JPH01280938A - Spread spectrum communication system - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution by receiving a demodulation spread code signal and a 1st spread spectrum signal, applying inverse spread to the 1st spread spectrum signal by multiplication and outputting a demodulated PSK signal. CONSTITUTION:Since a delay circuit 17 is constituted to retard a sum conversion output signal Ps(t) by one time slot, the input and output sides of the delay circuit 17 are as shown in waveforms C, D. Both the signals are multiplied by a multiplier 5 and a carrier component is eliminated by an LPF 24 to detect a spread code signal P(t) equivalent at modulation as shown in (E). The spread code signal P(t) is supplied to a multiplier 4 to apply inverse spread by the multiplication with the spread spectrum signal S1(t) from an adder 18. Thus, a signal being the demodulation of the spread spectrum signal S1(t) is obtained from the multiplier 4 and an undesired frequency component is eliminated by a BPF 11 and a biphase PSK signal d(t)cosomegac1t is outputted from an output terminal Out2. Thus, the circuit is simplified.

Description

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

[Technical background]

The recent development of communication technology and the diversification of system technology in Japan are remarkable. Multiplex communication, typified by optical communication technology, is one such technology, and multichannel access (MCA) has become mainstream in communication technology using radio waves in order to make effective use of radio waves using analog modulation.

However, although this MCA has the advantage that one specific person cannot monopolize the same frequency, since the number of channels is limited, it is naturally impossible to make calls on more than one channel at the same time.

As a result, it is common for people to have to wait for calls, especially in large cities where the number of calls is high. This is because frequency resources, which are limited resources, are used by simply dividing the bandwidth. It seems that there are.

Therefore, we are researching even more efficient communication methods.

It has been developed by many researchers since ancient times.
One of them is the spread spectrum communication method.

This spread spectrum (Spread 5pectru1
1: S S ) communication system was developed in Europe about 50 years ago, and the basic idea was established in the 1950s.

In the 1960s, pseudo-noise code generation circuits were created using picture-side transistors, but the technology in those early days was immature, and there was a long-awaited development in the active elements and manufacturing technology that made up these circuits. In recent years, with the development of high-density IC technology and the reduction in the price of ICs, it has become possible to create small and inexpensive devices, and such communication systems are once again attracting attention.

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 frequency band. Generally, depending on the difference in the secondary modulation method, there are direct spread <DS) method, frequency hopping (FH) method, hybrid method, etc. The method of the present invention is the former DS method.
Regarding the method. Such spread spectrum communication has two characteristics: 1. Very high confidentiality (secrecy); 2. External interference and noise.

Resistant to intentional interference; ■Can coexist with conventional systems.

■No control station or control channel like an MCA station is required. ■Can be managed using address code.

■With the DS (direct diffusion) method, the power density is low, so it appears as if no radio waves exist (can be transmitted with low power). ■The number of stations can be increased if a slight reduction in call quality is tolerated. ■It has features such as the ability to multiplex within the same band by changing pseudo-noise code signals, and these have been recognized and are now being applied not only to the communication field but also to various fields. It has begun to be applied to consumer devices.

[Conventional technology]

A conventional spread spectrum communication system will be explained with reference to FIGS. 9 and 10. FIG. 9 is a basic block configuration diagram for realizing a spread spectrum communication system using the DS system, and FIG. 10 is a spectrum waveform diagram of each component. As shown in FIG. 9, the signal (Fl) as shown in FIG. 10(a), which has been primary modulated by the primary modulator 31 of station A on the transmitting side, is transmitted in the spread modulation circuit Fl@36. The signal from the spreading code generation circuit 39 (F ss ; see FIG. 3B) undergoes secondary modulation, is power amplified, and is output as a transmission signal (FlS) from the antenna A1. There are no particular restrictions on primary modulation, and frequency modulation (“H”) or P
S K (Phase 5hift Keying)
etc. (this specification will be explained assuming that modulation is performed using PSK), and secondary modulation (spread modulation) is generally a pseudo noise code (Pseudo No1se: P
PSK modulation using N code). This PN code needs to be as random noise-like as possible and have a certain period so that the code can be extracted on the receiving i side.

