JP2006339924A - Spread spectrum communication system and demodulation circuit therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spread spectrum communication system capable of retaining secrecy and capability against ECCM neither causing an increased number of plurality of PN code generators on the transmission/reception side to cope with an increased number of transmittable information bits, nor requiring a linear power amplifier. <P>SOLUTION: On a transmission side, a PN code from a PN code generator (#1) 11 is transmitted as a reference channel, and the phase and the polarity of a PN code from another PN code generator (#2) 12 are modified by use of information bits so as to generate a new product code with the PN code on the reference channel side, and to transmit to an orthogonal transmission line 31. On a reception side, PN code acquisition and tracing for the reference channel are performed to a PN code generator (#3) 41 on the reference channel side of the product code. In a parallel correlator 71, correlation integration of an inverse spread of the PN code on the information transmission channel side is performed simultaneously for a plurality of phases, and an output having the largest correlation value among the outputs of the parallel correlator 71 is detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spread spectrum communication system and a demodulation circuit used therefor, and more particularly to a spread spectrum communication system using a product code.

  In a spread spectrum communication system, by spreading the spectrum in a very wide band with respect to the amount of information to be transmitted, the confidentiality of the signal is enhanced, and the ability to eliminate electromagnetic interference (ECCM) is also provided. In recent years, it has been adopted in many communication systems.

  In a spread spectrum communication system, a code sequence having a low cross-correlation is used for the spreading PN code used to spread the spectrum over a wide band, so that the code division multiple access (CDMA) using the spreading code in the used band is performed. : Code Division Multiple Access) (see, for example, Patent Document 1).

  FIGS. 11 to 15 are block diagrams showing a configuration example of a spread spectrum communication system in which a Gold code, which is one of product codes having low cross-correlation, is used as a spread spectrum code.

On the transmission side, a PN (Pseudorandom Noise) code generator (# 1) 11a and a PN code generator (# 2) 12a that generate an M-sequence code with a period of 2 ^k-1 are paired. On this transmission side, from the PN code generator (# 2) 12a having an initial phase, one of the 2 ^k-1 PN code phases is selected based on the initial phase of the PN code generator 11a. A Gold code generator that outputs a product code that is a product of the generated PN code and a multiplier 21a spreads 1-bit information in one period of the PN code and transmits it to the transmission line 31a.

  The spread signal input via the transmission line 31a is received on the receiving side having a gold code generator composed of a PN code generator (# 3) 41a and a PN code generator (# 4) 42a which are equal to those on the transmitting side. Based on the local signal on the receiver side, the multiplier 51a and the integrator (Σ) 52a perform correlation integration for a time corresponding to one period of the PN code. The correlation integral value is input to the phase controller 61a, and the generation timing of the goal code is controlled and tracked by the phase controller 61a so as to maximize the magnitude of the absolute value of the correlation integral. On the other hand, the +/- polarity of the correlation integral value is input to the polarity discriminator 62a, and 1-bit information is demodulated per one period of the PN code.

Here, as shown in FIG. 12, the PN code generator (# 1) 11a includes an initial phase setter (all'1 ') 111a, a shift register (# 1) 112a, and a multiplier 113a. ing. Further, as shown in FIG. 13, the PN code generator (# 2) 12a includes a phase setter (2 ^k ) 121a, a shift register (# 2) 122a, and a multiplier 123a.

  As shown in FIG. 14, the PN code generator (# 3) 41a includes an all '1' detector 411a, a shift register (# 3) 412a, and a multiplier 413a. Further, as shown in FIG. 15, the PN code generator (# 4) 42a includes an initial phase setting unit 421a, a shift register (# 4) 422a, and a multiplier 423a.

Spatial multiple access is possible in a linear multiplex transmission line by a receiver that selects one of the 2 ^k-1 transmitters having different Gold codes. On the other hand, assuming a single communication channel for transmission and reception, by having multiple gold code generators on the transmission side, multiple spread waves for multiple information bits are generated, and communication is performed after performing amplitude linear addition on this A spread spectrum communication system is constructed that can receive a plurality of information bits simultaneously by transmitting to a channel and despreading and demodulating each spread spectrum wave on the receiving side.

