JP2000115027A - Spread spectrum communication method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum communication method and a device thereof reduced in malfunction. SOLUTION: A transmission side sends a PN series for data 1 more than once for synchronism establishment and a reception side correlates a receive signal and the PN series for data 1 with each other for the synchronism establishment. The correlation output is detected by a peak detector 17 for a data section, and when the correlation peak value exceeds the threshold of a comparator 23, the peak value and peak position of the correlation peak are held. A control part 18 sets the load value of a counter 19 so that the peak position is at a given position in the data section and also controls a selector 22 to places a peak detector 17 in operation in an observation section which is much narrower than the data section and has its center at the specific position with the output of a after the observation section is set, the control part 18 judges that synchronism is established and outputs a synchronism establishment signal when the correlation peak is larger than the threshold of the comparator 23 and the frequency of the generation of a correlation peak exceeding the threshold value exceeds a predetermined frequency or a prescribed rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication method for transmitting and receiving data using a power line, and a transmission / reception unit of a communication device.

[0002]

2. Description of the Related Art A spread spectrum communication method (hereinafter referred to as SS communication) is disclosed in Japanese Patent Application Laid-Open No.
132929 to JP-A-6-129331 are disclosed.

In these SS communication methods, the transmitting side modulates bit data "1" and "0" with pseudo noise sequences having different phases from each other (hereinafter referred to as PN sequence) and transmits the modulated data.
On the receiving side, the correlation between the received signal and the same PN sequence used on the transmitting side is taken, the peak values from both correlation outputs are compared in magnitude, and the PN used to find the larger correlation peak value is obtained.
It demodulates the bit data assigned to the stream.

[0004] At the first position of the transmission data, a bit "1" is continuously arranged for a predetermined number of times for synchronization. On the receiving side, the bit for establishing synchronization is captured a predetermined number of times, and then the data is demodulated. Is going. After this synchronization was established, the maximum peak position was to occur within the observation section,
This observation interval was relatively wide.

[0005]

However, in the conventional SS communication, when the SS signal is not transmitted and only noise occurs, a relatively large correlation peak is generated in the correlator on the receiving side as shown in FIG. Sometimes. Since this is due to noise, it appears randomly, but still, in a wide observation section, a correlation peak appears a predetermined number of times in the observation section,
The receiving side sometimes erroneously synchronized.

As shown in FIG. 11, when the SS signal is being transmitted, the correlation value from the correlator may be such that the correlation peak becomes small, or a secondary peak appears at a distant place. Depending on the case, this secondary peak may be larger than the correlation peak. Therefore, when the synchronization is established during the reception of the SS signal, synchronization may not be achieved due to the secondary peak.

The present invention has been made in view of such a problem, and it is considered that synchronization is achieved when a correlation peak equal to or higher than a threshold is detected due to noise during non-transmission of an SS signal. A spread spectrum communication method and apparatus capable of preventing a correlation peak from becoming smaller and becoming out of synchronization due to a secondary peak even when a malfunction occurs or an SS signal is sent to an intended receiving side. The purpose is to provide.

[0008]

In order to solve the above-mentioned problems, the spread spectrum communication method according to the first aspect of the present invention provides a method for transmitting two data having the same code length different from each other for data 1 and data 0 on the transmitting side. A PN sequence is prepared, a PN sequence for data 1 is assigned to a logical value “1” of each bit constituting transmission data, and a PN sequence for data 0 is assigned to a logical value “0” of a bit, and transmitted.

On the receiving side, the transmission data is received, the received signal is correlated with the same PN sequence for data 1 and data 0 used on the transmitting side, and the maximum peak of both correlation outputs is obtained. It is determined whether the maximum peak is obtained by the correlation between the received signal and the PN sequence of the PN sequence, and demodulated into data corresponding to the determined PN sequence, or the correlation peak value appearing in both correlation outputs is determined. PN of which one is compared with each other to obtain the larger correlation peak
In a spread spectrum communication method for demodulating to data corresponding to a sequence,

[0010] The transmitting side transmits either the PN sequence for data 1 or the PN sequence for data 0 a plurality of times to establish synchronization, and the receiving side transmits a received signal and the above-mentioned transmitting side to establish synchronization. First, a correlation peak value and a correlation peak position of a correlation output are obtained over one entire period of a 1-bit data section. When exceeding, the length of the next data section is corrected so that the correlation peak position is at a predetermined position in the data section in the next data section,
From the next data section onward, the above-mentioned predetermined position is included as the approximate center, an observation section having a sufficiently narrow width is set for the data section, and a correlation peak value is obtained within this observation section. Synchronization is established when a state exceeding the threshold value exists a predetermined number of times.

In the spread spectrum communication method according to a second aspect of the present invention, two PN sequences for data 1 and data 0 having the same code length different from each other are prepared on the transmitting side, and each bit constituting the transmission data is prepared. P for data 1 to logical value "1"
N sequences are assigned, and a data 0 PN sequence is assigned to a bit logical value “0” and transmitted.

