Bicameral LLC v. NXP USA, Inc. et al

Western District of Texas, txwd-6:2018-cv-00294

Exhibit Ex. 538EX1

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7 Exhibit 538EX1 7 USOO6639538B1 (12) United States Patent (10) Patent No.: US 6,639,538 B1 Sechi et al. (45) Date of Patent: Oct. 28, 2003 (54) REAL-TIME TRANSIENT PULSE 5,724.219 A 3/1998 Narita MONITORING SYSTEMAND METHOD 5,740,080 A 4/1998 Shook et al. 5,914,662 A 6/1999 Burleigh (75) Inventors: Paolo G. Sechi, Woodside, CA (US); 5,959,815 A 9/1999 Gilbert Richard C. Adamo, Palo Alto, CA 6,018,300 A 1/2000 Dowden et al. 6,026,355 A 2/2000 Rahman et al. (US) 6,064,172 A 5/2000 Kuznetsov 6,097,582 A 8/2000 John et al. (73) Assignee: SRI International, Menlo Park, CA 6,104,582 A 8/2000 Cannon et al. (US) 6,118,639 A 9/2000 Goldstein 6,175,808 B1 1/2001 Chai Notice: Subject to any disclaimer, the term of this 6,297,760 B1 * 10/2001 Hungerbuehler ............ 341/155 patent is extended or adjusted under 35 6.424,927 B1 7/2002 Sechi et al. U.S.C. 154(b) by 0 days. FOREIGN PATENT DOCUMENTS (21) Appl. No.: 10/145,492 DE 41 33 209 A1 4/1993 (22) Filed: May 14, 2002 * cited by examiner (51) Int. Cl.................................................. H03M 1/12 Primary Examiner Brian Young (52) U.S. Cl. ........................................ 341/155; 341/161 (74) Attorney, Agent, or Firm-Guerin & Rodriguez, LLP, (58) Field of Search ................................. 341/155, 161, Michael A. Rodriguez 341/159, 160, 158 (57) ABSTRACT (56) References Cited Described are a System and method for monitoring and U.S. PATENT DOCUMENTS characterizing a Stimulus in order to detect transient phe nomena. An analog signal represents the Stimulus. Conver 3,578,957 A 5/1971 Gatlin Sion circuitry receives the analog Signal and continuously 3,629,852 A 12/1971. Thexton et al. converts the analog Signal into digital data. Digital circuitry 3,711,771 A 1/1973 Hume et al. continuously receives the digital data from the conversion 4,023,071 A 5/1977 Fussell circuitry and dynamically computes from the digital data a 4,301,508 A 11/1981 Anderson et al. value that characterizes a parameter of the Stimulus while 4,368,519 A 1/1983 Kennedy the digital circuitry continuously receives new digital data 4,422,037 A 12/1983 Coleman from the conversion circuitry. The digital circuitry can be 4,442,496 A 4/1984 Simon et al. 4870,534 A 9/1989 Harford reconfigured to characterize a different parameter for the 5,170,359 A 12/1992 Sax et al. Same type or for a different type of Stimulus. 5,440,566 A 8/1995 Spence et al. 5,666.255 A 9/1997 Muelleman 24 Claims, 6 Drawing Sheets 2 10 SAMPLING CLOCK 66 SEIF-EST CIRCURY 98. PROGRAMMABLE LOGIC PROCESSING UNET 58 86 ATTENATOR SIGNAL MEMORY 52 CONTIONER BUEER 54 DGIAI SGNAL PROCESSOR 78 ROGRAYABLE ROGRAM OGIC MEMORY CONTRO 82 (PLC) 70 CONVERSION CIRCUITRY 20 DIGITAL CIRCUITRY 22 7 U.S. Patent Oct. 28, 2003 Sheet 1 of 6 US 6,639,538 B1 Z 8 Hz?OLINOW TIVALÐC ?èHLIOC ZO ©J8NTLHOITQW T 0 HNGOAICS) Q?èHILC)Q 5'XIOVTNÐS GHONIQS 7 7 7 7 U.S. Patent Oct. 28, 2003 Sheet S of 6 US 6,639,538 B1 15 O FIG. 5A RECEIVE ANALOG SIGNAL 152 ATTENUATE THE ANALOG T 154 SIGNAL CONDITION THE ANALOG SIGNAL 156 PROCESS CONTINUOUSLY SAMPLE THE ANALOG SIGNAL - 158 CONVERTSAMPLED ANALOG - SIGNAL INTO DIGITAL DATA FORWARD DIGITAL DATA TO MEMORY BUFFER - 162 7 U.S. Patent Oct. 28, 2003 Sheet 6 of 6 US 6,639,538 B1 FROM FIG. 5A TRANSFER DIGITAL DATA FROM THE MEMORY BUFFER 164 TIME TO OUTPUT VALUE p OUTPUT THE VALUE (S) OF PARAMETER (S) TO THE OUTPUT DATA BUS OUTPUT DONE p FIG. 5B 7 US 6,639,538 B1 1 2 REAL-TIME TRANSIENT PULSE which the monitor can miss a transient. Another objective is MONITORING SYSTEMAND METHOD to make accurate real-time measurements. Yet another objective is for the monitor to process large amounts of data with minimal data storage. Still another objective is for the FIELD OF THE INVENTION monitor to be readily reconfigurable. The invention relates generally to monitoring Systems. In brief overview, the system and method of the invention More particularly, the invention relates to Systems and feature continuously receiving an input analog signal; con methods for real-time monitoring and measuring of transient tinuously Sampling and digitizing the analog signal; buffer phenomena. ing the digitized data, computing in real-time from the digitized data a parameter value that represents a character BACKGROUND istic of the Stimulus, discarding the digitized data after the data is used to compute the parameter value; outputting Transient phenomena pose a Serious threat to Systems computed parameter values, for example, to a System bus or exposed to Such phenomena. Transients can occur at any to a Storage medium; and continuing to Sample, digitize, and time with varying amplitude, frequency, and duration. The 15 buffer while outputting the parameter values to the System magnitude or energy content of the transient phenomena can buS or Storage medium, So as not to miss any transients that affect the electronic and mechanical components of these may have occurred during this period. Systems to cause permanent or temporary malfunction. In one aspect, the invention features a System for char Because of the destructive potential of transients, industry acterizing a Stimulus represented by an analog signal. Con has developed various transient monitoring Systems for version circuitry continuously receives the analog Signal and detecting and measuring transients that occur near important converts the analog Signal into digital data. Digital circuitry or critical Systems. continuously receives the digital data from the conversion Lightning is one potentially destructive transient phenom circuitry. The digital circuitry dynamically computes from enon. For example, current Spacecraft launching procedures the digital data a value that characterizes a parameter of the typically Suspend launch operations should lightning occur 25 Stimulus while the digital circuitry continuously receives directly or nearby until System level tests are performed to new digital data from the conversion circuitry. In one ensure that electromagnetic transients produced by the light embodiment, the digital circuitry is re-programmable So as ning have not damaged or disturbed the payload or launch to be capable of characterizing a different parameter or vehicle Systems. These retest operations are costly and often parameters of the same or of a different type of Stimulus. The unnecessary. By Strategically placing electromagnetic Sen conversion circuitry and the digital circuitry can be provided Sors near the payload and launch vehicles, an assessment of on the same or different integrated circuit chips, on the same the potential damage caused by lightning-induced transients or different circuit boards, and in a computer System or other can be made by evaluating the transient information cap electronic device, Such as a meter. tured by the Sensors. 