Spread spectrum communication device and communication system

Abstract

It is the object of the invention to provide a structure of a novel spectrum spreading communication device which solves the problem with the conventional spectrum spreading communication using Barker codes, etc. and limits the rise of the side-lobe of a correctional signal independently of the order of information codes by use of a code sequence having a code length of at least 14. The spectrum spreading communication device uses a pseudo-noise code having a code length of at least 14 and a self-correlation side-lobe of not greater than 3 as a pseudo-noise code of a direct spreading communication device which uses the pseudo-noise codes whose polarities are inverted so as to deal with also digital information. Thus, even when the pseudo-noise code length is 14 or more, the side-lobe of the correction coefficient can be restricted. Accordingly, the error rate of the spectrum spreading communication device is reduced and the processing gain is improved.

Description

TECHNICAL FIELD

The present invention relates to surface acoustic wave devices and communication devices.

BACKGROUND ART

In conventional spread spectrum communication devices using the direct spreading method, a Barker code was used as a pseudo noise code as described in 1985 ULTRASONICS SYMPOSIUM proceedings, pp. 145-148, for example. It is known that this code does not depend on the arrangement of an information code sequence and this code has an auto-correlation side lobe of 1.

The Barker code has been found with the code length of 13 or less. The Barker code has not been found with a code length exceeding it. In the case where a processing gain of a code length of at least 14 was required, therefore, a code other than the Barker code, such as the longest code sequence was used. In these code sequences, however, a large side lobe rise is caused when the sign of the information code is inverted. In general, therefore, the error rate is increased.

An object of the present invention is to solve the above described problem and provide a novel structure of a spread spectrum communication device which uses a code sequence having a code length of at least 14, which does not depend on the arrangement of the information code, and which suppresses the side lobe rise of correlation signals.

SUMMARY OF INVENTION

The above described object can be achieved by employing a code sequence used by the present invention, i.e., a code shown in TABLES 1 through 9 as the pseudo noise code for spreading the power density spectrum of an input signal.

It has been confirmed by calculation conducted by the present inventors that the code shown in TABLES 1 through 9 has an auto-correlation coefficient side lobe of 3 or less. If this code is used, therefore, there is obtained a novel spread spectrum communication device and communication system which has a processing gain having an auto-correlation coefficient side lobe of at least 14, which does not depend on the arrangement of the information code, which suppresses the side lobe rise of the correlation signal, and which makes the error rate small. In addition, a surface acoustic wave device utilizing this characteristic is obtained.

The present invention relates to a novel code having a processing gain with a code length of at least 14 and an auto-correlation side lobe of 3 or less. The code length is determined in some cases by using harmonics of the crystal (oscillation frequency in the case here a frequency multiplier is used). In other cases, the code length is generated independently of the clock frequency of the baseband digital circuit.

It is now assumed that the code length is determined by using harmonics of the crystal. If harmonics are generated by distorting the oscillation waveform of the clock frequency in order to make harmonic components large, for example, only odd-number components included in harmonic components are typically generated. If its odd-number components are used as the clock of pseudo noise code generator, therefore, a value obtained by dividing the clock of the pseudo noise code generator by the clock frequency of the baseband digital circuit, i.e., the code length is obtained. To be concrete, an odd-numbered code length such as 15, 17, 19, . . . is obtained.

In the case where the obtained odd-numbered code length is applied to a spread spectrum communication device, two code lengths are combined and used in some cases. To be concrete, it is a result of multiplication of odd-numbered code lengths. A value of at least 14 such as 15, 21, 25, 27, . . . is used as the code length.

In the case where the code length is generated independently of the clock frequency of the baseband digital circuit, it doesn't matter at all whether the code length is even-numbered or odd-numbered and consequently values of at least 14, i.e., values 14, 15, 16, 17, . . . are obtained.

In either case, a pseudo noise code formed by a large number of combinations in respective code lengths is present. Out of them, the present inventors found a novel code which is 3 or less in auto-correlation side lobe and which is effective as the pseudo noise code used for spreading the power density spectrum of an input signal. The present inventors also found a novel pseudo noise generator capable of executing spreading (or de-spreading) of the power density spectrum of an input signal by using those codes.

The following TABLES 1 through 9 show the pseudo noise code concerning the present invention.

