JP2896817B2 - Spread spectrum communication equipment - 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 apparatus and, more particularly, to an improvement for enabling data demodulation in a spread spectrum receiver by using a single correlator.

[0002]

2. Description of the Related Art FIGS. 6 and 7 show an example of a conventional multiplex communication apparatus using a spread spectrum communication system for performing high-speed data communication.
Shown in FIG. 6 shows a transmitter, 1 is a serial-parallel converter, 2-1 to 2-n are multipliers, and 3-1 to 3-n are PNs.
A code generator, 4-1 to 4-n are BPSK modulators, and 5 is an adder.

In the above transmitter, the input high-speed data (A) is converted by the serial-parallel converter 1 into parallel data (A1), (A2),... (In). Parallel data (a1), (a2), ... (in)
Is input to one input of the multipliers 2-1, 2-2,..., 2-n. On the other hand, the multipliers 2-1, 2-2,...
PN code generators 3-1, 3-2,.
The different PN codes (U1), (U2),... (Un) output from... 3-n are input. Multipliers 2-1 and 2-2
-2-,... 2-n outputs (d1), (d2),... (N) are BPSK modulators 4-1, 4-2,.
And modulates the high-frequency carrier signal (e). .. (N) are output from the BPSK modulators 4-1, 4-2,..., 4-n, and input to the adder 5. . The adder 5 outputs and transmits the n-multiplexed spread spectrum signal (g).
FIG. 7 is a receiver, 7-1 to 7-n are convolvers, 8-1.
8-n is a multiplier, 9-1 to 9-n are PN code generators, 10-1 to 10-n are detectors, and 12 is a data demodulator.

In the above receiver, the received signal (k) is distributed and inputted to one of the inputs of the convolvers 7-1, 7-2,..., 7-n. On the other hand, the PN code generator 9
-1, 9-2,..., 9-n, the PN codes (co1), (co2),.
2,... 8-n are added to one input. Multiplier 8
, 8-2,..., 8-n are supplied with a high-frequency carrier signal (s). Multipliers 8-1, 8
The outputs (sa1), (sa2),... (San) of −2,..., 8-n are applied to the other inputs of the convolvers 7-1, 7-2,. You.

[0005] Convolver outputs (S1), (S2), ...
.. (Sin) are detectors 10-1, 10-2, 10-n, respectively.
Is input to At this time, a correlation spike is generated at the same timing from each data channel in the output from the convolver. The outputs (SO1), (SO2), and (SON) of the detectors 10-1, 10-2, and 10-n are input to the data demodulator 12. Data demodulator 12 outputs demodulated data (data).

[0006]

The above-described conventional multiplex communication apparatus requires synchronization of a carrier signal,
There is a disadvantage that a plurality of convolvers (or matched filters) as correlators are required.

[0007]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the disadvantage that a conventional multiplex communication apparatus requires a plurality of correlators and to provide a multiplex communication apparatus capable of demodulation with a single correlator.

[0008]

According to a first aspect of the present invention, there is provided a serial-parallel conversion means for converting serial transmission data into a plurality of parallel data, and a spread spectrum using the plurality of parallel data. Spread modulation means for performing modulation, and a sounder comprising a spread spectrum modulation signal independent of the plurality of parallel data.
Delay means for delaying each output of the spread modulation means with reference to the phase of the sounder , addition means for adding the spread spectrum modulation signal and each delay means output, and high-frequency modulation of the output of the addition means A transmitter including a high-frequency modulator; a correlator for correlating a received signal with a reference signal; a conversion unit for converting an output signal of the correlator to a signal in a baseband information band; The gist of the present invention consists of a receiver including a binarizing circuit for converting the output of the means into a digital signal and data demodulating means for demodulating data from the digital signal.

According to a second aspect of the present invention, there is provided means for converting serial transmission data into a plurality of parallel data, spread modulation means for performing spread spectrum modulation on the plurality of parallel data, and output from the spread modulation means. Means for synthesizing the spread spectrum modulation signal and the spread spectrum modulation signal that does not depend on the transmission data and outputting a multiplexed spread spectrum modulation signal, and a transmitter, and the multiplexed spread spectrum modulation signal and a reference signal. A means for generating a correlation pulse by converting the output of the correlator into a signal in a baseband information band and binarizing the signal; and a spectrum independent of the transmission data from the correlation pulse Detecting means for detecting a correlation pulse component corresponding to the spread modulation signal; Zui and the gist in that it consists, means for demodulating said data.