35 In accordance with the type of transients being monitored, Transient monitoring Systems measure certain key param the System characterizes certain key parameters. For eters that are indicative of the potentially destructive nature example, for electromagnetic transients, the characterized of detected transients. For lightning-induced electromag parameters include positive and negative peak amplitudes, netic transients, for example, key parameters include posi duration of positive and negative transients, the rate of rise tive and negative peak amplitudes, and duration, energies, 40 of the positive and negative transients, and energy. and maximum rates-of-change or rise-times of positive and The System includes a program memory Storing a first negative transients. Often, Such parameters are empirically program. In one embodiment, a digital signal processor is in determined to correlate to problems experienced by elec communication with the program memory and computes the tronic Systems due to transients. value that characterizes the parameter according to the first To characterize key parameters of transient phenomena, 45 program. In another embodiment, the System includes pro conventional transient monitoring Systems digitize the ana grammable logic in communication with the digital Signal log input Signal and Save the digital data in memory for processor. In this embodiment, the programmable logic Subsequent download and evaluation. A disadvantage of this computes the value that characterizes a Second parameter as technique is that the digital data must be post-processed, directed by the first program. Also, the programmable logic thus the characterization of the key parameters is not avail 50 is reprogrammable by the digital Signal processor as directed able in real time. Secondly, while the digital data is being by the Second program. In Still another embodiment, the downloaded from the memory, the System is offline, that is, digital transient pulse monitoring System includes Self-test the System is not collecting additional digital data. For circuitry. applications monitoring transient events, input transients The digital circuitry is in communication with a bus. will go undetected if they occur during this transfer period. 55 While the digital circuitry outputs the computed value over Repetitive or closely-grouped high frequency transients, the bus, the digital circuitry continuously receives new Such as those that occur with lightning, increase the likeli digital data from the conversion circuitry. The conversion hood of a missed transient. The loSS of Such information can circuitry can include a Signal conditioner that receives the lead to an erroneous and potentially catastrophic conclusion analog signal and modifies the analog Signal to produce a that the monitored System has not been exposed to harmful 60 modified analog signal having a particular Voltage range. transients. In another aspect, the invention features a System that SUMMARY includes an analog-to-digital converter, a processing unit, and a memory buffer. The analog-to-digital converter Objectives of the present invention are to provide a receives an analog signal representing a Stimulus and con transient pulse monitor that is capable of measuring tran 65 verts the analog Signal into digital data. The processing unit Sients in real-time and to perform Such real-time measure dynamically computes from the digital data a value that ments without experiencing dead time, i.e., a period during characterizes a parameter of the Stimulus. The memory 7 US 6,639,538 B1 3 4 buffer is in communication between the analog-to-digital (electromagnetic) energy, heat, light, chemical, and electri converter and the processing unit and continuously receives cal. Examples of types of Stimuli include, but are not limited new digital data from the analog-to-digital converter while to, electromagnetic fields, Static electricity, lightning, ther the processing unit processes digital data obtained from the mal shock, mechanical Shock, Vibration, noise, acoustic memory buffer to compute the parameter value. The rate at waves, RF signals, electric signals (digital and analog), which the memory buffer receives new digital data from the photoelectric impulses, optical impulses, ultraViolet, infra A/D converter is less than the rate at which the processing red and Visible light, radiation, chemical reactions, the flow unit receives digital data from the memory buffer. In one of air (e.g., wind), gases and fluids, humidity, and pressure. embodiment, the processing unit continuously obtains digi Generally, the monitor 12 is configured to measure one or tal data from the memory buffer except while the processing more parameters of a particular Stimulus or Stimuli. These unit is outputting a computed value. parameters are those generally known to indicate the pres In one embodiment, the processing unit includes a digital ence of transient phenomena in the Stimulus. Signal processor. The System can also include programmable Also known as Spikes or Surges, electrical transients in logic in communication with the memory buffer to receive general are momentary Voltage or current changes that can concurrently the same digital data that are received by the 15 have either a positive or a negative polarity and can add to digital Signal processor. The programmable logic and the or reduce energy in the affected waveform. Transient phe digital signal processor dynamically compute, from the nomena can be caused, for example, by the Switching and Same digital data, values that characterize different param commuting of electric motors, faults, electrostatic eters of the Stimulus. Thus, in this embodiment, digital data discharges, lightning, different types of loads, and abnor passes from the memory buffer to the programmable logic malities in the electrical impulses of an organism (e.g., an and the digital Signal processor concurrently, and while the abnormal heart rate). Such electrical transients can also be digital signal processor characterizes a first parameter (e.g., produced by a transducer or Sensor that converts any tran energy), the programmable logic computes a second param Sient Stimulus into a measurable current or Voltage Signal. eter (e.g., peak amplitude). The monitor 12 includes a monitoring unit 18 having 25 In another aspect, the invention features a method of conversion circuitry 20 and digital circuitry 22. The con characterizing a stimulus represented by an analog signal. version circuitry 20 is in communication with the analog Digital data are continuously received. These digital data are Signal Source 14 over the channel 16 to receive the analog digitized from the analog Signal representing the Stimulus. A Signal representing the Stimulus. The conversion circuitry 20 value that characterizes a parameter of the Stimulus is Samples and converts the analog signal into a digitized dynamically computed from the continuously received digi Signal that represents the Stimulus (referred to hereafter as tal data while new digital data, digitized from the analog digital data or digital data samples). Signal representing the Stimulus, are received. The new The digital circuitry 22 is in communication with the digital data that are received while the computed value is conversion circuitry 20 over a digitized Signal buS 24 to being outputted, for example, to a Storage medium, are 35 receive the digital data, and is programmed to determine Stored for Subsequent processing. The continuously received information about that digital data. In brief, the digital digital data are processed at a rate that is greater than a rate circuitry 22 is programmed to compute from the digital data at which the new digital data are received. at least one value that characterizes a parameter of the BRIEF DESCRIPTION OF THE DRAWINGS Stimulus represented by that digital data. 40 The types of parameters characterized and computations The invention may be more completely understood in performed by the digital circuitry 22 depend upon the type consideration of the detailed description