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Rfcalibration of saw interrogatorsRfcalibration of saw interrogators description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070182624, Rfcalibration of saw interrogators. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] The present application is a Divisional Application of U.S. Ser. No. 10/861,663, filed on Jun. 4, 2004. FIELD OF THE INVENTION [0002] The present invention generally concerns interrogators for use with electronics assemblies that transmit information related to identification variables and/or measurements of selected physical or environmental conditions. More particularly, the subject calibration methodology utilizes a transmitter and receiver pair to evaluate sensed transmitter power. In an alternative embodiment, paired interrogator transceivers in a symmetrical arrangement yield self-evaluating devices for relaying digital data as well as sensed parameter information. BACKGROUND OF THE INVENTION [0003] The incorporation of electronic devices with pneumatic tire and wheel structures yields many practical advantages. Tire electronics may include sensors and other components for relaying tire identification parameters and also for obtaining information regarding various physical parameters of a tire, such as temperature, pressure, tread wear, number of tire revolutions, vehicle speed, etc. Such performance information may become useful in tire monitoring and warning systems, and may even potentially be employed with feedback systems to regulate proper tire parameters. [0004] Yet another potential capability offered by electronics systems integrated with tire structures corresponds to asset tracking and performance characterization for commercial vehicular applications. Commercial truck fleets, aviation craft and earth mover/mining vehicles are all viable industries that could utilize the benefits of tire electronic systems and related information transmission. Radio frequency identification (RFID) tags can be utilized to provide unique identification for a given tire, enabling tracking abilities for a tire. Tire sensors can determine the distance each tire in a vehicle has traveled and thus aid in maintenance planning for such commercial systems. Vehicle location and performance can be optimized for more expensive applications such as those concerning earth-mining equipment. [0005] One particular type of sensor, or condition-responsive device, that has recently become desirable for use in certain tire electronics systems to determine various parameters related to a tire or wheel assembly is an acoustic wave device, such as a surface acoustic wave (SAW) device. SAW devices have desirable properties for certain sensor applications since they are sensitive, use very little power, and can be operated at RF frequencies convenient for relaying information in a wireless fashion. SAW devices may include at least one resonator element made up of interdigitated electrodes deposited on a piezoelectric substrate. [0006] When an electrical input signal is applied to a SAW device, selected electrodes cause the SAW to act as a transducer, thus converting the input signal to a mechanical wave in the substrate. Other structures in the SAW reflect the mechanical wave and generate an electrical output signal. In this way, the SAW acts like an electromechanical resonator. A change in the output signal from a SAW device, such as a change in frequency, phase and/or amplitude of the output signal, corresponds to changing characteristics in the propagation path of the SAW device. In some SAW device embodiments, monitored device frequency and any changes thereto provide sufficient information to determine parameters such as temperature, and strain to which a SAW device is subjected. [0007] Additional background information regarding RFID technology and SAW devices may be had by reference to co-pending, commonly owned U.S. patent application Ser. No. 10/697,576, filed Oct. 30, 2003, entitled "Acoustic Wave Device With Digital Data Transmission Functionality" incorporated herein for all purposes. [0008] In conventional implementations of SAW devices in tire-related applications, SAW sensors transmit information about the parameters being sensed. However, it is often the case that in radio frequency transmissions systems, especially low power systems, signal strength and/or noise, or more specifically the signal to noise ratio (S/N) becomes a limiting factor. While various implementations of acoustic wave devices such as SAW sensors in tire electronic systems have been developed, and while various combinations of information have been wirelessly relayed from a tire or wheel assembly using conventional technologies, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology. SUMMARY OF THE INVENTION [0009] In view of the recognized features encountered in the prior art and addressed by the present subject matter, an improved methodology for the testing and calibration of interrogators for use with SAW based devices has been developed. It should be noted that although the principle portion of the remainder of the present disclosure may refer to the use of SAW based devices as being integrated with a tire or wheel structure, neither such use nor such particular type device is a limitation of the present technology as, in fact, such devices, whether SAW based or not, may be used in combination with a variety of other devices or elements or even as stand alone environmental sensors. [0010] In an exemplary configuration, SAW based devices may include an acoustic wave device connected as a feedback element in an oscillator/amplifier and may be further coupled to an antenna element, thus forming an active transmitter arrangement. The acoustic wave device determines the carrier frequency (or frequencies) produced by such an active transmitter, and therefore, the frequency (or frequencies) of the transmitted RF signal represents one or more sensed parameters with the acoustic wave device itself functioning as a sensor. At the same time, the transmitted signal