JP 2001-007733 A

  In the above-described conventional spread spectrum communication system, in order to further expand the information bits that can be transmitted while maintaining confidentiality and ECCM resistance, a broadband spread spectrum wave is generated by a faster PN code generator, Alternatively, it is necessary to generate a plurality of spread waves by a plurality of PN code generators on the transmission side, add them linearly, and simultaneously operate a despreading circuit by the plurality of PN code generators on the reception side.

  In a conventional spread spectrum communication system, in order to maintain confidentiality and anti-ECCM, it is necessary to keep the spread rate ratio to the transmission information rate constant, so the spread rate is widened as the information bit rate increases. There is a need. Therefore, in the conventional spread spectrum communication system, the occupied frequency band is increased, which is practically a restriction from the viewpoint of effective use of the radio frequency band.

On the other hand, a spread spectrum wave linear addition method using a plurality of PN codes is possible as long as circuit increase of a PN code generator, a despreading demodulator, etc. is allowed, but a linear power amplifier is required. There is a difficult problem for downsizing.
The present invention has been made in view of the above points, and an object thereof is to provide a spread spectrum communication system. Another object of the present invention is to provide an efficient spread spectrum demodulating circuit system that enables downsizing of the apparatus.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and without increasing the number of PN code generators on the transmission / reception side for the increase of information bits that can be transmitted, and without requiring a linear power amplifier, it is concealed. It is an object of the present invention to provide a spread spectrum communication system and a demodulating circuit used therefor that can maintain the performance and the anti-ECCM.

A spread spectrum communication system according to the present invention includes first and second PN code generators for generating a PN (Pseudorandom Noise) code, between PN codes output from the first and second PN code generators. A spread spectrum communication system that uses a product code created by a product as a spread spectrum PN code, and transmits 1-bit information in one cycle time of the spread spectrum PN code,
Means for transmitting one of the elements of the product code as a reference signal; and by modulating the phase and polarity of the other elements of the product code with information bits, k bits ( k is a positive integer).

The demodulating circuit according to the present invention includes first and second PN code generators for generating a PN (Pseudorandom Noise) code, and a product between PN codes output from the first and second PN code generators. A demodulating circuit that demodulates the information on the receiving side in a spread spectrum communication system that uses the produced product code as a spread spectrum PN code and transmits 1-bit information in one cycle time of the spread spectrum PN code,
When one of the elements forming the product code is used as a reference channel and the other is used as an information transmission channel and multiplexed on a communication path that is orthogonal in either phase or time axis, the reference channel is set on the receiving side. Means for independent demodulation tracking;
Means for performing spectrum despreading on the information transmission channel side based on the reproduction reference signal obtained by the demodulation tracking,
Information of k bits (k is a positive integer) is transmitted in one cycle time of the PN code for spread spectrum.

  That is, in order to achieve the above object, the spread spectrum communication system of the present invention uses a product of PN codes generated from two or more element PN (Pseudorandom Noise) code generators as a PN code for spreading. On the transmitting side, a PN code generated from one element PN code generator constituting the product code is transmitted as a reference channel, and the phase and polarity of the PN code generated from the other element PN code generator are information bits. To change the relative phase and polarity of the PN code on the reference channel side, generate a new product code with the element PN code on the reference channel side, and transmit it to the information transmission channel. That is, in the spread spectrum communication system of the present invention, one element of the product code serving as the reference signal is orthogonally transmitted by the reference channel and the product code by the information transmission channel.

  The receiving side includes the conventional product code generator, which is the same as the transmitting side, but in which the generation phase of the PN code generator used on the information transmission channel side is fixed to the generation phase on the reference channel side. As a second step, the PN code despreading on the information transmission channel side is performed by a parallel correlator. Simultaneously correlate the phases, and as a third step, detect the correlator output with the largest correlation value among the parallel correlator outputs for a plurality of phases, and enable decoding of information bits from the PN code phase and the polarity of the correlation value It is a configuration.

