JPH01101030A - Receiver - Google Patents

Abstract

PURPOSE:To form a receiver in which a jitter restraint is high and a transmitting quality is good by detecting the jitter of an output through the equalizer of transmitted data and controlling the equalizing characteristic of equalizer according to the detected jitter. CONSTITUTION:A phase detector 150 to extract jitter components from the equalizing output signal of an equalizer 114, a phase control device 151 and a jitter phase predicting device 160 are provided, and a feedback control is executed. The jitter phase predicting device 160 predicts the future unknown jitter components from the past jitter components, and the output of the jitter predicting device 160 is fed each to respective tap gains of the equalizer 114. Respective tap gains of the equalizer 114 are shored onto a memory as a tap gain register 161, for example, when the tap gains are composed of a DSP. Respective gains are multiplied by the output of the jitter predicting device 160 by means of a multiplier 162. Namely, the jitter components by a time width which the equalizer covers are predicted, respective tap gains are adjusted by using the prediction data, and thereby, the jitter can be correctly suppressed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a receiving device, and in particular, to
This invention relates to a receiving device that absorbs f.

<Prior Art> Conventionally, an equalizer is used as a device to remove distortion in a transmission line, but one component that cannot be removed by the equalizer itself is phase jitter generated in the transmission line (line). This means that the phase of the transmitted data is mainly at the commercial frequency (50
Hz.

This is a phenomenon in which the signal is rotated (that is, phase modulated) by the 60 Hz) component, and from the perspective of an equalizer, it becomes a very fast fluctuation component that cannot be absorbed by a conventional equalizer. For this reason, conventionally, in order to remove such a strange S component, a seventh
The method shown below was adopted.

A block diagram of a conventional jitter suppression method is shown in FIG.

FIG. 7 is a block diagram of the flower vase section.

114 and 115 are an equalizer that removes distortion from received data, and a determiner that determines data transmitted from the output of the equalizer 114, respectively, and a phase detector 150 that extracts a jedder component from the equalized output signal. A phase controller 151 is provided to perform feedback control. The reason why the jitter correction -1 is performed at this position is that since the line distortion has been equalized in advance by the equalizer 11.4, it is easy to detect the jitter component.

Furthermore, since the shadow caused by sick appears as a rotational component of data, the phase controller 152 applies rotation in the opposite direction to the jedder phase detected by the phase detector 150 to remove the jedder component. Note that this phase rotation is performed by multiplying the output of the flower vase 114 by a wave of a predetermined phase.

<Problems to be Solved by the Invention> Here, the isometric vase 114 outputs something calculated using data in a certain time range, and its output itself has jitter components in the same time range. It includes everything.

Therefore, in the conventional control example (Figure 7), phase control is applied according to the amount of jitter detected from this equalized output, so the amount of phase to be controlled is the average value seen within the time span of the equal flower. Only.

This caused a deterioration in quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiving apparatus that eliminates the drawbacks of the conventional example and has a high jitter suppression ability, that is, a high transmission quality.

Means for Solving the Problems The present invention includes means for detecting jitter, and means for controlling equalization characteristics of the equalizer in accordance with the jitter detected by the detecting means.

Effect>' In the above configuration, the equalization characteristic of the equalizer is controlled according to the jitter detected by the detection means.

<Example> The outline of this example is that instead of performing jitter phase control using an average value, the jitter component within the isoflower span is detected and each tap gain of the transversal filter included in the isoflower span is directly controlled. This makes it possible to remove jitter components within the same span, thereby increasing the jitter suppression ability compared to the conventional example.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a block diagram of an equalization section to outline an embodiment of the present invention.

114.115 is the above-mentioned flower vase and judgment device, and 15
0,151 is also the phase detector and jitter phase controller described in the conventional example. For example, in the case of phase modulation, the phase detector 150 can detect by dividing the constant output yk by the judgment value ak and taking its imaginary part (the signal is treated as a complex number).
The phase controller becomes a filter with a transfer function of second order or higher.

FIG. 2 shows the output of the jitter phase controller 151 when the only fluctuation component of one line is actually phase jitter. Assuming that the arrow point is the current point, in the conventional method, the phase detector 150 at the arrow point
The output value was feedback-controlled to the output of the flower vase.

Therefore, whereas in the past, the average jitter component over the span width of the iso-vase was fed back to the iso-vase output, in this embodiment, the jitter component is fed back to the iso-vase output at the current time shown in Fig. 3(a). The purpose is to feed back the real-time jitter component to each tap gain of the equalizer, rather than the average jitter in the width (equalizer span width). Show the configuration. - In the container 114, 130 is a transmission data shift register that transfers received data bit by bit; 131 is a tap gain register that generates a tap gain to be multiplied by the output of each stage of the register 130; 132; 133 is a multiplier that multiplies the output of each stage of the shift register 130 by a tap gain, and 133 is an adder that calculates the sum of the outputs of the multiplier 132. - Here, it is stored in the glue gain register 131 in the flower vase 114 in this embodiment. Tap gain is 3rd
It is set for a signal of a period corresponding to the time width shown in FIG. Generally, the tap gain stored in the tap gain register 131 is called a uniform impulse response, and distortion in the transmission path can be removed by making it equal to the inverse Fourier transform of the frequency characteristics of the transmission path. That is, the equal flower vase output signal yk is expressed by the following formula.

In setting the tap gain, prior to data communication, training is performed to transmit predetermined data between transmission and reception.

Generally, tap gain (CN to CN) is calculated using Mean
Using the 5-square Frollor method (MSE method), it is calculated sequentially using the following formula.

α: Convergence coefficient (α<<1) ak: Predicted value of received signal ak (during training ak = ak) The above calculation is also performed during data communication after training to follow gradual fluctuations in line characteristics.