[0010]

In the multiplex communication apparatus having the above structure, the transmitting side does not modulate the PN code with the data, that is, does not depend on the data, for example, a state of "all 1s", which is called a sounder. ) And transmit. On the transmitting side, the input high-speed data is subjected to serial-parallel conversion, and spread modulation is performed for each channel.
Then, these modulated signals are sequentially delayed for each channel based on the phase of the sounder, for example, a spread spectrum modulated signal that does not depend on the data, and the respective spread signals are combined with the spread spectrum modulated signal as a sounder. Then, a high frequency carrier signal is multiplied and transmitted.

On the receiving side, the received signal is correlated by a single correlator. The PN code used for the reference signal of the correlator is selected so that, for example, when the data is "1", a correlation spike occurs. The output of the correlator is different from the conventional method. For example, a correlation spike by a sounder is output at the head, and subsequently, a correlation spike of a delayed data channel is serially output.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. 1A and 1B respectively show an embodiment of a spread spectrum (SS) communication device according to the present invention.
A transmitter and a receiver. As shown in FIG. 1A , the transmitter includes a serial-parallel conversion circuit 101, a group of selectors 102, a group of delay units 103, an adder 104, a PN code (code) generator 105, and a high-frequency carrier generator 10.
6. It comprises a multiplier 107.

As shown in FIG . 1B , the receiver includes a convolver 201 as a correlator, a multiplier 202, a high-frequency carrier generator 203, a PN code (code) generator 204, a high-pass filter (HPF) 205, and an amplifier. 206, a detector 207, a binarization circuit 208, a sounder pulse detection circuit 209, a sampling pulse generation circuit 210, an information detection circuit 211, and a parallel-serial conversion circuit 212.

Next, the operation of the above embodiment will be described. First,
In the transmitter, the transmission data a is converted by the serial-parallel conversion circuit 101 into signals of a plurality of channels. Here, the number of channels is assumed to be N for simplifying the explanation. The output of the transmission data a is converted by the serial-parallel conversion circuit 101 to a lower transmission speed. For example, it is converted into parallel data having a transmission rate of 1 / N or a transmission rate arbitrarily lower than the transmission rate of the transmission data a. Spread spectrum modulation (SS modulation) according to the polarity of the signal of each channel from the serial-parallel conversion circuit 101 is performed.

The SS modulation uses, for example, the following two methods. CSK (Code Shift Keying) method: Two types of PN codes (PN1 and PN) according to the polarity of data (signal)
2) Select and output. OOK (On Off Keying) method: A method of selecting whether or not to output a PN code (PN1) according to the polarity of data (signal).

In order to realize the above two types of SS modulation operation, PN codes (PN1 and PN2) must be
Code generator 105 and serial-parallel conversion circuit 1
Each of the selector groups 102 for performing the above-described selection by each output of No. 01 constitutes a spread modulator. Next, the output of each selector of the spread modulator is input to each delay unit of the delay unit group 103. The output of each delay unit is an SS modulated signal (information channel) in which a different arbitrary delay amount is set with reference to the phase of a PN code (here, PN1) of a sounder channel serving as a data demodulation synchronization signal. can get. This is shown in FIG. In FIG. 3,
The information channel represents the difference between the CSK method and the OOK method with different delay amounts (τ _{1 to} τ ₄ ) when the information channels are 11 to 14. S is a sounder channel. It also shows that the transmission rate of the transmission data is converted to the slow transmission rate of each information channel. Here, 1/4
Has been converted to the transmission speed. N obtained from each delay unit
The adder 104 performs analog addition (multiplexing) of the SS modulation signal of the information channels and the signal of the sounder channel in the adder 104, and multiplies the output of the adder 104 by the output of the high-frequency carrier generator 106 by the multiplier 107. , To obtain a multiplexed SS signal.

Next, in the receiver, the multiplexed SS signal obtained by the transmitter is input to one input terminal of the convolver 201 as a reception signal. The other input terminal of the convolver is connected to the PN code obtained by the PN code generator 204 (here, the PN code (PN used in the transmitter)).
PN code (PN1) that has a temporally inverted relationship with 1)
Is multiplied with the output of the high-frequency carrier generator 203 by the multiplier 202 to obtain a high-frequency modulated P.
The N code is input as a reference signal. The convolver 201 performs a correlation operation between the received signal and the reference signal to obtain a high-frequency correlation output (see FIG. 4). Note that the gate length (processing time) of the convolver in this description corresponds to 2T.