Next, the configuration and functions of the receiving side will be explained. At station B, which is the receiving side, the F1s signal obtained from the antenna A2 by a predetermined filter and high-frequency amplifier is despread in a despreading circuit 37 using a spreading code from a spreading code generation circuit 49. These four spreading code generating circuits are synchronized with the three spreading code generating circuits of station A, and the PN codes are also the same (F3,). By the way, the radio waves that enter antenna A2 are not limited to only Fls, but as shown in FIG. 10(C), radio waves from other 88 stations (F25, F33, .
) and general radio waves (Fn) exist. Therefore, by performing despreading in the despreading circuit 37, the desired radio wave F1s as shown in FIG. 2(d) is returned to the spectrum as shown in FIG.
At demodulation step #143, most of the components other than Fl are removed (see (e) in the same figure), and the signal is demodulated to the original information signal and output. In addition, as can be seen from the same figure (e),
In the output signal of the filter 41, there is an interference wave F in the Fls pond.
n and a portion of the multi-station SS waves remain. The ratio of this residual power to the power of the target signal is the DN ratio (signal power to interference power ratio)
In order to obtain a large DN ratio, it is advantageous to make the spreading band as wide as possible, and it is generally about 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 1.2 when performing spread spectrum communication.
Next, we will theoretically explain the specific operations in each modulation/demodulation.2 Spread spectrum signal S (t) (Fls in Fig. 9) in spread spectrum communication
(t) (+1 or - month, spreading code Fss is P(t)[+
1 or -1], and if the JI12 transmission wave is CO3ωct, it is expressed by the following equation.

S (t) = d (t) P (t) CO3ωct
--(1) (However, ωc = 2πfc) This spread spectrum signal s (B generates a clock signal for a spread code from an incoming spread spectrum signal during reception (demodulation), and also generates a spread spectrum signal during transmission. Obtain a spreading code P(t) (actually p(t) with some delay) that is synchronized with the spreading code at (also called spreading) and is converted into a two-phase PSK signal d(t)cosωat. Furthermore, the regenerated carrier COS
Synchronous detection is performed by multiplication with ωct (actually CO3ωct), and d (j) (CO3(JJct) ' = d (t
) (1+cos2ωat)/2 is obtained and the carrier wave component 2ωat is removed by a filter, thereby demodulating the information data d(t).

Here, the bandwidth of the two-phase PSK signal d(t)CO3ωct (which is assumed to be the main lobe of the spectrum) is Bo, and the bandwidth of the spread spectrum signal spread by the spreading code p(t) (which is assumed to be the main lobe of the spectrum) is Bo. ) is B, then the process gain G in spread spectrum communication is
G=B/BD・・・・・・・・・・・・・・・
... (2) Represented by p. The process gain G is a value of several hundred to several thousand in a normal design value, and since interference signals, noise, etc. are 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.

5. Problems to be Solved by the Invention] In such a spread spectrum communication system, ``despreading j is the most important, and it is not easy to generate the spreading code necessary for this, and at present, the AFC$ control loop , a despreading method using a delay locked loop and a multiplier, and a despreading method using a synchronized loop using a matched filter and a multiplier are generally 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. In addition, since it requires a very wide frequency band, there is a problem in terms of effective use of the frequency band (or radio waves), and in reality, the frequency band that can be used is limited, making it difficult to design as desired. There are drawbacks such as.