TABLE 1______________________________________(n = 14) max. corr. max. corr.number bj (forward) (back) dc level______________________________________202 00000011001010 2 6 -6332 00000101001100 2 6 -6404 00000110010100 2 8 -6405 00000110010101 2 6 -4410 00000110011010 2 10 -4470 00000111010110 2 10 -2665 00001010011001 2 10 -4691 00001010110011 2 10 -2811 00001100101011 2 10 -2821 00001100110101 2 10 -21883 00011101011011 2 10 22375 00100101000111 2 10 -22656 00101001100000 2 8 -62767 00101011001111 2 10 23232 00110010100000 2 6 -63247 00110010101111 2 10 23322 00110011111010 2 10 24021 00111110110101 2 10 44622 01001000001110 2 10 -45145 01010000011001 2 6 -45251 01010010000011 2 10 -45312 01010011000000 2 6 -65313 01010011000001 2 8 -45327 01010011001111 2 10 25535 01010110011111 2 6 45728 01011001100000 2 10 -45758 01011001111110 2 10 46092 01011111001100 2 10 26118 01011111100110 2 10 46575 01100110101111 2 10 46645 01100111110101 2 6 46650 01100111111010 2 10 46880 01101011100000 2 10 -27186 01110000010010 2 10 -47989 01111100110101 2 8 48090 01111110011010 2 10 48293 10000001100101 2 10 -48394 10000011001010 2 8 -49197 10001111101101 2 10 49503 10010100011111 2 10 29733 10011000000101 2 10 -49738 10011000001010 2 6 -49808 10011001010000 2 10 -410265 10100000011001 2 10 -410291 10100000110011 2 10 -210625 10100110000001 2 10 -410655 10100110011111 2 10 410848 10101001100000 2 6 -411056 10101100110000 2 10 -211070 10101100111110 2 8 411071 10101100111111 2 6 611132 10101101111100 2 10 411238 10101111100110 2 6 411761 10110111110001 2 10 412362 11000001001010 2 10 -413061 11001100000101 2 10 -213136 11001101010000 2 10 -213151 11001101011111 2 6 613616 11010100110000 2 10 -213727 11010110011111 2 8 614008 11011010111000 2 10 214500 11100010100100 2 10 -215562 11110011001010 2 10 215572 11110011010100 2 10 215692 11110101001100 2 10 215718 11110101100110 2 10 415913 11111000101001 2 10 215973 11111001100101 2 10 415978 11111001101010 2 6 415979 11111001101011 2 8 616051 11111010110011 2 6 616181 11111100110101 2 6 6______________________________________ TABLE 2______________________________________(n = 15) max. corr. max. corr.number bj (forward) (back) dc level______________________________________ 202 000000011001010 3 7 -7 332 000000101001100 3 7 -7 345 000000101011001 3 7 -5 394 000000110001010 3 7 -7 404 000000110010100 3 9 -7 405 000000110010101 3 7 -5 410 000000110011010 3 11 -5 618 000001001101010 3 7 -5 652 000001010001100 3 11 -7 664 000001010011000 3 11 -7 665 000001010011001 3 11 -5 678 000001010100110 3 7 -5 691 000001010110011 3 7 -3 710 000001011000110 3 11 -5 718 000001011001110 3 7 -3 808 000001100101000 3 11 -7 809 000001100101001 3 11 -5 810 000001100101010 3 7 -5 811 000001100101011 3 9 -3 821 000001100110101 3 7 -3 922 000001110011010 3 11 -3 1140 000010001110100 3 11 -5 1221 000010011000101 3 11 -5 1299 000010100010011 3 11 -5 1305 000010100011001 3 11 -5 1356 000010101001100 3 11 -5 1380 000010101100100 3 11 -5 1610 000011001001010 3 11 -5 1620 000011001010100 3 11 -5 1642 000011001101010 3 11 -3 1672 000011010001000 3 11 -7 2152 000100001101000 3 11 -7 2224 000100010110000 3 11 -7 2228 000100010110100 3 11 -5 2281 000100011101001 3 11 -3 2579 000101000010011 3 11 -5 2587 000101000011011 3 11 -3 2656 000101001100000 3 11 -7 2824 000101100001000 3 11 -7 3232 000110010100000 3 11 -7 3748 000111010100100 3 9 -3 3821 000111011101101 3 9 3 4188 001000001011100 3 11 -5 4305 001000011010001 3 11 -5 4419 001000101000011 3 11 -5 4449 001000101100001 3 11 -5 4792 001001010111000 3 9 -3 4874 001001100001010 3 7 -5 4944 001001101010000 3 11 -5 5079 001001111010111 3 11 3 5139 001010000010011 3 11 -5 5145 001010000011001 3 11 -5 5312 001010011000000 3 9 -7 5313 001010011000001 3 11 -5 5424 001010100110000 3 11 -5 5535 001010110011111 3 9 3 5619 001010111110011 3 11 3 5649 001011000010001 3 11 -5 5768 001011010001000 3 11 -5 5904 001011100010000 3 11 -5 6154 001100000001010 3 7 -7 6165 001100000010101 3 7 -5 6187 001100000101011 3 11 -3 6304 001100010100000 3 11 -7 6405 001100100000101 3 11 -5 6464 001100101000000 3 7 -7 6465 001100101000001 3 11 -5 6480 001100101010000 3 11 -5 6495 001100101011111 3 7 3 6645 001100111110101 3 11 3 6922 001101100001010 3 11 -3 7087 001101110101111 3 11 5 7127 001101111010111 3 11 5 7147 001101111101011 3 11 5 7428 001110100000100 3 11 -5 7867 001111010111011 3 11 5 7901 001111011011101 3 11 5 7989 001111100110101 3 11 3 8369 010000010110001 3 11 -5 8377 010000010111001 3 11 -3 8394 010000011001010 3 11 -5 8610 010000110100010 3 11 -5 8730 010001000011010 3 11 -5 8734 010001000011110 3 11 -3 8771 010001001000011 3 11 -5 8898 010001011000010 3 11 -5 9230 010010000001110 3 9 -5 9287 010010001000111 3 9 -3 9738 010011000001010 3 11 -510252 010100000001100 3 7 -710265 010100000011001 3 7 -510278 010100000100110 3 11 -510290 010100000110010 3 11 -510291 010100000110011 3 11 -310340 010100001100100 3 7 -510348 010100001101100 3 11 -310432 010100011000000 3 7 -710544 010100100110000 3 11 -510624 010100110000000 3 7 -710625 010100110000001 3 7 -710626 010100110000010 3 11 -510627 010100110000011 3 11 -310655 010100110011111 3 7 310848 010101001100000 3 7 -511040 010101100100000 3 7 -511056 010101100110000 3 11 -311070 010101100111110 3 9 311071 010101100111111 3 7 511238 010101111100110 3 7 311251 010101111110011 3 7 511298 010110000100010 3 11 -511456 010110011000000 3 11 -511488 010110011100000 3 11 -311518 010110011111110 3 11 511887 010111001101111 3 11 511998 010111011011110 3 11 512211 010111110110011 3 11 512217 010111110111001 3 11 512238 010111111001110 3 11 512262 010111111100110 3 11 512549 011000100000101 3 11 -512609 011000101000001 3 11 -512669 011000101111101 3 11 312704 011000110100000 3 11 -512810 011001000001010 3 11 -512929 011001010000001 3 11 -512960 011001010100000 3 7 -512991 011001010111111 3 7 513151 011001101011111 3 11 513231 011001110101111 3 11 513290 011001111101010 3 7 313291 011001111101011 3 11 513301 011001111110101 3 7 513306 011001111111010 3 11 513329 011010000010001 3 11 -513431 011010001110111 3 11 313727 011010110011111 3 11 514254 011011110101110 3 11 514354 011100000010010 3 9 -514717 011100101111101 3 11 514752 011100110100000 3 7 -314842 011100111111010 3 11 514971 011101001111011 3 11 515094 011101011110110 3 11 515307 011101111001011 3 11 515337 011101111101001 3 11 515394 011110000100010 3 11 -315547 011110010111011 3 11 515802 011110110111010 3 11 515978 011111001101010 3 9 315979 011111001101011 3 11 516051 011111010110011 3 11 516057 011111010111001 3 11 516181 011111100110101 3 9 516217 011111101011001 3 11 516282 011111110011010 3 11 516485 100000001100101 3 11 -516550 100000010100110 3 11 -516586 100000011001010 3 9 -516710 100000101000110 3 11 -516716 100000101001100 3 11 -516788 100000110010100 3 11 -516789 100000110010101 3 9 -316965 100001001000101 3 11 -517220 10001101000100 3 11 -517373 100001111011101 3 11 317430 100010000010110 3 11 -517460 100010000110100 3 11 -517673 100010100001001 3 11 -517796 100010110000100 3 11 -517925 100011000000101 3 11 -518015 100011001011111 3 7 318050 100011010000010 3 11 -518413 100011111101101 3 9 518513 100100001010001 3 11 -519040 100101001100000 3 11 -519336 100101110001000 3 11 -319438 100101111101110 3 11 519461 100110000000101 3 11 -519466 100110000001010 3 7 -519476 100110000010100 3 11 -519477 100110000010101 3 7 -319536 100110001010000 3 11 -519616 100110010100000 3 11 -519776 100110101000000 3 7 -519807 100110101011111 3 7 519838 100110010111110 3 11 519957 100110111110101 3 11 520063 100111001011111 3 11 520098 100111010000010 3 11 -320158 100111010111110 3 11 520218 100111011111010 3 11 520505 10100000000101 3 11 -520529 101000000110001 3 11 -520550 101000001000110 3 11 -520556 101000001001100 3 11 -520769 101000100100001 3 11 -520880 101000110010000 3 11 -521249 101001100000001 3 11 -521279 101001100011111 3 11 321311 101001100111111 3 11 521469 101001111011101 3 11 521516 101010000001100 3 7 -521529 101010000011001 3 7 -321696 101010011000000 3 7 -521697 101010011000001 3 9 -321711 101010011001111 3 11 321727 101010011011111 3 7 521919 101010110011111 3 7 522112 101011001100000 3 7 -322140 101011001111100 3 11 322141 101011001111101 3 11 522142 101011001111110 3 9 522143 101011001111111 3 7 722223 101011011001111 3 11 522335 101011100111111 3 7 722419 101011110010011 3 11 322427 101011110011011 3 7 522476 101011111001100 3 11 322477 101011111001101 3 11 522489 101011111011001 3 11 522502 10101111110110 3 7 522515 101011111110011 3 7 723029 101100111110101 3 11 523480 101101110111000 3 9 323537 101101111110001 3 9 523869 101110100111101 3 11 523996 101110110111100 3 11 524033 101110111100001 3 11 324037 101110111100101 3 11 524157 101111001011101 3 11 524373 101111100110101 3 11 524390 101111101000110 3 11 324398 101111101001110 3 11 524778 110000011001010 3 11 -324866 