KR20030065148A - Correlation system and method to compensate for group delay property - Google Patents

Abstract

PURPOSE: A group delay compensation correlation system which is not influenced by a group delay characteristic of a filter in a frequency spread PLC(Power Line Communication) and a method therefor are provided so that a band-spread data symbol maintains stable correlation in a group delay characteristic generated in a power line channel and group delay environment by a receiving filter. CONSTITUTION: A falling edge detector(301) detects a falling edge of a pulse train of an inputted receiving signal. A rising edge detector(303) detects a rising edge of the pulse train of the inputted receiving signal. The first pulse generator(307) generates a pulse having a uniform time width whenever receiving a falling edge signal from the falling edge detector(301). The second pulse generator(309) generates a pulse having a uniform time width whenever receiving a rising edge signal from the rising edge detector(303). An adder(311) receives a result value of the first pulse generator(307) and a result value of the second pulse generator(309), and adds the received result values. A correlator(313) receives a result value of the adder(311) and a reference signal, and outputs the correlation of two signals.

Description

Group delay compensation correlation system not affected by filter group delay characteristics in frequency spread power line communication and its method {Correlation system and method to compensate for group delay property}

The present invention relates to a group delay compensation correlation system and method thereof used for power line communication. More particularly, the present invention relates to a group delay compensation correlation system that is stable in a group delay characteristic caused by a spreading data symbol and a reception filter. The present invention relates to a group delay compensation correlation system and a method for maintaining correlation and not being affected by a group delay characteristic of a filter in a frequency spread power line communication in which spreading frequencies have the same correlation value in time.

In spread spectrum power line communication, power line communication channels have various frequency transfer characteristics and various noise characteristics. For this reason, the front-end of the receiver must use various filters for communication signal extraction.

However, due to the application of such a filter, a group delay of a received signal occurs, and a change of the group delay characteristic occurs due to a change in power line communication channel characteristics. Group delay is an indispensable element of the filter configuration, and has a unique delay characteristic for each frequency according to the function characteristic of the filter. This group delay characteristic has a problem in that the phase information of the communication data symbol (Symbol) is changed to seriously affect the reception correlator.

Therefore, even in a situation where the phase information of the data symbol is changed by the group delay characteristic and the communication channel characteristic of the filter, a correlator capable of accurately detecting data correlation is urgently needed.

FIG. 1A is a waveform diagram showing a symbol for representing data in a conventional spread spectrum scheme, FIG. 1B is a diagram illustrating group delay characteristics of a filter in a conventional spread spectrum scheme, and FIG. 1C is received data having a group delay characteristic. FIG. 1D is a waveform diagram of a symbol, and FIG. 1D illustrates a difference between phase data of a reference data symbol and a data symbol received through a filter.

The configuration of the filter for receiving the frequency band of the symbol upon reception is made by a band pass filter. 1A shows a symbol for representing data in such a spread spectrum method.

In this case, as shown in FIG. 1B, the group region characteristic of the filter has a characteristic that the greatest delay occurs at a low frequency, which is a start point of a pass band, and decreases toward a high frequency. Here, reception of data symbols consisting of four frequencies, namely f1, f2, f3, and f4, for example, data symbols received through a filter becomes as shown in FIG. 1C due to the influence of group delay characteristics of the filter.

At this time, to be.

Due to the nature of the power line communication channel, the detection of data symbols is generally configured using only phase information rather than symbol size. FIG. 1D illustrates a difference between phase information of the reference data symbol and the data symbol received through the filter.

2A is a graph showing a relationship between a sampling period of a reference signal and a correlation value, and FIG. 2B is a graph showing a correlation between a reference signal and a filter reception signal.

Assuming that the correlation value of one sampling period is 1, autocorrelation of the data symbols is obtained. As shown in FIG. 2A, it can be seen that the correlation value is 30. However, the correlation value of the group-delayed received signal through the filter is 24, as shown in FIG. 2B.

That is, in the spread spectrum power line communication, the group delay characteristic of the filter greatly affects the correlation of the correlator.

