JP2987721B2 - Spread spectrum communication system - Google Patents

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 system for transmitting a predetermined PN sequence to a transmission line in accordance with a state value of information data to be transmitted.

[0002]

2. Description of the Related Art Conventionally, in a local area network system, a home control system, and the like, in which a transmission line is laid in a building to transmit an information signal or a control signal, the cost of laying the transmission line is reduced. In order to do so, it has been considered to use a power line or the like already laid in a building as a transmission line for communication. Conventionally, impedance characteristics and the like have not been taken into account as such a communication line, and a communication method suitable for use in a circuit having a lot of noise is NEC Technical Report vo1.42 NO.9 / 1989:
C as described in "High performance SS power line modem"
A spread spectrum communication system called the SK system has been developed. In this communication method, as shown in FIG. 7, a modulator T has a PN sequence PN having a period length equal to each other and a small correlation value.
₀ and PN ₁ are prepared respectively. When the status value of the information data to be transmitted is “0”, the PN sequence PN ₀ is used. When the status value of the information data to be transmitted is “1”, the PN sequence PN ₀ is prepared. PN
It sends the sequence PN ₁ to power line 1. On the other hand, the demodulation device R comprises a PN sequence generator G _R1 to generate the PN sequence PN ₀ PN sequence generator G _R0 to generate the same PN sequence and, and the PN sequence PN ₁ with the same PN sequence , A correlation value between the output signal of the PN sequence generator G _R0 and the received signal is calculated using a correlator H _0, and a voltage corresponding to the calculated value is output. comparator C _r is the reset state "0" to the RS flip-flop 2 in the case of exceeding the _a [V]. Similarly, the correlation value between the output signal of the PN sequence generator G _R1 and the received signal is obtained using the correlator H ₁ , and when the correlation value exceeds the reference voltage V _a [V], the comparator C _s Sets the RS flip-flop 2 to the set state "1" to obtain the original information data from the output terminal of the RS flip-flop 2.

For example, a PN sequence PN ₀ corresponding to each state value of information data “110...” Of bit length _Ta [s].
Or if the PN ₁ modulator T is sent sequentially to the power line 1, and outputs a correlator H ₀ is the correlation peak waveform at the third cycle as shown in FIG. 8 (a) of the demodulator R, also since the correlator H ₁ outputs the correlation peak waveform at the first and second periods, respectively, as shown in FIG. 8 (b), demodulating device R either side of the H ₁ Oyobi the correlator H ₀ by the output voltage level is detected whether exceeds the reference voltage V _a [V], in which makes it possible to demodulate the original information data "110 ...". Therefore, according to this communication method, even if the output waveform of each of the correlators H ₀ and H ₁ is distorted due to the transmission signal of the modulator T being affected by the transmission characteristics of the power line or the like, the correlation peak is obtained from the output waveform of each correlator. If the demodulator R can detect the original information data,
A power line or the like that is not originally intended for communication can be used as a communication transmission path.

However, in this communication system, a large delay deviation and a large amplitude deviation occur in the transmission characteristics of a transmission line such as a power line, and as a result, as shown in FIG. When the level of the correlation peak waveform to be output from the demodulator is deteriorated as shown in FIG. 8 (c), the difference between the level of the correlation peak waveform and the level of the other waveforms becomes small. It is very difficult to detect the presence or absence of the correlation peak waveform, and there is a problem that the communication error rate increases.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem of the spread spectrum communication system. A large delay deviation and a large amplitude deviation occur in the transmission characteristics of a transmission line, and the correlation between output waveforms of a correlator is obtained. It is an object of the present invention to provide a spread spectrum communication system capable of increasing a communication error rate and allowing a demodulation side to demodulate the original information data even if a difference between a peak waveform level and a level of other waveforms is small. I do.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is configured as follows. That is, in means for performing communication using a spread spectrum signal modulated so as to output a predetermined PN sequence corresponding to a state value of information data to be transmitted, the same PN sequence and information data as those on the modulation side are used. Sending
Before the PN sequence is output from the modulation side for the required period before
A correlation signal between the received signal by storing in the memory, the In subsequent data demodulated so as to demodulate the information data according to the correlation between the correlation signal of the correlation signal and the memory of the received signal and the PN sequence It is characterized by the following.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described in detail. FIG. 1 shows the spread spectrum signal of the present invention.
Block diagram showing an embodiment of a modulation device and a demodulation device according to a communication system.
It is a lock figure. In the figure, T is a modulator,
A PN sequence P having small correlation values and a period length of 31 bits
N₀ And PN₁ PN sequence generator G that generates_T0as well as
G_T1Transmission at a bit rate of 300 [b / s].
If the status value of the power information data is "0", the PN sequence P
N₀And when the status value is "1", the PN sequence PN
₁ Are transmitted to the power line 1 respectively.
This performs spread modulation. That is, the modulation device T is
Switch S via the synchronization circuit 3₁Control end of
And a timing signal for the transmission request signal RS.
Liveware CL_A Switch S through_Two Supply to the control terminal of
You. Also, the timing generator CL_A Is 9.3 [kHz]
Clock signal and the bit of the information data synchronized with the clock signal.
Generates a clock signal of 300 [Hz] which is the same as the rate
At least, the clock signal of 300 [Hz] is synchronized with the synchronization.
Supply to the clock input terminal of the
9.3 [kHz] clock signal to the PN sequence generator
G_T0And G_T1To each clock input terminal. Furthermore,
The modulator T is a PN sequence generator G_T0And G_T1Output terminal
Each switch S₁Connected to terminals a and b of the
To switch S_TwoAnd terminal e.
It is connected to the power line 1 via the band 4 and the transformer 5 and
The apparatus is configured to transmit a spread spectrum signal from the slave e.
You.