which follows in of Stimulus targeted for monitoring by the monitoring Sys connection with the accompanying drawings, in which: tem 10. Generally, the parameters of interest for a particular FIG. 1 is a block diagram illustrating an embodiment of type of Stimulus have been empirically determined to cor a monitoring System, including a monitor in communication 45 relate to certain problems experienced by electronic and with an analog signal Source; mechanical Systems due to transients. FIG. 2 is a block diagram illustrating an embodiment of For example, key parameters associated with electrical the monitor; transients, Such as those encountered on utility power lines or with lightning, are positive and negative peak amplitudes, FIG. 3 is a block diagram illustrating another embodiment 50 duration of positive and negative transients, the rate of rise of the monitor; of the positive and negative transients, and energy of the FIG. 4 is a block diagram illustrating an embodiment of transients. An example of waveform norms (i.e., key a monitoring unit of the monitor shown in FIG. 1; and parameters) are described in G. Baker, J. P. Castillo, and E. FIG. 5A and FIG. 5B are flow diagrams of an embodiment F. Vance, "Potential for a Unified Topological Approach to of a proceSS used by the monitoring System to characterize 55 Electromagnetic Effects Protection', IEEE Transactions on a Stimulus for transients. Electromagnetic Compatibility, Vol. 34, No. 3, August 1992 DETAILED DESCRIPTION and in Mil-Std-188-125: Appendix B. As another example, key parameters associated with mechanical shock or motion, FIG. 1 shows an embodiment of a monitoring system 10 as measurable using appropriate transducers, include including a monitor 12 constructed in accordance with the 60 displacement, Velocity or acceleration. principles of the invention. The monitor 12 is in communi AS described further below, components of the digital cation with an analog signal Source 14 from which the circuitry 22 are re-programmable, that is, the monitor 12 can monitor 12 receives an analog signal over a channel 16. The be modified to characterize a different parameter or param analog signal Source 14 provides an analog signal that eters of the same or of a different type of stimulus, for represents a naturally occurring or manmade Stimulus. 65 example, after the monitor 12 has been deployed in the field. The Stimulus can originate from any form of energy, e.g., The digital circuitry 22 is in communication with a kinetic (dynamic) energy, potential (static) energy, radiation storage system 28 by a bus 26 by which the digital circuitry 7 US 6,639,538 B1 S 6 22 provides computed parameter values. Generally, the bus mine in near-real-time if transient phenomena have occurred 26 conveys digital Signals representing data, address, and (i.e., delayed from real-time by the time taken for the control information and provides an electrical path by which conversion circuitry 20 to receive and convert the analog a computer System can communicate with the monitoring Signal into digital data and for the digital circuitry 22 to unit 18. AS a Specific example, the bus 26 conveys computed compute and transmit the parameter values to the Storage parameter values to the Storage System 28. Although shown system 28). to be part of the monitor 12, the storage system 28 can be Application programs can also operate on the computed external to monitor 12. parameter values in a "post-processing fashion (i.e., non During operation of the monitor 12, the conversion cir real-time). For example, an application program can access cuitry 20 continuously receives the analog Signal over the the computed parameter values Stored in the Storage System 28 to perform a variety of post-processing analyses, Such as channel 16 and, in real time, Samples and converts the computing mean, median, Standard deviations, and the like. analog signal into a stream of digital data (i.e., the digitized FIG. 2 shows an embodiment of the monitoring system Signal) representing the Stimulus. The conversion circuitry 10' including a computer system 30 constructed in accor 20 places the Stream of digital data on the digitized signal dance with the principles of the invention. The computer bus 24 as the conversion circuitry 20 produces the digital 15 System 30 can be, for example, a personal computer (486, data. Accordingly, the Stream of digital data on the digitized Pentium-based, IBM PC-compatible, etc.), Macintosh Signal buS 24 is continuous. computer, RISC Power PC, X-device, workstation, mini The digital circuitry 22 continuously receives the Stream computer, mainframe computer or Similar computing of digital data representing the Stimulus from the digitized device. The computer system 30 can be connected to a Signal buS 24. While continuously receiving new digital computer network, for example, a local-area network data, the digital circuitry 22 computes from the digital data (LAN), a wide-area network (WAN), the Internet and the one or more values that characterize a parameter of the World WideWeb, by a network connection 32. The network Stimulus. After the parameter values are computed, the connection 32 can be through a Standard telephone line, digital data from which the values are computed are no 25 cable modem, digital subscriber line (DSL), LAN or WAN longer used and discarded, thus avoiding the need for a large link (e.g., T1, T3, 56 Kb, X.25), broadband connection amount of Storage to hold the digital data Samples. Although (ISDN, Frame Relay, ATM), or wireless connection. The discarding the digital data Samples is advantageous in this network connection 32 is established using a communication respect, in Some embodiments the monitor 12 can be con protocol, e.g., TCP/IP, HTTP, IPX, SPx, NetBIOS, Ethernet, figured with Storage to Save Some or all of the digital data RS232, and direct asynchronous connections. Samples for additional processing. The computer system 30 includes a monitor 12" having a The digital circuitry 22 temporarily Stores each computed plurality of monitoring units 18, 18", and 18" (generally, parameter value in local Storage (e.g., in at least one monitoring unit 18). The monitoring units 18, 18", and 18". register). At certain times, the digital circuitry 22 provides are each in communication with a storage System 28' by the computed value(s) over the bus 26 to the Storage System 35 busses 26, 26", and 26". (collectively, bus 26"), respectively, 28. The digital circuitry 22 can provide the computed for providing to the Storage System 28' parameter values parameter values to the buS 26 automatically at periodic computed by that monitoring unit 18". Although three moni intervals or upon receiving a request over the bus 26 (e.g., toring units 18' are shown, the invention can be practiced from an application program executing on a local System or with fewer (at least one) or more monitoring units 18'. In one remotely over a network). 