CDMA communication RF signal processing apparatus using SAW

• US 6,047,306 A
• Filed: 11/26/1997
• Issued: 04/04/2000
• Est. Priority Date: 11/29/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi Media Electronics Co., Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Shibagaki, Nobuhiko, Takubo, Chisaki, Sakiyama, Kazuyuki, Hikita, Mitsutaka
• Primary Examiner(s): Mai, Tan V.
• Application Number:
  US08/980,086
• Time in Patent Office: 860 Days
• Field of Search: 708/813, 708/815, 310/313 R
• US Class Current: 708/815
• CPC Class Codes: G06G 7/195 using electro- acoustic elements
• CPC Class Codes: H04B 1/70712 with demodulation by means of convolvers, e.g. of the SAW type SAW convolvers in general G06G7/195

Abstract

A surface acoustic wave signal processing apparatus for processing first and second high-frequency signals having frequencies f₁ and f₂ respectively, which comprises: first and second surface acoustic wave delay elements for receiving the first and second high-frequency signals respectively and independently of each other, the delay elements being formed as surface acoustic wave excitation and reception transducers on a piezoelectric substrate so that a phase delay φ₁ with respect to the frequency f₁ is substantially equal to a phase delay φ₂ with respect to the frequency f₂ (that is, φ₁ ≈φ₂); and a mixer for mixing first and second high-frequency output signals of the first and second surface acoustic wave delay elements so that a signal having a frequency |f₁ -f₂ | which is a difference between the two frequencies f₁ and f₂ is taken out as an output signal of the mixer.

Claims

1. A surface acoustic wave signal processing apparatus for processing first and second high-frequency signals having frequencies f₁ and f₂ respectively, wherein said first high-frequency signal is a modulated wave signal and said second high-frequency signal is a non-modulated wave signal, which comprises:

first and second surface acoustic wave delay elements for receiving said first and second high frequency signals respectively and independently of each other, said delay elements being formed as surface acoustic wave excitation and reception transducers on a piezoelectric substrate so that a phase delay φ

₁ with respect to the frequency f₁ is substantially equal to a phase delay φ

₂ with respect to the frequency f₂ (that is, φ

₁ ≈

φ

₂); and

a mixer for mixing first and second high-frequency output signals of said first and second surface acoustic wave delay elements so that a signal having a frequency |f₁ -f₂ | which is a difference between said two frequencies f₁ and f₂ is taken out as an output signal of said mixer.

2. A surface acoustic wave signal processing apparatus according to claim 1, wherein said frequency f₁ of said first high-frequency signal and said frequency f₂ of said second high-frequency signal are equal to each other except broadening of spectral bandwidth of said first high-frequency signal due to modulation so that a modulated signal of a base band is directly outputted from said mixer.

3. A surface acoustic wave signal processing apparatus according to claim 1, wherein:

said first and second surface acoustic wave delay elements are integrated to constitute a third surface acoustic wave delay element;

two kinds of surface acoustic wave excitation transducers and one kind of reception transducers are formed on said piezoelectric substrate;

first and second high-frequency signals which are a modulation signal such as a spread-spectrum signal, or the like, and a non-modulation signal having a frequency f equal to the frequency of the modulation signal except the spectral spread due to modulation are inputted to said two kinds of surface acoustic wave excitation transducers of said third surface acoustic wave delay element capable of propagating said two high-frequency signals in the same direction and in the same path on the same substrate;

said first and second high-frequency signals obtained simultaneously from outputs of said two kinds of surface acoustic wave excitation transducers are mixed by a mixer; and

a modulation signal of a base band is directly outputted from said mixer.

4. A surface acoustic wave signal processing apparatus according to claim 3, wherein:

said two kinds of surface acoustic wave excitation transducers include one kind of surface acoustic wave excitation transducers for exciting in-phase surface acoustic wave with respect to a center axis of excited surface acoustic wave, and the other kinds of surface acoustic wave excitation transducers for exciting anti-phase surface acoustic wave with respect to a center axis of excited surface acoustic wave;

said reception transducers output a sum of in-phase surface acoustic wave signals and a sum of in-phase and anti-phase surface acoustic wave signals independently of each other;

said outputs are mixed by balanced mixers so that N pairs of base-band modulation signals having phases reverse to each other are taken out independently of each other in the form of differential output pairs.