[Means to solve the problem]

In the present invention, on the modulation side, the information signal is transmitted using PSK on the first carrier wave.
means for modulating to obtain a PSK modulated signal; and means for inputting a clock signal to obtain a spreading code signal.

means for multiplying the PSK modulated signal by the spreading code signal to obtain a first spread spectrum signal; means for inputting the spreading code signal and the clock signal to obtain a phase conversion output signal; means for multiplying the second carrier wave by the fractional conversion output signal to obtain a second spread spectrum signal; and means for adding the second spread spectrum signal and the first spread spectrum signal to output an added spread spectrum signal. and a means for inputting the added spread spectrum signal to the demodulation side to separate and detect the first spread spectrum signal rP1 (t= signal and the second spread spectrum signal, a delay circuit for inputting a spread spectrum signal and adding a delay of one time slot to the spread spectrum signal; a means for inputting and multiplying the output of the delay circuit and a second spread spectrum signal to obtain a demodulated spread code signal; a demodulating means for inputting the demodulated spread spectrum code signal and the first spread spectrum signal, despreads the first spread spectrum signal by multiplication, and outputs a demodulated PSK signal;
We have realized a new communication method that can solve the above problems.

〔Example〕

In the spread spectrum communication system of the present invention, communication is carried out with the above configuration, so synchronization is made up of a clock recovery circuit, a spreading code generation circuit, and a loop, which are conventionally essential components in despreading. drop-in circuit and the same;
This eliminates the need for a time-holding circuit, etc., and a specific example of a device that can realize the system of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of a spread spectrum communication device that implements the spread spectrum communication system of the present invention, in which (A) shows the modulation section (transmission side) 10, and (B) shows the modulation section (transmission side) 10. This is a demodulation section (reception fll!I) 20.

Note that illustration of a part of the configuration, such as the antenna, is omitted.

As shown in FIG. 1(^), the modulation section 10 includes two multipliers 2 and 3; an arithmetic circuit (adder) 6. Phase conversion circuit 8. Spreading code generation circuit (PNG) 9 and BPF (band P wave device)
11, etc., and these are connected as shown in FIG. 1 fA). The phase conversion circuit 8 is, for example, EX-Of?
Gate 25 and D flip-flop circuit (r 0FF
(also written as J) 26 as shown in the figure. Furthermore, the demodulator 20 has two BPFs 13, 15;
1 delay circuit <0L) 16.17; 2 multipliers 4, 5
; Adder 18, subtracter 22. and LPF (band t!A'
P-wave devices) 24 are connected as shown in FIG. 1(B).

Note that the delay circuit 16. The adder XHIB and the subtractor 22 constitute one comb-shaped filter having two types of characteristics, and its frequency characteristics are shown as addition characteristics and subtraction characteristics in FIGS. 2(A) and (B), respectively. It is. Below, the specific IR capabilities and operations of the modulator 10 and demodulator 20 will be explained.
This will be explained with reference to the signal waveform diagrams in FIGS. 2 and 3 and the timing chart in FIG. 4.

First, when transmitting, in the modulation section 10, the information signal d(t) is modulated by a primary modulator (not shown) using the first carrier wave ωq, and the waveform ( Primary modulation signal dB) cosωc+t (here two-phase P
SK modulation signal), and the input terminal In +
The signal is supplied to the multiplier 2 via the multiplier 2. On the other hand, input terminal In
2 supplies the clock signal S c (t) to the spreading code generation circuit 9, which generates the spreading code signal pB) based on this signal. Pseudo-noise codes are used as spreading codes, and among these, M-sequence codes are often used, so they are sometimes called "pseudo-noise codes." The spreading code P([) generated by the spreading code generating circuit 9 is supplied to the multiplier 2, where the above two-phase PSK signal dB)cosωC+
The spectrum is spread by multiplying by j and the spectrum spread signal P (t) d (t)cosωc+t
(hereinafter also referred to as "5I(t)") (see Figure 2 (C)). This spread code signal P(1) and the clock signal 5
c(t) are also applied to the respective EX-OR gates 25 . and is supplied to the T (clock) terminal of the DFF 26. This phase conversion circuit 8 performs Hodulo2 addition, that is, modulo2 addition, and the spread code signal P (t
), the binary input signal at point (a) in Figure 1 (8) is ai
and the phase conversion output signal P 5ft) is (b)
If the signal at the point is b, then b, = Σa, = b, moa,
・Old and old... From... (3) + + +-1
+ (Nod, 2). The relationship between a and H is shown in Figure 4 (A
) and (8), respectively. That is, t)1 =
al+bo=1. b2=a2+bl=1°b3=a
*+b2=1. ba=aa+b3=o.