amplitude may be controlled by means of a separate circuit connected to the oscillator amplifier. [0011] In one of their simpler forms, the transmitted signal from a SAW based device is switched on and off in a timed sequence, but other methods are possible. Positive aspects of this information transmission methodology include circuit simplification and power savings. For example, instead of requiring the circuitry in the tire to measure the sensed parameters, covert them to digital format, and encode them in a transmitted digital data stream, the sensed parameter information is conveyed through the transmitted RF frequency. Such methodology provides for the transmission of any other information desired, however complex or simple, by amplitude modulation of the transmitted signal. Such a circuit configuration provides for the ability to actively transmit a combination of information from integrated tire electronics to a remote receiver location. The combination of information may correspond to the physical parameters sensed by the acoustic wave device as well as digital data superimposed on the RF signal emitted by the acoustic wave device by selectively switching the amplifier on and off. [0012] Another positive aspect of this type of device is that versatility is afforded to the types of information that can be transmitted via the electronics assemblies. Such information can include sensed information relating to parameters such as temperature and pressure associated with a tire or wheel assembly. Other information may include selected combinations of a unique tag identification, distance traveled, number of tire revolutions, vehicle speed, amounts of tread wear, amounts of tire deflection, the amount of static and/or dynamic forces acting on a tire, etc. So many different types of information are possible in part because a microcontroller can be configured to modulate any type of desired data on the RF output signal(s) from the electronics assembly and the subject calibration methodologies are able to insure reliable reception of the transmitted data. [0013] Having recognized the above mentioned positive aspect associated with SAW based devices, the present subject matter recognizes and addresses the fact that there are, never the less, negative aspects associated with SAW based devices that are based on the retransmission of RF energy. Significant among these aspects is the extremely low power level at which the SAW devices transmit signal energy. While such low signal levels may be considered a positive aspect when considering operating energy requirements, these low levels, coupled with other aspects present challenges to data reception and recovery. More specifically, operation of SAW based devices at such low signal level, coupled with often hostile operating conditions and environments, may produce such low signal to noise (S/N) ratios that the accuracy and performance characteristics of the SAW based device's interrogation systems may be compromised. [0014] In accordance with aspects of certain embodiments of the present subject matter, methodologies are provided to insure proper operation of the interrogation systems associated with SAW based devices. More particularly, methodologies have been developed to verify that the interrogators themselves are operating within established specifications. [0015] In accordance with certain aspects of other embodiments of the present subject matter, methodologies have been developed to track the performance of SAW based device interrogators over the operational lifetime of the interrogators to insure reliable identification of data read problems and to provide a means for diagnosing such problems. [0016] In accordance with yet additional aspects of further embodiments of the present subject matter, apparatus and accompanying methodologies have been developed to establish the health of the communications channel between a SAW device and it's associated interrogator. [0017] According to yet still other aspects of additional embodiments of the present subject matter, apparatus and methodologies have been developed to insure the accurate reporting of read data by providing a mechanism for performance testing that may be easily employed prior to each and every data read operation. [0018] In accordance with yet still further aspects of still further embodiments of the present subject matter, methodologies have been developed to account for the effects of ambient interference or background noise affecting the communication channel between a SAW device and it's associated interrogator. [0019] Additional objects and advantages of the present subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features and elements hereof may be practiced in various embodiments and uses of the invention without departing from the spirit and scope of the subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like. [0020] Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of the present subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures). Additional embodiments of the present subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objects above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification. Continue reading about Rfcalibration of saw interrogators... Full patent description for Rfcalibration of saw interrogators Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Rfcalibration of saw interrogators patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Rfcalibration of saw interrogators or other areas of interest. ### Previous Patent Application: Method and apparatus for on-vehicle calibration and orientation of object-tracking systems Next Patent Application: Combined antenna module with single output Industry Class: Communications: directive radio wave systems and devices (e.g., radar, radio navigation) ### FreshPatents.com Support Thank you for viewing the Rfcalibration of saw interrogators patent info. IP-related news and info Results in 0.21699 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , 174 |
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