5. A surface acoustic wave signal processing apparatus according to claim 4, wherein:

each of said N pairs of base-band modulation signals having phases reverse to each other and obtained from outputs of said balanced mixers are weighted so that when one of the differential outputs is weighted with +1 correspondingly to said spread code row, the other is weighted with -1 or when one of the differential outputs is weighted with -1 correspondingly to said spread code row, the other is weighted with +1;

said weighted outputs are added up correspondingly to phases perpendicular to each other so that the output signals are taken out as independent signals.

6. A surface acoustic wave signal processing apparatus according to claim 4, wherein:

said reception transducers of said surface acoustic wave delay elements and said balanced mixers are replaced by a plurality of pairs (N pairs) of uniform electrodes disposed symmetrically with each other with respect to a center axis of excited surface acoustic wave; and

two high-frequency signals are mixed by using a nonlinear phenomenon of surface acoustic wave in said piezoelectric substrate just under said uniform electrode pairs so that outputs thereof are taken out as differential base-band modulation signals from said N pairs of uniform electrodes independently of each other.

7. A surface acoustic wave signal processing apparatus according to claim 4, wherein:

each of said surface acoustic delay elements has a configuration using a multilayer structure of a piezoelectric matter such as ZnO, or the like, and a semiconductor such as Si, or the like;

said reception transducers of said surface acoustic wave delay elements and said balanced mixers are replaced by a plurality of pairs (N pairs) of uniform electrodes disposed symmetrically with each other with respect to a center axis of excited surface acoustic wave; and

two high-frequency signals are mixed by using nonlinear relation between potential and electric field in said semiconductor so that outputs thereof are taken out as differential base-band modulation signals from said N uniform electrode pairs independently.

8. A surface acoustic wave signal processing apparatus according to claim 3, wherein:

each of said surface acoustic delay elements has a configuration using a multilayer structure of a piezoelectric substrate and a semiconductor substrate such as an Si substrate, or the like; and

first and second high frequency signals obtained from N output terminals of said third and fourth delay elements are mixed by using a nonlinear element array such as a diode array, or the like, formed on said semiconductor substrate so that N modulation signals each having a frequency equal to the differential frequency, that is, of a base band are taken out independently of each other.

9. A surface acoustic wave signal processing apparatus according to claim 1, wherein:

each of said first and second surface acoustic wave delay elements has a plurality of output terminals the numbers of which is assumed to be N so that the phase delays φ

₁ (1), φ

₁ (2), . . . , φ

₁ (N) for said frequency f₁ at the respective output terminals of said first surface acoustic wave delay element are substantially equal to the phase delays φ

₂ (1), φ

₂ (2), . . . , φ

₂ (N)for said frequency f₂ at the respective output terminals of said second surface acoustic wave delay element correspondingly respectively (that is, φ

₁ (1)≈

φ

₂ (1), φ

₁ (2)≈

φ

₂ (2), . . . , φ

₁ (N)≈

φ

₂ (N);

said first high-frequency signal is a DS spread spectrum signal having a spectrum mainly spread by a change in phase whereas said second high-frequency signal is a non-modulation signal;

each difference (|φ

₁ (1)-φ

₁ (2)|, |φ

₁ (2)-φ

₁ (3)|, . . . , φ

₁ (N-1)-φ

₁ (N)|) between phase delays in outputs at adjacent terminals in said N output terminals of said first delay element is substantially equal to a value 2 π

f₁ times as large as a length Tc of each of chips constituting a unit spread code row (corresponding to a unit symbol of the modulation signal) of said spread-spectrum signal or an integer (K) multiple of said value 2 π

f₁ times as large as the length Tc; and

said first and second high-frequency signals obtained correspondingly respectively from the terminals of said first and second delay elements are mixed by N independent mixers so that N independent output signals (O(1), O(2), . . . , O(N)) each of which is equal to a differential frequency between the frequencies f₁ and f₂ are taken out from said mixers respectively.