40 embodiment, each monitoring unit 18" is on a separate circuit In accordance with the principles of the invention, the board that plugs into a motherboard of the computer System digital circuitry 22 continues to receive new digital data 30. The bus 26' can be a proprietary or industry standard while computing parameter values and outputting the electrical Signal bus (e.g., ISA (Industry Standard parameters values to the Storage System 28 over the buS 26. Architecture), PCI (Peripheral Component Interconnect), In one embodiment, the digital circuitry 22 achieves the 45 Compact-PCI, USB (Universal Serial Bus), Ethernet), that continuous operation by temporarily buffering the newly conveys digital Signals representing data, address, and con received digital data, as described in more detail below. trol information. Consequently, the monitor 12 encounters no periods of Each monitoring unit 18' includes conversion circuitry 20' "dead time' during which data representing the Stimulus are in communication with digital circuitry 22 over a digitized lost before the monitor 12 can evaluate that data. This 50 signal bus 24'. The conversion circuitry 20' and digital continuous operation provides an advantage over monitors circuitry 22 of one monitoring unit 18" can be implemented that can miss transients due to dead time. on one or more integrated circuit (IC) chips. In one From the Storage System 28, the computed value(s) can embodiment, one circuit board has a plurality of Such IC pass to an application program running locally on a com chips, with each IC chip providing the functionality of a puter System or remotely over a computer network. The 55 monitoring unit 18". application program can perform a variety of operations on The computer system 30 is in communication with an the computed parameter values to determine if the computed analog signal source 14 over channels 16', 16", 16". The parameter values indicate the occurrence of transient phe analog signal Source 14' includes a plurality of detectors or nomena. For example, the application program can graphi transducers 34, 34", and 34" (generally, transducer 34). The cally present the computed values to a user in a graphic user 60 transducers 34 are placed at various locations at a monitor interface by which the user can visually determine from the Site 36 for detecting a type of targeted Stimulus. displayed parameter values whether potentially harmful Each transducer 34 is an electronic device that converts transient phenomena have occurred. AS another example, the energy from one form to another. Examples of transducers application program can compare each computed parameter include position and pressure Sensors, thermometers, value with a predetermined threshold value and Set an 65 microphones, and antennas. PreSSure Sensors for example, audible or visible System alarm if the parameter value measure force. AS another example, microphones convert exceeds the threshold value. Accordingly, a user can deter Sound energy into electrical Signals. 7 US 6,639,538 B1 7 8 The type of transducer 34 used in the monitoring System The monitoring unit 45 includes conversion circuitry 20" 10' depends upon the type of targeted Stimulus. For example, in communication with digital circuitry 22" over a digitized in the detection of transient phenomena associated with signal bus 24". Similar to the embodiment shown in FIG. 2, lightning, the transducers are electromagnetic Sensors. Such the conversion circuitry 20" and digital circuitry 22" can be electromagnetic Sensors include current Sensors, electric implemented on one or more integrated circuit (IC) chips. field Sensors, and B-dot Sensors for measuring rate-of The metering device 44 is in communication with an change of the magnetic field of free Space. Typically, all of analog Signal Source 14" over a channel 48. The analog the transducers 34 of the monitoring system 10 detect the Signal Source 14" includes utility or power lines 46 that carry Same type of Stimulus. In Some embodiment, the monitoring electricity. In contrast to the embodiment shown in FIG. 2, system 10 uses a first transducer to detect a first type of the monitoring system 10" of FIG. 3 does not use a trans Stimulus and a Second transducer to detect a Second different type of Stimulus. ducer 34 to detect and convert the Stimulus into the analog Each transducer 34, 34, 34" is in communication with a Signal. In this embodiment, the electricity on the power lines respective monitoring unit 18, 18", 18" over a respective 46 is the analog signal that passes to the monitor 12". The channel 16, 16', 16" to provide an analog Signal representing monitoring unit 45 of the monitor 12" then digitizes and the stimulus detected by that transducer 34 from its position 15 analyzes the analog Signal for transients. Specifically, the at the monitor site 36. The monitor site 36 is any indoor or conversion circuitry 20" receives the analog Signal and outdoor location where the particular Stimulus of interest can converts the analog signal into a continuous digital data occur. Examples of monitor Sites include, but are not limited Stream. The Stream of digital data passes to the digital to, power networks, transmission lines, consumer facilities, circuitry 22", which, in accordance with the principles of the Spacecraft launch Sites, and living organisms. Although not invention, computes key parameters of the Stimulus from the necessary to the practice of the invention, a monitored object digital data in real-time, and, at certain times, provides the 38 (shown in phantom) can be at the monitor site 36, with computed parameter values to the Storage System 28" Over one or more the transducers 34 positioned about the object the bus 47. 38 so as to detect transients that may potentially affect the AS another example, the analog Signal Source 14" can be functionality of the object 38. 25 a cable outlet that provides a cable connection between a To illustrate this particular embodiment of the monitoring home and the Internet. In this case, the analog signal is the System 10", consider, for example, a Spacecraft with its RF signal carried by the cable, and the monitoring unit 45 is payload (i.e., the monitored object 38) awaiting launch at a in communication with the cable outlet and designed to launch site (i.e., monitor site 36). The spacecraft and payload receive, convert, and analyze the RF signal for transients in have electronic and mechanical Systems that are Sensitive to accordance with the principles of the invention described transients induced by lightning. The monitor 12" is config below. ured to monitor a stimulus (electromagnetic energy) near the spacecraft at the launch site. Transducers (here, electromag FIG. 4 shows an embodiment of the conversion circuitry netic Sensors) 34 are placed at the launch Site, near the 20 and of the digital circuitry 22 of the monitoring unit 18 Spacecraft, So as to detect transients induced by direct or 35 of FIG. 1. The conversion circuitry 20 includes an analog nearby lightning Strikes. Each transducer 34 continuously to-digital (A/D) converter 50 and, optionally, an attenuator detects and converts the Stimulus into an analog Signal, and 52, a signal conditioner 54 and an offset DAC 56 to make the the analog signals pass to the monitoring units 18, 18", and input analog signal 58 suitable for input to the A/D converter 50. 