On the other hand, R is a demodulation device, which is a PN sequence generator G _R0 for generating the same PN sequence as the PN sequence PN ₀ and a PN sequence generator G _R1 for generating the same PN sequence as the PN sequence PN _1. A signal received through the power line 1 is converted into a transformer 6, an amplifier 7 and a pass band of 1
After passing through a band-pass filter 8 of ~ 9.3 [kHz], A /
It is supplied to the input terminal of the D converter 9. The output signal of the A / D converter 9 is supplied to the input terminals of the correlators H _A0 and H _A1 , and the output terminal of the PN sequence generator G _R0 is connected to the other input terminal of the correlator H _A0. And the input terminals of the correlator H _B0 and the memory M ₀ are connected to the output terminal of the correlator H _A0 , and the output terminal of the PN sequence generator G _R1 is connected to the other input terminal of the correlator H _A1. And the input terminals of the correlator H _B1 and the memory M ₁ are connected to the output terminal of the correlator H _A1 . Furthermore, 18.6 clock oscillator CL correlator H _A0 output terminal _B that generates a clock signal [kHz],
H _A1 , H _B0 , H _B1, and each clock input terminal of the A / D converter 9, and the output terminal of the memory M ₀ is connected to the correlator H _B0.
Of the other input terminal, and with respectively connected to the other input terminal of the correlator H _B1 an output terminal of the memory M _1, one input of each comparator 10 the output terminal of the correlator H _B0 and H _B1 The output terminal is connected to the input terminal of the processing circuit 11. The demodulator R also outputs the output signal of the correlator H _A0 via the squaring circuit 12 to the comparator 13 and the adder 1.
4 to one of the input terminals, and outputs the output signal of the correlator H _A1 via the squaring circuit 15 to the comparator 13.
And the adder 14 is supplied to the respective other input terminal of the comparator processor 16 the output signal of the 13, the memory M ₀ through the control circuit 17, M _1, processing circuit 11 and the control of the clock oscillator CL _B The signal is supplied to a signal input terminal, and the output signal of the adder 14 is supplied to a processing circuit 11 via a timing extractor 18.
And 16 are supplied to the input terminals of the processing circuit 11 to output the original information data from the output terminal of the processing circuit 11, respectively.
Is configured to output the carrier detection signal CD from the output terminal.

[0009] The spread spectrum signal thus configured
Operate as follows. Destination
The modulator T transmits the transmission request signal RS to the timing generator.
CL_A To switch S_Two Terminal e to terminal d
And the timing generator CL_A And make
This timing generator CL_A PN sequence generator based on
G_T0And G_T1 From each PN series PN₀ And PN₁ Each
1 bit per 1/9300 [s]
Close. And then switch S₁ Terminal c to terminal a
Then PN series PN₀ Is the first bit for 60 periods, for example.
From the power line 1 repeatedly, and then switch S₁ 
Of the PN series PN₁ For 60 cycles
The signal is repeatedly transmitted to the power line 1 sequentially from the first bit. So
After that, the modulator T converts the information data to be transmitted to a synchronization circuit.
3 and the timing generator CL_A Occurs 300
Every 1/300 [s] based on a clock signal of [Hz]
To the switch S sequentially.₁ Supply to
And the state value of each bit of the information data is “0”.
Switch S in case₁ Terminal c is connected to terminal a.
When the status value is "1", the terminal is connected to the terminal b and PN of one cycle
Series PN₀ Or PN₁ From the first bit to the power line
Send to 1. Here, the modulation device T is shown in FIG.
PN series PN₀Is transmitted to the power line 1 as shown in FIG.
The PN sequence PN as shown in FIG.₀ The transmission waveform of the power line
1 under the influence of the transmission characteristic of FIG.
The amplitude and phase are deformed, and the deformed signal and the PN sequence P
N₀ As shown in FIG.
The shape level is attenuated, and the correlation peak waveform and other waveforms
And the level difference is small in the conventional demodulator described above.
It is difficult to obtain information data. Also, the PN series PN₁ 
The same applies to.

