Coherent surface acoustic wave unique word detector

• US 5,056,055 A
• Filed: 08/29/1989
• Issued: 10/08/1991
• Est. Priority Date: 09/07/1988
• Status: Expired due to Term

• Current Assignee: KDDI Corporation
• Original Assignee: Kokusai Denshi Denwa Company Limited (KDDI Corporation)
• Inventors: Shinonaga, Hideyuki
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): TRAMMELL, JAMES P
• Application Number:
  US07/400,297
• Time in Patent Office: 770 Days
• Field of Search: 364/821, 364/724.11, 310/313 R, 310/313 B, 333/195, 333/24 R, 333/150, 333/30 R, 333/193, 333/194, 333/196
• US Class Current: 708/815
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A unique word in a digital communication system is detected on a receiving side by using an acoustic surface wave matched filter (4) having a piezoelectric substrate, an input interdigital electrode (4c) and and output interdigital electrode (4a, 4b) on the substrate. An input signal is applied to the input interdigital electrode in the form of a phase modulated IF band signal. A pattern of the output interdigital electrode is designed depending upon a unique word to be detected where data 1 corresponds to an upper finger (4a) followed by a lower finger (4b), data 0 corresponds to a lower finger (4b) followed by an upper finger (4a) or vice versa, and progagation time of the surface acoustic wave over the spacing (d) between each pairs of fingers (4a, 4b) is equal to a bit time duration of the unique word. An output of the acoustic surface wave matched filter is coherently detected, and when absolute value of the coherent detection exceeds a predetermined value, a unique word is recognized and the received phase in the demodulator is determined at the same time.

Claims

1. A unique word detector in an absolute phase-shift keyed system, wherein a coherent phase demodulator is used which outputs a correct data stream or an inverted data stream of the correct data stream in accordance with a recovered phase in a coherent phase demodulator, said unique word detector comprising:

a first mixer, to which baseband data stream output from said coherent phase demodulator and a local frequency from a local oscillator are supplied, for binary-phase-shift keying said baseband data stream;

a surface acoustic was matched filter, coupled with said first mixer, having a) a piezoelectric substrate, b) a first interdigital electrode disposed on said substrate to which binary-phase-shift keyed signal by said baseband data stream is applied from said first mixer, and c) said second interdigital electrode disposed on said substrate wherein a relationship thereof is so designed as to provide a maximum envelope output in response to a predetermined unique word pattern of absolute phase coding;

a second mixer, coupled with said second interdigital electrode, to which a local frequency from said local oscillator is supplied, for coherently detecting an output signal of said surface acoustic wave matched filter; and

determining means, coupled with said second mixer, for detecting a unique word and determining a recovered phase in said coherent phase demodulator, wherein a unique word detection pulse is output when an absolute value of the output signal of said second mixer exceeds a predetermined value, and at the same time, recovered phase information is determined and output in accordance with a polarity of the output signal of said second mixer.

2. A unique word detection system according to claim 1, wherein said input means comprises a conversion means, which is supplied with the local frequency, to convert input baseband data to said binary shift keyed IF band signal.

3. A unique word detection system according to claim 1, wherein said input means is a frequency converter which is a part of a receiver.

4. A unique word detection system in a digital communication system comprising:

an acoustic surface wave matched filter having a piezoelectric substrate, a first interdigital electrode disposed on said substrate, and a second interdigital electrode disposed on said substrate wherein a pattern of said second interdigital electrode is based upon a unique word to be detected;

an input means for applying an input signal, which is binary phase modulated in an IF band, to said first interdigital electrode;

an output means coupled with said second interdigital electrode, said output means for coherently detecting an output signal of said second interdigital electrode; and

determining means for recognizing a unique word based on an output of said second interdigital electrode exceeding a predetermined value and recognizing a received phase based on a polarity of an output signal of said acoustic surface wave matched filter in a demodulator coupled with said output means.

5. A unique word detection system according to claim 4, wherein said input means comprises a conversion means, which is supplied a local frequency, to convert input baseband data to said binary phase modulated in said IF band signal.

6. A unique word detection system according to claim 4, wherein said input means is a frequency converter which is a part of a receiver.

7. A unique word detection system according to claim 4, wherein said input means and said output means are supplied with a common local frequency.

8. A unique word detector in an absolute multiphase-shift keyed system, in which one transmit symbol contains m (an integer more than or equal to two) bits, a coherent multiphase demodulator outputs m parallel baseband data streams or m channels through which partial patterns of a unique word are transmitted and a relationship between data streams of m channels at a transmitter and a receiver depends on a recovered phase in said coherent multiphase demodulator, said unique word detector comprising:

m number a first mixers, to which m parallel baseband data streams from said coherent multiphase demodulator and a same local frequency from a local oscillator are supplied, for binary-phase-shift keying said each of baseband data streams;

m number of surface acoustic wave matched filters, coupled with m numbers of said first mixers, each having a) a piezoelectric substrate, b) a first interdigital electrode disposed on said substrate to which binary-phase-shift keyed signal by said each of baseband data streams is applied from said each of first mixer, and c) said second interdigital electrode disposed on said substrate wherein a relationship thereof is so designed as to provide a maximum envelope output in response to each of predetermined partial patterns of a unique word of absolute phase coding;

m number of second mixers, each coupled with said m number of second interdigital electrodes, to which the same local frequency from said local oscillator is supplied for coherently detecting each of m output signals of said m number of surface acoustic wave matched filters; and

determining means, coupled with said m number of second mixers, for determining the recovered phase in said coherent multiphase demodulator, wherein a plurality of correlation values are calculated by performing arithmetic operations on m number of output signals of m second mixers, a unique word detection pulse is output when an absolute value of one of said m correlation values exceeds predetermined values, and at the same time, recovered phase information is determined and output in accordance with type and polarity of said correlation value whose absolute value exceeds said predetermined value.

9. A unique word detection system according to claim 8, wherein an arithmetic means is coupled with outputs of said second mixers, said arithmetic means combines said baseband data streams.