In FIG. 4, based on the phase of the PN code of the sounder channel described in FIG. 3, a temporally separated correlation peak corresponding to each PN code having a different phase relationship of each information channel is obtained. Here, a state is shown in which a correlation peak that is an autocorrelation is obtained in the sounder channel and all information channels. Therefore, when autocorrelation cannot be obtained in either the CSK method or the OOK method (CSK method: cross-correlation, OOK method: no correlation)
No correlation peak occurs.

In the above embodiment, the case where a convolver is used as a correlator is described. However, there is no problem if a matched filter is used. However, the location where the reference signal is generated is unnecessary because it is replaced with a pattern on the matched filter. Next, the convolver output is converted to a high-pass filter 20.
5 and an amplifier 206, detects the signal in the detector 207, converts the signal into a baseband information band signal,
At 08, a pulse train of a logic level is obtained.

In the binarization circuit 208, a threshold value is set so that the correlation peak and the spurious level can be optimally separated. Since the correlation output corresponding to the sounder channel always generates a periodic correlation peak, the correlation peak is detected by the sounder pulse detection circuit 209 to obtain a reference time signal. The purpose of requiring such a reference time signal is to eliminate the need for spreading code synchronization in the normal DS-SS system.

That is, in the present invention, the phase of the PN code of the received signal on the convolver and the PN
Instead of a method of synchronizing codes and performing data demodulation, an asynchronous method without a code synchronization process is realized. The sampling pulse generation circuit 210 is based on the reference time signal output from the sounder pulse detection circuit 209.
Generates a sampling pulse for sampling a correlation output corresponding to each information channel.

When a convolver is used as a correlator, the received signal and the reference signal input to the convolver are:
Correspondingly, the correlation peak occurs at gate delay time / 2. That is, the correlation output corresponding to the delay amount (τ _{1 to} τ ₄ ) of each information channel based on the phase of the PN code of the sounder channel on the transmission side shown in FIG. 3 is also τ _{1/2 to} τ ₄ /. About two are separated in time and occur.

Therefore, the sampling pulse is generated in consideration of the above. Thus, based on the sampling pulse, the information detection circuit 211 samples the correlation output corresponding to each information channel and demodulates the data sequence of each information channel. The data obtained here is data having a transmission rate equal to the low transmission rate after serial-parallel conversion on the transmission side. Next, this N
By converting the parallel data strings into serial data in the parallel-serial conversion circuit 212,
Restore transmitted data.

FIG. 5 shows an outline of this series of operations. As described above, in the receiver, the correlation operation is performed by the correlator, and the correlation output is detected and binarized to obtain a logic-level correlation pulse train. A correlation pulse component corresponding to the sounder channel is detected from the correlation pulse train signal by a sounder detection circuit.Detection of the sounder channel, which is a reference signal of such an information channel, can be said to be an initial synchronization process in a broad sense. Next, a specific example of the sounder detection circuit will be described.

The PN code of the sounder channel is set in the transmitter so that the correlation output corresponding to the sounder channel always occurs periodically. For example, the P
N1 is set continuously. In this case, sounder detection can be performed by utilizing the periodicity that the noise always occurs periodically. FIG. 8 shows a configuration example of a sounder detection circuit. In the figure, 300-1 to 300-n are delay units, 301 is an adder, 302 is a reference value generation circuit, 30
3 is a comparator.

As described above, assuming that the generation cycle of the correlation pulse component corresponding to the sounder channel is known,
The delay time of each of the delay units 300-1 to 300-n is set to the cycle. And each of the delay units 300-1 to 300
The output of −n is analog-added by the adder 301. Thus, the number of pulses at that time is obtained for each correlation pulse component generation cycle. For example, if there are four delay units,
The maximum number of detectable pulses is 5.

The output of the adder 301 is compared with the reference value (5) from the reference value generation circuit 302 by the comparator 303.
When they match, an output signal is obtained from the comparator 303. When this signal is obtained, it is determined that a periodic signal has been input, that is, a sounder pulse has been detected. It should be noted that the signal judgment accuracy can be improved by increasing the number of stages of the delay unit. However, the number of stages is set to an appropriate number in consideration of the circuit scale or the usage environment.