Next, the operation of the demodulator R according to the present invention will be described below. First, the demodulator R is a clock oscillator CL.
After the operation of _B , as shown in FIG. 4A, the 60-period PN sequence PN ₀ and the 60-period PN sequence PN ₁ transmitted before the modulator T supplies information data to the synchronization circuit 4 are transmitted. When sequentially received, the received signal is amplified to a required level using the amplifier 7 and the filter 8, and
Remove unnecessary signal components. Also shows the amplitude value of the output signal of the A / D converter 9 based on the clock signal of the clock generator CL _B using 1/18600 [s] every filter 8, for example, in FIG. 2 (c) with sampling the amplitude values of such signals as sequential data DA ₀ to DA ₆₁ as shown in FIG. 2 (d), the correlator H _A0 and H _A1 using the sampling data and the PN sequence generator G _R0 and G The correlation value with the output signal of _R1 is obtained, and the correlator H _A0
Are the first through 60th cycles of the received signal as shown in FIG.
Data SA ₀ through SA ₆₁ of the correlation waveform correlation peak waveform is attenuated as shown in FIG. 3 In th cycle respectively outputs. Further, the correlator H _A1 also outputs the data SB ₀ to SB ₆₁ similar correlation waveform at the 61 th cycle to 120 th cycle of the received signal as shown in FIG. 4 (c). Further, the demodulator R outputs the output signals of the correlators H _A0 and H _{A1 to} the squaring circuit 12 respectively.
As shown in FIGS. 4D and 4E, a correlation peak waveform having a higher level than the correlation peak waveforms shown in FIGS. 4B and 4C is output as shown in FIGS.
The output signals of the squaring circuits 12 and 15 are added using an adder 14 to generate a signal as shown in FIG. 4 (f). A signal component of 300 [Hz] as shown in FIG.
That is, a signal component having the same data rate as the information data is extracted, and the 300 [H
When the level of the signal z] continuously exceeds a predetermined value for, for example, 20 [ms], the arrival of the transmission signal of the modulation device T is determined, and the carrier detection signal CD is output. The demodulator R compares the levels of the output signals of the squaring circuits 12 and 15 with each other by using the comparator 13. If the output signal level of the squaring circuit 12 is higher than the output level of the squaring circuit 15, Causes the comparator 13 to output a signal having a state value of "0", and in the opposite case, causes the comparator 13 to output a signal having a state value of "1" to generate a signal as shown in FIG. The timing extraction circuit 18 using the processing circuit 16
Of the state value of the output signal of the comparator 13 when the output signal is 0 [V] and allowed to output from the processing circuit 16 as shown in FIG. 4 (i), the received signal from the state value PN sequence PN ₀ or determining one of the PN _1.

The demodulator R is provided with the processing circuit 1 as described above.
6 to determine the arrival of the signal transmitted from the modulator T, and
Is the PN sequence PN₀ Judge that
After that, the timing extraction circuit is
18 based on the timing at which the output signal of 18 generates 0 [V].
And the clock oscillator CL_B Clock signal
And the correlator H_A0Output data SA₀ Or
SA₆₁To the PN sequence PN over a predetermined M cycle.₀ of
The data signal synchronously added for each cycle is converted to the correlation waveform data SA.
₀ ^'Or SA₆₁ ^' As memory M₀ To memorize. here,
The correlator H_A0 The process of synchronously adding the output data of
To remove random noise contained in the data.
The principle is described in the document: Digital Signal Processing by Shinji Ozawa
”PP. 114-121, described in Practical Science and Engineering Complete Book
Although the description is omitted because of the
To improve the S / N by 10 logM [dB].
Can be. Thus, the demodulation device R is in a state before the noise is removed.
Correlation waveform data SA₀ ^'Or SA₆₁ ^' Is the memory M₀ Written in
After the storage, the control circuit 17 uses the memory M₀ Inside phase
Related waveform data SA₀ ^'Or SA₆₁ ^' To the correlator H_B0Supply to
You. After that, the demodulation device R sets the modulation device T to the above-mentioned 60 cycles.
PN series PN₁ Is transmitted to the processing circuit 16.
When the determination is made by using the control circuit 17 as described above,
Using the correlator H_A1Output data SB₀ Or SB₆₁
To the PN sequence PN over a predetermined M cycle.₁ Every cycle of
The data signal synchronously added to the correlation waveform data SB₀ ^'Or
SB₆₁ ^'As memory M₁ After being stored in the memory M₁ 
Waveform data SB inside₀ ^'Or SB₆₁ ^' To the correlator H_B1To
Supply.