On the receiving side, the transmission data is received, the received signal is correlated with the same data 1 and data 0 PN sequence used on the transmitting side, and the maximum peak of both correlation outputs is obtained. It is determined whether the maximum peak is obtained by the correlation between the received signal and the PN sequence of the PN sequence, and demodulated into data corresponding to the determined PN sequence, or the correlation peak value appearing in both correlation outputs is determined. PN of which one is compared with each other to obtain the larger correlation peak
In the spread spectrum communication method of demodulating to a data corresponding to a sequence, the transmitting side transmits either the PN sequence for data 1 or the PN sequence for data 0 multiple times to establish synchronization,

[0013] To establish synchronization, the receiving side uses the same P as the received signal and the same PN sequence sent by the transmitting side for establishing synchronization.
Correlate with N series, and start with 1-bit data section 1
Find the correlation peak value and correlation peak position of the correlation output over the entire cycle, and when the correlation peak value exceeds the threshold,
The correlation peak position is set to be substantially at the center, and an observation section having a sufficiently narrow width with respect to the data section is set. From the next data section onward, a correlation peak value is obtained within this observation section. Synchronization is established when a state exceeding the threshold value exists a predetermined number of times.

The spread spectrum communication method according to claim 3 of the present invention is the spread spectrum communication method according to any one of claims 1 and 2, wherein the PN sequence for data 1 and the PN sequence for data 0 have the same PN sequence phase. It is characterized by being shifted.

In the spread spectrum communication method according to a fourth aspect of the present invention, in the spread spectrum communication method according to any one of the first to third aspects, the synchronization is established when a peak value larger than the threshold value continues for a predetermined number of times. It is characterized in that it occurs when it occurs.

A spread spectrum communication method according to a fifth aspect of the present invention is the spread spectrum communication method according to any one of the first to fourth aspects, wherein the number of times of occurrence of a peak value exceeding a threshold value as a condition for establishing synchronization is present. When the occurrence or the predetermined number of consecutive occurrences is not satisfied, the synchronization is not established, and a transition is made again to an initial state in which the correlation peak value and the correlation peak position are observed over the entire one bit data section period.

The transmitting section of the spread spectrum communication apparatus according to claim 6 of the present invention is the transmitting section of the spread spectrum communication apparatus used in the spread spectrum communication method according to any one of claims 1 to 5, wherein P that generates the PN sequence for
N-sequence generator and PN0 for generating PN sequence for data 0
It is characterized by comprising a sequence generator, and a control unit for transmitting either the data 1 PN sequence or the data 0 PN sequence a predetermined number of times to establish synchronization.

The receiving section of the spread spectrum communication apparatus according to claim 7 of the present invention is the receiving section of the spread spectrum communication apparatus used in the spread spectrum communication method according to any one of claims 1, 3, 4, and 5, A time measuring unit for setting the length of the data section, a correlator for outputting a correlation value between the received signal and the same PN sequence sent for establishing synchronization on the transmission side, and a peak value and a peak position of the correlation output And the detection area has a peak that can select either one whole period of the 1-bit data section or an observation section set in advance with a width sufficiently narrower than the one cycle of the data section. A detector, a comparator for comparing a peak value of a correlation peak output from the peak detector with a threshold value, and in an initial state of reception, the peak over one period of a 1-bit data section. When the output of the comparator exceeds a threshold, the correlation peak position is located at a substantially central position in the observation section in the next data section. Instruct the time measurement unit to correct the length of the next data section, and after the next data section, make the peak detector observe the correlation peak value in the observation section, and the observed correlation peak value is When the state exceeding the threshold value exists a predetermined number of times,
A control unit that determines that synchronization has been established and outputs a synchronization establishment signal;
It is characterized by having.

The receiving section of the spread spectrum communication apparatus according to claim 8 of the present invention is the receiving section of the spread spectrum communication apparatus used in the spread spectrum communication method according to any one of claims 2 to 5, wherein A time measurement unit that sets the length of the signal, a correlator that outputs a correlation value between the received signal and the same PN sequence sent for synchronization establishment on the transmission side, and detects the peak value and peak position of the correlation output And a peak detector capable of selecting one of the entire 1-bit data section or the observation section set by the control unit described below in one cycle of the data section. A comparator for comparing the peak value of the correlation peak output from the peak detector with a threshold value, and in the initial state of reception, the peak detector over one cycle of a 1-bit data section. Seki peak value and peak position are observed, and when the output of the comparator exceeds a threshold, the correlation peak position is included substantially at the center, and an observation section having a sufficiently narrow width with respect to the data section is set. After the next data section, the peak detector makes the peak detector observe the correlation peak value in the observation section, and when there is a state in which the observed correlation peak value exceeds the threshold for a predetermined number of times, it is determined that synchronization is established. And a control unit for outputting a synchronization establishment signal.