The output signal of the comparator 303 is sent to the sampling pulse generation circuit as described above, and the information is reproduced by sampling the correlation pulse corresponding to each information channel by the sampling pulse obtained from the circuit. In the above sounder detection, when a multiplexed SS signal is obtained at the transmitter, if the data is data such that 1 is continuous as the transmission data, that is, the multiplexing is performed in such a manner that PN1 is continuously output in SS modulation. SS
When a signal is obtained and output, a correlation pulse corresponding to each information channel in the correlator output is continuously and periodically generated similarly to the sounder channel. In this case, there is a possibility that the sounder pulse detection circuit will make a detection decision on either the sounder channel or the correlation pulse corresponding to the information channel.

As a result, when a sounder channel cannot be detected according to any of the information channels, sampling of a correlation pulse corresponding to the information channel is not performed, and erroneous data is demodulated. As a method for solving this problem, there is the following method (a) or (b).

(A) When data (information) to be transmitted is generated, only the sounder channel is output as shown in FIG. 9A before multiplexing the transmission data and outputting the multiplexed SS signal. Note that the transmission period is set to a time period long enough to allow the sounder detection circuit to detect the correlation pulse component corresponding to the sounder channel. In this case, when there is no advanced handshake between the transmitter input side, that is, the side where the data to be transmitted is generated (for example, a personal computer in the case of communication between personal computers, etc.) and the transmitter, for example, FIG. As shown in the figure, a delay unit 400 is provided before the serial-parallel conversion circuit 101.
The data (information) to be transmitted with the delay is delayed by the transmission period from the start of generation.

(B) When data (information) to be transmitted is generated, the transmitter codes and multiplexes the transmission data as shown in FIG. 9B, and outputs a multiplexed SS signal. As this coding method, there is a method of inserting a 0 into a portion of transmission data in which ones are consecutive by a predetermined algorithm so that a correlation pulse corresponding to a sounder channel can be reliably detected by a sounder detection circuit. . As a result, 1 does not continue, so that there is no erroneous detection in the sounder detection circuit.

In data demodulation at the receiver,
The transmission data is decoded before being reproduced and output, that is, contrary to the processing on the transmission side, the inserted data is removed by a predetermined algorithm to restore the transmission data to a coded one. FIGS. 11A and 11B show configuration examples of the main parts of the transmitter and the receiver in that case.
Shown in In the figure, reference numeral 500 denotes a coding circuit;
Is a decoding circuit, and the other configuration is as shown in FIGS. 1 (a) and 1 (b).

Thus, the above-described sounder detection is performed in a normal DS
-Spread code synchronization in the SS system is not required. That is,
This is for realizing the asynchronous system. Therefore, in this case, the correlation peak must be output reliably by the convolver, and therefore, the information channel needs to be longer than the gate length of the convolver. That is, the gate length (processing time) of the convolver corresponds to 2T (T is the transmission data transmission speed). Therefore, each information channel has a transmission rate (for example, 1/100) that is lower than twice the transmission rate of transmission data.
It is better to convert to 4). As a result, a plurality (for example, four) of correlation peaks from the convolver in one bit of each information channel occurs. However, in practice, since the level of the correlation peak at the data change point is undefined, in the case described above, it is necessary to detect a reliable correlation peak point in the information channel data 1-bit length.

As a method for reliably detecting such a correlation peak point, a method of recognizing and avoiding a data change point may be used. That is, in the case of data "0", some level is generated at a change point of the data before and after the change point although no correlation output is generated. Therefore, before the data to be transmitted is generated, any dummy data having a data change point for detecting an optimum point equal to the information channel length is transmitted before the data is generated. Since this dummy data is also subjected to serial-parallel conversion in the same manner as ordinary data, the dummy data is placed on one of the information channels in any of the finally obtained multiplexed SS signals, and the dummy data is received by the receiver. Detect only by looking at the channel.