Thereafter, the modulation device T sets the PN of the 60 cycle
After sending the sequence PN _1, for example, FIG. 5 (a) PN sequence of one cycle as shown in PN ₀ and the information data "110
PN series corresponding to each state value of PN ₁ , PN ₁ , P
When N ₀ ,... Are sequentially transmitted to the power line 1, the demodulation device R uses the A / D converter 9 as described above, and as shown in FIG. Are sequentially converted to data D (1) _{0 to} D (1) ₆₁ , D (1) _{0 to} D (1) ₆₁ , D (1) _{0 to} D (1) ₆₁ , D (0) _{0 to} D ( 0) Sampling as ₆₁ and correlator H
Use _A0 and H _A1 respectively obtains a correlation value between the sampling data and the PN sequence PN ₀ and PN sequence PN _1, the correlator H _A0 in the first and fourth cycles, as shown in FIG. 5 (c) The correlation data SA _{0 to} SA ₆₁ are output as described above, and the correlator H _A1 outputs the correlation data SB _{0 as} described above in the second and third periods as shown in FIG.
Or outputs the SB _61. Further, the demodulator R is provided with a correlator H _B0
Is used to determine the correlation value between the output data of the correlator H _A0 and the correlation waveform data SA ₀ ^{′ to} SA ₆₁ ^′ in the memory M ₀ , and the output data of the correlator H _A1 is obtained using the correlator H _B1. And a correlation value between the correlation waveform data SB ₀ ^{′ to} SB ₆₁ ^′ in the memory M ₁ . Here, the correlation waveform data SA ₀ ^{′ to} SA ₆₁ ^′ in the memory M ₀ is the correlation waveform data SA of the sampling data of the received signal corresponding to the PN sequence PN ₀ and the output signal of the PN sequence generator G _R0 as described above. _{0 to} SA ₆₁
Where data SA ₀ and SA ₀ ^′ , SA ₁ and SA ₁ ^′ ,
..., SA ₆₁ and SA ₆₁ ^'values of the are the same unless change the transmission characteristics of the respective power line 1 together, and the correlation waveform data SB ₀ in the memory M ^_1' is the same for to SB ₆₁ ^' _Therefore , the correlator H _B0 shows a correlation peak waveform in which the level difference between the correlation peak waveform and the other waveform is much larger than that shown in FIG. 4D, as shown in FIG. Occurs in the first and fourth cycles. Similarly, the correlator H _B1 also outputs a correlation peak waveform in the second and third periods as shown in FIG. Further, the demodulation device R is configured such that the modulation device T has a PN of 60 periods.
As processing circuit 16 described above that it has sent a series PN ₁
, And the levels of the output signals of the correlators H _B0 and H _B1 are compared with each other using the comparator 10, and the output signal level of the correlator H _{B0 is} the output of the correlator H _B1 . If the signal level is larger than the signal level, the comparator 10 outputs the state value “0”.
Is output, and in the opposite case, the comparator 10
The signal of the state value "1" is output from the control circuit 11 and the output signal of the comparator 10 when the output signal of the timing extraction circuit 18 is 0 [V] as shown in FIG. by state value to detect a first reception of the PN sequence PN _1, and determines that the subsequently received signal is a PN sequence corresponding to the state value of the information data, shown in FIG. 5 (h) Thus, the original information data "110 ..." is output.

Therefore, according to this communication system, a large delay deviation and a large amplitude deviation occur in the transmission characteristics of a transmission line such as a power line, and the conventional communication system has a large communication error rate when demodulating the original information data. Even so, the level difference between the correlation peak waveform of the correlation waveform to be obtained and the other waveforms can be increased on the demodulation side, and the original information data can be demodulated normally. Even if the transmission characteristics of the transmission line fluctuate, the output data of the correlator using the output signal of the PN sequence generator as a reference signal and the data in the memory have different values, but have different polarities. , The reduction of the correlation peak waveform can be made much smaller than in the conventional method, and the data error rate when demodulating the original data can be reduced.