According to a ninth aspect of the present invention, in the receiving section of the spread spectrum communication apparatus according to any one of the seventh and eighth aspects, the control section determines whether synchronization has been established. It is characterized in that a peak larger than the value occurs continuously for a predetermined number of times.

According to a tenth aspect of the present invention, in the receiving unit of the spread spectrum communication apparatus according to any one of the seventh to ninth aspects, the control unit is a condition for establishing synchronization. When the predetermined number of occurrences of the peak value exceeding the threshold value or the predetermined number of consecutive occurrences is not satisfied,
As synchronization is not established, a transition is made to an initial state in which a correlation peak is again observed over one period of data. A spread spectrum communication apparatus according to an eleventh aspect of the present invention includes the transmitting unit according to the sixth aspect and the receiving unit according to any one of the seventh to tenth aspects.

According to the spread spectrum communication method of the present invention and the receiving section of the spread spectrum communication apparatus of the present invention, it is possible to set an observation section at a predetermined position of a data section and establish synchronization. . According to the spread spectrum communication method of the second aspect of the present invention and the receiving section of the spread spectrum communication apparatus of the eighth aspect, it is possible to establish synchronization in an observation section at a position independent of a position of a data section.

According to the spread spectrum communication method of the third aspect of the present invention, the configuration for generating the PN sequence can be reduced to one. According to the spread spectrum communication method of claim 4 of the present invention and the receiving section of the spread spectrum communication apparatus of claim 9,
False synchronization establishment can be avoided more reliably. According to the spread spectrum communication method of the present invention and the receiving section of the spread spectrum communication apparatus of the present invention, the synchronization can be re-established even if the synchronization has failed. According to the transmitter of the spread spectrum communication apparatus of claim 6 of the present invention,
A PN sequence for data 1 and a PN sequence for data 0 can be generated without complicated control.

[0024]

Next, a spread spectrum communication method and a communication apparatus according to a preferred embodiment of the present invention will be described with reference to the drawings.

[Transmission Section of SS Communication Apparatus] FIG. 1 shows a transmission section of a spread spectrum communication apparatus according to an embodiment of the present invention. The output of the PN sequence generator 1 that outputs the logical value “1” of the bit data as a PN1 sequence which is a pseudo noise signal can be output through the shift register 2.
Output selection between the PN sequence generator 1 and the shift register 2 is as follows.
This is performed by the selector 3, and the selector 3 sets the logical value “1” of the bit data of the transmission data input to the control unit 4.
The selection is controlled by “0”. That is, a PN1 sequence and a PN0 sequence that is phase-shifted to the PN1 sequence are assigned according to the logical values “1” and “0” of the bit data. The output from the selector 3 is output to a power line communication interface (not shown) and output via the power line.

In this embodiment, the PN sequence generator 1 includes a five-stage shift register 5 and an E
XOR gates 6 and 7 and AND gate 8 are provided. Set terminals 9A to 9E are provided at each stage of the shift register 5.
, One of the predetermined logical values “1” and “0” is set. The output of the EXOR gate 6 is input to the first stage 5A of the shift register 5, and a clock signal is input by a clock enable signal. The outputs of the second stage 5B and the fifth stage 5E of the shift register 5 are input to the EXOR gate 6. The output of the fifth stage 5E of the shift register 5 is E
The clock signal is input to the XOR gate 7, and the clock signal is input to the EXOR gate 7. The shift register 5 becomes capable of inputting a clock signal by inputting a clock enable signal, and moves to a subsequent stage whenever a clock signal is input to the shift register 5 (each stage). The EXOR gates 6 and 7 output the Manchester-encoded M
The sequence is periodically output and becomes a PN sequence for data 1 (hereinafter referred to as PN1). A PN sequence for data 0 (hereinafter referred to as PN0) is obtained by shifting the PN1 by a predetermined phase by the shift register 2.

The logical value of each stage of the shift register 5 is input to an AND gate 8, and all stages 5A to 5A of the shift register 5
When all the logical values of E become 1, the AND gate 8 outputs a PT signal indicating one cycle of bit data. The PT signal functions as a switching timing of PN1 and PN0 corresponding to the bit data 1 and 0 forming the transmission data. When the bit data is 1, the M sequence signal of the PN sequence generator 1 is output as an SS signal. PN when bit data is 0
PN obtained by logically shifting the M-sequence signal of the sequence generator 1 by a predetermined number
The 0 signal is output as the SS signal. The control unit 4 transmits PN1 a predetermined number of times to establish synchronization before transmitting transmission data. Since this is the first agreement,
PN0 may be transmitted a predetermined number of times.