  Thus, in the spread spectrum communication system of the present invention, a product code system such as a Gold code generator is used as a PN code generator, one element PN code constituting the product code is used as a reference signal, and the other is used for information transmission. A new PN code generator is added when a Gold code generator is already used to transmit multiple information bits by providing a few additional circuits that allow the phase and polarity to be changed. It becomes unnecessary to do. In addition, the PN code of the information transmission channel whose phase and polarity are shifted only generates one of the Gold codes within one period of the PN code, and the confidentiality and ECCM (Electronic Counter Counter Measurement) resistance are It does not deteriorate the characteristics of the gold code.

  Further, in the spread spectrum communication system of the present invention, since one element PN code constituting a product code is used as a reference channel and is not modulated by an information bit, it is transmitted independently of an information transmission channel. It is sufficient that the channel has a PN code acquisition / tracking function having a very simple PN code acquisition / tracking function, and the required S / N improvement can be easily realized by increasing the integration time.

  Furthermore, in the spread spectrum communication system of the present invention, it is possible to accurately obtain the symbol period (integration time) of the information transmission channel based on the PN code period tracked of the independently transmitted reference channel, Since the relative shift with respect to the PN code phase and polarity of the reference channel is used as information, it is not necessary to detect the absolute phase and polarity of the information transmission channel.

  Furthermore, in the spread spectrum communication system of the present invention, it is possible to employ a parallel correlator (digital matched filter) for one PN code as the code phase detector of the information transmission channel, and the demodulation circuit can be miniaturized. It becomes.

  The present invention is configured and operated as described below, so that an increase in the number of information bits that can be transmitted does not cause an increase in the number of PN code generators on the transmission and reception side, and a linear power amplifier is not required. Therefore, it is possible to maintain the confidentiality and the ECCM resistance.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a spread spectrum communication system according to an embodiment of the present invention. FIG. 1 shows a system in which a transmitting side and a receiving side are connected by an orthogonal transmission path 31 and a Gold code, which is one of product codes, is used as a spread spectrum PN (Pseudorandom Noise) code.

  Here, the transmission side includes a PN code generator (# 1) 11, a PN code generator (# 2) 12, and multipliers 13 and 21. On the receiving side, a PN code generator (# 3) 41, a PN code generator (# 4) 42, multipliers 51, 53, 54, an integrator (Σ) 52, a phase controller 61, The circuit includes a polarity discriminator 62, a parallel correlator 71, and a peak detection circuit 81 with polarity discrimination.

  2 is a block diagram showing the configuration of the PN code generator (# 1) 11 shown in FIG. 1, and FIG. 3 is a block diagram showing the configuration of the PN code generator (# 2) 12 shown in FIG. 4 is a block diagram showing the configuration of the PN code generator (# 3) 41 shown in FIG. 1, and FIG. 5 is a block diagram showing the configuration of the PN code generator (# 4) 42 shown in FIG. FIG. 6 is a block diagram showing the configuration of the parallel correlator 71 shown in FIG.

  7 is a diagram showing a configuration of a phase quadrature modulator used in the orthogonal transmission path 31 shown in FIG. 1, and FIG. 8 is a diagram showing a configuration of a time division multiplexer used in the orthogonal transmission path 31 shown in FIG. is there.

As shown in FIG. 2, the PN code generator (# 1) 11 includes an initial phase setter (all'1 ') 111, a shift register (# 1) 112, and a multiplier 113. The PN code generator (# 2) 12 includes a phase setter (2 ^k−1 ) 121, a shift register (# 2) 122, and a multiplier 123, as shown in FIG. .

  As shown in FIG. 4, the PN code generator (# 3) 41 includes an all “1” detector 411, a shift register (# 3) 412, and a multiplier 413. Further, as shown in FIG. 5, the PN code generator (# 4) 42 includes an initial phase setter (all'1 ') 421, a shift register (# 4) 422, and a multiplier 423a. Yes. The parallel correlator 71 includes a shift register (# 5) 711, a multiplier 712, and an integrator (Σ) 713, as shown in FIG.