In the above-described embodiment, when the transmission characteristic of the transmission line gradually changes with time, such as a distribution line,
Before transmitting a PN sequence corresponding to information data to be transmitted every time communication is performed, PN sequences PN ₀ and PN ₁ having a predetermined period are transmitted.
In order to update the data in the memories M ₀ and M ₁ . When the attenuation of the transmission path is large and the received signal level is lowered, the maximum level of the correlation data, which has been subjected to the required period synchronous addition processing to be stored in the memory, is represented by a predetermined bit of the memory. What is necessary is just to store the data obtained by multiplying the whole by a required coefficient so as to obtain the maximum value and normalized, in the memory. In the above-described embodiment, the carrier detection signal CD is output from the processing circuit 16 based on the output signal of the timing extractor 18. However, the present invention is not limited to this. For example, when the original information data is demodulated. Alternatively, the carrier detection signal CD may be output from the processing circuit 11, and the means for removing noise included in the output signals of the correlators H _A0 and H _A1 is not limited to the synchronous addition processing means as described above. It will be obvious that other noise suppression means may be employed. Furthermore, the provided absolute value circuit in the subsequent stage of each correlator H _A0 and H _A1 in order to facilitate correlates correlator H _A0 and H _A1 respective output signals, squaring circuits, the intermediate processing circuit such as a filter It is effective. Further, the output signal of the timing extraction circuit 18 is 0
If the timing (zero crossing point) at which [V] is shifted from the timing at which the correlator outputs the correlation peak waveform, the timing may be adjusted to one of the two timings by using a phase adjusting means or the like. In the embodiment, the comparator 1 at the zero crossing point of the output signal of the timing extraction circuit 18 is used.
3, the state value of the output signal is supplied to the processing circuit 16. However, the present invention is not limited to this. For example, a pulse signal based on the output signal of the timing extraction circuit 18 is generated and supplied to the processing circuit 16. It is obvious that a demodulated signal as shown in FIG. 4 (i) may be output. Further, in the above-described embodiment, the determination of the arrival of the received signal and the demodulation of the original information data are performed based on the output signal of the timing extractor 18. However, the present invention is not limited to this. A periodic signal having the same transmission rate as the information data is extracted from a signal obtained by adding the output signals of HB ₀ and HB ₁ to each other, and the arrival of a received signal is determined based on the periodic signal.
Alternatively, demodulation of the original information data may be performed.
In the above-described embodiment, the frequency of the clock signal of the clock oscillator on the demodulation side is set to twice the frequency of the clock signal of the clock oscillator on the modulation side. However, the present invention is not limited to this. It is obvious that any frequency necessary for sampling the received signal is sufficient.

Further, in the above-mentioned embodiment, the modulation side sends one of two types of PN sequences to the transmission line according to the state value "0" or "1" of the information data to be transmitted, and the demodulation side transmits the PN sequence. The original information data was obtained from this transmission signal.
The present invention need not be limited to this. For example, the present invention may be modified as described below. That is, as shown in FIG. 6, the modulator T generates the PN sequence PN ₀ based on the clock signal of the timing generator CL _A as described above.
Comprising a N sequence generator G _T0, a PN sequence PN ₀ of a predetermined period after sending the power line 1, the PN sequence PN ₀ only when the state value of the information data to be transmitted is "0" in the power line 1 It is configured to perform spread spectrum modulation by transmitting. On the other hand, the demodulator R includes the A / D converter 9, the correlators H _A0 , H _B0 , the memory M ₀ , the PN sequence generator G _R0 , the clock oscillator CL _B , the squaring circuit 12, the comparators 10, 13 as described above. , Processing circuits 11 and 16, timing extractor 1
8 and the control circuit 17 and the modulator T
Receives the PN sequence PN ₀ transmitted before transmitting the PN sequence to the power line 1 according to the state value of the information data,
_A0 is used to obtain a correlation signal between the sampling data of the received signal and the output signal of the PN sequence generator G _R0 to extract a periodic signal corresponding to the signal speed of the information data, and to extract the correlation signal and the periodic signal. Then, the arrival of the received signal is determined. Further, storing the obtained by adding the correlation signal by a predetermined cycle synchronization signal to the memory M _0. Thereafter, the demodulator R obtains a correlation value between the output signal of the correlator H _{A0 and} the signal in the memory M ₀ using the correlator H _B0, and uses the comparator 10 to calculate the correlation value to a predetermined reference voltage. The original information data is obtained by determining whether or not V _a [V] is exceeded. In this way, even if the transmission characteristics of the transmission line such as a power line are poor, it will be convenient for performing the above spread spectrum communication with a very simple configuration. Further, the present invention inverts the phase of the PN sequence PN ₀ with respect to the state value “0” of the information data to be transmitted on the modulation side and the phase of the PN sequence PN _{0 with} respect to the state value “1” by 180 degrees. Send it out,
Even if the demodulation side detects whether or not the phase of the correlation value is inverted and demodulates the original information data, it is obvious that the above-described spread spectrum communication can be performed by a simple configuration. .