10. A surface acoustic wave signal processing apparatus according to claim 9, wherein:

a difference |φ

₁ (1)-φ

₁ (N)| between phase delays in outputs at the first and N-th output terminals of the first delay element is substantially equal to a product (Ts×

2 Π

f₁ ×

M) of the unit symbol length (Ts) of the spread-spectrum signal and a value M times as large as 2 Π

f₁ ;

when M is an integer satisfying M≧

1, output signals O(1), O(2), . . . , O(N) obtained from the respective N mixers are classified into M groups, namely, from 1 to N/M, from N/M+1 to 2N/M, . . . , from (M-1)N/M+1 to N;

each of the groups corresponds to a unit symbol of said spread-spectrum signal; and

after N/M outputs in each group are weighted with +1 or -1 correspondingly to chips of a spread code row constituting said unit symbol, the N/M outputs are added up correspondingly to each group so that M output signals (OO(1), OO(2), . . . , OO(M)) are taken out independently of each other.

11. In an apparatus according to claim 10 in which M is equal to 1, a synchronous detector for demodulating a spread-spectrum signal by using the amplitude and phase of said output signal OO(1).

12. In an apparatus according to claim 5 in which M is equal to 2, a delay detector for demodulating a spread-spectrum signal by using correlation in amplitude and phase between said output signals OO(1) and OO(2).

13. In an apparatus according to claim 10, a spread-spectrum signal delay detector in which:

data detection clock pulses for demodulating a spread-spectrum signal are determined on the basis of a result of an arithmetic operation |OO(1)+OO(2)|² +|OO(1)-OO(2)|² ; and

data are detected on the basis of a result of an arithmetic operation |OO(1)+OO(2)|² -|OO(1)-OO(2)|² or on the basis of a result of an output of a mixer to which OO(1) and OO(2) are inputted.

14. A surface acoustic wave signal processing apparatus according to claim 10, wherein:

the order of weighting with +1 or -1 and addition by said groups is reversed so that corresponding outputs to be weighted with +1 or -1 are added up, weighted with +1 or -1 and then added up.

15. A surface acoustic wave signal processing apparatus according to claim 4, wherein:

the output signals O(1), O(2), . . . , O(N) obtained from the N mixers are classified into M groups in the same manner as the apparatus described in claim 10;

said groups correspond to unit symbols of said spread-spectrum signal respectively;

each of said unit symbols is constituted by modulation wave which is obtained by applying modulation to two phases perpendicular to each other on the basis of corresponding two spread code rows; and

after said output signals O(1), O(2), . . . , O(N) are weighted with +1 or -1 correspondingly to respective chips of said two spread code rows, said output signals O(1), O(2), . . . , O(N) are added up for every groups corresponding to said two perpendicular phases, that is, said two spread code rows so that M output signals OOi(1), OOi(2), . . . , OOi(M) and M output signals OOq(1), OOq(2), . . . , OOq(M) are taken out independently of each other.

16. In an apparatus according to claim 15 in which M is equal to 1, a synchronous detector for demodulating a spread-spectrum signal by using the amplitude and phase of said output signals OOi(1) and OOq(1).

17. In an apparatus according to claim 15 in which M is equal to 2, a delay detector for demodulating a spread-spectrum signal by using correlations in amplitude and phase between said output signals OOi(1)and OOi(2), and between said output signals OOq(1) and OOq(2).

18. In an apparatus according to claim 15 a spread-spectrum signal delay detector in which:

data detection clock pulses for demodulating a spread-spectrum signal are determined on the basis of a result of an arithmetic operation |OOi(1)+OOi(2)|² +|OOi(1)-OOi(2)|² or |OOq(1)+OOq(2)|² +|OOq(1)-OOq(2)|² ; and

data corresponding to two phases perpendicular to each other are demodulated by said arithmetic operation |OOi(1)+OOi(2)|² -|OOi(1)-OOi(2)|² or mixture of OOi(1) and OOi(2) or by said arithmetic operation |OOq(1)+OOq(2)|² -|OOq(1)-OOq(2)|² or mixture of OOq(1) and OOq(2).