In this case, a dummy information is placed before transmission data in consideration of the number of multiplexes so that an alternate pattern such as 1,0,1,0,1,0,... Data must be sent.
FIGS. 2A and 2B show configuration examples of main parts of a transmitter and a receiver when the above-described method of detecting a correlation peak point is used. In FIG. 2A, 600 is a delay unit, 601 is a dummy data generation circuit, 602 is a counter (or delay unit) for a time equivalent to the above-mentioned delay unit, and 604 is a selector. 1 (a) or FIG. 10 or FIG.
It is configured to include the circuit of (a). FIG. 2B shows a configuration example of the information detection circuit 211 in the receiver. In the figure, reference numeral 700 denotes a shift register, 701-1 and 701.
701-n are delay units, 702 is a pattern correction circuit, 703 is a reference value generation circuit, 704 is a comparator, and 705 is an adder. Pattern correction circuit 702
Includes, for example, inverters INV1 and INV2.

In the transmitter of FIG. 2A, for example, when the number of multiplexed information is 4, the dummy data generation circuit 601
1000000000100000000000 generated by ...
Is input before the transmission data by the selector 604 in response to the transmission data start signal,
After serial-parallel conversion, a multiplexed SS signal is obtained via an SS modulator or the like. During this dummy data transmission period,
Since the serial transmission data to be transmitted is delayed by the delay unit 600 for a time equivalent to the period, there is no problem. After the period elapses, the selector 604 switches from the dummy data to the transmission data in response to the output of the counter 602.

In the receiver of FIG. 2B, the correlation pulse from the binarization circuit 208 is sampled by a sampling pulse by the shift register 700, and the correlation pulse corresponding to one of the information channels of the correlation pulse is delayed by a delay unit. 7
.. 701-n. Here, the delay time of each delay unit is set equal to the information channel length. The output of each delay device is a pattern correction circuit 702
Are analog-added by the adder 705 via. In the pattern correction circuit 702, inverters INV1 and INV2 are provided for every other delay device because an alternate pattern of 101010... Is obtained. In this case, the pattern of 101010 ... is 1
11111... Have the same polarity. Thus, the comparator 7
When the final comparison output with the reference value is obtained in step 04, the optimum point of the data, that is, the point suitable for sampling and demodulating the data. Although the dummy pattern may be anything, the inverter of the pattern correction circuit of the receiver is set according to the dummy pattern. However, the dummy pattern length is equal to or longer than the maximum delay time of the delay unit group 701, ie,
There must be enough time to detect.

[0038]

As described above, according to the present invention, even if multiplexed spread spectrum communication is performed, only one correlator is required, and the circuit can be simplified. And when using a convolver or a matched filter as a correlator,
Although the upper limit of the data transfer rate that can be handled is determined by the processing time of the correlator, data transmission at a high speed can be performed beyond that limit. In addition, even if high-speed data transmission is performed, there is no need to increase the clock of the PN code.
There is no expansion of the communication band, and there is no interference with other communication systems. In addition, since a spread spectrum modulation signal that does not depend on data is multiplexed and modulated as a reference time signal, phase synchronization of a PN code is not required in a correlator, and therefore, high-speed data can be obtained without considering processing relaxation of the correlator. Transmission becomes possible. Further, since a correlation pulse corresponding to a sounder channel serving as a reference at the time of data demodulation can be reliably detected and a data sampling point can be reliably detected, data demodulation performance is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a transmitter and a receiver of an apparatus according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operation of the transmitter.

FIG. 4 is an explanatory diagram of the operation of the receiver.

FIG. 5 is an explanatory diagram of the operation of the receiver.

FIG. 6 is a block diagram illustrating an example of a conventional device.

FIG. 7 is a block diagram illustrating an example of a conventional device.

FIG. 8 is a block diagram illustrating a configuration example of a sounder detection circuit.

FIG. 9 is an explanatory diagram of an example of a reliable data sampling method.

FIG. 10 is a block diagram showing a configuration example for implementing this method.

FIG. 11 is a block diagram showing a configuration example for implementing this method.

