EP0409538A2
Expired / Lapsed
EP
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Spread spectrum signal demodulator
Assignee: NCR International Inc
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Filing: 1990-07-17
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Granted: —
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Expires: 2010-07-17
Abstract
Abstract In a digital data receiver (80) for demodulating a direct sequence spread spectrum differential phase shift keyed data signal, the signal is applied to the input transducer (140) of a SAW device (100) which has first and second output transducers (142, 144) spaced apart on the SAW substrate (130) so as to produce first and second output signals on output lines (102, 104), which are relatively delayed by a time corresponding to a symbol period. The output transducers are of identical construction and are matched to the spread spectrum code utilized in the data signal. Thus, a single SAW device (100) effects both correlation and delay. The output signals on the output lines (102, 104) are processed by a circuit including multipliers (106, 110) and a phase shifter (108) to produce output data signals representing the received data.
Inventors
- 👤 Hans Van Driest
- 👤 Jacobus Cornelis Haartsen
- 👤 Bruce Tab Tuch
- 👤 Maarten Visee
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 16:17
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/709; H04B1/7093; H04B1/70712
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
181 words
A digital data receiver, for demodulating a fixed code spread spectrum differential phase shift keyed received data signal, representing a succession of data symbols having a predetermined symbol rate, characterized by input means (82-98) adapted to apply said received data signal to a surface acoustic wave device (100) having an input transducer (140) located on a piezoelectric substrate (130), and first and second output transducers (142,144), each matched to said fixed code, and relatively displaced on said substrate from said input transducer (140) by a distance dependent on said symbol rate so as to produce respective first and second signals, having a relative delay corresponding to a symbol period, first multiplying means (106) adapted to multiply said first and second signals to provide a third signal, phase shifting means (108) adapted to phase shift said second output signal, second multiplying means (110) adapted to multiply said first signal and the phase shifted second signal to produce a fourth signal, and decision means (112-120) responsive to said third and fourth signals and adapted to produce output data signals representing the received data.
Claim 2
Dependent Claim
181 words
A digital data receiver, for demodulating a fixed code spread spectrum differential phase shift keyed received data signal, representing a succession of data symbols having a predetermined symbol rate, characterized by input means (82-98) adapted to apply said received data signal to a surface acoustic wave device (100) having an input transducer (140) located on a piezoelectric substrate (130), and first and second output transducers (142,144), each matched to said fixed code, and relatively displaced on said substrate from said input transducer (140) by a distance dependent on said symbol rate so as to produce respective first and second signals, having a relative delay corresponding to a symbol period, first multiplying means (106) adapted to multiply said first and second signals to provide a third signal, phase shifting means (108) adapted to phase shift said second output signal, second multiplying means (110) adapted to multiply said first signal and the phase shifted second signal to produce a fourth signal, and decision means (112-120) responsive to said third and fourth signals and adapted to produce output data signals representing the received data.
Claim 3
Dependent Claim
51 words
A digital data receiver according to claim 1, characterized in that said decision means includes first and second decision circuits (116,118) responsive respectively to said third and fourth signals, and parallel-to-serial conversion means (122) coupled to said first and second decision circuits (116,118) and adapted to provide said output data signals.
Claim 4
Dependent Claim
48 words
A digital data receiver according to claim 1 or claim 2, characterized in that each of said output transducers includes first and second electrodes (152,154;172,174) and a plurality of groups (156-162;176-182) of metallic fingers, the fingers of each group extending alternatively from said first and second electrodes (152,154;172,174).
Claim 5
Dependent Claim
25 words
A digital data receiver according to claim 3, characterized in that said groups (156-162;176-182) of fingers are all separated apart by the same distance (L).
Claim 6
Dependent Claim
37 words
A digital data receiver according to any one of the preceding claims, characterized in that said input transducer (140) and said first and second output transducers (142,144) are arranged in a linear configuration on said substrate (130).
Claim 7
Dependent Claim
23 words
A digital data receiver according to any one of the preceding claims, characterized in that said piezoelectric substrate (130) is composed of quartz.
Claim 8
Dependent Claim
36 words
A digital data receiver according to any one of the preceding claims, characterized in that said fixed code is a time-reversed replica of the impulse response of each of said first and second output transducers (142,144).
References Cited (Backward Citations)
No citation records indexed.
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