19. In an apparatus according to claim 9, a spread-spectrum signal demodulator in which said spread-spectrum signal is modulated by a modulation system using BPSK based on two-valued BPSK, π

/2-shift BPSK, etc.

20. In an apparatus according to claim 9, spread-spectrum signal demodulator in which said spread-spectrum signal is modulated by a modulation system using QPSK based on four-valued QPSK, MSK, GMSK, OQPSK, π

/4-shift QPSK etc.

21. A surface acoustic wave signal processing apparatus according to claim 9, wherein:

mixers, adders and weighting circuits with +1 or -1 are achieved by CMOS circuit elements.

22. A spread-spectrum communication radio machine in which said surface acoustic wave signal processing apparatus according to claim 9 is mounted.

23. A spread-spectrum communication radio machine in which:

said surface acoustic wave signal processing apparatus according to claim 4 is mounted;

said spread-spectrum signal is a reception signal for said radio machine or an intermediate frequency signal whereas said non-modulation signal is a local oscillation signal for said radio machine; and

said radio machine has an external circuit (that is, a carrier reproducing circuit) for setting the frequency and phase of said local oscillation signal on the basis of said spread-spectrum signal or said radio machine corrects the frequency and phase equivalently by digital signal processing.

24. In an apparatus according to claim 22, a spread-spectrum communication radio machine comprising an external circuit (that is, a clock reproducing circuit) for detecting the symbol-repetition frequency of a spread-spectrum signal on the basis of a reception signal.

25. A surface acoustic wave signal processing apparatus for processing first and second high-frequency signals which are a spread-spectrum signal having a frequency f_RF and a non-modulation signal having a frequency f_LO respectively so that each of said frequencies f_RF and f_LO are equal to a frequency f except the broadening of the spectral bandwidth due to modulation (that is, f_RF ≈

f_LO ≈

f), said apparatus comprising;

a first surface acoustic wave delay element having N output terminals at which phase delays in outputs are φ

₁ (1), φ

₁ (2), . . . , φ

₁ (N) respectively;

a second surface acoustic wave delay element having N output terminals at which phase delays in outputs are φ

₂ (1), φ

₂ (2), . . . , φ

₂ (N) respectively so that said phase delays in outputs at said output terminals of said second surface acoustic wave delay element are substantially equal to said phase delays in outputs at said output terminals of said first surface acoustic wave delay element respectively correspondingly (that is, φ

₁ (1)≈

φ

₂ (1), φ

₁ (2)≈

φ

₂ (2), . . . , φ

₁ (N)≈

φ

₂ (N));

a third surface acoustic wave delay element having N output terminals at which phase delays in outputs for said frequency f are φ

₃ (1), φ

₃ (2), . . . , φ

₃ (N) respectively with phase differences of about 90°

from those in said second delay element (that is, φ

₂ (1)≈

φ

₃ (1)±

90°

, φ

₂ (2)≈

φ

₃ (2)±

90°

, . . . , φ

₂ (N)≈

φ

₃ (N)±

90°

); and

independent N mixers in which the differences (|φ

₁ (1)-φ

₁ (2)|, |φ

₁ (2)-φ

₁ (3)|, . . . , |φ

₁ (N-1)-φ

₁ (N)|, |φ

₂ (1)-φ

₂ (2)|, |φ

₂ (2)-φ

₂ (3)|, . . . , |φ

₂ (N-1)-φ

₂ (N)| and |φ

₃ (1)-φ

₃ (2)|, |φ

₃ (2)-φ

₃ (3)|, . . . , |φ

₃ (N-1)-φ

₃ (N)|) between phase delays in outputs at adjacent ones of said N output terminals in each of said delay elements are substantially equal to a value 2 π

f times as large as the length Tc of each chip constituting a unit spread code row (corresponding to a unit symbol) of a spread-spectrum signal or to an integer (K) multiple of said value 2 π

f times as large as the length Tc of each chip;

said first and second high-frequency signals are inputted to said first and second delay elements, and first and second high-frequency output signals respectively obtained from corresponding terminals of said first and second delay elements are mixed by said independent N mixers so that N modulation signals (l(1), l(2), . . . , l(N)) which are equal to differential frequencies respectively, that is, which are of a base band, are taken out independently from said N mixers; and

a third high-frequency signal which is the same signal as said second high-frequency signal is inputted to said third delay element, and first and third high-frequency output signals respectively obtained from corresponding terminals of said first and third delay elements are mixed by said independent N mixers so that N modulation signals (Q(1), Q(2), . . . , Q(N)) which are equal to differential frequencies respectively, that is, which are of a base band, are taken out independently from said N mixers.