It is...

On the other hand, from the input terminal IYL3, a carrier wave signal COSω02j as shown in FIG. After performing spreading, the spread spectrum signal S 2(t) = P 5(t) CO3ωc as shown in the same figure (01)
2t is output and supplied to the adder 6. Therefore here,
Addition with the spread spectrum signal S+(j) is performed (see (E) in the same figure), and the added signal output is sent to the next stage BPF.
ll passes only the main lobe of the spread spectrum signal,
The signal is transmitted and output from output terminal 1.

This added spread spectrum signal S 1 (j) + S t (j
l is expressed by the following formula.

51 (t) + 52 (j) = P (j) d (j
)CO3(c)C+ tmoPs(t) cosωczt
--- (4) Here, the frequency spectrum of the spread spectrum signal will be explained. The same figure (C
) and (D), the gap between the sideband waves Sal and Sa2 and the gap between Sb1 and Sb2 are based on the clock signal 5cft)
Let To be the 1-bit time length of , and let the number of stages be ((2n -1) T o) The interval is given by -1, and the two types of sideband waves +Sal ~ -1-Sar,
, -3a1 to -8an, sideband wave 1Sb, ~+S
bn, -5bl to -3bn are arranged alternately at equal intervals, as shown in FIG. Therefore, the frequency interval between the double-sided band S81 series and the sb series is (2(2n
-1) Given by T ol-1. Figure 3 is a frequency characteristic diagram of a spread spectrum signal.
Between a) and (b)) shows its main lobe.

In the present invention, the selection of the frequency is an important point, and the frequency is selected so that the spectrum of the spread spectrum signal S2(t) exists between the sidebands of the spread spectrum signal S+(i). This means that the carrier CO3ωCUt and CO3ω
(2t) and the two-phase PSK modulated signal d(t)cosωC8, the use of a 1-bit time length 1M sequence code of the clock signal SC(t), and the number of stages of the shift register.

Next, with reference to FIG. 1 CB), the functions of the demodulator 20 will be explained with reference to FIG. 5 as well. Spread spectrum signal S M (t) (= s + (
t) + 82(t)) (see Figure 2(E)) is BP
Frequency components other than the spread spectrum signal are removed at F13, and the delay circuit 16. Adder 18. and '$4 unit 2
2 positive input terminal. Additionally, the output of the delay circuit 16 is sent to an adder 18. and the negative input terminal of the subtracter 22, these delay circuits 16. A comb-shaped filter 1 having an addition characteristic and a subtraction characteristic (see FIGS. 5(A) and (8), respectively) with an adder 18 and a subtracter 22.
is formed. Now, assuming that the delay time in the delay circuit 16 is T (=1/F), in the case of addition, as shown in FIG.
As shown in A), 1/T, 2/T, 3/T
, . . . , the gain is doubled at a frequency of N/T (N is a natural number), and at each intermediate frequency, the output becomes 0, creating a steep dip. In the case of subtraction, the same figure (
8), 1/T, 2/T, 3/T
, . . . There is a valley (gain is O) at a frequency of N/T, and the gain is doubled at each intermediate frequency. Therefore, by setting the delay time to T=(2n -1)T o and matching the peak or valley frequency of the comb-shaped filter 19 to the sideband frequency of the spread spectrum signal, the spread spectrum signal S+(t) and 52 (t) can be detected separately. Therefore, the output of the adder 18 is the spread spectrum signal S+(t) (see FIG. 2(C)), and the output of the subtracter 22 is the spread spectrum signal S2(D (see FIG. 2(D)). They can be obtained separately.