In fact, power line channels show unpredictable channel characteristics due to the influence of electrical devices and wiring schemes connected to the power lines, and these group delays occur frequently and the delay characteristics change constantly, which is a big obstacle that makes power line communication difficult. It is working.

Therefore, there is an urgent need for a correlation system capable of maintaining stable correlation even in a group delay characteristic of a spread spectrum data symbol in a power line channel and a group delay caused by a reception filter.

An object of the present invention to solve the problems of the prior art as described above is to maintain a stable correlation in the group delay characteristics that can be generated in the spread line data symbol in the power line channel and the group delay phenomenon by the reception filter, An object of the present invention is to provide a group delay compensation correlation system and a method which are not affected by a group delay characteristic of a filter in a frequency spread power line communication that has the same correlation value in time in a band.

1A is a waveform diagram showing a symbol for representing data in a conventional spread spectrum method;

1B is a diagram illustrating group delay characteristics of a filter in a conventional spread spectrum method.

1C is a waveform diagram of a received data symbol having group delay characteristics,

1D is a diagram illustrating a difference between phase data of a reference data symbol and a data symbol received through a filter,

2A is a graph showing a relationship between a sampling period and a correlation value of a reference signal,

2B is a graph showing a correlation between a reference signal and a filter reception signal.

3 is a block diagram of a group delay compensation correlation system according to an embodiment of the present invention;

FIG. 4 is a waveform diagram of the results of each component shown in FIG. 3 when autocorrelation is obtained using the reference signal shown in FIG. 2A.

FIG. 5 is a waveform diagram illustrating the operation of each component of the group delay compensation correlation system using the reference signal and the filter reception signal shown in FIG. 2B.

※ Explanation of code about main part of drawing ※

301: falling edge detector 303: rising edge detector

305: reference pulse unit 307: first pulse generator

309: second pulse generator 311: adder

313: Correlator

In order to achieve the above object, according to the present invention, in a correlation (Correlation) system used for frequency spread power line communication (PLC), the falling edge detector for detecting the falling edge of the pulse train of the received signal ( Falling Edge Detector); A rising edge detector for detecting a rising edge of a pulse train of an input received signal; A first pulse generator generating a pulse having a predetermined time width each time the falling edge signal is input from the falling edge detector; A second pulse generator for generating a pulse having a predetermined time width each time the rising edge signal is input from the rising edge detector; An adder which receives the result value of the first pulse generator and the result value of the second pulse generator and adds the result to OR to form a single signal; And a correlator receiving a result of the adder and a reference signal (reference data symbol) and outputting a correlation between the two signals. Provides a military delay compensation correlation system that is not received.

A correlation method used for frequency spread power line communication, the method comprising: detecting a falling edge and a rising edge of a pulse train of an input received signal; Generating a pulse having a predetermined time width each time the falling edge signal and the rising edge signal are received; Receiving a pulse result value for the falling edge signal and the rising edge signal, and adding the result values to form a single signal; And receiving the addition value and a reference signal (reference data symbol) and outputting a correlation between the two signals, wherein the filter is not affected by the group delay characteristic of the filter in the frequency spread power line communication. A group delay compensation correlation method is provided.

Even more preferably, the width of the generated constant reference pulse has a period of the highest frequency of the input reference signal (reference data symbol).

A computer-readable recording medium capable of executing a correlation program used for frequency spread power line communication, comprising: detecting a falling edge and a rising edge of a pulse train of an input received signal; Generating a pulse having a predetermined time width each time the falling edge signal and the rising edge signal are received; Receiving a pulse result value for the falling edge signal and the rising edge signal, and adding the result values to form a single signal; And receiving the addition value and a reference signal (reference data symbol) and outputting a correlation between the two signals, wherein generating the pulse having the predetermined time width is the highest of the reference signal (reference data symbol). A computer capable of executing a group delay compensation correlation program that is not influenced by a group delay characteristic of a filter in frequency spread power line communication, characterized in that it is generated by referring to a pulse having a period of frequency. It provides a recording medium that can be read by.