26. A surface acoustic wave signal processing apparatus according to claim 25, wherein the 90°

phase difference of said third surface acoustic wave delay element from said second delay element is achieved by a change (shortening or extension by a quarter wavelength) of a propagation path of each surface acoustic wave delay element.

27. A surface acoustic wave signal processing apparatus according to claim 25, wherein the 90°

phase difference of said third surface acoustic wave delay element from said second delay element is achieved by an external circuit regardless of a change of a propagation path of each surface acoustic wave delay element.

28. A surface acoustic wave signal processing apparatus according to claim 25, wherein:

the differences |φ

₁ (1)-φ

₁ (N)|, |φ

₂ (1)-φ

₂ (N)|, and |φ

₃ (1)-φ

₃ (N)| between phase delays in outputs at the respective first and N-th output terminals of said first, second and third delay elements are substantially equal to a product (Ts×

2 π

f×

M) of the unit symbol length (Ts) of the spread-spectrum signal and a value M times as large as 2 π

f;

when M is an integer satisfying M≧

1, output signals I(1), I(2), . . . , I(N) and Q(1), Q(2), . . . , Q(N) obtained from the respective N mixers are classified into M groups, namely, from 1 to N/M, from N/M+1 to 2N/M, . . . , from (M-1)N/M+1 to N;

each of said groups corresponds to a unit symbol of said spread-spectrum signal;

after N/M outputs in each group are weighted with +1 or -1 correspondingly to chips of a spread code row constituting said unit symbol, said N/M outputs are added up by said groups so that M output signals IIi(1), IIi(2), . . . , II(M) and M output signals QQi(1), QQi(2), . . . , QQi(M) are taken out independently.

29. In an apparatus according to claim 28 in which M is equal to 1, a synchronous detector for demodulating a spread-spectrum signal by using the amplitude and phase of said output signals IIi(1) and QQi(1).

30. In an apparatus according to claim 28 in which M is equal to 2, a synchronous detector for demodulating a spread-spectrum signal by using correlations in amplitude and phase between said output signals IIi(1) and IIi(2) and between said output signals QQi(1) and QQi(2).

31. In an apparatus according to claim 30 a spread-spectrum signal delay detector in which:

data detection clock pulses for demodulating a spread-spectrum signal are determined on the basis of a result of an arithmetic operation {IIi(1)+IIi(2)}² +(QQi(1)+QQi(2)}² +{IIi(1)-IIi(2)}² +{QQi(1)-QQi(2)}² ; and

data are demodulated by a result of an arithmetic operation {IIi(1)+IIi(2)}² +{QQi(1)+QQi(2)}² -{IIi(1)-IIi(2)}² -{QQi(1)-QQi(2)}².

32. A surface acoustic wave signal processing apparatus according to claim 25, wherein:

the differences |φ

₁ (1)-φ

₁ (N)|, |φ

₂ (1)-φ

₂ (N)|, and |φ

₃ (1)-φ

₃ (N)| between phase delays in outputs at the respective first and N-th output terminals of said first, second and third delay elements are substantially equal to a product (Ts×

2 π

f×

M) of the unit symbol length (Ts) of the spread-spectrum signal and a value M times as large as 2 π

f;

when M is an integer satisfying M≧

1, output signals I(1), I(2), . . . , I(N) obtained from N mixers and output signals Q(1), Q(2), . . . , Q(N) obtained from the respective N mixers are classified into M groups, namely, from 1 to N/M, from N/M+1 to 2N/M, . . . , from (M-2)N/M+1 to N;

each of said groups corresponds to a unit symbol of the spread-spectrum signal;

said unit symbol is constituted by wave modulated on the basis of two spread code rows corresponding to two phases perpendicular to each other;

after said output signals I(1), I(2), . . . , I(N) and output signals Q(I), Q(2), . . . , Q(N) are weighted with +1 or -1 correspondingly to chips of said two spread code rows, said output signals I(1), I(2), . . . , I(N) and output signals Q(1), Q(2), . . . , Q(N) are added up by said groups correspondingly to said two perpendicular phases, that is, correspondingly to said two spread code rows so that M output signals IIi(1), IIi(2), . . . , IIi(M), M output signals QQi(1), QQi(2), . . . , QQi(M), M output signals IIq(1), IIq(2), . . . ,IIq(M) and M output signals QQq(1), QQq(2), . . . , are taken out independently of each other.