In the above-described embodiment, the information data to be transmitted is binary data. However, the present invention is not limited to this, and the information transmitted by the modulation device according to the number of state values of the information data is not limited to this.
By increasing the number of types of N sequences, assigning data state values to each PN sequence, increasing the number of correlators, memories, etc., the demodulation side compares the output signal values of each correlator with each other,
If it is assumed that the state value corresponding to the PN sequence having the maximum value is demodulated data, it can be obviously applied to information data having a large number of state values. Further, in the above-described embodiment, the values of the output signals of the correlators are compared with each other, and the state value corresponding to the PN sequence having the maximum value is used as the demodulated data. The present invention is not limited to this as long as the information data is demodulated. For example, the original information data may be demodulated depending on whether any of the output signal values of each correlator has exceeded a predetermined reference value. May be.
In the above-described embodiment, the demodulation side determines the arrival of the received signal based on the periodic signal extracted from the correlation signal between the received signal and the PN sequence. However, the present invention is not limited to this. For example, ISDN (integrated) services digital network
If accurate time information is available due to the high-precision reference signal used in step (i), the timing for transmitting the spread spectrum signal is determined in advance by the modulation side, and the demodulation side determines the arrival of the received signal based on the timing. In this case, it is obvious that the demodulation side does not necessarily need to provide the means for extracting the periodic signal as described above. However, in using the timing on the demodulation side in this case, it is apparent that it is necessary to add a means for compensating the delay of the received signal due to the transmission path characteristics, for example, a phase shifter. Further, the determination of the type of the PN sequence corresponding to the correlation signal to be stored in the memory on the demodulation side does not need to be limited to the means described above. For example, the type of the PN sequence transmitted by the modulation side and its transmission timing are determined in advance based on the high-precision reference signal, and the demodulation side determines the type of the PN sequence corresponding to the correlation signal to be stored in the memory based on the timing. If the correlation signal between each PN sequence and the received signal is stored in a memory, the correlation signal corresponding to each PN sequence in the memory can be distinguished from each other.
The original information data can be demodulated even if there is almost no level difference between the waveform of the correlation peak with the series and the other waveforms. It will be obvious that the present invention is also applicable to wireless communication means.

[0017]

As described above, according to the present invention, the modulation side sends out a spread spectrum signal modulated to output a predetermined PN sequence corresponding to the state value of information data to be transmitted to a transmission path, The demodulation side has the same PN sequence and information as the modulation side.
The required period was output from the modulation side before the data was sent.
After storing the correlation signal with the received signal based on the PN sequence in the memory, the information data is demodulated according to the correlation between the correlation signal in the memory and the correlation signal in the memory. Even if the level difference between the correlation peak waveform and the other waveforms becomes smaller due to the above, it is possible to obtain the correlation waveform necessary for demodulating the original information data,
This is effective in providing a spread spectrum communication system capable of reducing a communication error rate.

[0018]

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining an embodiment of the present invention.

FIG. 3 is a waveform chart for explaining an embodiment of the present invention.

FIG. 4 is a waveform chart for explaining an embodiment of the present invention.

FIG. 5 is a waveform chart for explaining an embodiment of the present invention.

FIG. 6 is a configuration diagram showing a modified embodiment of the present invention.

FIG. 7 is a configuration diagram for explaining a conventional spread spectrum communication method.

FIG. 8 is a waveform chart for explaining a conventional spread spectrum communication method.

[Explanation of symbols]

T modulator R demodulator 1 power line GT ₀ , GT ₁ , GR ₀ and GR ₁ PN sequence generator CL _A and CL _B clock oscillators S _{1 and} S ₂ switches H _A0 , H _A1 , H _B0 and H _B1 correlator M ₀ and M ₁ memories 9 A / D converters 10 and 13 Comparators 11 and 16 Processing circuits 12 and 15 Square circuits 14 Adders 17 Control circuits 18 Timing extraction circuits

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 1/707

Claims (22)