18" over the channels 16', 16", and 16", respectively. The respective conversion circuitry 20' receives the analog signal 40 In embodiments without the attenuator 52, the signal and converts the analog signal into a continuous digital data conditioner 54, and offset DAC 56, the A/D converter 50 is Stream. The digital data passes to the respective digital in communication with the analog signal Source 14 to circuitry 22, which, in accordance with the principles of the receive the input analog signal over an analog signal buS 58. invention, computes key parameters of the Stimulus from the The AVID converter 50 is also in communication with the digital data in real-time. At certain times, the digital circuitry 45 digital circuitry 22 to provide a digitized signal Over a 22" provides the computed parameter values to the Storage digitized signal bus 60. system 28 over the bus 26'. In embodiments with the attenuator 52, the signal condi AS another example, the monitoring System 10' can be tioner 54 and the offset DAC 56, the attenuator 52 is in used for detecting transients in the heartbeat of a human (i.e., communication with the analog signal Source 14 to receive monitor site 36). The monitor 12' is configured to monitor a 50 the analog signal over the analog Signal bus 58. The attenu Stimulus (electrical impulses) produced by the heart. Trans ator 52 is in communication with the signal conditioner 54 ducers (here, electrical sensors) 34 are placed at various to provide an attenuated Signal over an attenuated analog places on the human body to detect the electrical impulses Signal line 62, and the Signal conditioner 54 is in commu that occur during the heartbeat. Again, each transducer 34 nication with the A/D converter 50 to provide a conditioned continuously detects and converts the Stimulus into an 55 analog signal over a conditioned analog Signal line 64. The analog signal, and the analog signals pass to the monitoring offset DAC 56 is in communication with the signal condi units 18, 18", and 18" over the channels 16', 16", and 16", tioner 54 over a signal line 55. respectively. In embodiments not having the attenuator 52, the Signal FIG. 3 shows another embodiment of the monitoring conditioner 54 is in communication with the analog signal System 10" including a metering device 44 embodying the 60 Source 14 to receive the input analog signal Over the analog principles of the invention. The metering device 44 includes signal bus 58 and with the AID converter 50 to provide the a monitor 12" having a monitoring unit 45. The monitoring conditioned analog Signal over the conditioned analog signal unit 45 is a specific embodiment of the monitoring unit 18 line 64. shown in FIG.1. The monitoring unit 45 is in communica Features of the A/D converter 50 include an input voltage tion with a storage system 28" by a bus 47 for providing to 65 range, a resolution, and a Sampling rate. In one embodiment, the Storage System 28" parameter values computed by the the A/D converter 50 is an AD9410, manufactured by monitoring unit 45. Analog Devices of Norwood, Mass., which has a +/-0.75 V 7 US 6,639,538 B1 10 full Scale input voltage range, a 10-bit resolution, and a 74 in the order that the digital data samples arrive at the sampling rate of at least 200 MHz. memory buffer 74. In one embodiment, the capacity of the The input voltage range depends upon the minimum and memory buffer 74 is 128K32-bit words. One component for maximum Voltages of the input analog Signal received from implementing the memory buffer 74 is an IDT72V36110, the analog signal Source 14 or of the conditioned analog manufactured by Integrated Device Technology of Santa Signal received from the Signal conditioner 54. Clara, Calif. The resolution determines the number of Voltage Steps The DSP 78 is programmable, has its own native instruc that are to be resolved by the AID converter 50. For tion code and local registers, and is designed to execute arithmetic operations more rapidly and efficiently than Stan example, an A/D converter with 10-bit resolution divides the dard microprocessors. The DSP 78 can implement input analog signal into 2" or 1,024 steps, producing 10 bits instruction-level parallelism and operate in an architecture of digital data for each Sample. that Supports multiple operations in a single clock cycle, for An external Sampling clock 66 is in communication with example, VLIW (Very Large Instruction Word). In one the A/D converter 50 to provide a clock signal over signal embodiment, the DSP 78 is implemented using a line 68 that controls the sample rate of the A/D converter 50. 15 TMS320C6201, manufactured by Texas Instruments of The sample rate determines how accurately the input analog Dallas, TeX. Signal is characterized. The Sample rate should be Suffi The program memory 82 Stores a program that instructs ciently high to capture transients associated with the type of the DSP 78 regarding which parameter values to compute Stimulus targeted by the monitor 12. As a general rule, the and where to Store the computed values. The program Sampling rate is at least twice the maximum frequency memory 82 also stores configuration information for the component in the analog signal 58. For example, to capture programmable logic units 86, 70, and 90 to be used during transients induced by lightning with frequency components operation by the DSP 78 to program the programmable logic as high as 10 MHz, the sampling rate is at least 20 MHz. For units 86, 70, and 90. In one embodiment, the program lower frequency components, Such as those present in the memory 82 is a re-programmable device, such as a FLASH electrical impulses of a heartbeat, the A/D converter 50 can 25 ROM. In this embodiment, the program stored in the pro Sample at a lower rate. gram memory 82 can be modified to reconfigure the func The digital circuitry 22 includes programmable logic tionality of the DSP 78, programmable logic units 86, 70, control 70 in communication with the attenuator 52 and and 90, and thus of the monitor 12. offset DAC 56 by a control signal line 72, with a memory The reconfigurability of the monitor 12 facilitates changes buffer 74 by a control signal line 76, with a digital signal to the monitor 12 functionality after the monitor 12 has been processor (DSP) 78 by a control signal line 80, with a deployed in the field. The program memory 82 can be programmable logic processing unit 86 by a control Signal reprogrammed in situ or replaced with a new ROM device line 87, and with a bus interface 90 by a control signal line having new program. For example, if the monitor 12 is 91. The DSP 78 is in communication with a program initially programmed to compute a value for a first type of memory 82 over signal line 84. The memory buffer 74 is in 35 parameter, Such as energy, the monitor 12 can be repro communication with the A/D converter 50 to acquire in grammed to compute a different parameter value. Also, by real-time the digitized signal produced by the A/D converter changing the program that controls the monitor 12, the 50 over the digitized signal bus 60. The memory buffer 74 monitor 12 that once was configured for a first type of is also in communication with the DSP 78 and the program transient, for example, electromagnetic transients associated mable logic processing unit 86 by digital signal lines 88 that 40 with lightning, can presently monitor a different type of carry digital data. In one embodiment, the DSP 78 and the transient, for example, transients associated with chemical programmable logic processing unit 86 are incorporated in reactions. Modifying the monitor 12 to work with a different a single processing unit. type of targeted Stimulus can require other changes, for The DSP 78 and the programmable logic processing unit example, a different type of transducer that is capable of 86 are in communication with the bus interface 90 by data 45 detecting the new target Stimulus. busses 92, 94 respectively. The bus interface 90 is in This re-programmability of the program memory 82 thus communication with the storage system 28 by the bus 26. provides the monitor 12 with greater flexibility than moni The bus interface 90 handles the transfer of digital