33. In an apparatus according to claim 32 in which M is equal to 1, a synchronous detector for demodulating a spread-spectrum signal by using the amplitude and phase of said output signals IIi(1) and QQi(1), and IIq(1) and QQq(1).

34. In an apparatus according to claim 32 in which M is equal to 2, a synchronous detector for demodulating a spread-spectrum signal by using correlations in amplitude and phase between said output signals IIi(1) and IIi(2), QQi(1) and QQi(2), IIq(1) and IIq(2), and QQq(1) and QQq(2).

35. In an apparatus according to claim 34, a spread-spectrum signal delay detector in which:

data detection clock pulses for demodulating a spread-spectrum signal are determined on the basis of a result of an arithmetic operation {IIi(1)+IIi(2)}² +{QQi(1)+QQi(2)}² +{IIi(1)-IIi(2)}² +{QQi(1)-QQi(2)}² or {IIq(1)+IIq(2)}² +{QQq(1)+QQq(2)}² +{IIq(1)-IIq(2)}² +{QQq(1)-QQq(2)}² ; and

data corresponding to two phases perpendicular to each other are demodulated on the basis of a result of an arithmetic operation {IIi(1)+IIi(2)}² +{QQi(1)+QQi(2)}² -{IIi(1)-IIi(2)}² -{QQi(1)-QQi(2)}² or {IIq(1)+IIq(2)}² +{QQq(1)+QQq(2)}² -{IIq(1)-IIq(2)}² -{QQq(1)-QQq(2)}².

36. A surface acoustic wave signal processing apparatus according to claim 25, wherein:

said first and second surface acoustic wave delay elements are integrated to constitute a fourth surface acoustic wave delay element;

said first and third surface acoustic wave delay elements are integrated to constitute a fifth surface acoustic wave delay element;

said fourth surface acoustic wave delay element has two kinds of surface acoustic wave excitation transducers and N reception transducers formed on said piezoelectric substrate and can propagate two high-frequency signals in the same direction and in the same path on the same substrate so that phase delays φ

₁^RF (1), φ

₁^RF (2), . . . , φ

₁^RF (N) in outputs at the respective terminals for said spread-spectrum signal having a frequency f are substantially equal to phase delays φ

₁^LO (1), φ

₁^LO (2), . . . , φ

₁^LO (N) in outputs obtained from the same terminals for said non-modulation signal (that is, φ

₁^RF (1)≈

φ

₁^LO (1), φ

₁^RF (2)≈

φ

₁^LO (2), . . . , φ

₁^RF (N)≈

φ

₁^LO (N);

said fifth surface acoustic wave delay element has two kinds of surface acoustic wave excitation transducers and N reception transducers formed on said piezoelectric substrate and can propagate two high-frequency signals in the same direction and in the same path on the same substrate so that phase delays φ

₂^RF (1), φ

₂^RF (2), . . . , φ

₂^RF (N) in outputs at the N output terminals for said spread-spectrum signal having said frequency f are equal to said phase delays φ

₁^RF (1), φ

₁^RF (2), . . . , φ

₁^RF (N) in outputs of said fourth delay element for said spread-spectrum signal and that phase delays φ

₂^LO (1), φ

₂^LO (2), . . . , φ

₂^LO (N) in outputs obtained from the same terminals for said non-modulation signal have a phase difference of 90°

from said phase delays φ

₁^LO (1), φ

₁^LO (2), . . . , φ

₁^LO (N) in outputs of said fourth delay element for said non-modulation signal (that is, φ