110000100100010 3 11 -524900 110000101000100 3 11 -525339 110001011111011 3 11 525620 110010000010100 3 11 -525640 110010000101000 3 11 -525680 110010001010000 3 11 -525845 110010011110101 3 11 326122 110011000001010 3 11 -326272 110011010100000 3 7 -326287 110011010101111 3 11 526302 110011010111110 3 11 526303 110011010111111 3 7 726362 110011011111010 3 11 526463 110011101011111 3 11 726580 110011111010100 3 11 326602 110011111101010 3 7 526613 110011111110101 3 7 726863 110100011101111 3 11 526999 110100101110111 3 11 527118 110100111101110 3 11 527148 110101000001100 3 11 -327232 110101001100000 3 9 -327343 110101011001111 3 11 527454 110101100111110 3 11 527455 110101100111111 3 9 727622 110101111100110 3 11 527628 110101111101100 3 11 527688 110110000101000 3 11 -327823 110110010101111 3 11 527893 110110011110101 3 7 527975 110110101000111 3 9 328318 110111010011110 3 11 528348 110111010111100 3 11 528462 110111100101110 3 11 528579 110111110100011 3 11 528946 111000100010010 3 9 -329019 111000101011011 3 9 329535 111001101011111 3 11 729943 111010011110111 3 11 730111 111010110011111 3 11 730180 111010111100100 3 11 330188 111010111101100 3 11 530486 111011100010110 3 11 330539 111011101001011 3 11 530543 111011101001111 3 11 730615 111011110010111 3 11 731095 111100101110111 3 11 731125 111100110010101 3 11 331147 111100110101011 3 11 531157 111100110110101 3 11 531387 111101010011011 3 11 531411 111101010110011 3 11 531462 111101011100110 3 11 531468 111101011101100 3 11 531546 111101100111010 3 11 531627 111101110001011 3 11 531845 111110001100101 3 11 331946 111110011001010 3 7 331956 111110011010100 3 9 331957 111110011010101 3 7 531958 111110011010110 3 11 531959 111110011010111 3 11 732049 111110100110001 3 7 332057 111110100111001 3 11 532076 111110101001100 3 7 332089 111110101011001 3 7 532102 111110101100110 3 11 532103 111110101100111 3 11 732115 111110101110011 3 11 732149 111110110010101 3 7 532357 111111001100101 3 11 532362 111111001101010 3 7 532363 111111001101011 3 9 732373 111111001110101 3 7 732422 111111010100110 3 7 532435 111111010110011 3 7 732565 111111100110101 3 7 7______________________________________ TABLE 3______________________________________(n = 17) max. corr. max. corr.number bj (forward) (back) dc level______________________________________2931 00000101101110011 3 9 -13253 00000110010110101 3 9 -33286 00000110011010110 3 9 -33685 00000111001100101 3 13 -33693 00000111001101101 3 11 -13893 00000111100110101 3 9 -13929 00000111101011001 3 11 -15555 00001010110110011 3 9 -15838 00001011011001110 3 11 -16443 00001100100101011 3 9 -36581 00001100110110101 3 13 -16775 00001101001110111 3 13 16877 00001101011011101 3 9 17386 00001110011011010 3 11 -17642 00001110111011010 3 9 17859 00001111010110011 3 9 17901 00001111011011101 3 11 37917 00001111011101101 3 13 39039 00010001101001111 3 13 -19125 00010001110100101 3 11 -39171 00010001111010011 3 9 -19189 00010001111100101 3 9 -111111 00010101101100111 3 9 112121 00010111101011001 3 9 112887 00011001001010111 3 9 -114773 00011100110110101 3 11 115269 00011101110100101 3 13 115284 00011101110110100 3 9 115716 00011110101100100 3 11 -115718 00011110101100110 3 9 116217 00011111101011001 3 9 317596 00100010010111100 3 13 -318110 00100011010111110 3 9 119499 00100110000101011 3 13 -319578 00100110001111010 3 11 -119832 00100110101111000 3 11 -120590 00101000001101110 3 9 -320716 00101000011101100 3 13 -321054 00101001000111110 3 13 -121310 00101001100111110 3 9 122223 00101011011001111 3 9 322427 00101011110011011 3 13 323075 00101101000100011 3 13 -323480 00101101110111000 3 9 124749 00110000010101101 3 9 -324757 00110000010110101 3 11 -324765 00110000010111101 3 9 -125183 00110001001011111 3 9 125775 00110010010101111 3 9 125871 00110010100001111 3 9 -126578 00110011111010010 3 9 126743 00110100001110111 3 9 128180 00110111000010100 3 13 -330539 00111011101001011 3 13 331300 00111101001000100 3 13 -331946 00111110011001010 3 9 131958 00111110011010110 3 13 333229 01000000111001101 3 9 -334291 01000010111110011 3 9 135087 01000100100001111 3 11 -335151 01000100101001111 3 9 -135193 01000100101111001 3 9 -135301 01000100111100101 3 13 -137135 01001000100001111 3 13 -337150 01001000100011110 3 9 -337663 01001001100011111 3 11 138387 01001010111110011 3 9 338860 01001011111001100 3 9 138862 01001011111001110 3 11 339165 01001100011111101 3 9 341433 01010000111011001 3 9 -142183 01010010011000111 3 11 -142191 01010010011001111 3 13 142399 01010010110011111 3 9 342483 01010010111110011 3 11 342527 01010011000011111 3 9 142620 01010011001111100 3 9 145175 01011000001110111 3 9 145277 01011000011011101 3 13 145855 01011001100011111 3 13 345953 01011001110000001 3 9 -346105 01011010000011001 3 9 -346151 010110100001000111 3 13 -146199 01011010001110111 3 11 346704 01011011001110000 3 11 -146960 01011011101110000 3 9 148228 01011110001100100 3 11 -148921 01011111100011001 3 9 349885 01100001011011101 3 9 150366 01100010010111110 3 13 151445 01100100011110101 3 9 151719 01100101000000111 3 9 -351735 01100101000010111 3 9 -151743 01100101000011111 3 11 152600 01100110101111000 3 9 152741 01100111000000101 3 9 -353157 01100111110100101 3 9 353486 01101000011101110 3 13 154880 01101011001100000 3 9 -354908 01101011001111100 3 13 356801 01101110111100001 3 13 359009 01110011010000001 3 13 -359088 01110011011010000 3 11 -159346 01110011111010010 3 11 360436 01110110000010100 3 9 -360950 01110111000010110 3 13 161577 01111000010001001 3 13 -361714 01111000100010010 3 9 -363636 01111100010010100 3 13 -163892 01111100110010100 3 9 164070 01111101001000110 3 13 164196 01111110001100101 3 9 164613 01111110001100101 3 9 364817 01111110100110001 3 13 366254 10000001011001110 3 13 -366458 10000001110011010 3 9 -366875 10000010100111011 3 9 -167001 10000010110111001 3 13 -167179 10000011001101011 3 9 -167435 10000011101101011 3 13 169357 10000111011101101 3 9 369494 10000111101110110 3 13 370121 10001000111101001 3 13 -170635 10001001111101011 3 9 371725 10001100000101101 3 11 -371983 10001100100101111 3 11 172062 10001100101111110 3 13 374270 10010001000011110 3 13 -376163 10010100110000011 3 13 -376191 10010100110011111 3 9 377585 10010111100010001 3 13 -177914 10011000001011010 3 9 -378330 10011000111111010 3 9 378471 10011001010000111 3 9 -179328 10011010111100000 3 11 -179336 10011010111101000 3 9 179352 10011010111111000 3 9 379626 10011011100001010 3 9 -180705 10011101101000001 3 13 -181186 10011110100100010 3 9 -182150 10100000011100110 3 9 -382843 10100001110011011 3 11 184111 10100100010001111 3 9 -184367 10100100110001111 3 11 184872 10100101110001000 3 11 -384920 10100101110111000 3 13 184966 10100101111100110 3 9 385118 10100110001111110 3 9 385216 10100110011100000 3 13 -385794 10100111100100010 3 13 -185896 10100111110001000 3 9 -188451 10101100110000011 3 9 -188544 10101100111100000 3 9 -188588 10101101000001100 3 11 -388672 10101101001100000 3 9 -388880 10101101100110000 3 13 -188888 10101101100111000 3 11 189638 10101111000100110 3 9 191906 10110011100000010 3 9 -392209 10110100000110001 3 11 -392211 10110100000110011 3 9 -192684 10110101000001100 3 9 -393408 10110110011100000 3 11 -193921 10110111011100001 3 9 393936 10110111011110000 3 13 395770 10111011000011010 3 13 195878 10111011010000110 3 9 195920 10111011010110000 3 9 195984 10111011011110000 3 11 396780 10111101000001100 3 9 -197842 10111111000110010 3 9 399113 11000001100101001 3 13 -399125 11000001100110101 3 9 -199771 11000010110111011 3 13 3100532 11000100010110100 3 13 -3102891 11001000111101011 3 13 3104328 11001011110001000 3 9 -1104493 11001100000101101 3 9 -1105200 11001101011110000 3 9 1105296 11001101101010000 3 9 -1105888 11001110110100000 3 9 -1106306 11001111101000010 3 9 1106314 11001111101001010 3 11 3106322 11001111101010010 3 9 3107591 11010010001000111 3 9 -1107996 11010010111011100 3 13 3108644 11010100001100100 3 13 -3108848 11010100100110000 3 9 -3109761 11010110011000001 3 9 -1110017 11010110111000001 3 13 1110355 11010111100010011 3 13 3110481 11010111110010001 3 9 3111239 11011001010000111 3 11 1111493 11011001110000101 3 11 1111572 11011001111010100 3 13 3112961 11011100101000001 3 9 -1113475 11011101101000011 3 13 3114854 11100000010100110 3 9 -3115353 11100001010011001 3 9 -1115355 11100001010011011 3 11 1115787 11100010001001011 3 9 -1115802 11100010001011010 3 13 -1116298 11100011001001010 3 11 -1118184 11100110110101000 3 9 1118950 11101000010100110 3 9 -1119960 11101010010011000 3 9 -1121882 11101110000011010 3 9 1121900 11101110000101100 3 9 1121946 11101110001011010 3 11 3122032 11101110010110000 3 13 1123154 11110000100010010 3 13 -3123170 11110000100100010 3 11 -3123212 11110000101001100 3 9 -1123429 11110001000100101 3 9 -1123685 11110001100100101 3 11 1124194 11110010100100010 3 9 -1124296 11110010110001000 3 13 -1124490 