(57) [Claims] In a means for performing communication using a spread spectrum signal modulated so as to output a predetermined PN sequence corresponding to a state value of information data to be transmitted, the same PN sequence as a modulation side is used. Before the information data is sent
A correlation signal between the PN sequence and the received signal output from the modulation side for a required period is stored in a memory. Thereafter, in data demodulation, the correlation signal between the PN sequence and the received signal and the correlation signal between the correlation signal in the memory are used. A spread spectrum communication system for demodulating the information data. 2. Communication is performed using a spread spectrum signal modulated so as to output any one of a plurality of PN sequences having the same period length and a small cross-correlation value in accordance with the state value of information data to be transmitted. In the means for performing, the same PN sequence and information data as those on the modulation side are transmitted.
The correlation signal between the received signal and the PN sequence output from the modulation side in the required cycle before is stored in the memory. Thereafter, in the data demodulation, the correlation signal between the PN sequence and the received signal and the correlation signal in the memory are used. A spread spectrum communication method, wherein the information data is demodulated according to a correlation. 3. A means for performing communication using a spread spectrum signal modulated by determining whether or not to transmit a predetermined PN sequence in accordance with a state value of information data to be transmitted. The same PN sequence and information data are transmitted
The correlation signal between the PN sequence and the received signal output from the modulation side in the required cycle before is stored in a memory. Thereafter, in data demodulation, the correlation between the correlation signal between the PN sequence and the received signal and the correlation signal in the memory is stored. A spread spectrum communication system characterized in that the information data is demodulated according to the following. 4. A means for performing communication using a spread spectrum signal modulated so as to invert a phase of a predetermined PN sequence by 180 degrees in accordance with a state value of information data to be transmitted. The PN sequence and information data are transmitted
After storing in a memory a correlation signal with a received signal based on a PN sequence output from the modulation side for a required period , the correlation signal between the PN sequence and the received signal and a correlation signal between the correlation signal in the memory are stored. A spread spectrum communication system characterized in that information data is demodulated. 5. Communication is performed using a spread spectrum signal modulated so as to output any one of a plurality of PN sequences having the same period length and a small cross-correlation value in accordance with the state value of information data to be transmitted. In the means for performing, the same PN sequence and information data as those on the modulation side are transmitted.
After storing in the memory the correlation signal with the received signal of the PN sequence output from the modulation side in the required period before, the correlation value between each correlation signal between the PN sequence and the received signal and the correlation signal in the memory is calculated. A spread spectrum communication system, wherein the information data is demodulated by comparing with each other and outputting a state value corresponding to a maximum correlation value. 6. A means for performing communication using a spread spectrum signal modulated by determining whether or not to transmit a predetermined PN sequence in accordance with a state value of information data to be transmitted. The same PN sequence and information data are transmitted
After storing in a memory a correlation signal with a reception signal of a PN sequence output from the modulation side for a required period , a correlation value between a correlation signal between the PN sequence and the reception signal and a correlation signal in the memory is obtained, A spread spectrum communication system, wherein the information data is demodulated by detecting whether or not the correlation value output level has exceeded a predetermined reference value. 7. A means for performing communication using a spread spectrum signal modulated so as to invert a phase of a predetermined PN sequence by 180 degrees in accordance with a state value of information data to be transmitted. The PN sequence and information data are transmitted
After storing in a memory a correlation signal with a reception signal of a PN sequence output from the modulation side for a required period , a correlation value between a correlation signal between the PN sequence and the reception signal and a correlation signal in the memory is obtained. A spread spectrum communication method, wherein the information data is demodulated by detecting whether or not the phase of the correlation value is inverted. 8. After outputting a predetermined PN sequence for a required period,
In the means for performing communication using a spread spectrum signal modulated so as to output the PN sequence corresponding to the state value of the information data to be transmitted, the same PN sequence and information data as those on the modulation side are transmitted. Before
The arrival of the received signal is determined by a periodic signal corresponding to the signal speed of the information data extracted from the correlation signal with the received signal of the PN sequence output from the modulation side for a required period, and the correlation signal is stored in a memory. In the spread spectrum communication method, the information data is demodulated in accordance with the correlation between the correlation signal between the PN sequence and the received signal and the correlation signal in the memory. 9. A method for outputting a plurality of PN sequences having the same cycle length and a small cross-correlation value in a required sequence in a predetermined order, and then corresponding to the state value of the information data to be transmitted.
In the means for performing communication using a spread spectrum signal modulated so as to output any one of the sequences, the same PN sequence and information data as those on the modulation side are transmitted.
The arrival of the received signal is determined by the periodic signal corresponding to the signal speed of the information data extracted from the signal obtained by adding all the correlation signals with the received signal of the PN sequence output from the modulation side in the required period , and From the value of the correlation signal, it is determined which of the plurality of PN sequences the received PN sequence is, and the correlation signals are respectively stored in a memory. When demodulating data thereafter, the correlation between the PN sequence and the received signal is determined. A spread spectrum communication method, wherein the information data is demodulated according to a correlation between a signal and a correlation signal in the memory. 10. After outputting a plurality of PN sequences having the same cycle length and a small cross-correlation value in a required cycle in a predetermined order, one of the PN sequences is corresponded to a state value of information data to be transmitted. In the means for performing communication using the spread spectrum signal modulated so as to output, the same PN sequence and information data as those on the modulation side are transmitted.