Hereinafter, a group delay compensation correlation system and a method which are not affected by a group delay characteristic of a filter in frequency spread power line communication according to an embodiment of the present invention with reference to the accompanying drawings will be described in detail. Shall be.

3 is a block diagram of a group delay compensation correlation system according to an embodiment of the present invention, the group delay compensation correlation system includes a falling edge detector 301, a rising edge detector 303, and a reference signal. Pulse width reference (305), first pulse generator (Pulse Generator # 1, 307), second pulse generator (Pulse Generator # 2, 309), adder (OR, 311) and correlator 313 It is provided.

The operation relationship will be described in detail as follows.

First, the falling edge detector 301 and the rising edge detector 303 detect the falling edge and the rising edge of the pulse train of the input signal, and then output the signal to the pulse generators 307 and 309.

The first pulse generator 307 generates a pulse having a predetermined time width whenever the falling edge signal is input from the falling edge detector 301. Similarly, the second pulse generator 309 generates a pulse having a predetermined time width whenever the rising edge signal is input from the rising edge detector 303. In this case, the reference pulse unit 305 transmits a constant pulse width to the pulse generators 307 and 309 so that the pulse units 307 and 309 refer to the pulse generation reference.

On the other hand, the constant pulse width data transmitted from the reference pulse unit to the pulse generators may have a period of the highest frequency among the reference signals input to the correlator 313 to be described later.

The reason why it is preferable to have the period of the highest frequency among the reference signals is as follows.

In the process of converting the received signal into a signal of the reference pulse, the correlation value outputted by the magnitude of the time width of the reference pulse is changed. That is, the narrower the pulse width, the lower the correlation value is output, and the higher the higher the correlation value may be. Thus, it is advantageous in many ways to obtain the maximum correlation value for the same received input, where the maximum pulse width that can be applied cannot exceed the highest frequency (the larger pulse width begins to be affected by group delay). box).

For that reason, the reference pulse width which makes the period of maximum frequency the time width becomes the highest pulse width which can be used, and then has the highest correlation value.

In addition, the adder 311 receives and adds a '+1' pulse that is a result of the first pulse generator 307 and a '-1' pulse that is a result of the second pulse generator 309. By OR, the signal is made into one signal and then output to the correlator 313 together with the reference signal (reference data symbol).

The correlator 313 outputs a correlation between two input signals.

At this time, if the result of the adder is y (t) and the reference signal is x (t), the correlation value R (x, y) is determined by Equation 1 below.

FIG. 4 is a waveform diagram of the results of each component shown in FIG. 3 when autocorrelation is obtained using the reference signal illustrated in FIG. 2A.

(A) is a waveform of a reference signal, (b) is a waveform of a rising edge, (c) is a waveform of a falling edge, (d) is a waveform of the result value of a 1st pulse generator, (e) ) Is the waveform of the output of the second pulse generator, (f) is the waveform of the output of the adder, and (g) is the waveform of the final output of the correlator.

FIG. 5 is a waveform diagram illustrating the operation of each component of the group delay compensation correlation system using the reference signal and the filter reception signal shown in FIG. 2B.

(A) is a waveform of a reference signal, (b) is a waveform of a filter reception signal, (c) is a waveform of a rising edge, (d) is a waveform of a falling edge, and (e) is a 1st waveform. (F) is the result waveform of the second pulse generator, (g) is the result waveform of the adder, and (h) is the waveform of the final output value of the correlator.

That is, FIG. 4 illustrates a case where the maximum correlation value is obtained by using the reference signal itself as the comparison input of the correlator, and it can be seen that the correlation value at this time is up to eight.

Although FIG. 5 illustrates a case in which the phase of a data symbol is delayed for each frequency according to the group delay characteristic of the filter, the correlation value is still 8 when the group delay compensation correlation system proposed by the present invention is applied.