₁^LO (1)≈

φ

₂^LO (1)±

90°

, φ

₁^LO (2)≈

φ

₂^LO (2)±

90°

, . . . , φ

₁^LO (N)≈

φ

₂^LO (N)±

90°

);

first and second high-frequency signals one of which is a modulation signal such as a spread-spectrum signal, or the like, having a frequency f_RF and the other of which is a non-modulation signal having a frequency f_RF equal to the frequency of the modulation signal except the spectral spread due to modulation (that is, f_RF ≈

f_LO ≈

f) are inputted to said two kinds of surface acoustic wave excitation transducers of said forth and fifth surface acoustic wave delay elements;

said first and second high-frequency signals obtained simultaneously from said N output terminals of said fourth delay element are mixed so that N modulation signals (I(1), I(2), . . . , I(N)) of a base band having frequencies equal to differential frequencies are taken out from said mixers;

said first and second high-frequency signals obtained simultaneously from said N output terminals of said fifth delay element are mixed so that N modulation signals (Q(1), Q(2), . . . , Q(N)) of a base band having frequencies equal to differential frequencies are taken out from said mixers; and

after said N outputs (I(1), I(2), . . . I(N)) and said outputs (Q(1), Q(2), . . . , Q(N)) are weighted with +1 or -1 correspondingly to said spread code rows, said N outputs (I(1), I(2), . . . , I(N)) and said outputs (Q(1), Q(2), . . . , Q(N)) are added up correspondingly to phases perpendicular to each other so that output signals are taken out independently of each other.

37. A surface acoustic wave signal processing apparatus according to claim 36, wherein:

a plurality of uniform electrodes the number of which is assumed to be N are formed instead of said reception transducers of said surface acoustic wave delay elements;

a nonlinear phenomenon of surface acoustic wave in said piezoelectric substrate just under said uniform electrodes is used instead of said mixers to thereby mix two high-frequency signals; and

outputs of mixing are taken out from said N uniform electrodes independently of each other.

38. A surface acoustic wave signal processing apparatus according to claim 36, wherein:

each of said surface acoustic wave delay elements uses a multilayer structure of a piezoelectric material such as ZnO, or the like, and semiconductors such as Si, or the like;

a plurality of uniform electrodes the number of which is assumed to be N are formed instead of said reception transducers of said surface acoustic wave delay elements; and

nonlinear relation between potential and electric field in said semiconductors is used so that mixture outputs of two high-frequency signals are taken out from said N uniform electrodes independently of each other.

39. A surface acoustic wave signal processing apparatus according to claim 36, further comprising:

a sixth surface acoustic wave delay element which is similar in configuration to said fourth delay element and in which surface acoustic wave having a phase reverse to the phase of said fourth delay element is excited from one of two kinds of surface acoustic excitation transducers; and

a seventh surface acoustic wave delay element which is similar in configuration to said fifth delay element and in which surface acoustic wave having a phase reverse to the phase of said fourth delay element is excited from one of two kinds of surface acoustic excitation transducers, wherein;

said first and second high-frequency signals are inputted to respective two kinds of surface acoustic wave excitation transducers of each of said fourth, fifth and sixth and seventh delay elements; and

said first and second high-frequency signals obtained simultaneously from respective N output terminals of at least said fourth and fifth delay elements are mixed, so that respective N modulation signals each having a frequency equal to the differential frequency, that is, of a base band are taken out independently from said mixers.

40. A surface acoustic wave signal processing apparatus according to claim 36, wherein:

said two kinds of surface acoustic wave excitation transducers include one kind of surface acoustic wave excitation transducers for exciting in-phase surface acoustic wave with respect to a center axis of excited surface acoustic wave, and the other kinds of surface acoustic wave excitation transducers for exciting anti-phase surface acoustic wave with respect to a center axis of excited surface acoustic wave;

said reception transducers output a sum of in-phase surface acoustic wave signals and a sum of in-phase and anti-phase surface acoustic wave signals independently of each other;

said outputs are mixed by balanced mixers so that N pairs of base-band modulation signals having phases reverse to each other are taken out independently of each other in the form of differential output pairs.

