data existing on the phase plane are randomly arranged scramble data sections, which are arranged immediately before the data.

The drawing-in operation of the block diagram of the second factor will be explained using FIG.

1. When no data is input, the tap coefficients of the 1 equalizer 4 are initialized, and the AGC circuit 1 is set to a gain that should detect the minimum level signal.

2. When the signal ABAB... for the next 1cAB period is input, the level detector 5 detects the level, and the A G C
Depending on the set gain value, the control circuit at 6 calculates the current input level and sets it to a high speed (standard level output). This is done by keeping the input level constant and eliminating initial timing errors and This is necessary to correct the initial frequency offset error.

3. When the carrier and timing are optimal at the initial stage and the training signal shifts from the AB defect signal to the CD signal, the pull-in operation of the equalizer 4 is performed using the aforementioned binary irregularly arranged data group (PN code). be exposed.

4. Next, the multi-level random signal during the scrambling period is
The tap coefficients input to the equalizer 4 and converged with binary random data are further updated to perform fine-grained equalization.

The training signals 1 to 4 above are used to complete the pull-in, and thereafter waveform equalization is performed using the data. At this time, the AGC circuit operates as a steady AGC that updates the initial setting level that is presented at high speed at the beginning of the AB period with a long time constant.

The equalizer used in this configuration uses the MS method (minimum control method) in which the correction signal is controlled by the equalized residual signal and the tap output, that is, the signal components at predetermined intervals of the base node signal after demodulation.
An automatic equalizer with a mean 5quare Method is used. The correction signal, that is, the tap gain, has the disadvantage that it takes a considerable amount of time to correct the equalization coefficient until the PN code given during training can be correctly equalized and output.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a waveform equalization system that can quickly set the equalizer so as to eliminate the following drawbacks.

[Summary of the invention]

The present invention receives a signal obtained by modulating a training signal and a data signal with a carrier signal, and is equipped with an equalizer that makes the amplitude constant using an AGC circuit (an AGC circuit) and equalizes the signal waveform of the data signal period without demodulation. In a data demodulator, means for quickly initializing the AGC circuit by a two-point alternating repeated signal at a data point constellation diagram H following no signal of the training signal, and a two-point random repeating signal following the alternating repeating signal. By detecting the equalizer adjustment signal and setting the initial value of the AGC circuit again so that the equalizer adjustment gain is large to the same constraint, the rise time and establishment of the subsequent automatic equalizer are improved. It is characterized by this.

[Embodiments of the invention]

Below, a block diagram of one embodiment of the present invention is shown in FIG. 1.
This will be explained in detail using this figure. In the figure, those used in FIG. 2 are indicated by the same symbols. Next, the operation in FIG. 3 will be explained using ('B) in FIG. When there is no signal, it is the same as the conventional example. Similarly, level, timing, and carrier corrections are performed during the AB signal period, and preparations for adjustment of the equalizer are completed.

When the training signal transitions from AB to CD period, equalizer pull-in begins. This switching point is detected by the ABCD period detector 9 of 7. At this point AG
The C value should be 2 to 3 times the initial setting value.
The GC circuit performs steady AGC @ operation to update to the optimum level at a certain time constant. As a result, the adjustment gain of the automatic equalizer is busy with equal constraints, and is large at the beginning of adjustment, but as the AGC value approaches the set value, it settles to a steady value, which makes it possible to shorten the initial pull-in time of the equalizer, and after the pull-in. , the adjustment gain becomes smaller and stabilized.

In other words, the tap adjustment algorithm of the transversal filter as an equalizer is as follows: C (N+ 1
) :y--t-X K-JN In this formula, the signal of double side band modulation is expressed by a vector. K is a tap adjustment coefficient, which is adjusted by taking the correlation of the input signal. is the data input signal and is the error signal. Also? is the adjustment gain. Is it possible to vary the AGC setting level from the formula? This corresponds to a change in the value of , and it is possible to realize that the initial value 2 gradually becomes the set value.

〔Effect of the invention〕

As described below, according to the present invention, by equivalently varying the adjustment gain of the equalizer using the AGC circuit,
Since the pull-in time can be shortened and the gain after the pull-in can be made small, equalization loss after stabilization can be prevented, and synchronization establishment can be improved. Further, variable gain can be achieved only by setting the AGC without adding an equalizer lead.

[Brief explanation of the drawing]

Fig. 1 (α) and (h) are explanatory diagrams of the pull-in operation of a data demodulator with a built-in equalizer, Fig. 2 is a block diagram of a conventional demodulator with a built-in equalization amount, and Fig. 3 is a diagram of the present invention. 1 is a block diagram of an example waveform equalization system; FIG. l...AGC circuit, 5...level detector 6
...Control circuit.ゝ＼〜−−′

Claims (1)

[Claims] 1. A data demodulator that receives a signal obtained by modulating a training signal and a data signal with a carrier signal, makes the amplitude constant by an AGC circuit, and includes an equalizer that equalizes the signal waveform of at least a data signal period after demodulation, Means for quickly initializing the AGC circuit by an alternately repeating signal between two points on a data point constellation diagram following no signal of the training signal, and equalizer adjustment of random repeating between two points following the alternatingly repeating signal. By detecting the signal and setting the initial value of the AGC circuit again so that the equalizer adjustment gain becomes equivalently large, the rise time and establishment of the subsequent automatic equalizer are improved. Entrainment control method for waveform equalization system.