JPH01293723A - Spread spectrum communication equipment - Google Patents

Abstract

PURPOSE:To easily spread a spectrum inversely and to widely reduce a circuit by spreading the spectrum by an NRZ spreading code at a modulating side and removing an interference wave mixing into an influential frequency band and inversely spreading the spectrum at a demodulating side. CONSTITUTION:At a modulating part 10, information data are supplied through an LPF1 to a multiplier 2, and a primary modulated (PSK modulated) signal is generated by multiplying the data by a first carrier at this multiplier 2 and supplied to an adder 6. The adder 6 supplies an added signal obtained by adding the PSK modulated signal and a second carrier to a multiplier 3. At the multiplier 3, a spreading code obtained from a spreading code generating circuit 9 and another spreading code obtained from a multiplier circuit 4 are multiplied with each other, a spectrum spreading signal SM(t) is outputted, and only the main lobe of the signal is outputted through a BPF11. At a demodulating part 20, only the pass band component of the input signal SM(t) is passed through BPFs 12 and 13, the outputs of the BPFs 12 and 13 are added and supplied to spreading filters 18 and 19, and only a primary modulated wave and a carrier are separated into respectively spread signals. At a multiplier 4, both the signals are inversely spread, obtained two two-phase PSK signals are passed through a BPF14, and only one out of the two two-phase PSK signals is separated and outputted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spread spectrum communication device, and particularly relates to a reception (
The present invention relates to a spread spectrum communication device that eliminates the need for a spreading code generation circuit for generating pseudo noise for despreading on the demodulation side.

[Technical background]

Spread spectrum communication method is a carrier that is first modulated with an information signal and then modulated into two parts using a wideband noise-like spreading code.
This method modulates the signal and spreads it over a very wide band. −
Numerically, due to the difference in secondary modulation methods, direct spread (DS)
) Method 1 There are frequency hopping (FH) methods, hybrid methods, etc., of which the present invention relates to the former DS method.

Such spread spectrum 3i! ! This communication has: ■ extremely high confidentiality, ■ strong resistance to external interference, noise, and intentional interference, and ■ ability to coexist with conventional systems. ■No control station or control channel like an MCA station is required. ■Can be managed using address code. ■Since the power density of the DS (direct diffusion) method is low, it can be transmitted using very weak power. ■The number of stations can be increased with only a slight decrease in call quality. ■By changing the pseudo-noise code signal, it is possible to multiplex within the same frequency band.These advantages have been recognized, and now it is used not only in the communication field.
Its application in various fields is progressing, and its application to consumer equipment is about to begin.

[Conventional technology]

The basic principle of spread spectrum communication will be explained with reference to FIGS. 16 and 17. FIG. 16 is a basic configuration diagram of a conventional spread spectrum communication device using the DS method, and FIG. 17 is a spectrum waveform diagram of each component.

As shown in FIG.
The signal (Fl) as shown in FIG. 17 (FIG. 18) which has been primary modulated by the next modulator 31 is transmitted to the spreading modulation circuit 31 by the spreading code signal (Fss" (see FIG. 18(b)) from the spreading code generating circuit 39. After being secondarily modulated and amplified at antenna A,
It is output as a transmission signal FIs. There are no particular restrictions on the type of primary modulation, and frequency modulation ([H) or PSK
(Phase Shit Key-ing) etc. (in this specification, it will be explained that modulation is performed by PSK), and the secondary modulation (spreading modulation) is numerically equivalent to a pseudo noise code (Pseudo No.1se: P N PSK modulation is performed according to the code). This PN code must be as random noise-like as possible, and must have a certain period in order to extract the code on the receiver side.

Next, the configuration and operation of the receiving (demodulating) side will be explained. At station B on the receiving side, a despreading circuit 47 despreads the Fl signal obtained from the antenna A2 by a predetermined filter or a high frequency amplifier using a spreading code from a spreading code generation circuit 49. This spreading code generation circuit 49 is synchronized with the spreading code generation circuit 39 of station A, and the PN code is also the same (F,).By the way, the radio waves that enter the antenna A2 are not limited to Fls only. , radio wave F25. F35.・
... (see Figure 17(c)), etc., and other SS stations (-several rounds)
There are radio waves (Fn) from Therefore, the despreading circuit 4
By performing despreading in step 7, the desired radio wave F1s as shown in FIG.
Most of the components other than s are removed (see FIG. 3(e)), and the demodulation circuit 43 demodulates the signal to the original information signal, which is then output. In addition, as shown in the same figure (e), the filter 4
In addition to Fl, the interference wave Fn and a portion of the multi-station SS waves remain in the output signal of No. 1. The ratio of this residual power to the power of the target signal is called the DU ratio (signal power to interference power ratio), and in order to obtain a large DU ratio, it is advantageous to have as wide a spreading band as possible; The frequency band is approximately 100 to 1000 times the frequency band of the information signal.