FIGS. 3 and 4 show another embodiment of the transmission section. In this embodiment, a PN1 generator 101 that outputs a logical value “1” of bit data as a PN1 sequence and a PN0 generator 100 that outputs a logical value “0”
And PN1 generator 101, PN0 generator 1
00 has the configuration of FIG. 4, that is, the configuration including the five-stage shift register 5 and the EXOR gates 6 and 7,
Different values are selected so that the values set in the set terminals 9A to 9E have a desired phase shift amount. Prior to the start of communication, the set terminals 9A through 9A
The value of 9E is set in the shift register 5 of both generators 100 and 101 at the same time.
1 are operated in synchronization with each other, the same SS signal as that described with reference to FIGS. 1 and 2 can be generated.

[Receiver of SS Communication Apparatus] Next, the receiver will be described. FIG. 5 is a block diagram of the demodulation unit. Reference numeral 10 denotes a correlator for data 1 and reference numeral 11 denotes a correlator for data 0, to which an SS signal (reception signal) is input from a power line. Reference numeral 30 denotes a data determination unit, and reference numeral 31 denotes a synchronization control unit. The synchronization control section 31 outputs a synchronization establishment signal, the details of which are shown in FIG.

FIG. 7 shows the structure of the correlators 10 and 11. The correlators 10 and 11 are provided with a shift register 12 having the number of chips in one cycle of the M-sequence signal, a PN code pattern 13 having the number of stages corresponding to the shift register 12, and an exclusive logic of the shift register 12 and the PN code pattern 13. It comprises an EXOR gate 14 for obtaining a sum and an adder 15 for adding the number of outputs of the EXOR gate 14.

The AD-converted received signal is input to the shift register 12 while being logically shifted, and the logical value of each stage of the shift register 12 is determined to match or not match the logical value of each stage of the PN code pattern 13. Can be The received signal advances by logically shifting each stage of the shift register 12 to the right side of FIG. 7 together with the input of the clock signal. Is shown. The adder 15 outputs the coincidence result for each clock.

The output of the adder 15 is supplied to the synchronization control unit 3 shown in FIG.
1 is input to the selector 16. This selector 1
After the selection of the PN1 signal and the PN0 signal by 6 is performed, the signal is output to the peak detector 17. Since the maximum correlation peak value output to the peak detector 17 may not completely match the PN code pattern of the receiving unit due to noise in the transmission path or the like, the maximum correlation peak value is within a range where the reliability can be obtained. Threshold is set.

On the receiving side, a correlation is made between the received signal and the same PN sequence for data 1 and PN sequence for data 0 as those used on the transmitting side. If only the establishment of synchronization is considered here, synchronization is established by one of the data 1 correlator 10 and the data 0 correlator 11, but both are necessary when considering subsequent operations. . If a matched filter as shown in FIG. 7 is used, the correlation peak can be calculated in real time.

When the communication has not started, the control unit 18
Selects the output of the selector 16 to be the output from the data 1 correlator 10. Further, the control unit 18 stores data 1
Control is performed so as to detect a correlation peak over a period section (here, one PN sequence period section). Control for detecting the correlation peak is performed by a counter 19 for setting a data section in FIG.
Is performed by the peak detector 17.

When a correlation peak larger than the threshold value is observed from the peak detector 17, the output of the comparator 23 is received, and the control section 18 sets the observation section for observing the peak to a sufficiently narrow section around the peak position. I do. The area of this observation section is an area sufficiently narrower than the 1-bit data section, and is, for example, about 1 to 4 chips.

FIG. 8 shows an example of an observation section setting circuit for setting the observation section. Window comparator 20
Is composed of a comparator 2001, a comparator 2002, and an AND gate 2003, and the window comparator 21 includes a comparator 2101 and a comparator 2102.
And an AND gate 2103, and are arranged in parallel with the window comparator 20. The outputs of the window comparators 20 and 21 are input to the selector 22. The counter 19 is set so that the correlation peak with the first captured PN1 sequence is at a predetermined position C in the next data period.
Is controlled by using a window comparator 20 to which the output of the counter 19 is input.
An observation section (B is sufficiently smaller than the data section) is set. Note that the load value of the counter 19 can be changed.

As shown in FIG. 9, the control section 18 stores the peak position of the correlation peak that has become larger than the threshold value by using an observation section setting circuit, and stores the peak position ±
In B, an instruction may be given to the peak detector 17 and the counter 19 so as to detect the next PN sequence correlation peak.

The window comparator 2 arranged in parallel to the window comparator 20 in FIGS.
1 is for observing a correlation peak value over the entire data section. Under the control of the control unit 18, the selector 22 first outputs the output of the window comparator 21 to the peak detector 17 before synchronization is established, and operates the peak detector 17 over the entire data section. When a correlation peak exceeding the threshold value appears, the output from the window comparator 20 is selected by the selector 22 according to the control signal from the control unit 18, and the output from the window comparator 20 is selected.
The peak detector 17 operates in the observation section of. Such an operation is performed by setting the output of the selector 22 to the peak detector 1.
7 can be realized.