[Explanation of symbols]

 Reference Signs List 102 Selector group 103 Delay group 104 Adder 105 PN code generator 107 High frequency modulator 201 Correlator 204 PN code generator 207 Detector 208 Binarization circuit 209 Sounder pulse detection circuit 210 Sampling pulse generation circuit 211 Information detection circuit 212 Parallel-serial conversion circuit

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shigeo Akazawa 5-35-2 Hakusan, Bunkyo-ku, Tokyo Inside Clarion Co., Ltd. (56) References JP-A-58-171143 (JP, A) JP-A-58 197934 (JP, A) JP-A-2-121424 (JP, A) JP-A-2-299334 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04J 13/00

Claims (12)

(57) [Claims] 1. A serial-parallel conversion means for converting serial transmission data into a plurality of parallel data, a spread modulation means for performing spread spectrum modulation using the plurality of parallel data, and a spread spectrum independent of the plurality of parallel data. A sounder comprising a modulated signal and the sound
Delay means for each output respective delay allowed to the spread modulation means based on the phase of Sunda, adding means for adding the said spread spectrum modulation signal and the respective delay means output, a high-frequency modulation of the high frequency modulating said adding means output A correlator for correlating the received signal with the reference signal; a conversion means for converting an output signal of the correlator into a signal in a baseband information band; A spread spectrum communication apparatus comprising: a receiver including a binarizing circuit for converting an output into a digital signal and data demodulating means for demodulating data from the digital signal. 2. The spread spectrum communication apparatus according to claim 1, wherein said spread modulation means selects two types of spread codes according to the polarity of each data of said plurality of parallel data. 3. The spread modulation means selects whether to output one spread code according to the polarity of each data of the plurality of parallel data.
2. The spread spectrum communication apparatus according to claim 1. 4. The data demodulating means includes detecting means for detecting, via the binarizing circuit, a correlation peak of the output signal from the correlator corresponding to the spread spectrum modulated signal. Item 2. A spread spectrum communication device according to item 1. 5. A sampling pulse for sampling a correlation peak corresponding to the plurality of parallel data of an output signal from the correlator from the output signal of the detection means via the binarization circuit. The spread spectrum communication apparatus according to claim 1, further comprising a generation unit. 6. The data demodulation means, by means of a sampling pulse obtained by the sampling pulse generation means, outputs a correlation peak corresponding to the plurality of parallel data of an output signal from the correlator via the binarization circuit. 2. The information processing apparatus according to claim 1, further comprising: information detecting means for sampling and demodulating the plurality of parallel data; and parallel-serial converting means for demodulating transmission data from the plurality of parallel data obtained by the information detecting means. A spread-spectrum communication device as described . 7. A means for converting serial transmission data into a plurality of parallel data; a spread modulation means for performing spread spectrum modulation on the plurality of parallel data; a spread spectrum modulation signal output from the spread modulation means; Means for synthesizing a data-independent spread spectrum modulation signal and outputting a multiplexed spread spectrum modulation signal, and a transmitter comprising: a correlator for correlating the multiplexed spread spectrum modulation signal with a reference signal. Means for generating a correlation pulse by converting the output of the correlator into a signal in a baseband information band and binarizing the signal; and calculating a correlation corresponding to the spread spectrum modulation signal independent of the transmission data from the correlation pulse. Detecting means for detecting a pulse component; and Spread spectrum communication device comprising means for demodulating over data, a receiver with, in that it consists of. 8. The detecting means comprises: a plurality of delay units; an adder for adding the outputs of the delay units in an analog manner; and a comparator for comparing the output of the adder with a reference value. The spread spectrum communication apparatus according to claim 7, wherein: 9. The method according to claim 1, wherein, before converting the serial transmission data into the plurality of parallel data,
8. The spread spectrum communication apparatus according to claim 1, further comprising delay means for delaying the data by a predetermined time. 10. The transmitter, further comprising, before converting the serial transmission data into the plurality of parallel data, encoding means for encoding the data according to a predetermined algorithm, and at the receiver, 8. The spread spectrum communication apparatus according to claim 1, further comprising decoding means for decoding the demodulated data and restoring the serial transmission data when demodulating the data. 11. A transmitter for generating any dummy data before converting the serial transmission data into the plurality of parallel data, and a means for selectively outputting the transmission data and the dummy data. 8. The spread spectrum communication apparatus according to claim 1, further comprising: a dummy data detecting unit for detecting the dummy data from the correlation pulse in the receiver. 12. The dummy data detecting means includes: a plurality of delay units for delaying a correlation pulse corresponding to one of the information channels; a pattern correcting unit for correcting each output of the delay units; 12. The spread spectrum communication apparatus according to claim 11, further comprising an adder for adding the respective outputs to analog, and a comparator for comparing the output of the adder with a reference value.