The basic principles of spread spectrum communication have been explained above, but next we will discuss 1 and 2 when performing spread spectrum communication.
We will theoretically explain specific operations in suboptimal modulation and demodulation. A spread spectrum signal S (t) (P 1.) in spread spectrum communication transmits information data as d (t
) [+1 or -1, the spreading code Fss is p(t) 1 or -1], and the carrier is CO3ωct, it is expressed by the following equation.

3 (t) = d (t) P (I)CO3ωct
・＋＋＋＋・H”・H”” (1) (However, ωc
= 2πfc) This spread spectrum signal s (B generates a clock signal for a spreading code from the incoming spread spectrum signal on the reception (demodulation) side, and further generates a clock signal for the spreading code in synchronization with the spreading code in the spread spectrum signal at the time of transmission. d(t) cosωC
The regenerated carrier wave COSωct (actually, 7'\ is converted into a two-phase PS signal t by synchronous detection by multiplication with COSωctl,
d (t) (CO3ωct) ' = d (t)
By obtaining [1+cos2ωct)/2 and removing the carrier component 2ωct with a filter, the information data d
([) is demodulated.

Here, the bandwidth (main lobe of the spectrum) of the signal d(t)CO3ωct in the two-phase PS is Bo, and the bandwidth (main lobe of the spectrum) of the spread spectrum signal spread by the spreading code P(t). BI), the process gain G in spread spectrum communication is: G = B /BD ・・・・・・・・・・・・・・・
...... (2) Represented by p. The 10-cess gain Gp has a value of several hundred to several thousand in a normal design value, and since the interference signal, my, etc. is suppressed according to this value, the information data d (t
), the wider the frequency band of the spread spectrum signal, the greater the improvement effect in anti-jamming properties, noise resistance, etc. That is, the improvement effect is almost uniquely determined by the process gain G.

[Problem to be solved by the invention]

In such spread spectrum communication, despreading on the demodulation side is most important, and it is not easy to realize the spreading code generation circuit necessary for this, so currently despreading using an AFC control loop, a delay lock loop, and a multiplier is difficult. Generally, the despreading method using a synchronized loop using a matched filter and a multiplier is used. Despreading using these configurations all have complicated circuit configurations, and furthermore, there are problems in terms of adjustment and cost, and it is necessary to solve these problems when deploying them to consumer equipment.

[Means to solve the problem]

The spread spectrum communication device of the present invention includes a first
means for modulating a carrier wave with an information signal to obtain a primary modulated wave signal; and a means for obtaining a composite primary modulated wave signal by adding a second carrier wave having a frequency different from that of the first carrier wave to the primary modulated wave signal. means, a pseudo-noise code generator for generating an NRZ pseudo-noise code sequence by inputting a spreading code clock signal;
A first multiplier that multiplies two pseudo-noise codes and a tarok signal to obtain a spread code signal, and a second multiplier that performs spread modulation by multiplying the spread code signal and a composite primary modulated wave signal to obtain a composite spread spectrum signal. a multiplier, and on the demodulation side, a single-wavelength amplifier inputting the composite spread spectrum signal and having a frequency pass characteristic corresponding to the spectral distribution of the main lobe;
A means for reducing and removing noise and interference wave components in the vicinity of the center frequency of the main lobe through this single wave filter, and a composite spread spectrum signal that has passed through this removing means is divided into a spectrum in which the primary modulated wave is spread. means for separating and detecting a spread signal and a modulated spread code signal in which a second carrier wave is spread; a third multiplier for despreading the separated and detected signals by multiplication; The above-mentioned drawbacks are solved by providing an elliptical configuration with means for demodulating the information signal from the next modulated wave signal.

