JPS6058622B2 - Reception timing extraction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting reception timing by determining the peak value of a timing waveform from sample points of a timing filter output, calculating the reciprocal of the peak value, and multiplying the reciprocal of the peak value by the timing output. It is.

Conventionally, as shown in FIG. 1, an analog timing signal received by a data transmission modem is passed through an automatic gain control circuit (AGC) 1 and then sent to a sample and hold circuit (S/H).
2 and converted into a digital signal by the A/D converter 3, and then regenerated by the filter 4.

However, as shown in the figure, the reproduced timing output level varies depending on the line characteristics or the input level, which causes a reduction in the dynamic range with respect to timing pull-in.

An object of the present invention is to provide a reception timing extraction method that does not affect the dynamic range of timing due to line characteristics or input levels.

In order to achieve the above object, the reception timing extraction method of the present invention converts a received analog signal including a timing component into a digital signal and extracts the timing of the reception signal through filter means. means for determining the peak value of the received signal from sampling amplitude values at at least two sampling points obtained by sampling the output signal, and calculating the reciprocal value of the peak value; and means for calculating the average value of the calculated reciprocal values. and multiplying the obtained average value by the output signal of the filter means to obtain a normalized waveform,
This method is characterized in that the reception timing is extracted after that.

The present invention will be described in detail below with reference to examples.

FIGS. 2a and 2b are explanatory diagrams of the principle of the present invention.

In FIG. 1A, at least one of the sampling amplitude values of the timing waveform passed through the filter 4 in FIG. 1 corresponds to, for example, point P1, and the rising or falling time of the pulse in FIG. 1 is detected. If the digital amplitude values of the timing waveform at this time point P and the next time point P2 are S1 and S2, then the value of A can be calculated from equations (2) and (3) for the peak value A.

By multiplying the timing output waveform by the reciprocal of the peak value A obtained in this way to obtain a normalized waveform and pulling in the reception timing, timing with a constant amplitude can be obtained. FIGS. 3A and 3B are explanatory diagrams showing the configuration of an embodiment of the present invention. In FIG. 1A, the configuration up to filter 4 is as shown in FIG. Digital amplitude value Sl, S2 and its phase difference T between the time point and the next P2 time point
From this, A can be found using equation (3).

The reciprocal number 1/A of this A is input to the average value circuit 12, and the amplitude S
The average value of the reciprocal 1/A is calculated and input to the multiplier 13 so that l, S2 is not affected by noise, and is multiplied by the output of the filter 4. In this way, a normalized timing signal, that is, a timing signal whose amplitude is kept constant at 1 as shown in FIG. 5B, is obtained. As explained above, according to the present invention,
The peak value of the timing waveform is determined from at least two sample points of the timing filter output, and the reciprocal of the peak value is calculated and multiplied by the timing output, thereby obtaining a timing signal with a constant amplitude and extracting the timing. be.

As a result, the phase information extracted from the amplitude value is accurate without the amplitude changing due to line characteristics or input level, so that the dynamic range of timing is not affected, and stable timing can be extracted.

[Brief explanation of drawings]

Figures 1A and b are explanatory diagrams of the conventional example, Figures 2A and b are illustrations of the principle of the present invention, and Figures 3A and b are explanatory diagrams a and operation waveform diagrams showing the configuration of the embodiment of the present invention. In the figure, 1 is an automatic gain control circuit, 2 is a sample hold circuit, 3 is an A/D converter, 4 is a filter, 11 is a reciprocal calculation circuit, 12 is an average value circuit, and 13 is a multiplication section. .

Claims (1)

[Claims] 1. In a reception timing extraction method that converts a received analog signal including a timing component into a digital signal and extracts the timing of the received signal through filter means,
means for determining the peak value of the received signal from the sampling amplitude values at at least two sampling points obtained by sampling the output signal of the filter means and calculating the inverse value of the peak value; 1. A reception timing extraction method, comprising: obtaining means, multiplying the obtained average value by the output signal of said filter means to obtain a normalized waveform, and then extracting the reception timing.