Implementation of on-off passive wireless surface acoustic wave sensor using coding and switching techniques
First Claim
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1. A method for coding surface acoustic wave devices in a passive wireless system to increase code diversity comprising the step of:
- providing a first set of two or more orthogonal frequency coded surface acoustic wave devices having a first acoustical path between a first transducer and the first set of two or more surface acoustic wave devices;
providing a second set of two or more orthogonal frequency coded devices having a second acoustical path between a second transducer and the second set of two or more orthogonal frequency coded devices;
coupling the first and second transducer to a switching device with one-half of the surface acoustic wave device having an on state while the other one-half have an off state to switch between connecting the first and second transducer to one of an antenna and a matching network.
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Abstract
Methods and systems for passive wireless surface acoustic wave devices for orthogonal frequency coded devices to implement ON-OFF sensors reusing orthogonal frequency code and distinguishing between ON and OFF states using additional PN sequence and on/off switches producing multi-level coding as well as external stimuli for switching and identification of a closure system. An embodiment adds a level of diversity by adding a dibit to each surface acoustic wave devices, thus providing four different possible coding states. The PN on-off coding can be with the dibit for coding in a multi-tag system.
16 Citations
22 Claims
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1. A method for coding surface acoustic wave devices in a passive wireless system to increase code diversity comprising the step of:
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providing a first set of two or more orthogonal frequency coded surface acoustic wave devices having a first acoustical path between a first transducer and the first set of two or more surface acoustic wave devices; providing a second set of two or more orthogonal frequency coded devices having a second acoustical path between a second transducer and the second set of two or more orthogonal frequency coded devices; coupling the first and second transducer to a switching device with one-half of the surface acoustic wave device having an on state while the other one-half have an off state to switch between connecting the first and second transducer to one of an antenna and a matching network. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A multi-sensor passive wireless system comprising:
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two or more acoustical paths each having two or more orthogonal frequency coded surface acoustic wave devices, each acoustical path coupled with a transducer; a master network connected with the two or more transducers to connect one or more of the acoustical paths to an output port of the master network, the master network including a switching device for alternating between at least two of the acoustical paths to form orthogonal frequency coded surface acoustic wave devices with alternating pseudo noise codes; an external stimuli applied to the surface acoustic wave devices, an orthogonal frequency code reflected in response to the external stimuli; and a receiver to correlate the reflected response against both of an ON code and an OFF code, wherein two of the plural orthogonal frequency coded devices have a same orthogonal frequency code and an opposite pseudo noise code. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for producing a dibit chip having a dibit code sequence for surface acoustic wave devices in a multi-sensor passive wireless system comprising the steps of:
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fabricating two adjoining surface acoustic wave reflectors having a same chip frequency on a substrate as a dibit chip; coupling a transducer and antenna pair to the two adjoining reflectors; and assigning a dibit code sequence to the dibit chip, the dibit code selected from four different coding states, each dibit chip in the multi-sensor passive wireless system having a different chip frequency. - View Dependent Claims (20, 21, 22)
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Specification