〔Example〕

The spread spectrum communication device of the present invention has the above-mentioned configuration, so that the clock regeneration circuit, the spreading code generation circuit, and the synchronization pull-in circuit configured with the loop, which are conventionally essential components in despreading. This eliminates the need for a synchronization holding circuit, etc., and an example of the configuration of the device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the first embodiment of the spread spectrum communication device of the present invention, in which the modulation section (transmission rs
)10. FIG. 2B shows the demodulator (receiving side) 20. In this figure, illustration of a part of the structure such as the antenna is omitted.

The modulation section 10 includes an LPF (low frequency filter) 1 and three multipliers 2 to 4. Adder 6. Spreading code generation circuit (PNG)9.
and BPF (bandwidth filter) 11, which are connected to the first
(A) They are connected and configured as shown. The demodulation unit 20 also includes three BPFs 12 to 14 and two adders 7 and 8.
and delay circuit (L) 21°22; addition/subtraction circuit 231 multiplier 5. and two weighting gain adjusters 24 and 25, which are connected as shown in FIG. 1(8). Note that the first separation filter (first-order transversal filter) 18 is formed by the delay circuit 21 and the adder 8, and includes the delay circuit 21 (shared), the delay circuit 22, the gain adjuster 24, 25, and the addition/subtraction circuit. 23 constitutes a second separation filter (second-order transversal filter) 19, and their frequency characteristics are shown in Figures 2 (^) and (8), respectively.
As shown. Below, specific functions of the device of the present invention,
The operation will be explained with reference to the signal waveform diagrams shown in FIGS. 3 to 6.

First, when transmitting, in the modulation section 10, the information data d(t) is supplied from the input terminal lit to the multiplier 2 via the LPF 2, where it is multiplied by the first carrier wave COSωC+j supplied from the input terminal 1rL2. , carrier wave COS
Figure 3 shows ωclt modulated by information data d(t) (^
) is generated and supplied to the adder 6. Its bandwidth is 2Δf as shown. Further, from the input terminal In3, the second carrier wave COSωcwt (unmodulated) as shown in (b) of FIG.
(t) Multiplier 3 for creating an addition signal COSωCt j ”CO3ωc2t and performing spectrum spreading.
Output to. Reference numeral 9 denotes a spreading code generation circuit, which generates an NRZ (Non Return) signal based on the tarok signal 5C(t) as shown in FIG.
PN (noisy code PN(t)
(See figure (B)). Its frequency spectrum (envelope) is as shown in Figure 6 (^). Note that To is the period of the tarok signal 5C(t).

This PN code PN(t) is supplied to the multiplier 4 to undergo phase modulation by the tarok signal 5c(t). Here, by phase modulating the NRZ PN code, a spreading code p (B (see No. 6 UyJ (B) for its frequency spectrum) as shown in FIG. 5(C) is generated. Pseudo-noise codes are usually often used as spreading codes, and among these, M-sequence codes are often used, so they are sometimes called "pseudo-noise codes." Such spreading codes P (t) are supplied to the multiplier 3. Here, the above addition signal d (t)CO3(1) C1t +CO3ωc
2 t (spread spectrum) is performed, and the spread spectrum signal P (tHd (t) cosωC+ t”
CO5ωcttl (hereinafter also referred to as rsM(t)J) (see # in FIG. 3(C)), only the main lobe of the spread spectrum signal passes through and is transmitted in BPFII, and is output from output terminal -1.

Here, the frequency spectrum of the spread spectrum signal will be explained. The frequencies f C+ (= ωc+/2 yc) and fc-(
= ωc2/2π) is the period of the tarok signal (1
If To is the bit time length), an M-sequence code is used in the spreading code generation circuit 9, and a shift register is used in the M-series code generation circuit (not shown), and the number of stages is n, then (2(2 '-1) The frequency interval is given by 'Te l'.
t (In the frequency spectrum of No. 8, sideband + Sa
The frequency interval between l and MoSa2 and the frequency interval between +Sb+ and Mosb2 are 1 /'r= ((2n -1)xTo
)”, and the sideband waves are Sa1~
Mo San, -5al ~ -3an, sideband +sb
1 to Mo Sb, , -sb, and -3bn are arranged alternately at equal intervals. FIG. 4(^) shows the spectrum of such a spreading code, and FIG. 4(B) shows the main lobe of the spectrum of the spread spectrum signal SH(t).

Next, with reference to FIG. 1(8) and FIG. 7, the circuit operation performance of the demodulator 20 will be explained. Input terminal 1n5
The spread spectrum signal 5N as shown in Fig. 3(C) entered the
(t) is (a) in Figure 7 (A) at BPF 12.13.
Only the bus band components shown in (and) are passed through, and added in the adder 7 to generate frequency components other than the main lobe of the spread spectrum signal.