When a state in which the correlation peak value observed in a sufficiently narrow observation section for each successive data section is larger than a threshold value occurs a predetermined number of times, the control section 18 determines that synchronization has been established, Activate the synchronization establishment signal. Here, the predetermined number of occurrences may be a predetermined number of consecutive occurrences, or may occur n times during m data reception, and may be determined according to the characteristics of the transmission path, communication speed, required specifications, and the like.

The width of the observation section of the window comparator 20 is preferably narrower than a peak randomly generated when the SS signal is absent so that erroneous synchronization does not occur.
On the other hand, even when the peak position of the normal correlation peak slightly shifts due to the influence of the transmission path when the SS signal is received, it is necessary to keep the peak in sight. For this reason, the width of the observation section is preferably set to about 1 to 4 chips of the PN sequence.

In the synchronization tracking after the synchronization is established, the correlation peak may be observed only within the observation section, and the synchronization control may be performed when the synchronization point deviates from the synchronization point by a predetermined number of times. Also,
A small number of times is sufficient to confirm that a sufficiently large correlation peak is generated at the same position in one cycle period of data.

In the spread spectrum communication method according to this embodiment, on the transmitting side, the logical value "1" of each bit constituting transmission data is converted into a PN sequence for data 1 by the PN sequence generator 1, and The logical value "0" is shifted by the shift register 2 from the data 1 PN sequence to a data 0 PN sequence. What is constituted by these PN sequences is transmitted as transmission data.

In the transmitting section in the embodiment shown in FIGS. 3 and 4, prior to the start of communication, the values of the set terminals 9A to 9E are simultaneously output from the generators 1 according to an instruction from the control section 4 or the like.
The SS signal can be generated in the same manner by setting the shift registers 5 of the counters 00 and 101 and then operating the generators 100 and 101 in synchronization.

Next, on the receiving side, at the time of data reception, the correlator 1 correlates the PN sequence for data 1 with the received signal. The output of the correlator 1 is detected by the peak detector 17 and becomes a correlation peak. The correlation peak is input to the comparator 23 and compared with a threshold value. When the correlation peak exceeds the threshold value, the control unit 18 starts an operation for establishing synchronization.

In this case, the transmitting side transmits the PN sequence for data 1 a plurality of times to establish synchronization, and the receiving side first sets the selector 16 to the correlator 1 side, and sets the data for synchronization. The correlation between the PN sequence for 1 and the received signal is obtained over the data section. This correlation output becomes a correlation peak in the peak detector 17. When the correlation peak value detected by the peak detector 17 exceeds the threshold value of the comparator 23, the peak value and the peak position of the correlation peak are held. In FIG. 8, the control unit 18 sets the load value of the counter 19 so that this peak position comes to a predetermined position in the next data section, and operates the peak detector 17 in the observation section by the output of the window comparator 20. The selector 22 is controlled so as to cause the selection.

After the observation section is set, the correlation peak of the PN sequence for data 1 is observed in this observation section. In this observation section, the correlation peak value is larger than the threshold value of the comparator 23. When the number of occurrences of the correlation peak exceeds a predetermined number or a predetermined ratio or more,
The control unit 18 outputs a synchronization establishment signal assuming that the synchronization has been established.

[Case where a Large Correlation Peak Occurs During No Signal] As shown in FIG. 10, even if a relatively large correlation peak appears due to noise or the like during no signal, this occurs randomly and continues. Since all observations are performed within a narrow observation section, the probability of satisfying the condition that the above-described predetermined number of occurrences is satisfied is low (but not 0). For this reason, the probability of occurrence of erroneous synchronization due to noise or the like can be reduced.

[When the correlation peak of the SS signal is small and a secondary peak occurs at a distant position] Further, when the SS signal is received, the correlation peak becomes small as shown in FIG. Even when a correlation peak similar to the correlation peak appears at a distant position, no distant correlation peak is observed because the distant correlation peak is not observed.

[When the correlation peak does not occur a predetermined number of times]
If the predetermined number of times does not occur, the control unit 1
8 determines that synchronization is not established. Therefore, the synchronization establishment signal is not activated. The control unit 18 selects the window comparator 21 by the selector 22, designates the correlation peak observation section again as the one cycle data observation section, observes the correlation peak by the peak detector 17, and waits for the start of communication of the SS signal.