11110011001001010 3 13 1124628 11110011011010100 3 9 3125233 11110100100110001 3 11 1125516 11110101001001100 3 9 1127142 11111000010100110 3 11 1127178 11111000011001010 3 9 1127378 11111000110010010 3 11 1127386 11111000110011010 3 13 3127785 11111001100101001 3 9 3127818 11111001101001010 3 9 3128140 11111010010001100 3 9 1______________________________________ TABLE 4______________________________________(n = 19) max. corr. max. corr.number bj (forward) (back) dc level______________________________________3241 0000000110010101001 3 15 -710342 0000010100001100110 3 15 -726897 0000110100100010001 3 15 -728946 0000111000100010010 3 7 -733705 0001000001110101001 3 11 -534996 0001000100010110100 3 11 -737560 0001001001010111000 3 15 -559976 0001110101001001000 3 15 -561146 0001110111011011010 3 7 364429 0001111101110101101 3 9 566385 0010000001101010001 3 11 -770117 0010001000111100101 3 15 -374076 0010010000101011100 3 15 -586785 0010101001100000001 3 15 -792296 0010110100010001000 3 11 -795265 0010111010000100001 3 11 -597651 0010111110101110011 3 15 5100875 0011000101000001011 3 15 -5104970 0011001101000001010 3 15 -5119844 0011101010000100100 3 15 -5129885 0011111101101011101 3 11 7130261 0011111110011010101 3 15 5139806 0100010001000011110 3 11 -5141571 0100010100100000011 3 11 -7145426 0100011100000010010 3 15 -7147682 0100100000011100010 3 15 -7148592 0100100010001110000 3 7 -7151815 0100101000100000111 3 9 -5164556 0101000001011001100 3 15 -5173571 0101010011000000011 3 15 -5181179 0101100001110111011 3 15 3187320 0101101101110111000 3 7 3204961 0110010000010100001 3 15 -7209056 0110011000010100000 3 15 -7217591 0110101000111110111 3 11 5218751 0110101011001111111 3 15 7229006 0110111111010001110 3 15 5232438 0111000101111110110 3 15 5240123 0111010100111111011 3 11 7244559 0111011101101001111 3 15 7246306 0111100001000100010 3 11 -5251865 0111101011111011001 3 15 7253579 0111101111010001011 3 11 5260523 0111111100110101011 3 15 7263764 1000000011001010100 3 15 -7270708 1000010000101110100 3 11 -5272422 1000010100000100110 3 15 -7277981 1000011110111011101 3 11 5279728 1000100010010110000 3 15 -7284164 1000101011000000100 3 11 -7291849 1000111010000001001 3 15 -5295281 1001000000101110001 3 15 -5305536 1001010100110000000 3 15 -7306696 1001010111000001000 3 11 -5315231 1001100111101011111 3 15 7319326 1001101111101011110 3 15 7336967 1010010010001000111 3 7 -3343108 1010011110001000100 3 15 -3350716 1010101100111111100 3 15 5359731 1010111110100110011 3 15 5372472 1011010111011111000 3 9 5375695 1011011101110001111 3 7 7376605 1011011111100011101 3 15 7378861 1011100011111101101 3 15 7382716 1011101011011111100 3 11 7384481 1011101110111100001 3 11 5394026 1100000001100101010 3 15 -5394402 1100000010010100010 3 11 -7404443 1100010101111011011 3 15 5419317 1100110010111110101 3 15 5423412 1100111010111110100 3 15 5426636 1101000001010001100 3 15 -5429022 1101000101111011110 3 11 5431991 1101001011101110111 3 11 7437502 1101010110011111110 3 15 7450211 1101101111010100011 3 15 5454170 1101110111000011010 3 15 3457902 1101111110010101110 3 11 7459858 1110000010001010010 3 9 -5463141 1110001000100100101 3 7 -3464311 1110001010110110111 3 15 5486727 1110110110101000111 3 15 5489291 1110111011101001011 3 11 7490582 1110111110001010110 3 11 5495341 1111000111011101101 3 7 7497390 1111001011011101110 3 15 7513945 1111101011110011001 3 15 7521046 1111111001101010110 3 15 7______________________________________ TABLE 5______________________________________(n = 21) max. corr. max. corr. dcnumber bj (forward) (backward) level______________________________________14773 000000011100110110101 3 15 -323865 000000101110100111001 3 13 -329546 000000111001101101010 3 11 -331157 000000111100110110101 3 11 -147731 000001011101001110011 3 15 -155754 000001101100111001010 3 11 -359029 000001110011010010101 3 11 -359093 000001110011011010101 3 15 -159245 000001110011101101101 3 15 160249 000001110101101011001 3 15 -162294 000001111001101010110 3 17 -181210 000010011110100111010 3 15 -189708 000010101111001101100 3 21 -1183260 000101100101111011100 3 17 1231861 000111000100110110101 3 15 -1248388 000111100101001000100 3 13 -5255570 000111110011001010010 3 13 -1257750 000111110111011010110 3 13 5276270 001000011011100101110 3 11 -1281208 001000100101001111000 3 13 -5281571 001000100101111100011 3 13 -1331699 001010000111110110011 3 15 1336446 001010010001000111110 3 13 -3397237 001100000111110110101 3 15 1406623 001100011010001011111 3 15 1410091 001100100000111101011 3 15 -1442901 001101100001000010101 3 13 -5446288 001101100111101010000 3 21 -1459446 001110000001010110110 3 11 -3460219 001110000010110111011 3 13 1490088 001110111101001101000 3 17 1509010 001111100010001010010 3 13 -3521034 001111111001101001010 3 17 3521046 001111111001101010110 3 17 5549238 010000110000101110110 3 17 -3598815 010010010001100011111 3 15 -1607356 010010100010001111100 3 13 -3609528 010010100110011111000 3 13 -1614638 010010110000011101110 3 13 -1659673 010100001000011011001 3 15 -5672243 010100100000111110011 3 15 -1674879 010100100110000111111 3 11 1674943 010100100110001111111 3 15 3675271 010100100110111000111 3 15 1678396 010100101100111111100 3 17 3684896 010100111001101100000 3 11 -3693023 010101001001100011111 3 15 1709407 010101101001100011111 3 11 3711104 010101101100111000000 3 11 -3718739 010101111011110010011 3 13 5759696 010111001011110010000 3 15 -1783558 010111111010011000110 3 21 3812538 011000110010111111010 3 21 3813247 011000110100010111111 3 13 3827125 011001001111011110101 3 15 5828703 011001010010100011111 3 15 1846657 011001110101101000001 3 15 -1874976 011010101100111100000 3 17 -1875004 011010101100111111100 3 17 5880376 011010110111011111000 3 13 5895004 011011010100000011100 3 11 -3896785 011011010111100010001 3 13 1905410 011011101000011000010 3 17 -3957828 011101001110110000100 3 11 -1975058 011101110000011010010 3 13 -1975177 011101110000101001001 3 13 -11018004 011111000100010010100 3 13 -31025305 011111010010100011001 3 15 11071846 100000101101011100110 3 15 -11079147 100000111011101101011 3 13 31121974 100010001111010110110 3 13 11122093 100010001111100101101 3 13 11139323 100010110001001111011 3 11 11191741 100100010111100111101 3 17 31200366 100100101000011101110 3 13 -11202147 100100101011111100011 3 11 31216775 100101001000100000111 3 13 -51222147 100101010011000000011 3 17 -51222175 100101010011000011111 3 17 11250494 100110001010010111110 3 15 11268448 100110101101011100000 3 15 -11270026 100110110000100001010 3 15 -51283904 100111001011101000000 3 13 -31284613 100111001101000000101 3 21 -31313593 101000000101100111001 3 21 -31337455 101000110100001101111 3 15 11378412 101010000100001101100 3 13 -51386047 101010010011000111111 3 11 31387744 101010010110011100000 3 11 -31404128 101010110110011100000 3 15 -11412255 101011000110010011111 3 11 31418755 101011010011000000011 3 17 -31421880 101011011001000111000 3 15 -11422208 101011011001110000000 3 15 -31422272 101011011001111000000 3 11 -11424908 101011011111000001100 3 15 11437478 101011110111100100110 3 15 51482513 101101001111100010001 3 13 11487623 101101011001100000111 3 13 11489795 101101011101110000011 3 13 31498336 101101101110011100000 3 15 11547913 101111001111010001001 3 17 31576105 110000000110010101001 3 17 -51576117 110000000110010110101 3 17 31588141 110000011101110101101 3 13 31607063 110001000010110010111 3 17 -11636932 110001111101001000100 3 13 -11637705 110001111110101001001 3 11 31650863 110010011000010101111 3 21 11654250 110010011110111101010 3 13 51687060 110011011111000010100 3 15 11690528 110011100101110100000 3 15 -11699914 110011111000001001010 3 15 -11760705 110101101110111000001 3 13 31765452 110101111000001001100 3 15 -11815580 110111011010000011100 3 13 11815943 110111011010110000111 3 13 51820881 110111100100011010001 3 11 11839401 111000001000100101001 3 13 -51841581 111000001100110101101 3 13 11848763 111000011010110111011 3 13 51865290 111000111011001001010 3 15 11913891 111010011010000100011 3 17 -12007443 111101010000110010011 3 21 12015941 111101100001011000101 3 15 12034857 111110000110010101001 3 17 12036902 111110001010010100110 3 15 12037906 111110001100010010010 3 15 -12038058 111110001100100101010 3 15 12038122 111110001100101101010 3 11 32041397 111110010011000110101 3 11 32049420 111110100010110001100 3 15 12065994 111111000011001001010 3 11 12067605 111111000110010010101 3 11 32073286 111111010001011000110 3 13 32082378 111111100011001001010 3 15 3______________________________________ TABLE 6______________________________________(n = 23) max. corr. (for- max. corr.number bj ward) (backward) dc level______________________________________29362 00000000111001010110010 3 15 -775541 00000010010011100010101 3 11 -786422 00000010101000110010110 3 15 -7115861 00000011100010010010101 3 11 -7271825 00001000010010111010001 