In particular, remove the interference waves, noise, etc. that are mixed into C2 from <fc, -Δf) to f C2 in the same figure (^), and use the separation filter ts.
, 19.

Note that the first-stage filter consisting of the BPFs 12 and 13 and the adder 7 is not limited to this configuration, but may also be configured by connecting a PF 15 and a BEF (notch filter, band-elimination filter) 17 in series, as shown in FIG. 8, for example. It may be composed of
The frequency characteristics of the BPF 15 in this case are (fcl-fp) to Cfc2+fP) as shown in FIG. 7(B).
is the bus band, and the frequency characteristics of BEF17 are shown in the same figure (C
), it goes without saying that it is constructed so that (fcl-Δf) to fC2 is the erasure band.

The separation filters 18 and 19 at the next stage have a delay time T=(2
n-1) Since the structure includes delay circuits 21.22 of T o, if the delay time in the delay circuits 21.22 is T, the frequency characteristic of the separation filter 18 (the output waveform of the adder 8) is the second As shown in Figure (A), there is a valley (steep dip) where the gain becomes 0 at frequencies that are odd multiples of 172T.
The frequency characteristic of the separation filter 19 (the output waveform of the adder/$4 arithmetic circuit 23) is a cosine wave whose gain becomes 0 at frequencies that are even multiples of 172T, as shown in FIG. 2(B). When the separation filters 18 and 19 having such characteristics are supplied with spread spectrum signals 5N(t) having carrier frequencies f C+ and f C2 that are even and odd multiples of the frequency of 1/2T, respectively, the output is Each P (tHa (t)+a
(-d)) CO3(1)C1t (=S, (t)) and P(t)CO3ωC2t (=S2(t)), and the primary modulated wave is Spread signal S+(j) and signal S2(j) with only the carrier wave spread
It is detected separately.

Therefore, the output signal from the adder 8 becomes S+(t) (see FIG. 3 (0)), and the output signal from the addition/subtraction circuit 23 becomes 5y(
j) (see (E) in the same figure), and the delay circuit 21.
For convenience of explanation, the expression of the delay of the spread spectrum signal 5s(t) due to 22 is omitted.

The true output signal S+(
j) and 32(j) are supplied to a multiplier 4, where despreading by multiplication of both signals is performed. Then, the spreading code signal P (t) becomes DC due to multiplication, so the signal is converted into two-phase ps equivalent to that during modulation ( + d (t) + d (t - T)).
XCO3(ωcz-(dcl t ) and (d (t)
−d (t−T))cos(ωc+tenωcz) t (
(d) and (C) of FIG. 3(F), respectively.

However, f CI=(J)C1/2 x, f cz
=(ldcz/2yr) is obtained. In addition,
If the delay time T is sufficiently short compared to the 1-bit length of the information signal d (t), d (t - T) is two two-phase PS despread in such a way that it is greater than 0 and can be approximated to d (t). By passing the signal through the narrow band BPF 14, only one of the two-phase PSK signals can be separated and output to the output terminal -2.

The above is an explanation of the overall operation, but next, the operation of the main parts when the interference wave with the strongest influence exists on the communication channel will be explained with reference to FIGS. 9 to 11. First, consider the following model.

(1) On the modulation side, spectrum spreading is performed using an NRZ spreading code.

■There is an interference wave T(t) in the communication channel, and the interference wave 1(t
) is a continuous wave of A CO3ωcIt (A: constant), and the frequency f I4 is the frequency band 'r of the composite primary modulation wave.
<fc++fcq)-Δf≦fc1≦+<fC++fC
2) +Δf; 2Δf is the bandwidth).

(Because the interference waves in this frequency band are the interference waves that have the strongest influence on the demodulated signal during despreading) ■ On the demodulation side, the signal near the center frequency of the spread spectrum signal (f c, -Δf ~ f
No filter is provided to block the noise of c-).

A model with the above conditions is shown in Figs. 9 and 10, where the spread spectrum signal 5N(t) and interference wave 1(t) (
(see Figure 11 (8)) is the input terminal Ins shown in Figure 10.
, the output of each filter can be expressed approximately as follows.

S + (t) = P (t) D (t) cosωQ+
t + I + (j) ... - (3) S 2 (
t)=P(t)cosωC2t+I2(t)
−= −−(4) However, D (t) = d (t)+
d (t-T) and I + (j).