  As shown in FIG. 7, the phase quadrature modulator 32 used in the quadrature transmission path 31 includes a variable resistor 321, low-pass filters 322 and 326, multipliers 323 and 327, an oscillator 324, and a phase shifter (φ ) 325 and an adder 328. The time division multiplexer 33 used for the orthogonal transmission path 31 includes a duty (DUTY) control unit 331 and a multiplexer (MUX) 332 as shown in FIG.

  A spread spectrum communication system according to an embodiment of the present invention will be described with reference to FIGS.

  Assuming that k-bit information per symbol is input from the information source, the PN code generator (# 1) 11 inputs a symbol clock, and the initial phase setter (all ′) is input to the shift register 113 at this timing. 1 ′) The initial value of all′1 ′ is set at 111, and an M-sequence PN code is generated with a chip rate clock to be a reference phase signal.

On the other hand, the PN code generator (# 2) 12 inputs k bits (k is a positive integer) information at the timing of the symbol clock, and the phase setter (2 ^k-1 ) 121 sets 2 ^k-1 . Dividing into a phase pattern and one polarity bit, the former is set as the initial phase state of the PN code generator (# 2) 12, and the latter is inverted or not output from the PN code generator (# 2) 12. The inverted output control signal is output to the multiplier 13. The PN code modulated inverted or non-inverted is then formed into a product code by the multiplier 21 with the PN code pattern from the PN code generator (# 1) 11 to form a product code for the information transmission channel. Generate.

  The reference phase signal from the PN code generator (# 1) 11 and the information transmission channel from the PN code generator (# 2) 12 are transmitted to the orthogonal transmission paths 31 associated with the Q phase and the I phase, respectively. For the orthogonal transmission path 31, a phase quadrature modulator 32 and a time division multiplexer 33 as shown in FIGS. 7 and 8 are used. The phase quadrature modulator 32 can also perform modulation by lowering the modulation level with respect to a reference channel that does not transmit information. When the time division multiplexer 33 is used, time distribution between the reference channel and the information transmission channel is possible. It is also possible to optimize the power distribution between the reference channel and the information transmission channel by changing a certain duty.

  On the reception side, the multiplier 51 and the integrator 52 perform correlation integration between the Q phase reference channel signal from the orthogonal transmission path 31 and the local PN code generated from the PN code generator (# 3) 41. Generate a value. The correlation integral value is input to the phase controller 61, where the absolute value is taken, and the PN code generator (# 3) 41 operates so as to control the code phase so that the absolute value of the correlation value is always maximized. .

  On the other hand, the correlation integral value is input to the polarity discriminating circuit 62, and when it is identified as polarity inversion, the polarity pattern of the local PN code of the PN code generator (# 3) 41 is inverted by the multiplier 53 to obtain the input reference phase. Play a PN code equal to the PN code pattern of the channel.

The reproduction PN code pattern of the reference phase channel output from the multiplier 53 is despread by the multiplier 54 with respect to the I-phase information transmission channel, and one of the product codes is demodulated. The output of the multiplier 54 is then passed to the local PN code generated from the PN code generator (# 4) 42 by the parallel correlator 71 for each of the 2 ^k-1 local PN code phases. To obtain a correlation integral value.

The peak detection circuit 81 with polarity discrimination inputs 2 ^k−1 correlation integral values as shown in FIG. 9, takes each absolute value, and gives the largest correlation value among the 2 ^k−1 values. and outputs it is determined that the 2 ^k-1 th phase, to identify the +/- sign of 2 ^k-1 th correlation value, a 1-bit and 2 ^k-1 -th obtained by the code identification From the phase information, 2 ^k states are generated, decoded into k information bits, and output.

The phase reference of the PN code generator (# 4) 42 is generated in synchronism with the timing of all '1' of the PN code generator (# 3) 41 tracked by the reference channel. The phase 2 ^k-1 and polarity of the correlation peak detected by the peak detection circuit 81 directly reproduces the phase offset with respect to the reference channel added to the transmission side information transmission channel, and thus reproduces k bits of the information source. It becomes possible to do.