41. A surface acoustic wave signal processing apparatus according to claim 40, wherein:

each of said N pairs of base-band modulation signals having phases reverse to each other and obtained from outputs of said balanced mixers are weighted so that when one of the differential outputs is weighted with +1 correspondingly to said spread code row, the other is weighted with -1 or when one of the differential outputs is weighted with -1 correspondingly to said spread code row, the other is weighted with +1;

said weighted outputs are added up correspondingly to phases perpendicular to each other so that the output signals are taken out as independent signals.

42. A surface acoustic wave signal processing apparatus according to claim 41, wherein:

said reception transducers of said surface acoustic wave delay elements and said balanced mixers are replaced by a plurality of pairs (N pairs) of uniform electrodes disposed symmetrically with each other with respect to a center axis of excited surface acoustic wave; and

two high-frequency signals are mixed by using a nonlinear phenomenon of surface acoustic wave in said piezoelectric substrate just under said uniform electrode pairs so that outputs thereof are taken out as differential base-band modulation signals from said N pairs of uniform electrodes independently of each other.

43. A surface acoustic wave signal processing apparatus according to claim 40, wherein:

each of said surface acoustic delay elements has a configuration using a multilayer structure of a piezoelectric matter such as ZnO, or the like, and a semiconductor such as Si, or the like;

said reception transducers of said surface acoustic wave delay elements and said balanced mixers are replaced by a plurality of pairs (N pairs) of uniform electrodes disposed symmetrically with each other with respect to a center axis of excited surface acoustic wave; and

two high-frequency signals are mixed by using nonlinear relation between potential and electric field in said semiconductor so that outputs thereof are taken out as differential base-band modulation signals from said N uniform electrode pairs independently.

44. A surface acoustic wave signal processing apparatus according to claim 25, wherein:

K is an integer satisfying the relation K≧

2;

N base-band modulation signals I(1), I(2), . . . , I(N) and N base-band modulation signals Q(1), Q(2), . . . , Q(N) obtained from said mixers are inputted to K digital or analog delay circuits D(1), D(2), . . . , D(K) for successively increasing the quantities of delays by the chip length Tc of said spread-spectrum signal (that is, τ

(1)=0, τ

(2)-Tc, τ

(3)-2Tc, . . . , τ

(K)=(K-1)×

Tc) so that N×

K outputs, namely, I'"'"'(1), I'"'"'(2), . . . , I'"'"'(K) form I(1), I'"'"'(K+1), I'"'"'(K+2), . . . , I'"'"'(2K) from I(2), . . . , I'"'"'((N-1)K+1), I'"'"'((N-1K+2), . . . , I'"'"'(N×

K) from I(N), and N×

K outputs, namely Q'"'"'(1), Q'"'"'(2), . . . , Q'"'"'(K) from Q(1), Q'"'"'((N-1)K+2, . . . , Q'"'"'(2K) from Q(2), . . . , Q'"'"'((N-1)K+1), Q'"'"'((N-1)K+2), . . . , Q'"'"'(N×

K) from Q(N), are taken out independently of each other; and

the outputs thus taken out are weighted with +1 or -1 correspondingly to spread code rows and then added up correspondingly to phases perpendicular to each other so that output signals are taken out independently of each other.

45. A surface acoustic wave signal processing apparatus according to claim 25, wherein:

M is smaller than 1;

base-band modulation signals I(1) , I(2), . . . , I(N) and Q(1), Q(2), . . . , Q(N) obtained from said mixers are weighted with +1 or -1 correspondingly to spread code rows and then added up on the basis of two phases perpendicular to each other; and

results of addition are inputted to h(≈

1/M) digital or analog delay circuits D(1), D(2), . . . , D(h) for successively increasing the quantities of delay by N times of the chip length Tc of the spread-spectrum signal (that is, τ

(1)=0, τ

(2)=N×

Tc, τ

(3)=N×

2Tc, . . . , τ

(h)=N×

(h-1)×

Tc) so that N×

h is not smaller than the number of chips constituting a unit symbol;

respective h outputs are taken out from said digital or analog delay circuits and added up on the basis of phases perpendicular to each other so that output signals IIi and QQi, and output signals IIq and QQq are taken out independently of each other.