3 11 -7272197 00001000010011101000101 3 15 -7333508 00001010001011011000100 3 11 -7345892 00001010100011100100100 3 15 -7463141 00001110001000100100101 3 11 -7476197 00001110100010000100101 3 11 -7496708 00001111001010001000100 3 15 -7543651 00010000100101110100011 3 11 -5789930 00011000000110110101010 3 15 -51031085 00011111011101110101101 3 11 71082833 00100001000010111010001 3 11 -71083205 00100001000011101000101 3 11 -71116052 00100010000011110010100 3 11 -71119472 00100010001010011110000 3 15 -71142932 00100010111000010010100 3 11 -71160272 00100011011010001010000 3 11 -71181041 00100100000010101110001 3 15 -71208656 00100100111000101010000 3 15 -71345348 00101001000011101000100 3 11 -71372228 00101001111000001000100 3 11 -71524769 00101110100010000100001 3 11 -71906423 00111010001011011110111 3 11 51994730 00111100110111111101010 3 15 72285833 01000101110000100001001 3 11 -72429191 01001010001000100000111 3 11 -72533120 01001101010011100000000 3 15 -72807832 01010101101100000011000 3 15 -52846271 01010110110111000111111 3 11 72854335 01010111000110110111111 3 11 72882364 01010111111101100111100 3 15 72965230 01011010011111011101110 3 15 72997135 01011011011101110001111 3 11 73010191 01011011110111010001111 3 11 73050991 01011101000110111101111 3 15 73051387 01011101000111101111011 3 11 73128430 01011111011110001101110 3 11 73141006 01011111110110110001110 3 15 73458368 01101001100010101000000 3 15 -73652701 01101111011110001011101 3 11 73715035 01110001010111111011011 3 15 73726330 01110001101101111111010 3 15 73812847 0111010001011011110111 3 11 73813243 01110100010111101111011 3 11 73874554 01110110001111011111010 3 11 73910974 01110111010110100111110 3 11 73915354 01110111011111001011010 3 15 73922494 01110111101101000111110 3 11 74058763 01111011110111010001011 3 11 74074990 01111100010110111101110 3 11 74086510 01111100101101011101110 3 11 74302097 10000011010010100010001 3 11 -74313617 10000011101001000010001 3 11 -74329844 10000100001000101110100 3 11 -74466113 10001000010010111000001 3 11 -74473253 10001000100000110100101 3 15 -74477633 10001000101001011000001 3 11 -74514053 10001001110000100000101 3 11 -74575364 1000101110100001000010 3 11 -74575760 10001011101001000010000 3 11 -74662277 10001110010010000000101 3 15 -74673572 10001110101000000100100 3 15 -74735906 10010000100001110100010 3 11 -74930239 10010110011101010111111 3 15 75247601 10100000001001001110001 3 15 75260177 10100000100001110010001 3 11 -75337220 10100010111000010000100 3 11 -75337616 10100010111001000010000 3 15 -75378416 10100100001000101110000 3 11 -75391472 10100100100010001110000 3 11 -75423377 10100101100000100010001 3 15 -75506243 10101000000010011000011 3 15 -75534272 1010100011100100100000 3 11 -75542336 1010100100100011100000 3 11 -75580775 10101010010011111100111 3 15 55855487 10110010101100011111111 3 15 75959416 10110101110111011111000 3 11 76102774 10111010001111011110110 3 11 76393877 11000011001000000010101 3 15 -76482184 11000101110100100001000 3 11 -56863838 11010001011101111011110 3 11 77016379 11010110000111110111011 3 11 77043259 11010110111100010111011 3 11 77179951 11011011000111010101111 3 15 77207566 11011011111101010001110 3 15 77228335 11011100100101110101111 3 11 77245675 11011101000111101101011 3 11 77269135 11011101110101100001111 3 15 77272555 11011101111100001101011 3 11 77305402 11011110111100010111010 3 11 77305774 11011110111101000101110 3 11 77357522 11100000100010001010010 3 11 -77598677 11100111111001001010101 3 15 57844956 11101111011010001011100 3 11 57891899 11110000110101110111011 3 15 77912410 11110001011101111011010 3 11 77925466 11110001110111011011010 3 11 78042715 11110101011100011011011 3 15 78055099 11110101110100100111011 3 11 78116410 11110111101100010111010 3 15 78116782 11110111101101000101110 3 11 78272746 11111100011101101101010 3 11 78302185 11111101010111001101001 3 15 78313066 11111101101100011101010 3 11 78359245 11111111000110101001101 3 15 7______________________________________ TABLE 7______________________________________(n = 25) max. corr. max. corr. (for- (back- dcnumber bj ward) ward) level______________________________________381638 0000001011101001011000110 3 11 -5446005 0000001101100111000110101 3 13 -3465770 0000001110001101101101010 3 13 -3473782 000000111001110101011010 3 13 -1897941 0000011011011001110010101 3 13 -1947565 0000011100111010101101101 3 15 12054758 000011111010110100110010 3 13 12054886 0000111110101101011100110 3 11 33275446 000110001111110101011010 3 17 33672501 0001110000000100110110101 3 15 -53672793 0001110000000101011011001 3 13 -54808590 0010010010101111110001110 3 15 14945678 0010010110111011100001110 3 13 16550893 0011000111111010101101101 3 13 56561626 0011001000001111101011010 3 11 -16692698 0011001100001111101011010 3 13 17093738 0011011000011110111101010 3 11 37345002 0011100000001001101101010 3 13 -57345586 0011100000001010101101010 3 17 -59609331 0100100101010000001110011 3 13 -59610015 0100100101010001100011111 3 15 -110178588 0100110110101000000011100 3 17 -510805191 0101001001101111111000111 3 15 510950975 0101001110001100100111111 3 13 311297951 0101011000110010010011111 3 13 111374620 0101011011001000000011100 3 13 -511383232 0101011011011000111000000 3 13 -311499628 0101011110111100001101100 3 11 311923532 0101101011111000001001100 3 11 -111923660 0101101011111000011001100 3 13 113014848 0110001101001011101000000 3 11 -513197255 0110010010101111111000111 3 13 513415920 0110011001011010111110000 3 13 113546992 0110011101011010111110000 3 11 314334400 0110110101011100111000000 3 13 -114335768 0110110101011111100011000 3 17 314802340 0111000011101110110100100 3 13 114939428 0111000111111010100100100 3 15 118615003 1000111000000101011011011 3 15 -118752091 1000111100010001001011011 3 13 -119218663 1001001010100000011100111 3 17 -319220031 1001001010100011000111111 3 13 120007439 1001100010100101000001111 3 11 -32013851 1001100110100101000001111 3 13 -120357176 1001101101010000000111000 3 13 -520539583 1001110010110100010111111 3 11 521630771 1010010100000111100110011 3 13 -121630899 1010010100000111110110011 3 11 122054803 1010100001000011110010011 3 11 -322171199 1010100100100111000111111 3 13 322179811 1010100100110111111100011 3 13 522256480 1010100111001101101100000 3 13 -122603456 1010110001110011011000000 3 13 -322749240 1010110110010000000111000 3 15 -523375843 1011001001010111111100011 3 17 523944416 1011011010101110011100000 3 15 123945100 1011011010101111110001100 3 13 526208845 1100011111110101001001101 3 17 526209429 1100011111110110010010101 3 13 526460693 1100100111100001000010101 3 11 -326861733 1100110011110000010100101 3 13 -126992805 1100110111110000010100101 3 11 127003538 1100111000000101010010010 3 13 -528608753 1101101001000100011110001 3 13 -128745841 110110110101000001110001 3 15 -129881638 1110001111111010100100110 3 13 529881930 1110001111111011001001010 3 15 530278985 1110011100000010101001001 3 17 -331499545 1111000001010010100011001 3 11 -331499673 1111000001010010110011001 3 13 -132606866 1111100011000101010010010 3 15 -132656490 1111100100100110001101010 3 13 133080649 1111110001100010101001001 3 13 133088661 1111110001110010010010101 3 13 333108426 1111110010011000111001010 3 13 333172793 1111110100010110100111001 3 11 5______________________________________ TABLE 8______________________________________(n = 27) max. corr. max. corr. (for- (back- dcnumber bj ward) ward) level______________________________________930410 000000011100011001001101010 3 15 -71624362 000000110001100100100101010 3 15 -91860757 000000111000110010010010101 3 15 -715798573 000111100010001000100101101 3 11 -539566215 010010110111011101110000111 3 11 544341440 010101001001001100011000000 3 15 -945245312 010101100100110001110000000 3 15 -745534783 010101101101100111000111111 3 15 7______________________________________ TABLE 9______________________________________(n = 29) max. max. corr. corr. (for- (back- dcnumber bj ward) ward) level______________________________________11687143 00000101100100101010011100111 3 15 -320815162 00001001111011001110100111010 3 15 129650650 00001110001000110111011011010 3 17 -152082271 00011000110101011011001011111 3 15 352401586 00011000111111100101011011010 3 15 152417970 00011000011111101010110110010 3 11 369590574 00100001001011101111000101110 3 13 170752046 00100001101111001011100101110 3 19 179132430 00100101101110111011100001110 3 15 3162536693 01001101100000001110011110101 3 15 -1162873112 01001101101010011111100011000 3 15 1162889496 01001101101010111111100011000 3 11 3169410125 01010000110001111111001001101 3 15 1191808624 01011011011101100010001110000 3 17 -1494459536 01011100101110011011110010000 3 15 1236838308 01110000111011101110110100100 3 15 3244282500 01110100011110111010010000100 3 19 -1245185924 01110100111010011110110000100 3 19 1______________________________________