FIG. 12 is a waveform diagram for explaining the operation of establishing synchronization as described above. It is assumed that a correlation peak [A] which occurs when there is no signal and is larger than a threshold appears in the data section (1) in the output from the data 1 correlator 10. However, in the next observation section (2), no correlation peak exceeding the threshold appears, so synchronization is not considered established and the next data section
In (3), a peak is observed again over the entire data section. Since a correlation peak [B] exceeding the threshold occurs in the data section (3) and the observation section (4) (5) (6), the observation section
After confirming the correlation peak in (6), the control unit activates the synchronization establishment signal (synchronization is established three times in a row here, but this is merely an example, and it goes without saying that other times may be used. FIG. 13 shows a case where the correlation peak is brought to a predetermined position C in one data period section in FIG. At this time, even if a secondary peak [C] which is not a regular peak occurs, it is outside the observation section, so that it is not confused by this and stable synchronization can be established. As described above, according to such a method, in the case of a special carrier digital transmission device specified by the Radio Law, the transmission speed is
Since it is 9600 bps or less, the SS signal can be synchronized at high speed in a sufficiently short time of 1 to 2 ms.

In the above embodiment, an example in which the correlation value from the data 0 correlator 11 is not used has been described. However, when a relatively large correlation peak frequently appears due to noise or the like when there is no signal, an error is detected. To further reduce the possibility of syncing,
The correlation value from the data 0 correlator 11 can also be used. An embodiment in this case is shown in FIG. This figure 1
3, the correlator 10 for data 1 and the correlator 11 for data 0
Is provided, and the output of the comparator 25 is input to the control unit 18. The output of the comparator 25 and the output of the control unit 18 are also input to the selector 16 via the OR circuit 26. This allows
The correlation peak of the correlation output from the data 1 correlator 10 can be obtained, or the data 1 correlator 10 and the data 0
It is also possible to obtain a correlation peak from both correlation values of the use correlator 11. That is, the maximum peak of both correlation values can be obtained. Alternatively, two peak detectors may be prepared, the correlation peaks of the correlation values of the correlators 10 and 11 may be obtained, and then the magnitudes of the two may be compared to obtain the maximum peak.

Further, in the embodiment shown in FIG.
Selects the correlation output from the data 1 correlator 10 by the selector 16 and sets an observation section to obtain a correlation peak within the section. In the embodiment of FIG. The magnitude relation between the output from the correlator for 1 and the output from the correlator for data 0 is checked, and the larger correlation output is selected by the selector 16 to obtain a correlation peak. At this time, the condition for establishing synchronization is the same as before, but a condition that the correlation peak is from the data 1 correlator 10 is further added.

On the transmitting side, at the start of communication, PN1 is transmitted a predetermined number of times for establishing synchronization.
Is very small, so that synchronization can be correctly established even under the synchronization establishment condition. On the other hand, even if communication has not started and a large output exceeding the threshold value is obtained from the data 1 correlator 10 due to noise, the correlation value of the data 0 correlator 11 is also changed after the observation section is set. In a state where only noise is present, the probability that a correlation peak is obtained only from the data 1 correlator 10 is very low.
Since a correlation peak is also obtained from the use correlator 11), the possibility of erroneous synchronization can be further reduced.

In addition, the following condition may be added. In the previous embodiment, at first, only the correlation output from the data 1 correlator 10 is observed over the entire period of the data section, and the observation section is set when the correlation peak value exceeds the threshold value. However, even at this first time, the correlation output from the data 0 correlator 11 is also observed over one period of the data section. Even in the case described above, the observation section is not set, and the observation of the correlation output over the entire one cycle of the data section can be continued.
With this configuration, the possibility of erroneous synchronization can be further reduced with a simple configuration. FIG. 14 is a waveform chart showing the operation of establishing synchronization in the embodiment of FIG. When the transmission characteristics of the power line are poor, the correlation peak of the SS signal becomes small, so the threshold value also needs to be lowered. On the contrary, the correlation peak [A] generated when there is no signal occurs in the data section (1) and the observation section (2) (3) (4) with a value exceeding the threshold, and the synchronization establishment signal is activated. And erroneous synchronization may occur.

In such a case, the correlation output from the data 0 correlator 11 is output in the observation section (3) within the data 1 correlator 10.
Correlation peak [X] larger than the correlation peak [A] from
But also in the first data section (1), the correlator 1 for data 1
A correlation peak [Y] larger than the correlation peak [A] from 0 occurs. In such a situation where there is no signal and only noise, the correlation from the data 0 correlator 11 may still have a larger correlation peak. On the other hand, as shown after the data section (3) in FIG. 12, when the SS signal is received, the correlation value from the data 0 correlator 11 is small.

In FIG. 13, the correlation output from the data 1 correlator 10 and the correlation output from the data 0 correlator 11 and the maximum peak between them can be obtained. The output of the comparator 25 is also input to the control unit 18, and the control unit 1
8 also recognizes which correlator the maximum peak was obtained from. Accordingly, the control unit 18 can determine that the correlation peak in the observation section (3) or the data section (1) is obtained from the correlator 11 for data 0.
8 Synchronization is not considered. By using information from the data 0 correlator 11 in this manner, more stable synchronization can be established.