  In this embodiment, the integration time of the parallel correlator 62 is set to one period of the PN code generator (# 3) 41, so that one period of the PN code is one symbol, and k bits / symbol information transmission is performed. It works to make it possible.

  FIG. 9 is a time chart showing the operation of the demodulation circuit on the receiving side of the spread spectrum communication system according to one embodiment of the present invention. The operation of the demodulation circuit on the receiving side of the spread spectrum communication system according to one embodiment of the present invention will be described with reference to FIGS.

Assuming that the PN code phase of the local PN code generator (# 3) 41 on the receiving side is stopped with respect to the reference channel input signal from the orthogonal transmission path 31, as shown in FIG. An M-sequence correlation characteristic is obtained, and a correlation value peak occurs equally in the PN code period 2 ^k−1 . The reference channel phase controller 61 controls the timings of the PN code generator (# 3) 41 and the PN code generator (# 4) 42 so as to maintain the peak of the correlation value.

On the other hand, since the information transmission channel is input to the parallel correlator 71 for a plurality of phases with respect to the local PN code from the PN code generator (# 4) 42, it outputs 2 ^k-1 correlation values, A correlation peak as shown in FIG. 9B is generated.

  The first two correlation patterns shown in FIG. 9B are the cases where the PN code of the information transmission channel is in phase with the reference channel, and the third correlation pattern is in phase with the reference channel and phase. In this case, the polarity is reversed, and the sign of the correlation value is inverted.

  The fourth correlation pattern shown in FIG. 9B indicates that the PN code phase of the information transmission channel is transmitted 5 phases ahead of the reference channel, but the polarity is positive. .

The peak detection circuit 81 with polarity discrimination for the peak phase and polarity of these parallel correlators 71 can discriminate the 2 ^k state, thereby enabling k bit / symbol information transmission.

  FIG. 10 is a block diagram showing a configuration of a transmission side of a spread spectrum communication system according to another embodiment of the present invention. In FIG. 10, the transmission side includes a long-period PN code generator (# 1) 14, a short-period PN code generator (# 2) 15, and multipliers 13 and 21.

The long cycle PN code generator (# 1) 14 includes a short cycle counter 141, a long cycle counter 142, an initial phase setter (all'1 ') 143, a shift register (# 1) 144, and a multiplier 145. It consists of and. The short cycle PN code generator (# 2) 15 includes a phase setter (2 ^k ) 151, a shift register (# 2) 152, and a multiplier 153.

  In an embodiment of the present invention shown in FIG. 1, in a spread spectrum communication system using a product code, an embodiment using a gold code sequence using two PN code generators having the same period as a spread spectrum signal. Although shown, it is generally possible to implement with product codes from two or more PN code generators of different lengths in the reference channel and the information transmission channel.

  FIG. 10 shows an example of the transmission side of a spread spectrum communication system using two PN code generators having different lengths. In this example, the long-period PN code generator (# 1) 14 is used for the reference channel, and the short-period PN code generator (# 2) 15 is used for the information transmission channel. This symbol timing indicates a method for obtaining a phase counter of a long-period PN code by a remainder operation with a length of the short-period PN code.

  As described above, in the present invention, a product code system such as a Gold code generator is used as a PN code generator, one element PN code constituting the product code is used as a reference signal, and the other is used as a phase and a phase for information transmission. By adding a few additional circuits that allow the polarity to change, a new PN code generator can be added when a Gold code generator is already used to transmit multiple information bits. It becomes unnecessary. In addition, the PN code of the information transmission channel whose phase and polarity are shifted only generates one of the Gold codes within one period of the PN code, and the confidentiality and ECCM (Electronic Counter Counter Measurement) resistance are It does not deteriorate the characteristics of the gold code.

  Further, in the present invention, since one element PN code constituting the product code is used as a reference channel and transmitted independently of the information transmission channel without being modulated by information bits, the receiving side captures the PN code of the reference channel. It is sufficient that the tracking has a very simple PN code acquisition and tracking function, and the required S / N improvement can be easily realized by increasing the integration time.

