JP2616622B2 - Frame correlation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame correlation used in a receiving section of a communication apparatus used in a digital communication system.
It concerns the device .

[0002]

2. Description of the Related Art In recent years, in the field of communications, especially in land mobile communications, a time division multiplex digital communication system has been adopted, and the detection of a slot, which is a unit of a time-division signal group, is performed on a transmitting side and a receiving side by frame correlation. Depending on the method.

FIG. 2 is a block diagram showing a configuration for realizing a conventional frame correlation apparatus . In FIG. 2, 1
A correlation unit 01 generates a correlation output signal by calculating a correlation between the input correlated signal and the other input correlation signal, and is configured by an AND circuit. Reference numeral 102 denotes a shift register unit that generates a correlation signal to be used as the other input of the correlation unit 101 based on a correlation output signal from the correlation unit 101 and a clock signal synchronized with the correlated signal, and stores data for one frame. It has a possible number of stages (for example, N stages).

Next, the operation of the above conventional example will be described. First, the shift register unit 102 is initialized, and data “1” is stored in all registers (not shown) of each stage. When the correlated signal A of one frame is input to the correlator 101, the correlated signal A and the shift register 10
The logical product of the outputs of the two, that is, the correlation signal B of all “1” is obtained, and the same correlation output signal Y as the signal to be correlated is input to the shift register unit 102. When the correlated signal A is input in the next frame, the correlation signal B (=
A) and a correlation is obtained, and a correlation output signal Y (BA) is obtained. That is, when A = 1 and B = 1, the correlation unit 10
The output Y of "1" becomes "1", indicating that the correlation has been obtained.

As described above, the correlation with the signal one frame before is always obtained. Shift register section 102
Are shifted by a shift clock which is a clock signal synchronized with the correlated signal, and the shift register unit 1
Since the number of stages of 02 matches the number of data in one frame, the output of the shift register unit 102, that is, the correlation signal and the correlated signal have the same relative position in the frame, so that the frame correlation can be obtained. .

[0006]

However, in the above-described conventional frame correlation apparatus , since a clock signal synchronized with the correlated signal is used as the shift clock, frame correlation can be realized. When the shift clock cannot be used, there is a problem that the frame correlation cannot be obtained.
In particular, in the case of time division multiplexing, intermittent reception is performed, so that it may be difficult to reproduce a clock signal synchronized with the correlated signal due to the influence of jitter or the like depending on the modulation method.

[0007] The present invention is to solve the above problems,
An object of the present invention is to provide an excellent frame correlation apparatus capable of calculating a frame correlation even when a clock signal synchronized with a signal to be correlated is not used as a shift clock.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a sampling means for oversampling a correlated signal having one frame as a unit of signal format, Correlation means for performing a correlation with the signal to generate a correlation output signal;
The correlation output signal is shifted by the shift clock to generate a correlation signal exceeding one frame and counted from the last stage.
A correlation signal generating means for outputting a correlation signal from each of the plurality of terminals and a timing adjusting means for outputting a logical sum of the plurality of correlation signals as a correlation signal to be input to the correlation means.

[0009]

According to the present invention, the correlated signal is oversampled to generate a correlated signal exceeding one frame, and a plurality of correlated signals are counted from the last stage of the correlated signal generating means.
Output a correlation signal from each terminal and determine the presence or absence of a correlation within the time width of the plurality of data, so that the frame correlation can be obtained even when the shift clock is not synchronized with the correlated signal. effective.

[0010]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a configuration for realizing the frame correlation method of the present invention, wherein 1 is an oversampling section (sampling means) for performing high-speed oversampling on an input correlated signal, and 2 is an oversampling section. A correlation unit (correlation means) for correlating the correlated signal obtained from 1 with the correlation signal input from the other to generate a correlation output signal. Reference numeral 3 denotes a shift register unit (correlation signal generation means) that generates a correlation signal by shifting the correlation output signal from the correlation unit 2 using a shift clock, and has a plurality of (2α + 1) output terminals (for α). Will be described later). Reference numeral 4 denotes a timing adjustment unit (timing adjustment means) for adjusting the timing by taking the logical sum of the data from the shift register unit 3.

Next, the operation of the configuration of the above embodiment will be described. First, the correlated signal A input to the oversampling unit 1 is oversampled at a speed higher than the expected maximum data rate of the signal, and a correlated signal C is generated. This oversampling is performed to prevent data loss due to a shift in sampling frequency.

The correlated signal C is correlated through the correlator 2 and then input to the shift register 3 as the correlation signal Z. The number of stages of the shift register 3 depends on the speed deviation.
In order to absorb the generated shake, α is provided by α more than the data number (N) of one frame. Therefore, the number of stages of the shift register is N + α. The shift register section 3 counts up to the 2α + 1-th number from the last stage.
From the terminal, the data is adjusted in timing as parallel data.
It is output to the adjusting unit 4. The 2α + 1 pieces of data are input to the timing adjustment unit 4 and ORed. If at least one data is “1”, that is, there is correlated data, the data of the correlation signal D of “1” is converted to the timing adjustment unit 4. 4 to correlator 2
Supplied to

As described above, since the presence or absence of a correlation is determined within the time width of 2α + 1 data, even if the timing of the correlated signal and the correlation signal is shifted due to jitter or the like, erroneous detection of the correlation due to this shift is performed. Can be prevented.

The value of α is determined by the maximum deviation of the clock signal speed in the frame correlation method with respect to the data speed of the correlated signal. For example, when the speed difference is 1%, the total time length of the shift register unit 3 is set to 1% or more than the time length when the data speed of the correlated signal and the clock signal speed of the frame correlation method are synchronized. It should be longer.

[0015]

As described above, according to the frame correlation method of the present invention, the sampling means for oversampling the input correlated signal and the timing for correcting the output of the shift register unit as the correlation signal generating means. By providing the adjusting means, the presence or absence of a correlation is determined within the time width of a plurality of data. Therefore, the timing shift of the shift register unit is corrected, and even if a clock signal synchronized with the correlated signal cannot be obtained, the normality can be obtained. This has the effect that a frame correlation can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram of a configuration of an embodiment for realizing a frame correlation method according to the present invention;

FIG. 2 is a block diagram of a configuration for realizing a conventional frame correlation method.

[Explanation of symbols]

 Reference Signs List 1 oversampling unit 2 correlation unit 3 shift register unit 4 timing adjustment unit

Claims (3)

(57) [Claims] 1. A sampling means for oversampling a correlated signal having one frame as a unit of signal format, and a correlation for generating a correlation output signal by correlating the correlated signal with the oversampled correlated signal. means and, by shifting the correlation output signal to generate a correlation signal greater than one frame by the shift clock, the last stage
A correlation signal generation unit that outputs a correlation signal from each of the plurality of terminals counted from the first and a timing adjustment unit that outputs a logical sum of the plurality of correlation signals, and an output of the timing adjustment unit is provided to the correlation unit. A frame correlation device for inputting as a correlation signal. 2. The method according to claim 1, wherein the number of correlation signals exceeding one frame of said correlation signal generation means is determined by a maximum deviation of a speed of said shift clock from a data speed of said correlated signal. Described frame correlation
Equipment . 3. The number of correlation signals output from the correlation signal generation means is a number obtained by adding 1 to twice the number of correlation signals exceeding one frame.
A frame correlation device as described.