The delay circuit 17 is configured to delay the phase conversion output signal P5(t) by one time slot. Therefore, the input side and output side of the delay circuit 17 are respectively shown in FIG.
The waveforms are as shown in C) and (D), respectively. These two signals are multiplied by the multiplier 5, and the carrier component is removed by the LPF 24, thereby detecting a spreading code signal p(B) equivalent to that during modulation, as shown in FIG.

This spread code signal P(t) is supplied to the multiplier 4, and is despread by multiplication with the spread spectrum signal S+(j) from the adder 18. Therefore, a signal obtained by demodulating the spread spectrum signal S+(t) is obtained from the multiplier 4, and B
Unnecessary frequency components are removed by PFil, and a two-phase PSK signal d(t)cosωC,t is output from the output terminal shaft 2. Note that the expression of the delay of the spread spectrum signal S N (t) by the delay circuit 16 has been omitted for the sake of convenience of explanation.

Here, the separation and detection operation of the spread spectrum signal SM(t) (the operating principle of the comb-shaped filter 19, etc.) will be explained. The spread spectrum signal S N (t-T) output from the delay circuit 16 shown in FIG. 1(B) is S M (t
-T) = S 1 (t-T) + 32 (t-T) =
P (t-T) d (t-T)cosωG+ (t-
T) + P 5(t-T) cosωC2(t-T)
−・= −(5), where, as a precondition, P
(t) (or P5(t)) period and delay time T
are equal, cosωC+j is a continuous wave that repeats at the same phase and level with a period of P(t), and COSωCx f− is P(
If it is a continuous wave that repeats at the same level and opposite phase with a period of t),
5Mftzu) is SM (t-T) = P(t) d(
tzu) cosωC+j-Ps(t) cosωc2t
・・・・・・・・・・・・・・・(6) Therefore, the addition output SM (t)”SM(tzu)(・S+(t)
l is S + (t) = SM (t) = SM (t-T) =
I d ft)+d (t-T))P (t)
cosωC+lL (7). on the other hand,
Subtraction output S M (t) + S M (t-T) (・'
S2(j)) is S2(i)=SM(t)SM(t-T)
= 2 P 5(j) C03(Llc2 t-1-d
(t)-d (t-T))P (t)cosωC+j
......(8), where +d(t)-d (t-T))P (t)c seen in equation (8)
osωC+j is a Talostok component that cannot be separated by the comb-shaped filter 19, but the information data d′ −d (t)
Since the delay time is very short compared to the 1-chip time length (1-bit time length), it can be approximately omitted. Therefore, the subtraction output S2(t) is 52(t)”=
2PSft) CO3ωczt ”・”=・””・+9
).

Next, the despreading operation will be specifically explained according to the configuration shown in FIG. 1(B). First of all, the spreading code signal P(t
) generation (demodulation operation) will be explained.

The subtracted output S 2 (j) is supplied to the multiplier 5 and the delay port 1i17 for generating the spreading code signal P (t).

The delay circuit 17 is for delaying the phase conversion output signal P5(t) by one chip time length (one time slot), and when the delay time is τ, the delay subtraction output is S, (t
-τ) 6 Therefore, by multiplying the delay subtraction output 5t(t-τ) by 5t(t), the spreading code signal P(
t>. This method is a conventional "delayed detection" method, so a detailed explanation of its principle will be omitted.Unwanted carrier components are removed from the output of the 4-multiplier 5 by the LPF 24, and the spread code signal P during modulation is (A signal equivalent to t> is demodulated and supplied to the multiplier 4. Since the above addition output S+(t) is also supplied to the multiplier 4, the two signals are multiplied here and p B ) is converted to DC and demodulated 2-phase PS
K signal 1 d (j) + d (t-T) ) CO3ωc
Only 1t is output. The demodulated two-phase PSK signal is output from the output terminal shaft 2 after unnecessary noise components are removed by the BPF 15.