The arrival of the received signal is determined by the periodic signal corresponding to the signal speed of the information data extracted from the signal obtained by adding all the correlation signals with the received signal of the PN sequence output from the modulation side in the required period , and From the value of the correlation signal, it is determined which of the plurality of PN sequences the received PN sequence is, and the correlation signals are respectively stored in a memory. When demodulating data thereafter, the correlation between the PN sequence and the received signal is determined. A signal for comparing a correlation value between the signal and a correlation signal in the memory, and demodulating the information data by outputting a state value corresponding to the maximum correlation signal. Communication method. 11. After outputting a plurality of PN sequences having the same period length and a small cross-correlation value in a required cycle in a predetermined order, one of the PN sequences is corresponded to a state value of information data to be transmitted. In the means for performing communication using the spread spectrum signal modulated so as to output, the same PN sequence and information data as those on the modulation side are transmitted.
The arrival of the received signal is determined by the periodic signal corresponding to the signal speed of the information data extracted from the signal obtained by adding all the correlation signals with the received signal of the PN sequence output from the modulation side in the required period , and From the value of the correlation signal, it is determined which of the plurality of PN sequences the received PN sequence is, and the correlation signals are respectively stored in a memory. When demodulating data thereafter, the correlation between the PN sequence and the received signal is determined. A spread spectrum method, wherein a correlation value between a signal and a correlation signal in the memory is obtained, and the information data is demodulated by detecting which of the correlation values exceeds a predetermined reference value. Communication method. 12. After outputting a predetermined PN sequence for a required period, the PN sequence corresponding to the state value of the information data to be transmitted.
In means for performing communication using a spread spectrum signal modulated by determining whether or not to transmit a sequence, before transmitting the same PN sequence and information data as the modulation side ,
The arrival of the received signal is determined by a periodic signal corresponding to the signal speed of the information data extracted from the correlation signal with the received signal of the PN sequence output from the modulation side for a required period, and the correlation signal is stored in a memory. Thereafter, upon data demodulation, a correlation value between a correlation signal between the PN sequence and the received signal and a correlation signal in the memory is obtained, and whether or not the correlation value exceeds a predetermined reference value is detected. A spread-spectrum communication system characterized by demodulating a signal. 13. After outputting a predetermined PN sequence for a required period, the PN sequence corresponding to the state value of the information data to be transmitted is output.
In the means for performing communication using a spread spectrum signal modulated so that the phase of the sequence is inverted by 180 degrees, before transmitting the same PN sequence and information data as the modulation side ,
The arrival of the received signal is determined by a periodic signal corresponding to the signal speed of the information data extracted from the correlation signal with the received signal of the PN sequence output from the modulation side for a required period, and the correlation signal is stored in a memory. Thereafter, upon data demodulation, a correlation value between the correlation signal between the PN sequence and the received signal and a correlation signal in the memory is obtained, and the information data is detected by detecting whether or not the phase of the correlation value is inverted. A spread spectrum communication system characterized in that demodulation is performed. 14. The spread spectrum communication system according to claim 8, wherein said information data is demodulated at a timing based on said periodic signal. 15. The information data is demodulated by outputting a state value corresponding to the maximum correlation signal at a timing based on the periodic signal. The spread spectrum communication method described. 16. The information data is demodulated by detecting, at a timing based on the periodic signal, which of the correlation values exceeds a predetermined reference value. 12. The spread spectrum communication system according to claim 11. 17. The information data is demodulated by detecting whether or not the correlation value exceeds a predetermined reference value at a timing based on the periodic signal. Spread spectrum communication method described in the item. 18. and characterized by being adapted to demodulate the information data by detecting at the timing based whether the phase of the correlation value is inverted to the periodic signal
14. The spread spectrum communication system according to claim 13, wherein: 19. A PN sequence and a reception signal identical to those on the modulation side, and a correlation signal between them and a correlation signal in the memory are synchronized based on the periodic signal. The spread spectrum communication system according to claim 8 to claim 18. 20. A correlation signal stored in the memory before the same PN sequence and information data as on the modulation side are transmitted.
20. The spread spectrum communication method according to claim 1, wherein the signal is a signal obtained by synchronously adding a correlation signal with a reception signal of a PN sequence output from the modulation side in a required period for a predetermined period. 21. A plurality of PNs having the same period length and a small cross-correlation value corresponding to the state value of the information data to be transmitted.
In the spread spectrum communication means for transmitting any of the sequences to the transmission line, the modulating side transmits each of the plurality of PN sequences for a plurality of predetermined periods before transmitting the PN sequence corresponding to the state value of the information data. The demodulation side transmits the data in order, and the demodulation side needs
A correlation value between the received signal based on the PN sequence output in advance and each of the PN sequences is obtained, and the arrival of the reception signal corresponding to the predetermined PN sequence is determined from the correlation value and the periodic signal extracted from the correlation signal. A signal waveform value obtained by synchronously adding the correlation signals for a predetermined period is stored in a memory, and when demodulating data thereafter, a correlation value between each signal waveform value in the memory and the corresponding correlation signal is stored. A spread spectrum communication method, wherein the correlation values are compared with each other at a timing based on the periodic signal to demodulate the state value of the information data. 22. A spread spectrum communication system according to claim 21, wherein said periodic signal is extracted from a signal obtained by adding a correlation value between a received signal and each of said PN sequences to each other.