[0057]

As described above in detail, according to the spread spectrum communication method and apparatus of the present invention, when the SS signal is first captured, the correlation peak position due to the continuous transmission of the PN sequence is equal to one data period. Since synchronization is established using the periodicity of occurrence at a position, the number of observations can be reduced and synchronization can be established at high speed. Also, SS
If a correlation peak equal to or higher than the threshold occurs due to noise during no signal transmission, the next observation is made in a sufficiently narrow area, so a large correlation peak exceeding the threshold in that observation area Is less likely to be
The possibility of false synchronization is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a transmission unit of a spread spectrum communication apparatus according to the present invention.

FIG. 2 is a block diagram showing details of a PN sequence generator in the transmission unit of FIG. 1;

FIG. 3 is a block diagram showing another embodiment of the transmitting section of the spread spectrum communication apparatus of the present invention.

FIG. 4 is a block diagram showing details of a PN sequence generator in the transmission unit of FIG. 3;

FIG. 5 is a block diagram showing an embodiment of a demodulation unit of the spread spectrum communication apparatus according to the present invention.

FIG. 6 is a block diagram illustrating details of a synchronization control unit of the demodulation unit in FIG. 5;

FIG. 7 is a block diagram showing details of a correlator of the synchronization control unit in FIG. 6;

FIG. 8 is a block circuit diagram for setting a correlation peak observation section.

FIG. 9 is a block diagram when a correlation peak observation section is set by storage of a control unit.

FIG. 10 is a diagram showing a high correlation peak caused by noise or the like during non-communication of SS communication.

FIG. 11 is a diagram showing that a normal correlation peak is reduced due to the characteristics of a transmission path when an SS signal is received, and a secondary peak appears at a distant position.

FIG. 12 is a waveform chart for explaining the operation of establishing synchronization (part 1).

FIG. 13 is a block diagram showing another embodiment of the synchronization control unit of the demodulation unit.

FIG. 14 is a waveform diagram (part 2) illustrating the operation of establishing synchronization.

[Explanation of symbols]

 Reference Signs List 1 PN sequence generator for data 1 2 Shift register 3 Selector 4 Control unit 5 Shift register 6, 7 EXOR gate 10 Correlator for data 1 11 Correlator for data 0 12 Shift register 13 PN code pattern 14 EXOR gate 15 Adder 17 Peak detector 18 Control unit 19 Counter 20 Window comparator 21 Window comparator 22 Selector 23 Comparator

Claims (11)