  Furthermore, in the present invention, the symbol period (integration time) of the information transmission channel can be accurately obtained based on the tracked PN code period of the independently transmitted reference channel, and the PN code phase of the reference channel, Since the relative deviation with respect to the polarity is used as information, it is not necessary to detect the absolute phase and polarity of the information transmission channel.

  Furthermore, in the present invention, a parallel correlator (digital matched filter) for one PN code can be employed as the code phase detector of the information transmission channel, and the demodulation circuit can be easily downsized.

1 is a block diagram showing a configuration of a spread spectrum communication system according to an embodiment of the present invention. FIG. It is a block diagram which shows the structure of PN code generator (# 1) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 2) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 3) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 4) shown in FIG. It is a block diagram which shows the structure of the parallel correlator 71 shown in FIG. It is a figure which shows the structure of the phase quadrature modulator used for the orthogonal transmission path shown in FIG. It is a figure which shows the structure of the time division multiplexer used for the orthogonal transmission path shown in FIG. It is a time chart which shows operation | movement of the demodulation circuit of the receiving side of the spread spectrum communication system by one Example of this invention. It is a block diagram which shows the structure of the transmission side of the spread spectrum communication system by the other Example of this invention. It is a block diagram which shows the structure of the conventional spread spectrum communication system. It is a block diagram which shows the structure of PN code generator (# 1) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 2) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 3) shown in FIG. It is a block diagram which shows the structure of PN code generator (# 4) shown in FIG.

Explanation of symbols

11 PN code generator (# 1)
12 PN code generator (# 2)
13, 21, 51, 53,
54, 113, 123,
145, 153, 323
327, 413, 423
712 multiplier
14 Long-period PN code generator (# 1)
15 Short period PN code generator (# 2)
31 Orthogonal transmission line
32 Phase quadrature modulator
33 Time division multiplexer
41 PN code generator (# 3)
42 PN code generator (# 4)
52,713 Integrator (Σ)
61 Phase controller
62 Polarity discriminator
71 Parallel correlator
81 Peak detection circuit with polarity discrimination 111, 143, 421 Initial phase setter (all'1 ')
112, 144 Shift register (# 1)
121 Phase setter (2 ^k-1 )
122, 152 Shift register (# 2)
141 Short cycle counter
142 Long period counter
151 Phase setter (2 ^k )
321 Variable resistor
322,326 Low-pass filter
324 oscillator
325 Phase shifter (φ)
328 Adder
331 Duty control unit
332 Multiplexer (MUX)
411 all '1' detector
412 Shift register (# 3)
422 Shift register (# 4)
711 Shift register (# 5)

Claims (11)