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a system block diagram of a spread spectrum communication device showing a first application example of the present invention;

FIG. 2 is a diagram illustrating a signal code sequence;

FIG. 3 is a system block diagram of a part of a communication device showing a second application example of the present invention;

FIG. 4 shows a surface acoustic wave device using a second application example of the present invention;

FIG. 5 is a system block diagram of a spread spectrum communication device showing a third application example of the present invention;

FIG. 6 shows a code sequence used in the third application example of the present invention;

FIG. 7 shows a matched signal used in the third application example of the present invention;

FIG. 8 shows the frequency response of a matched filter used in the third application example of the present invention;

FIG. 9 shows a conventional Barker code (13 chips);

FIG. 10 shows a matched signal in the case where the conventional Barker code (13 chips) is used;

FIG. 11 shows the frequency response of a matched filter in the case where the conventional Barker code (13 chips) is used;

FIG. 12 shows tap coefficients of a matched filter using a fourth application example of the present invention;

FIG. 13 shows a matched signal used in the fourth application example of the present invention;

FIG. 14 shows tap coefficients of a matched filter using a fifth application example of the present invention;

FIG. 15 shows a matched signal used in the fifth application example of the present invention;

FIG. 16 is a system block diagram of a spread spectrum communication device showing a sixth application example of the present invention;

FIG. 17 is a system block diagram of a part of a communication device showing a seventh application example of the present invention;

FIG. 18 is a system block diagram of a part of a communication device showing an eighth application example of the present invention;

FIG. 19 is a system block diagram of a part of a communication device showing a ninth application example of the present invention;

FIG. 20 is a system block diagram of a part of a communication device showing a tenth application example of the present invention;

FIG. 21 is a system block diagram of a part of a communication device showing an eleventh application example of the present invention; and

FIG. 22 shows a communication system using a device shown in a twelfth application example of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, modes for carrying out the present invention will be described by referring to FIGS. 1 through 23.