data tors that are customized with Specific hardware components between the DSP 78 and the storage system 28 and between to compute certain parameters. For example, this program the programmable logic processing unit 86 and the Storage 50 mability enables the configuration of the monitor 12 to be system 28. customized during manufacturing, that is, in accordance In one embodiment, the programmable logic control 70, with Specified requirements of the customer. In another the programmable logic processing unit 86, and the bus example, the monitor 12 can be customized in Situ after interface 90 are implemented by a Single programmable being delivered to the customer and installed. logic device (PLD). This PLD is dynamically programmable 55 Unlike the monitor 12 of the invention, monitors with and its functionality can be changed in situ. An example of custom-specific hardware cannot be reconfigured to com such a PLD is the EPF10K100, manufactured by Altera of pute a different parameter or to respond to a different San Jose, Calif. A portion of this particular PLD is config Stimulus without having to replace the custom-Specific hard ured to communicate with an ISA bus. A different bus other ware with new custom-specific hardware tuned to charac than an ISA bus and a corresponding bus interface can be 60 terize the different parameter. The difficulty and complexity used without departing from the principles of the invention. of reconfiguring Such monitors effectively discourages any Depending upon designer preferences, the functionality of Such reconfiguration. In contrast, reconfiguring the monitor one or more of the other components of the digital circuitry 12 of the invention to compute a different parameter value 22, such as the DSP 78 and the memory buffer 74, can also or to Search for transients in a different type of Stimulus can be implemented in the PLD. 65 be achieved by reprogramming, and without having to The memory buffer 74 operates in FIFO (first-in, first-out) replace hardware components to tune the performance of the fashion; that is, digital data Samples exit the memory buffer monitor 12. 7 US 6,639,538 B1 11 12 Optionally, the monitor 12 includes self-test circuitry 98. In another embodiment, the Signal conditioner 54 ampli By activating the Selftest circuitry 98, a user can check fies the analog signal. Continuing with the preceding whether the monitor 12 is operating properly. In one example, the Signal conditioner 54 can amplify the biased embodiment, the self-test circuitry 98 is in communication Signal to produce the conditioned analog signal with a with the programmable logic control 70 by control line 104, voltage range between 0 and 10 volts (in this example, the and with an input terminal 106 of the conversion circuitry 20 Signal conditioner 54 has again of 5). The signal conditioner by control line 108. 54 provides the conditioned analog signal to the A/D con The DSP 78 activates a self-test by sending a first control verter 50 over conditioned analog signal line 64. Signal to the programmable logic control 70 over the control In another embodiment, the Signal conditioner 54 pro line 80. In response, the programmable logic control 70 vides an offset adjustment in order to accurately measure sends a control signal to the self-test circuitry 98 over small DC signals. The programmable logic control 70 pro control line 104. The self-test circuitry 98 issues a control vides a control signal to the offset DAC 56 over control line signal that allows the input terminal 106 to be disabled. 72, instructing the offset DAC 56 as to the voltage offset to Disconnecting the input terminal 106 prevents the monitor apply to the attenuated analog signal Over the Signal line 55. 12 from receiving the analog Signal from the analog signal 15 In yet another embodiment, the signal conditioner 54 Source 14. converts a single-ended input signal into a differential signal. When disconnecting the input terminal 106 to the con In this case, the input signal 62 is a single conductor with a version circuitry 20, the self-test circuitry 98 issues a dis Voltage referenced to ground. The Signal conditioner 54 connect signal over control line 108. The self-test circuitry converts this signal into a differential Signal. Output condi 98 generates an analog test Signal and injects the analog test tioned signal 64 thus consists of two conductors, each at a signal into the input terminal 106 over the signal line 108. common potential to ground, but with the potential between In an embodiment without the attenuator 52, the offset DAC them representing the Signal. For example, if the input Signal 56 generates the analog test signal and injects the analog test 62 is a Signal of +/-1 volt, referenced to ground, the Signal signal into the signal conditioner 54 over the signal line 55. 25 conditioner 54 transforms that input Signal 62 into an output From the analog test signal, the AID converter 50 produces conditioned signal 64 consisting of two conductors with a a stream of digital data Samples that passes to the memory potential difference of +/-1 volt between them. buffer 74. The DSP 78 computes parameter values from the The A/D converter 50 receives the conditioned analog digital data Samples and forwards the parameter values to Signal over Signal line 64 and, for each clock signal received the Storage System 28. An application program can then from the Sampling clock over clock signal line 68, Samples compare the computed parameter values with expected (step 158) and digitizes (step 160) the conditioned analog results to determine if the monitoring unit 18 is operating Signal into a continuous Stream of digital data. Upon digi properly. tizing the conditioned analog signal, the A/D converter 50 FIG. 5A and FIG. 5B show an embodiment of a process forwards (step 162) the digital data Samples to the memory 150 performed by the monitor 12 shown in FIG. 4. For the 35 buffer 74 over the digitized signal bus 60. The steps of purpose of illustration, the monitor 12 includes the attenu receiving, Sampling, and digitizing the analog signal to ator 52 and the signal conditioner 54. Referring to FIG. 5A produce digital data Samples, and forwarding the digital data and to FIG. 4, in step 152 the monitor 12 receives an analog Samples to the memory buffer 74 occur continuously during Signal Over input analog signal line 58. In one embodiment, the process 150. the analog Signal represents a Stimulus detected by a trans 40 Referring to FIG. 5B, in step 164, the programmable logic ducer placed at a monitor Site. control 70 sends a control signal over control line 76 to the The attenuator 52 attenuates (step 154) the input analog memory buffer 74 to prepare the memory buffer 74 to Signal 58 to produce an attenuated Signal. For example, if the receive digital data samples from the A/D converter 50. The input analog signal has an input voltage range between DSP 78 and the programmable logic processing unit 86 +/-20 volts, the attenuator 52 can produce an attenuated 45 concurrently obtain the digital data Samples from the Signal with a reduced Voltage range of +/-5 volts. The memory buffer 74 over the digital data bus 88. The pro programmable logic control 70 provides a control signal to grammable logic control 70 also sends a control Signal to the the attenuator 52 over control line 72. This control signal DSP 78 over the control line 80 instructing the DSP 78 when instructs the attenuator 52 as to the amount of attenuation to to compute parameter values, when