Next, FIG. 6 is a circuit block diagram of a second embodiment of a communication device that can implement the communication method of the present invention.

This will be explained with reference to the timing chart of FIG. 7 and the frequency spectrum waveform diagram of FIG. 8. FIG. 6(A) is a block diagram of the modulation section, and FIG. 6(B) is a block diagram of the demodulation section.
Components that are the same as those in the embodiment are given the same numbers and detailed explanation thereof will be omitted.

Compared to the modulation unit 10 of the first embodiment, the modulation unit 30 has a BP
F (bandwidth filter) 11 is inserted between the multiplier 2 and the arithmetic circuit 6, and another BPF 12 is added to form the multiplier 3.
The difference is that it is inserted between the and arithmetic circuit 6,
There are no changes to other components, and this BPFII is
Spread spectrum signal S+(t)(□P
(t) d (t) cosωc, BPFI 2 passes only the main lobe of the frequency spectrum of t 1 and supplies it to the arithmetic circuit 6, and the BPFI 2 transmits the spread spectrum signal S 2 (j) (= P 5(t) C0
3(1)C2tl Only the main lobe of the frequency spectrum is passed through and supplied to the arithmetic circuit 6. As a result, the arithmetic circuit 6 outputs an added spread spectrum signal S+(t)+32(t)I having a waveform as shown in FIG.
= 5N(j) (see equation (3)) is output from the output terminal 1 as in the first embodiment. Further, since the explanation of the operation of the phase conversion circuit 8 and the explanation of the signal waveform in FIG. Noh.

The explanation of the operating principle will be omitted. Note that two carrier waves ωc1
and ωc2 are selected with sufficient separation as shown in FIG. By configuring the bands (bands) so that they do not overlap with each other, the configuration of the demodulator 40 can be made -JII simpler than that of the demodulator 20, as will be described later. However, the frequency band used is 21 frequencies compared to the configuration of the first embodiment.

Next, with reference to FIG. 6fB), the configuration and functions of the demodulator 40 will be described with reference to the frequency characteristic diagram of the spread spectrum signal in FIG. 7 and the timing chart in FIG. 8. As is clear from a comparison between FIG. 6fB) and FIG. 1B, the demodulator 40 has a more simplified configuration than the demodulator 20, and one comb-shaped filter is omitted. There is. Instead, a BPF 14 is added and inserted between the input terminal Ina and the multiplier 5 and delay circuit 17. In such a configuration, the input terminal In a
Therefore, the added spread spectrum signal 5H(t)1 as shown in FIG.
=St(j)+32(j)=P(t)d(
t) cosωC1t+P 5(j) CO3ωc2 t
) is supplied to the BPFs 13 and 14. The BPF 13 passes only the spread spectrum signal S+(t) and supplies it to the multiplier 4. On the other hand, the BPF 14 passes only the spread spectrum signal S+(r) to the multiplier 5 and the delay circuit 17.
supply to. That is, the spread spectrum signals S+(t) and S2(t) are obtained separately by both BPFs 13 and 14, respectively.

The delay circuit 17 delays the phase conversion output signal Ps(t) by one time slot. Therefore, the delay circuit 17
The input side and output side of the signal have waveforms as shown in FIG. 8(C) and (DC), respectively.
By multiplying by , and further removing the carrier wave component by the LPF 24, a spreading code signal P (t) equivalent to that at the time of modulation is detected, as shown in FIG. This spread code signal P (t) is supplied to the multiplier 4, and is despread by multiplication with the spread spectrum signal S+(t) from the adder 18. Therefore, a signal obtained by demodulating the spread spectrum signal 5t(t) is obtained from the multiplier 4, unnecessary frequency components are removed by the BPFll, and the signal d(t)cosωC1t is sent from the output terminal shaft 2 to the two-phase ps. is output.