In this embodiment, it is necessary to predict the future unknown jitter component shown by the dotted line in FIG. 3(a) from the past jitter component. This prediction is performed using the jitter phase in FIG. A predictor 160.

An example of the prediction method is shown in FIG. 3(b). This involves folding back the jitter components obtained up to this point to create a mirror image, which is then used as the prediction part. Note that various other methods can be considered for this prediction.

In fact, such processing is often performed using a programmable digital signal processor (DSP).
To change this prediction method, it is only necessary to change the software, so there is no need to change the hardware configuration to create, for example, the above-mentioned jitter phase predictor.

In this embodiment, the output of the jitter predictor 160 is fed back as is to each tap gain of the isoflower. This situation is shown in Figure J84.

Incidentally, each tap gain of the flower vase 114 is stored as a tap gain register 161 on the memory when configured by, for example, a DSP. Each tap gain is multiplied by the output of the jitter predictor 160 using a multiplier 162. At this time, the tap gains are arranged from 01 to CN, and the smaller N is, the more future data there is, so the time axis of the predicted jitter to be multiplied is also in the opposite direction to that in FIG.

Also, at the time of this jitter correction, if it is possible to avoid losing the equalization function of a single equalizer, it is necessary to weight each tap gain before updating the taps using the collar signal in the MSE method of equation (2). You can also go as In this case, the original equalization performance of the vase is not degraded.

As described above, according to this embodiment, the jitter component of the time overlap portion covered by the flower vase is predicted, and each tap gain is adjusted using the predicted data, so the jitter is more accurate than in the past. Suppression becomes possible. - Next, the configuration of a modem including a receiving device into which the flower vase of the above-described embodiment is to be incorporated will be explained. An outline of this modem is shown in FIG. The part surrounded by the dotted line in the figure is the part included in the modem.

100 is a transmitting terminal that generates a transmitting digital signal, and 1
18 is a receiving terminal that receives the same signal.

Reference numeral 101 is a scrambler on the receiving side, which plays a role such as clarifying the delimitation of signals and whitens the transmitted data, and reference numeral 102 is an encoder that assigns a code to the scrambler output signal for each tribit, dibit, etc. 103 is a pulse shaping filter (roll-off filter) for preventing code amount interference of the □ signal.

104 is a modulator that puts a signal on a carrier wave. There are various modulation methods depending on the data transfer speed, etc., and typical ones include phase modulation (PS) that changes the phase of the carrier wave,
There are frequency modulation (FSX) that changes the same frequency, amplitude modulation (AM) that changes the same amplitude, and quadrature amplitude modulation (QAM) that changes the same amplitude and phase.

The signal modulated by the modulation base 104 is converted into an analog signal by a D/A converter 105 to be sent to an analog line, and excess harmonic components are removed by a low-pass filter 106 before being transmitted to a transmission line.

On the receiving side, the transmitted signal has components outside the transmission band removed by a bandpass filter 110, controlled by AGCl l 1 to a signal level that can be handled by the receiving side, roughly converted into a digital signal by an A/D converter 112, and then sent to a demodulator. In step 113, the signal is demodulated to the original signal (signal before modulation).

114 is the same flower vase shown in FIG. This extracts the original transmission signal.

This equalizer output signal is determined to be a code point by a determiner 115, further decoded by a decoder 116, and is converted into an original transmission signal by a descrunzer 117 for restoring the signal whitened by the scrambler 101. receiving terminal 1
Receive the same signal on 1B.

As described above, by using a modem to which the present invention is applied, data can be reliably transmitted through a general public line without the influence of jitter.

In the embodiment described above, the -g simple method of taking a mirror image up to the present time has been described as a prediction method for the unknown part of Jeddah, but there are various other prediction methods such as probability statistics. For example, by determining past jitter components, extracting the frequency component with the highest proportion among the past jitter components, or setting data corresponding to the jitter component that is most likely to occur based on the past cycle in the tap register. In addition, although the embodiment and conventional example have been described using a normal equal flower vase, the present invention is not limited to this. May
Needless to say, this method can also be applied to "equalization method for absorbing timing phase shift").

Furthermore, in this embodiment, a telephone line or the like is assumed as the transmission path, but the receiving apparatus of the present invention is not limited to this, and may of course include one that suppresses the jitter component of a signal reproduced from a recording medium having jitter, for example. be.

As explained below, according to this embodiment, since the method of removing all the jitter components for the span of the same flower vase is used, the jitter suppression power is greater than that of the conventional average value removal method, and as a result, the transmission error is reduced. This has the effect of enabling high-quality data communication with less traffic.

<Effects of the Invention> As explained above, according to the present invention, the jitter in the output of the transmitted data via the isolator is detected, and the equalization characteristic of the isolator is controlled according to the detected jitter. This makes it possible to effectively prevent jitter.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an image receiving device according to an embodiment of the present invention, Fig. 2 is a graph showing the jidder control amount, and Figs. 3 (a) and (b) explain the operation of the jidder predictor. Figure 4 is a diagram showing the Jeddah correction method according to the present invention, Figure 5 is a block diagram showing an overview of the modem, and the sixth factor is the first factor.
FIG. 7 is a block diagram showing the conventional line jitter control method. 114--Vase 150--Phase detector 151--Jitter phase control 160--Jitter phase predictor

Claims (2)

[Claims] (1) Means for detecting jitter in the output of transmitted data via an equalizer, and means for controlling equalization characteristics of the equalizer according to the jitter detected by the detecting means. Features of the receiving device. (2) The equalizer has a transversal filter, and the control means is a means for controlling the tap gain of the transversal filter in accordance with the jitter detected by the detection means. A receiving device according to claim 1.