As described above, the group delay compensation correlation system proposed by the present invention has an accurate correlation value for the group delay phenomenon of the power line channel and the group delay caused by the filter, and at this time, the maximum group delay that does not affect the correlation value is self The same correlation will be achieved up to a group delay that is half the frequency period. Therefore, the same correlation value can be obtained for any group delay.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, according to the present invention, an accurate correlation value can be obtained despite the group delay phenomenon of the power line channel and the group delay caused by the filter.

In addition, even in an environment where a specific frequency disappears, the correlation value is changed at the same correlation ratio regardless of the time share of the specific frequency, thereby providing a correlation system having characteristics suitable for the power line channel.

Claims (9)

In a correlation system used for frequency spread power line communication (PLC), Falling Edge Detector for detecting the falling edge of the pulse train of the received received signal (Falling Edge Detector); A rising edge detector for detecting a rising edge of a pulse train of an input received signal; A first pulse generator generating a pulse having a predetermined time width each time the falling edge signal is input from the falling edge detector; A second pulse generator for generating a pulse having a predetermined time width each time the rising edge signal is input from the rising edge detector; An adder which receives the result value of the first pulse generator and the result value of the second pulse generator and adds the result to OR to form a single signal; And It is not affected by the group delay characteristics of the filter in the frequency spreader power line communication, characterized in that it comprises a correlator for receiving the result of the adder and the reference signal (reference data symbol) and outputs the correlation between the two signals. No military delay compensation correlation system. The method of claim 1, And transmitting a constant pulse width to the first pulse generator and the second pulse generator so that the first pulse generator and the second pulse generator further generate a reference pulse to refer to as a reference. A group delay compensation correlation system which is not influenced by a group delay characteristic of a filter in a frequency spread power line communication. The method of claim 2, The group delay that is not affected by the group delay characteristic of the filter in the frequency spreading power line communication, characterized in that the width of the pulse generated by the reference pulse unit has a period of the highest frequency among the reference signals input to the correlator. Compensation correlation system. The method of claim 1, The correlator is a group delay compensation correlation system that is not affected by the group delay characteristics of the filter in the frequency spread power line communication, characterized in that to determine the correlation according to the following equation (1). [Equation 1] Here, y (t) is the result value of the adder, and x (t) is the reference signal. In the correlation method used for frequency spread power line communication (PLC), Detecting a falling edge and a rising edge of a pulse train of an input received signal; Generating a pulse having a predetermined time width each time the falling edge signal and the rising edge signal are received; Receiving a pulse result value for the falling edge signal and the rising edge signal, and adding the result values to form a single signal; And Receiving the addition value and a reference signal (reference data symbol) and outputting a correlation between the two signals, which are not affected by the group delay characteristics of the filter in the spread spectrum power line communication. Group Delay Compensation Correlation Method. The method of claim 5, And generating a constant reference pulse width so as to be referred to as a reference when generating a pulse having a predetermined time width, wherein the group delay compensation correlation method is not affected by the group delay characteristic of the filter. The method of claim 6, The width of the generated constant reference pulse has a period of the highest frequency among the input reference signals (reference data symbols), the group delay is not affected by the group delay characteristics of the filter in the frequency spread power line communication Compensation correlation method. The method of claim 5, Group delay compensation correlation method that is not affected by the group delay characteristics of the filter in the frequency spread power line communication, characterized in that the correlation is determined by the following [Equation 2]. [Equation 2] Here, y (t) is the addition value, and x (t) is the reference signal. A computer-readable recording medium capable of executing a correlation program used for frequency spread power line communication (PLC), Detecting a falling edge and a rising edge of a pulse train of an input received signal; Generating a pulse having a predetermined time width each time the falling edge signal and the rising edge signal are received; Receiving a pulse result value for the falling edge signal and the rising edge signal, and adding the result values to form a single signal; And Receiving the addition value and a reference signal (reference data symbol) and outputting a correlation between the two signals; Generating the pulse having a predetermined time width is generated by referring to the pulse having the period of the highest frequency of the reference signal (reference data symbol) group delay of the filter in the frequency spread power line communication, characterized in that (Computer Delay) A computer-readable recording medium capable of executing a group delay compensation correlation program which is not affected by the characteristics.