〔effect〕

As is clear from the above description, the spread spectrum communication system of the present invention has the following various excellent features.

■The circuit configuration has been greatly simplified because the black/yellow regeneration circuit, the synchronization pull-in circuit and the synchronization holding circuit consisting of one loop of spreading code generation circuit, etc., which were essential components in the conventional method, are no longer required. Because it can contribute to cost reduction,
It has become very easy to apply it to consumer devices.

■Since circuits to achieve synchronization, such as synchronization pull-in circuits and synchronization hold circuits that require advanced technology, are no longer required, the drawbacks of conventional methods such as the time it takes to pull in synchronization and the possibility of loss of synchronization, etc. This problem can be resolved and it can also contribute to stabilizing the operation of spread spectrum communication systems.

■If the frequencies of the two carrier waves for spread spectrum are selected in a sufficiently specific manner, and if the main lobe bands of the frequency spectra of each spread spectrum signal are configured so as not to overlap with each other, the usable frequency band can be doubled. However, the configuration of the demodulator can be made simpler by -N.

[Brief explanation of the drawing]

Figures 1 [A] and (B) are block configuration diagrams of the modulation section and 1\L tuning section of the first embodiment that realizes the spread spectrum communication system of the present invention, and Figure 2 fA) to (E) are The frequency spectrum diagrams for explaining the operation of each component of the first embodiment, FIGS. 3 and 7, are shown in FIGS. The frequency characteristic diagrams of the spread spectrum signal in the second embodiment, FIGS. 4 and 8, are shown in the first embodiment. A timing chart for explaining the operation of the main components of the second embodiment, FIG. 5 (^), CB) is a characteristic diagram of a comb-shaped filter,
FIGS. 6A and 6B are block configuration diagrams of a modulation section and a demodulation section, respectively, of a second embodiment that implements the method of the present invention, FIG. 9 is a basic block configuration diagram of conventional spread spectrum communication, and FIG. This figure is a spectral diagram for explaining the operation of the configuration of FIG. 9. 2 to 5... Multiplier, 6... Arithmetic circuit, 8... Phase conversion circuit, 9... Spreading code generation circuit, 11 to 15...
・BPF (band P wave device), 10.30...Modulation section, 1
6゜17...Delay circuit, 18...Adder, 19...
・Comb-shaped filter, 20.40... demodulation section, 22...
- Subtractor, In1-IfL4...Input terminal, Recommended)-Prefecture2...Output terminal. Decoration drawing with ten canes (Yago 8 prison) + ~1 no \yu/
U \, Procedural Amendment (Method) June 2, 1986

Claims (1)

[Claims] The modulation side includes means for PSK modulating the information signal with a first carrier wave to obtain a PSK modulated signal, means for inputting a clock signal to obtain a spreading code signal, and means for obtaining a spreading code signal by inputting a clock signal, and converting the PSK modulated signal into the obtained spreading code. By multiplying the signal, it is spread and the first
means for obtaining a spread spectrum signal, means for inputting the spread code signal and the clock signal to obtain a phase conversion output signal, and a second carrier wave for multiplying the obtained phase conversion output signal by a second carrier wave means for obtaining a spread spectrum signal of the second
and means for adding the first spread spectrum signal and the first spread spectrum signal to output an added spread spectrum signal; means for separating and detecting a second spread spectrum signal; a delay circuit for inputting the separated and detected second spread spectrum signal and adding a delay of one time slot; and an output of the delay circuit; means for inputting the second spread spectrum signal and performing multiplication to obtain a demodulated spread code signal; 1. A spread spectrum communication system comprising: demodulation means for despreading a first spread spectrum signal and outputting a demodulated PSK signal.