I 2 (j) is the interference wave r (t) separated by the separation filter 18.1
This is the output signal when input to 9. Therefore, multiplier 5
The despread output signal R(t) from the above equation becomes as follows.

R(t) = 5t(t)X S, (t) = I P
(t) D (j) CO3 (c) cHtmo I+ (L))
X (P (t) cosωC2t + I 2 (j))
= p 2(t)D (t)cosωc+7 C03(
c) (2F.

+ P (tHI +(t) cosωC2j±It(
j) x D (t) cosωc+ t ) + I +
(t) I 2 (B-- (5) In this fifth equation, the first term is the despreading term ((/'; J in Figure 11 [8)),
The second term is the diffusion term of the interference wave ((→) in the same figure, and the third term is the term in which the interference wave is not spread (see (a) in the same figure). Here, I 1 (t) = AI CO3 (1) C3tI z(t)
= A 2 cos ωC3t, then the fifth
In Eq., the third undiffused term 1 + (t) I 2 (j
) is a multiplication of signals with strong correlation, and is expressed as the following equation.

I + (L) I z (t) = A + A2
CO3” ω C3t= し A + A
2 (1+CO32(A)C3t) ---
(6) By the way, the frequency f cz of interference wave 1(t) has 'z < f C+ 1 f 02) - Δf≦f C3≦
Since there is a condition of +(fc++fcz)+Δf,
2 f C3 exists within the band of (fCI f c = ) ±Δf, that is, within the band of the despread primary modulation wave,
It becomes an interference wave component.

Next, a communication system using the device of the present invention will be explained with reference to the spectrum diagram shown in FIG.

The demodulator 20 of the device of the present invention reduces interference waves 1(t) (see Fig. 12 (^)) etc. that mix in the vicinity of the center frequency (fcl-Δf~fc-) of the spread spectrum signal. The same figure (B
), during despreading, the center frequency is set at (IC+Mo f c-), and the influence of the interference wave component that comes within the band □ of the Bi-tuned primary modulation wave is reduced or brought to a negligible level. It can be lowered to

A model with the above conditions is shown in Figs. 9 and 10. Also, since the spread spectrum signal 5N(t) is spread so that the spectrum components near the center frequency become small, Even if a filter for blocking passage is added to the demodulator, there is no effect on the spread spectrum signal.

Next, the second modulation side of the spread spectrum communication device of the present invention
An embodiment will be described with reference to the block diagram of FIG. 13(A) and the timing chart of FIG. 14. This embodiment uses biphase (Bi) as the spreading code.
In this figure, the same components as those in the first embodiment shown in FIG.

As shown in FIG. 13 (TA), the modulation section 30 of this embodiment is
Noise (PM) of the output signal NRZ from the spreading code generation circuit
The code PN(t) (see Fig. 14 (8)) and the tarok signal 5C(t) (see Fig. 14 (A)) are supplied to the exclusive OR circuit 32 for calculation, resulting in biphasing. , this signal P (see tH figure (C)) is supplied as a spreading code to the multiplier 3, where the composite 1 from the adder 31 is
Next modulated wave (d (t)CO3ωc1 t +cosωc
, C) is used to perform spectrum spreading. Note that the noise (PN) code P N (t) and the spreading code p
The frequency spectrum of (t) is the first frequency spectrum shown in Figure 6.
It is the same as the example.

After fi, a third embodiment of the modulation side of the spread spectrum communication device of the present invention will be described with reference to the block diagram of FIG. 13(B) and the frequency spectrum diagram of FIG. 15. In this figure as well, the same reference numerals are given to the same components as in the first embodiment shown in FIG. This embodiment 40 includes the composite 1 from adder 6
The next modulated wave is converted into NRZ noise code PN(t) by multiplier 3.
(see FIG. 5(A)), and further multiplier 4.
Phase modulation is performed using the tarok signal 5C(t) (see (8) in the same figure), and spectrum spreading is performed. The configuration on the demodulation side is the same as that of the first embodiment shown in FIG. 1+8), so a detailed explanation thereof will be omitted.

〔effect〕

Since the spread spectrum communication device of the present invention communicates as described above, it has the following features.