However, some modes hereafter described are shown in order to explain application examples for carrying out the present invention. Modes for carrying out the present invention are never limited to application examples described here.

FIG. 1 is a diagram schematically showing a spread spectrum communication device to which the present invention has been applied. An information signal is inputted from an input terminal 1, multiplied in a mixer 2 by a signal supplied from a pseudo noise code generator 3, furthermore multiplied in a mixer 4 by a carrier supplied from an oscillator 5, amplified in an amplifier 6, and outputted from an antenna 7. Here, a code shown in TABLES 1 through 9 was used as the pseudo noise code.

In a receiving system, a signal inputted from the antenna 7 is amplified in an amplifier 8, demodulated, converted to a digital signal in a square wave output circuit 9, and taken out from an output terminal 10 as an information signal. Here, a code similar to the above described code was used as a reference code for demodulating the information. (It coincides with the pseudo noise code of the transmitter.) FIG. 2 is a diagram showing a signal code sequence. In the case of the synchronous detection system, a signal code sequence Sk corresponds to 1 and 0 of the information code, and it is represented as ##EQU1## where mj (j=1, 2, . . . , n; n=code length) corresponds to a pseudo noise code bj shown in TABLES 1 through 9, and it is represented by the following equation. ##EQU2## In the same way, in the case of the delay detection system, the signal code sequence Sk is represented by the following equation. ##EQU3## Denoting a reference code of the receiving side by Mj, a correlation coefficient Ok is represented by the following equation. ##EQU4## In the case where Mj=mj, the correlation coefficient Ok represents an auto-correlation coefficient and it is represented by the following equation. ##EQU5## Sub-peaks other than correlation peaks (mod(k/n).noteq.1) are referred to as side lobes. As this value becomes smaller, the error rate of the receiver is typically reduced. For the case where the code length is at least 14, such a code that the side lobe value calculated by using the Expression 5 is 3 or less is shown in TABLES 1 through 9. Calculation conducted here corresponds to all arrangements (0, 0), (0, 1), (1, 0) and (1, 1) of 0 and 1 of the information code. (The above described 0 and 1 of the information code indicate that they are mutually in the relation of inverted code.) Calculation was conducted as to such an arrangement of Sk that signs whereby mj is multiplied are (+, +, -). That is, calculating to Expression 5 above is performed on a single code sequence S.sub.k which includes M.sub.js have signs (+, +, -), respectively (i.e., S.sub.k =+M.sub.j, +M.sub.j, -M.sub.j). (In the remaining case where the signs are (-, -, +), a result equal in absolute value and opposite in sign to the above described result is obtained. In other words, only the polarity is different. Therefore, the above described calculation alone suffices.)

In TABLES 1 through 9, "bj" is a derived code sequence, and "number" is a value obtained by regarding the "bj" as a binary number and converting it to a decimal number. Furthermore, "max corr. (forward)" is a side lobe value, and "max corr. (backward)" is a maximum value of correlation value obtained in the case where codes are reversed bilaterally. Furthermore, "dc level" is the sum total of n "mj"s. As a matter of course, similar results are obtained even if code inversion (1<=>0) is conducted on these codes. Since it takes an enormous time to conduct calculations, inverted codes are omitted for lengthy code lengths. If these codes are used as the pseudo noise code, there is obtained a spread spectrum communication device having a processing gain of at least 14 in auto-correlation side lobe, having smaller time-axis side lobes of received matched signal, having a smaller error rate, and having favorable characteristics.

A second application example of the present invention will now be described by referring to FIG. 3. The same components as those in FIG. 1 showing the first application example are denoted by like numerals. FIG. 3 is a diagram showing a receiving part of the second application example of the present invention. A received signal taken in from an antenna 7 is amplified in an amplifier 8, converted to a matched signal in a matched filter 11, detected in a detector circuit 12, demodulated, converted to a digital signal by a square wave output circuit 13, and outputted from an output terminal 10. In the present application example, a matched filter is used as a demodulating element. This results in a feature that the circuit can be simply formed.

A third application example of the present invention will now be described by referring to FIGS. 4 and 5.

FIG. 4 is a diagram schematically showing a SAW (surface acoustic wave) matched filter 18. On a SAW substrate 14, an input interdigital electrode set 15 and an output interdigital electrode set 16 are disposed. Furthermore, in order to suppress a reflected wave coming from a substrate face, a sound absorbing material 17 is coated. The input interdigital electrode set 15 has such a structure that the electrode polarity is inverted every electrode. (The electric polarity differs depending upon whether the electrode is connected to an upper common electrode or a lower common electrode.) The output interdigital electrode set 16 has a matched filter structure in which the electrode polarity is inverted in association with the pseudo noise code. As the substrate 14, an ST-cut crystal substrate is used in order to prevent the center frequency from being shifted due to the temperature.

FIG. 5 is a system block diagram of the present application example. The same components as those in FIG. 1 showing the first application example are denoted by like numerals. A received signal taken in from an antenna 7 is amplified in an amplifier 8, converted to a matched signal in a SAW matched filter 18 of the present application example, multiplied in a mixer 20 by a signal preceding it by one information bit and delayed in a SAW delay line 19 and thus detected, converted in a square wave output circuit 13 to a digital signal, and outputted from an output terminal 10. In the present application example, delay detection is conducted by using an SAW element. This results in a feature that the detector circuit can be formed more simply.

FIG. 6 is a diagram showing mj corresponding to a 25-chip code bj of number (num) 947565 shown in TABLE 7.

FIG. 7 is a diagram showing a matched signal waveform in the case where this mj code is used on the transmitting side and the reference code of the matched filter on the receiving side is made the same. The carrier frequency is 300 MHz, and the information rate is 1 Mbps. At this time, a favorable side lobe suppression factor (peak to side lobe ratio D/U=18.2 dB) is obtained.

FIG. 8 is a diagram showing the frequency response of the matched filter of the present application example. In FIG. 8, ripples on the frequency response correspond to side lobe deterioration. For the purpose of comparison, the case where the conventional 13-chip Barker code is used will now be also described.

FIG. 9 is a diagram showing mj corresponding to this Barker code.

FIG. 10 is a diagram showing the matched signal waveform in the case where this mj code is used on the transmitting side and the reference code of the matched filter on the receiving side is made the same.

In the same way as the present application example, the carrier frequency was set equal to 300 MHz and the information rate was set equal to 1 Mbps. A side lobe suppression factor (peak to side lobe ratio D/U=22.1 dB) was obtained.

FIG. 11 is a diagram showing the frequency response of the matched filter in the case where the Barker code is used. It is shown that ripples are comparatively small and the side lobe suppression factor is large.

As described above, use of the present application example makes it possible to obtain a communication device having a chip length of 25 and improve significantly the processing gain at the sacrifice of only a slight side lobe deterioration as compared with the case where the conventional Barker code is used.

A fourth application example of the present invention will now be described by referring to FIGS. 12 and 13. In the above described third application example, the side lobe suppression factor was D/U=18.2 dB. In the present application example, however, further side lobe suppression is conducted.