to cooperate with the apply to the input analog Signal. The attenuator 52 provides 50 programmable logic processing unit 86, and when to provide the attenuated Signal to the Signal conditioner 54 over the computed values to the bus interface 90. attenuated analog Signal line 62. The DSP 78 retrieves program instructions stored in the The signal conditioner 54 modifies (step 156) the attenu program memory 82 over the signal line 84. Under the ated analog signal received from the attenuator 52 to pro control of the retrieved instructions, the DSP 78 computes duce a conditioned analog signal having particular input 55 (step 166) one or more parameter values from the digital characteristics suitable for input to the A/D converter 50. data samples obtained from the memory buffer 74, for Examples of Signal conditioning that may be required by the example, in blocks or chunks of Samples. In one A/D converter 50 include additional gain or attenuation, embodiment, the computed parameters that are measured level shifting, offset trimming, and conversion of a single from the digital data include the peak negative amplitude, ended Sensor Signal into a differential A/D Signal. 60 peak positive amplitude, the duration and rate of rise of In one embodiment, a function of the Signal conditioner positive and negative transients, peak energy, and peak 54 is to bias the analog signal So that the analog signal has power of the input analog signal. Computing Such param a particular voltage input range compatible with the AID eters in the digital domain, rather than using analog circuitry converter 50 (e.g., having a minimum of 0 Volts). AS an to make the computations, improves the accuracy of the illustration, if the attenuated Signal has a Voltage range of 65 measurements. The DSP 78 then stores the parameter value +/-1 volt, the Signal conditioner 54 biases the analog signal (s) in a local register and, in one embodiment, no longer uses to have a Voltage range, for example, of 0 to 2 volts. the digital data Samples from which the parameter values are 7 US 6,639,538 B1 13 14 computed. In effect, the raw digital data Samples (i.e., the When the process of outputting parameter values is com digitized analog signal that represented the Stimulus) are plete (step 172), the DSP 78 sends a signal to the program thrown away. Other embodiments can Save the raw digital mable logic control unit 70, indicating that the DSP 78 is data Samples for Subsequent processing. available to receive new digital data. The DSP 78 resumes In one embodiment, the programmable logic processing obtaining digital data from the memory buffer 74 (step 164) unit 86 cooperates with the DSP 78 to perform parameter and computing parameter values (step 1.66). value computations. As the DSP 78 reads in digital data on During the process 150, the memory buffer 74 is typically buS 88, the programmable logic processing unit 86 decodes nearly empty. The rate at which the DSP 78 retrieves digital this operation and Simultaneously reads the Same digital data from the memory buffer 74 exceeds the rate at which data. Consider, for example, the computation of peak energy. the memory buffer 74 receives new digital data from the To compute the peak energy from the digital data, the DSP conversion circuitry 20. Unless the DSP 78 is outputting 78 performs the more computationally intensive calculations computed values, the DSP 78 processes digital data samples involved in computing the energy, Such as Squaring the (e.g., in blocks or chunks of Samples) Soon after the data digital data value, and the programmable logic processing samples are available in the memory buffer 74. When the unit 86 performs less complicated calculations, Such as 15 DSP 78 is outputting values to the bus interface 90, digital determining the peak amplitude by comparing the digital data Samples begin to accumulate in the memory buffer 74. data on the bus 88 with a currently stored amplitude, and The rate at which the memory buffer 74 receives new digital storing the value on the digital data bus 88, if that value is data Samples, the size (i.e., depth) of the memory buffer 74, larger. the time it takes for the DSP 78 to complete outputting parameter values, and the rate at which the DSP 78 retrieves In step 168, it is determined whether to output the digital data samples from the memory buffer 74 contribute computed parameter value to the bus 26. The programmable to preventing the memory buffer 74 from overflowing. logic control 70 provides a control signal over signal line 80 While the invention has been shown and described with instructing the DSP 78 to provide the computed parameter reference to specific preferred embodiments, it should be values to the bus interface 90. The programmable logic 25 understood by those skilled in the art that various changes in control 70 can be programmed to issue this control Signal form and detail may be made therein without departing from periodically, or under the control of the Storage System 28 by the Spirit and Scope of the invention as defined by the signal line 91 from the bus interface 90. following claims. More specifically, although the described In those embodiments in which the DSP 78 and program embodiments achieve real-time transient pulse monitoring mable logic processing unit 86 cooperate to compute values, without dead time by employing an A/D converter, buffer the programmable logic control 70 provides a control Signal memory, and a digital Signal processor, various changes to over Signal line 87 instructing the programmable logic this configuration may be made to ensure a continuous processing unit 86 to provide the computed parameter values Stream of digital data and real-time processing of that digital to the bus interface 90. Using the previous example involv data Stream. For example, one change is to use a digital ing the computation of peak amplitude, in response to 35 Signal processor that does not interrupt computing parameter receiving a control Signal from the programmable logic values to output data to the bus. In another example, control 70 over signal line 87, the programmable logic continuous processing of the digital data is achieved by processing unit 86 outputs the current Stored amplitude alternating between a pair of digital Signal processors; that value to the bus interface 90, for Subsequent forwarding to is, alternately, one digital signal processor receives digital the Storage System 28. This value represents the peak signal 40 data and computes parameter values while the other digital amplitude detected Since the previous amplitude value that Signal processor outputs the parameter values that it has the programmable logic processing unit 86 provided to the computed. In another example, multiple digital Signal pro bus interface 90. The stored amplitude value is then reset in ceSSors are employed, each computing, in parallel, a char preparation for Subsequent computations. acteristic or Set of characteristics of the input signal. In one embodiment of the process 150, providing param 45 What is claimed is: eter values to the bus interface 90 interrupts the processing 1. A System for characterizing a stimulus represented by of the digital data by the DSP 78 and, where applicable, by an analog signal, the System comprising: the programmable logic processing unit 86. The duration of conversion circuitry continuously receiving the analog the interruption is less than the size of the memory buffer (in Signal and converting the analog signal into digital Samples) divided by the frequency of the sampling clock 66. 