[Claims] On the transmitting side, two PN sequences for data 1 and data 0 having the same code length different from each other are prepared, and a PN sequence for data 1 is added to a logical value “1” of each bit constituting transmission data. PN sequence for data 0 is assigned to the logical value “0” of the bit and transmitted. The reception side receives the transmission data, and receives the same data 1 and data 0 as those used on the reception signal and the transmission side. For PN
Take the correlation with the series, find the maximum peak of both correlation outputs,
The maximum peak is P of either the received signal or the PN sequence.
Judgment as to whether or not it is obtained by correlation with the N sequence is performed, and demodulation is performed on data corresponding to the determined PN sequence, or correlation peak values appearing in both correlation outputs are compared with each other in magnitude to obtain a larger correlation peak. In a spread spectrum communication method for demodulating data corresponding to a given PN sequence, the transmitting side transmits either the PN sequence for data 1 or the PN sequence for data 0 a plurality of times to establish synchronization. Calculates the correlation between the received signal and the same PN sequence sent from the transmitting side for synchronization establishment, which is the same as the PN sequence sent from the transmitting side. Value and a correlation peak position, and when the correlation peak value exceeds a threshold value, the next data section is set so that the correlation peak position is located at a predetermined position in the data section in the next data section. The length of the section is corrected, and after the next data section, the above-mentioned predetermined position is included as the approximate center, and an observation section having a sufficiently narrow width with respect to the data section is set, and a correlation peak value is obtained within this observation section. A spread spectrum communication method, wherein synchronization is established when the correlation peak value exceeds the threshold value a predetermined number of times. 2. On the transmitting side, two PN sequences for data 1 and data 0 having different code lengths are prepared, and a PN sequence for data 1 is assigned to a logical value "1" of each bit constituting transmission data. , Assigning a PN sequence for data 0 to a bit logical value “0” and transmitting the same. On the receiving side, the transmission data is received, and the same data 1 and data as used on the receiving side and the receiving signal are used. PN for 0
Take the correlation with the series, find the maximum peak of both correlation outputs,
The maximum peak is P of either the received signal or the PN sequence.
Judgment as to whether or not it is obtained by correlation with the N sequence is performed, and demodulation is performed on data corresponding to the determined PN sequence, or correlation peak values appearing in both correlation outputs are compared with each other in magnitude to obtain a larger correlation peak. In a spread spectrum communication method for demodulating data corresponding to a given PN sequence, the transmitting side transmits either the PN sequence for data 1 or the PN sequence for data 0 a plurality of times to establish synchronization. Calculates the correlation between the received signal and the same PN sequence sent from the transmitting side for synchronization establishment, which is the same as the PN sequence sent from the transmitting side. When the correlation peak value exceeds a threshold value, the correlation peak position is included substantially at the center, and an observation section having a sufficiently narrow width with respect to the data section is set. Since the next data interval,
A spread spectrum communication method, wherein a correlation peak value is obtained in the observation section, and it is assumed that synchronization has been established when a state where the correlation peak value exceeds the threshold value exists a predetermined number of times. 3. The spread spectrum communication method according to claim 1, wherein the PN sequence for data 1 and the PN sequence for data 0 are obtained by shifting the phase of the same PN sequence. Spread spectrum communication method. 4. The spread spectrum communication method according to claim 1, wherein the synchronization is established when a peak value larger than the threshold value is continuously generated a predetermined number of times. Spread spectrum communication method. 5. The spread spectrum communication method according to claim 1, wherein the number of occurrences of a peak value exceeding a threshold value or a predetermined number of consecutive occurrences is not satisfied, which is a condition for establishing synchronization. A spread-spectrum communication method, characterized in that a transition is made again to an initial state in which a correlation peak value and a correlation peak position are observed over one entire period of a 1-bit data section as synchronization is not established. 6. A transmitting section of a spread spectrum communication apparatus used in the spread spectrum communication method according to claim 1, wherein said transmitting section generates a PN sequence for data 1.
N1 sequence generator and PN for generating PN sequence for data 0
A transmission of a spread spectrum communication apparatus, comprising: a 0-sequence generator; and a control unit for transmitting either the data 1 PN sequence or the data 0 PN sequence a predetermined number of times to establish synchronization. Department. 7. A receiving section of a spread spectrum communication apparatus used in the spread spectrum communication method according to claim 1, wherein the time measuring section sets a length of the data section, and a receiving section. A correlator that outputs a correlation value between the signal and the same PN sequence sent for synchronization establishment on the transmission side, detects a peak value and a peak position of the correlation output, and detects a 1-bit data. A peak detector capable of selecting one of the entire period of the section or an observation section set in advance with a sufficiently narrow width with respect to the period of the data section, and a correlation peak output from the peak detector. A comparator for comparing the peak value of the data with a threshold value, and in the initial state of reception, causing the peak detector to observe the correlation peak value and the peak position over one cycle of the 1-bit data section. When the output of the detector exceeds the threshold value, time measurement is performed to correct the length of the next data section so that the correlation peak position is located substantially at the center of the observation section in the next data section. And instruct the peak detector to observe the correlation peak value in the observation section after the next data section, and when the observed correlation peak value exceeds the threshold for a predetermined number of times,
A control unit that determines that synchronization has been established and outputs a synchronization establishment signal;
A receiving section of a spread spectrum communication apparatus, comprising: 8. A receiving section of a spread spectrum communication apparatus used in the spread spectrum communication method according to claim 2, wherein: a time measuring section for setting a length of a data section; A correlator that outputs a correlation value with the same PN sequence sent for synchronization establishment on the transmission side, detects a peak value and a peak position of the correlation output, and detects a 1-bit data section 1 A peak detector capable of selecting either the entire cycle or an observation section set by the control unit described below in one cycle section of the data section, and a peak value of a correlation peak output from the peak detector And a comparator for comparing a correlation peak value and a peak position with the peak detector over one cycle of a 1-bit data section in an initial state of reception. When the threshold value exceeds the threshold, the correlation peak position is included as substantially the center, and an observation section having a sufficiently narrow width is set for the data section. From the next data section onward, the peak detector sets the observation section. And a control unit for determining that synchronization has been established and outputting a synchronization establishment signal when there is a state in which the observed correlation peak value exceeds the threshold for a predetermined number of times. A receiving unit of a spread spectrum communication apparatus characterized by the following. 9. The receiving unit of the spread spectrum communication apparatus according to claim 7, wherein the control unit determines whether synchronization has been established when a peak greater than a threshold value occurs continuously a predetermined number of times. A receiving unit of the spread spectrum communication apparatus. 10. The receiving section of the spread spectrum communication apparatus according to claim 7, wherein said control section generates a predetermined number of peak values exceeding a threshold value, which is a condition for establishing synchronization, and generates a predetermined number of peak values. When the number of consecutive occurrences is not satisfied,
A receiving section of the spread spectrum communication apparatus, wherein a transition is made to an initial state in which a correlation peak is again observed over one period of data as synchronization is not established. 11. A spread spectrum communication apparatus comprising: the transmission section according to claim 6; and the reception section according to any one of claims 7 to 10.