■Since the clock recovery circuit, spreading code generation circuit, synchronization pull-in circuit and synchronization holding circuit consisting of a loop, etc., which were essential components in the demodulation section of conventional equipment, are no longer required, the circuit configuration can be considerably simplified. Since the cost can be significantly reduced, it has become very easy to apply it to consumer devices.

■By eliminating the need for synchronization pull-in circuits and synchronization holding circuits, the drawbacks of conventional devices such as the long synchronization pull-in time and problems such as loss of synchronization are eliminated, contributing to the stabilization of the operation of spread spectrum communication devices. can.

■The spectrum separation filter can reduce noise mixed into the spread spectrum signal.

■Since it blocks interference waves from entering the frequency band where the influence is greatest, it is resistant to interference and can perform good despreading.

[Brief explanation of the drawing]

Fig. 1 (^), fB) is a block diagram of the modulation section and demodulation section of the first embodiment of the spread spectrum communication device of the present invention, and Fig. 2 fA), (B) is a frequency characteristic diagram of the separation filter. , Fig. 3 fA) to (F) are frequency spectrum diagrams for explaining the operation of each component of the device of the present invention, Fig. 4 (A),
(B) is the same spread spectrum signal waveform diagram, Fig. 5 (A) ~
(C) is a timing chart for explaining the operation of each component in the modulation section shown in FIG. 1 (A), and FIG. 6 (^), (
8) are diagrams showing the frequency spectra of the PN code and spreading code in the modulation section, FIGS. 7(^) to (C) are frequency characteristic diagrams of each embodiment of the filter in the previous stage of the demodulation section, and FIG. 8 is the demodulation section. 9 and 10 are a block diagram of a modified example of the first-stage filter in the section, and FIGS. 9 and 10 show a model of the entire device and the configuration of the filter, respectively, to explain the operation when the interference wave with the strongest influence exists on the communication path. Block diagram showing the first
Figures 1 (A) and (B) are spectral diagrams for explaining the operation of the filter in Figure 10, and Figures 12 (A) and (B) are spectrum diagrams for when interference waves with the strongest influence are present in the communication channel. FIG. 13 is a spectral diagram for explaining the removal operation in the device of the present invention. A block configuration diagram of the third embodiment, FIG. 14 is a timing chart for explaining the operation of the second embodiment of the modulation section, FIG. 15 is a spectrum diagram for explaining the operation of the third embodiment of the modulation section, and FIG. 16 is a conventional Basic block configuration diagram of a communication device realizing the spread spectrum communication device, No. 17
The figure is a spectral waveform diagram of each component of the block diagram shown in FIG. 16. DESCRIPTION OF SYMBOLS 1...LPF (Low-frequency r-wave filter), 2-5... Multiplier, 6-8, 31... Adder, 9... Spreading code generation circuit, 10.30.40... Modulation section, 11 to 16...
BPF (band P wave filter), 17... BBF (band elimination P wave filter), 18.19... Separation filter, 20...
Demodulation unit, 21.22...Delay circuit, 23...Addition/subtraction circuit, 24°25...Gain adjuster, 32...Exclusive OR circuit, In+~Ins...Input terminal, OII?
+~Prefecture 2...Output terminal. Patent applicant: Kunio Umiki, representative of Victor Japan Co., Ltd.

Claims (2)

[Claims] (1) On the modulation side, a means for modulating a first carrier wave with an information signal to obtain a primary modulated wave signal, and a second carrier wave having a frequency different from the first carrier wave for the primary modulated wave signal. means to obtain a composite primary modulated wave signal by adding the NRZ pseudo-noise code and the clock signal; a first multiplier that multiplies to obtain a spread code signal, and a second multiplier that multiplies the spread code signal and the composite primary modulation wave signal to perform spread modulation and obtain a composite spread spectrum signal, On the demodulation side, there is a filter that inputs the composite spread spectrum signal and has a frequency passing characteristic corresponding to the spectral distribution of the main lobe, and filters noise near the center frequency of the main lobe through the filter. A means for reducing and removing interference wave components; and a means for converting the composite spread spectrum signal passed through the removing means into a spread spectrum signal in which the primary modulation wave is spread and a modulation spread spectrum code in which the second carrier wave is spread. a third multiplier for despreading the separated and detected signals by multiplication, and a means for demodulating the information signal from the primary modulated wave signal obtained by the despreading. A spread spectrum communication device configured with: (2) The spread spectrum communication device according to claim 1, wherein the composite spread spectrum signal is spread by a Manchester (bi-phase) coded spread code.