50 data; and During this interruption, the DSP 78 or the programmable digital circuitry in communication with the conversion logic processing unit 86 does not obtain digital data from the circuitry to receive continuously the digital data from memory buffer 74 and does not compute additional param the conversion circuitry, the digital circuitry dynami eter values Thus, the DSP 78 and the programmable logic cally computing from the digital data a value that processing unit 86 continuously retrieve digital data from 55 characterizes a parameter of the Stimulus while the the memory buffer 74 except while outputting a computed digital circuitry continuously receives new digital data value to the bus 26. from the conversion circuitry. If it is not yet time to output the computed parameter 2. The system of claim 1 wherein the digital circuitry is in value(s), the DSP 78 and programmable logic processing communication with a bus, and wherein the digital circuitry unit 86 continue to obtain digital data from the memory 60 outputs the computed value over the buS while the digital buffer 74 and to compute parameter values (steps 164 and circuitry continuously receives new digital data from the 166). If it is time to output computed values, in step 170 the conversion circuitry. DSP 78 and the programmable logic processing unit 86 3. The system of claim 1, wherein the characterized transfer the computed value(s) to the bus interface 90 over parameter is a first parameter, and wherein the digital data lines 92 and 94, respectively. The bus interface 90 65 circuitry is programmed to characterize the first parameter provides the parameter value(s) to the Storage System 28 and is re-programmable to characterize a Second parameter over the bus 26. that is different than the first parameter. 7 US 6,639,538 B1 15 16 4. The system of claim 3 wherein the stimulus is of a first memory buffer continuously receiving new digital data type of Stimulus and wherein the Second parameter is from the analog-to-digital converter while the process asSociated with a different type of Stimulus than the first type ing unit processes digital data received from the of Stimulus. memory buffer to compute the value that characterizes 5. The system of claim 1, wherein the characterized 5 the parameter of the Stimulus. parameter is a peak amplitude of the Stimulus. 15. The system of claim 14 wherein the processing unit 6. The system of claim 1, wherein the characterized includes a digital Signal processor in communication with parameter is a peak energy of the Stimulus. the memory buffer. 7. The system of claim 1, wherein the conversion circuitry 16. The system of claim 15 wherein the processing unit and the digital circuitry are provided on the same circuit includes programmable logic in communication with the board. 8. The system of claim 1 wherein the conversion circuitry memory buffer to receive concurrently the Same digital data and digital circuitry are provided in a computer System. that are received by the digital signal processor, the pro 9. The system of claim 1, wherein the conversion circuitry grammable logic and the digital Signal processor dynami and digital circuitry are provided on the same integrated 15 cally computing, from the same digital data, values that circuit chip. characterize different parameters of the Stimulus. 10. The system of claim 1, wherein the digital circuitry 17. The system of claim 14 wherein a rate at which the includes: memory buffer receives new digital data from the AID program memory Storing a first program; and converter is less than a rate at which the processing unit a digital signal processor in communication with the obtains digital data from the memory buffer. program memory, the digital Signal processor comput 18. The system of claim 14 wherein the processing unit continuously obtains digital data from the memory buffer ing the value that characterizes the parameter as except while the processing unit is outputting a computed directed by the first program, and value. wherein the program memory is re-programmable to Store 25 19. The system of claim 14, wherein the characterized a Second program that instructs the digital Signal pro parameter is a first parameter, and wherein the processing ceSSor to compute a value that characterizes a different unit is programmed to characterize the first parameter and is parameter than the parameter characterized according re-programmable to characterize a Second parameter that is to the first program. different than the first parameter. 11. The System of claim 10, further comprising program 20. The system of claim 19 wherein the stimulus is of a mable logic in communication with the digital Signal first type of Stimulus and wherein the Second parameter is processor, the programmable logic computing a value that asSociated with a different type of Stimulus than the first type characterizes a Second parameter as directed by the first of Stimulus. program, the programmable logic being re-programmable 21. A method of characterizing a Stimulus represented by by the digital signal processor as directed by the Second 35 an analog signal, the method comprising: program. continuously receiving digital data digitized from the 12. The system of claim 1 wherein the conversion cir analog signal representing the Stimulus, and cuitry comprises a Signal conditioner that receives the ana dynamically computing from the continuously received log signal, the Signal conditioner modifying the analog Signal to produce a modified analog Signal having a particu digital data a value that characterizes a parameter of the lar Voltage range. 40 Stimulus while receiving new digital data digitized 13. The system of claim 1 further comprising self-test from the analog signal representing the Stimulus. circuitry. 22. The method of claim 21 further comprising converting 14. A System for characterizing a Stimulus represented by the analog signal representing the Stimulus into the digital an analog signal, the System comprising: data that are continuously received. 45 23. The method of claim 21 further comprising processing an analog-to-digital converter receiving the analog signal the continuously received digital data at a rate that is greater and converting the analog signal into digital data; than a rate at which the new digital data are received. a processing unit dynamically computing from the digital 24. The method of claim 21 further comprising Storing, data a value that characterizes a parameter of the for Subsequent processing, new digital data that are received Stimulus, and 50 while the computed value is being provided to a bus. a memory buffer in communication between the analog to-digital converter and the processing unit, the k k k k k 7 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO.: 6,639,538 B1 Page 1 of 1 DATED: October 28, 2003 INVENTOR(S): Sechi et al. It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below: Column 6 Line 29, delete "SPx" and Substitute -- SPX --. Line33, delete "18".'" and Substitute -- 18'. -- Column 8 Line 43, delete "A/ID' and Substitute -- A/D --. Line 60, delete "AID' and Substitute -- A/D --, Column 9 Line 8, delete "AID' and Substitute -- A/D -- Column 11 Lines 25 and 62, delete "AID' and Substitute -- A/D --. Column 16 Line 17, delete "AID' and Substitute -- A/D --. Signed and Sealed this Sixth Day of January, 2004 JAMES E ROGAN Director of the United States Patent and Trademark Office