FIG. 12 is a diagram showing a reference 25-chip tap coefficient Mj of the receiving side in the present application example. In order to conduct side lobe suppression of the matched signal, respective taps are provided with weights.

FIG. 13 shows a matched signal waveform in the case where the mj code of the third application example are used on the transmitting side and respective taps of the matched filter of the receiving side are provided with weights corresponding to the above described reference code Mj. Coefficients of FIG. 12 were derived by using an optimization algorithm. The carrier frequency is 300 MHz, and the information rate is 1 Mbps. By doing so, a favorable side lobe suppression factor (peak to side lobe ratio D/U=19.8 dB) as compared with the third application example is obtained without increasing the number of taps of the receiving side.

A fifth application example of the present invention will now be described by referring to FIGS. 14 and 15. In the fourth application example, the number of taps was set equal to 25 equally for both the transmitting side and the receiving side. In the present application example, however, the number of taps on the receiving side was set equal to 49 in order to conduct further side lobe suppression.

FIG. 14 is a diagram showing the reference 49-chip tap coefficient Mj on the receiving side of the present application example. For matched signal side lobe suppression, respective taps are provided with weights.

FIG. 15 is a diagram showing a matched signal waveform in the case where the mj code of the third application example is used on the transmitting side and respective taps of the matched filter on the receiving side are provided with weights corresponding to the above described reference code Mj. Coefficients of FIG. 14 were derived by using the optimization algorithm. The carrier frequency is 300 MHz, and the information rate is 1 Mbps. As compared with the conventional case where the Barker code is used, a favorable side lobe suppression factor (peak to side lobe ratio D/U=24.4 dB) is obtained.

A sixth application example of the present invention will now be described by referring to FIG. 16. The same components as those in FIG. 5 showing the third application example are denoted by like numerals. In the third application example, demodulation is conducted directly in the transmission signal band. Since the frequency is high, however, signal processing is difficult in some cases. In the present application example, the frequency is lowered by multiplication with a signal with a signal generated by an oscillator 22 conducted in a mixer 21 and thereafter demodulation processing is conducted. If the present application example is used, demodulation processing with a comparatively low frequency band is possible, resulting in a feature of easy circuit design.

A seventh application example of the present invention will now be described by referring to FIG. 17.

FIG. 17 is a diagram showing a receiving part of a communication device in the seventh application example. The same components as those in FIG. 3 showing the second application example are denoted by like numerals. In the second application example, demodulation is conducted by using a matched filter. In the case where the information rate is slow, however, the device size of the matched filter becomes large. In the present application example, an signal outputted from a pseudo noise code generator 23 is multiplied in a mixer 24 by a carrier signal of an oscillator 25 having the same frequency as that of the carrier, and a resultant signal is synchronized with the received signal and it is multiplied in a mixer 26 by the received signal. As a result, a demodulated signal can be obtained. The present application example has a feature that signal demodulation can be conducted without increasing the device size even in the case where the information rate is comparatively slow.

An eighth application example of the present invention will now be described by referring to FIG. 18.

FIG. 18 is a diagram showing a receiving part of a communication device in the eighth application example. The same components as those in FIG. 3 showing the second application example are denoted by like numerals. In the seventh application example, a pseudo noise signal is generated to conduct demodulation. On the receiver side as well, however, a signal generator is needed, resulting in a large circuit scale. In the present application example, a carrier frequency oscillator 28 is multiplied in a mixer 27 by the received signal. Furthermore, a resultant signal is converted to a digital signal by a detector circuit 29 and a square wave output circuit 30. In a digital correlation signal processing circuit 31, the digital signal is subjected to processing according to the equation of the Expression 4 and the equation of the Expression 5. In the present application example, correlation demodulation processing can be conducted by using digital processing. This results in a feature that the device can be fabricated at comparatively low cost in the case where the information rate is comparatively slow, or the pseudo noise code length is short.

A ninth application example of the present invention will now be described by referring to FIG. 19.

FIG. 19 is a diagram showing a receiving part of a communication device in the ninth application example. The same components as those in FIG. 17 showing the seventh application example are denoted by like numerals. In the eighth application example, demodulation is conducted in the digital circuit. In the case where the information rate is fast and the pseudo noise code length is long, processing cannot be conducted in some cases because the clock frequency of the digital circuit is low. In the present application example, a signal outputted from a pseudo noise code generator 23 is multiplied in a mixer 24 by a carrier signal of an oscillator 25 having the same frequency as the carrier. A resultant signal and the received signal are subjected to convolution integral processing in a convolver 32 which is a correlation element. Furthermore, a resultant signal is subjected to demodulation in a detector circuit 33. The present application example has a feature that the demodulated signal can be obtained comparatively easily so long as the carrier frequency can be synchronized with the pseudo noise code cycle even in the case where the information rate is fast and the pseudo noise code length is long.

As compared with the sixth through ninth application examples, the case where the matched filter is used as in the second and third application examples has a feature that signal synchronizing is unnecessary because the code on the receiving side is fixed. On the contrary, the sixth through ninth application examples have a feature that the reference code on the receiving side can be changed freely so as to correspond to the code on the transmitting side because the code is variable.

A tenth application example of the present invention will now be described by referring to FIG. 20.

FIG. 20 is a diagram showing a detection part of a communication device in the tenth application example. In the present application example, a delay detection system is used as the detection system, and demodulation is conducted by multiplying a current signal, in a mixer 35, by a signal preceding a current signal by one information bit supplied from a delay line 34. In the present application example, the detector circuit can be simplified.

An eleventh application example of the present invention will now be described by referring to FIG. 21.

FIG. 21 is a diagram showing a detection part of a communication device of the eleventh application example. In the present application example, a synchronous detection system is used as the detection system, and demodulation is conducted by multiplying a clock reproduced by a clock detection circuit 36, in a mixer 35, by a signal. In the present application example, a better error rate than that of the delay detection system is obtained.

A twelfth application example of the present invention will be now described by referring to FIG. 22.

FIG. 22 is a diagram showing a communication system of the twelfth application example. In the present application example, communication devices of the present system are used in a LAN. Present communication devices 41 and 42 are connected to a LAN cable 38. Present communication devices 40 and 43 are connected to terminals 39 and 44. Present communication devices 46 and 47 are connected to terminals 45 and 48. Between terminals (without a wire system between), communication can be conducted freely. If the present application example is used, it is not necessary to connect each terminal to a LAN cable, and consequently terminals can be freely moved.

INDUSTRIAL APPLICABILITY

According to the present invention, the side lobes of the correlation coefficient can be suppressed with the pseudo noise code length of at least 14 as heretofore described. Therefore, the error rate can be reduced and the processing gain can be improved in a spread spectrum communication device and a communication system using the spread spectrum communication device.

Claims

1. A spread spectrum communication device in a direct spreading communication device using a pseudo noise code inverted in polarity so as to correspond to digital information,

wherein in said spread spectrum communication device, as said pseudo noise code, a pseudo noise code having a code length of at lease 14 and an auto-correlation side lobe of 3 or less is used, and

wherein said pseudo noise code is one of the codes listed in Tables 1-9 and "0"s and "1"s in each of the codes listed in Tables 1-19 are interchangeable with each other.

2. A surface acoustic wave device in which at least one set of at least two sets of interdigital electrodes forms an input electrode set or an output electrode set and disposition is conducted so as to mutually invert electrode polarities,

wherein an input signal inputted to an input electrode set is a signal subjected to spreading processing using a pseudo noise code, said pseudo noise code has a code length of at least 14, and a pseudo noise code having an auto-correlation side lobe of 3 or less is employed, and

wherein said pseudo noise code is one of the codes listed in Tables 1-9 and "0"s and "1"s in each of the codes listed in Tables 1-9 are interchangeable with each other.