A first and second PN code generator for generating a PN (Pseudorandom Noise) code, wherein a product code generated by a product between the PN codes output from the first and second PN code generators is spectrumd A spread spectrum communication system for transmitting 1-bit information in one cycle time of the spread spectrum PN code as a spread PN code,
Means for transmitting one of the elements of the product code as a reference signal; and by modulating the phase and polarity of the other elements of the product code with information bits, k bits ( a spread spectrum communication system comprising means for transmitting information of k being a positive integer). The PN code generator includes a shift register having a length of k bits for generating an M-sequence cyclic PN code having a period of 2 ^{k-1 and} an M-sequence cyclic PN code having the period of 2 ^k-1 as elements forming the product code. A multiplier that takes the product of two of
^One of the components of the gold code having a period of 2 ^k-1 generated by the product of the multiplier is modulated with 2 ^k phases and polarities by k-bit information, and one of them is selected. 2. The spread spectrum communication system according to claim 1, wherein transmission is performed within the same period as the other PN code period. The PN code generator, the period 2 and ^k-1 of the M-sequence cyclic PN code with two long M-sequence cyclically PN code than this, the M-sequence cyclic PN code side of the cycle 2 ^k-1 The 2 ^k kinds of phases and polarities are modulated by k-bit information, and one of them is selected to transmit a plurality of k-bit information in the other PN code period. Item 3. The spread spectrum communication system according to Item 2.   The multiplex transmission is performed on a communication channel orthogonal in either phase or time axis, with one of the elements forming the product code as a reference channel and the other as an information transmission channel. 4. The spread spectrum communication system according to any one of items 3.   And a means for demodulating and tracking the reference channel independently on the receiving side and a means for performing spectrum despreading on the information transmission channel side based on a reproduction reference signal obtained by the demodulation and tracking. Item 5. The spread spectrum communication system according to Item 4.   When using a phase orthogonal communication path in which the reference channel is Q phase and the information transmission channel is I phase in the communication path, the Q phase power is set lower than the I phase transmission power. The spread spectrum communication system according to claim 4 or 5.   When a time-orthogonal communication path that performs time division multiplexing combining the reference channel and the information transmission channel within one chip of a spreading PN code is used in the communication path, the duty ratio between the information transmission channel and the reference channel is changed. 6. The spread spectrum communication system according to claim 4, wherein the average power of the reference channel is set lower than the average power of the information transmission channel. An input signal multiplexed when the reference channel and the information transmission channel are multiplexed and transmitted on a communication path orthogonal in either the phase or the time axis is a PN code for a reference signal on the receiving side on the reference channel side Means for performing correlation integration using
A phase controller that controls and tracks the generation timing of the PN code generator on the receiving side so that the absolute value of the correlation integral value is maximized;
By determining the polarity of the correlation integral value, the polarity of the PN code generator for the reference signal on the receiving side is matched with the input reference channel, and the input signal on the information transmission channel side is determined by the PN code for the reference signal on the receiving side. Means for performing first despreading on
The first 2 to obtain the correlation integration values for one period with respect to a plurality of PN code phase with the PN code for the data traffic channel of the receiving side with respect to the despread signal obtained by despreading the ^k-1 Parallel correlators,
With polarity discrimination that selects the phase for obtaining the maximum correlation value from the correlation integral values obtained by the 2 ^k-1 parallel correlators and decodes k-bit information by this and the sign of the integral value The spread spectrum communication system according to any one of claims 4 to 7, further comprising a peak detection circuit. A first and second PN code generator for generating a PN (Pseudorandom Noise) code, wherein a product code generated by a product between the PN codes output from the first and second PN code generators is spectrumd A demodulation circuit that demodulates the information on the receiving side in a spread spectrum communication system that transmits a 1-bit information in one cycle time of the spread spectrum PN code as a spreading PN code;
When one of the elements forming the product code is used as a reference channel and the other is used as an information transmission channel and multiplexed on a communication path that is orthogonal in either phase or time axis, the reference channel is set on the receiving side. Means for independent demodulation tracking;
Means for performing spectrum despreading on the information transmission channel side based on the reproduction reference signal obtained by the demodulation tracking,
A demodulating circuit which transmits k-bit information (k is a positive integer) in one cycle time of the spread spectrum PN code.   The means for independently demodulating and tracking the reference channel is configured to input an input signal multiplexed and transmitted when the reference channel and the information transmission channel are multiplexed and transmitted on a communication path orthogonal to either the phase or the time axis. Control and track the generation timing of the PN code generator on the receiving side so that the correlation integration using the PN code for the reference signal on the receiving side on the channel side and the absolute value of the correlation integrated value become maximum The demodulation circuit according to claim 9, further comprising a phase controller. The means for performing spectrum despreading on the information transmission channel side matches the polarity of the PN code generator for the reference signal on the receiving side with the input reference channel by determining the polarity of the correlation integral value, and the reference signal on the receiving side Means for performing first despreading on an input signal on the information transmission channel side with a PN code for use, and an information transmission channel on the receiving side for the despread signal obtained by the first despreading correlation obtained in the plurality of PN code and the 2 ^k-1 pieces of parallel correlators for obtaining correlation integral value of one period for the phase, the 2 ^k-1 pieces of parallel correlators between PN code use 11. A peak detection circuit with polarity discrimination for selecting a phase for obtaining a maximum correlation value from integrated values and decoding k-bit information by using this and the sign of the integrated value. Demodulator circuit.

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