Patent Publication Number: US-2013239709-A1

Title: Multi-function measurement and signal generation device with application selector

Description:
BACKGROUND 
     1. Technical Field Disclosure 
     The present disclosure relates generally to test, measurement, signal generation and similar research and development as well as industrial control devices and methods. 
     2. Description of the Related Art 
     Test and measurement, or alternatively, measurement and signal generation, is typically used as a description for any measurement or signal generation function that receives at least one input from an electrical input or a sensor and that can optionally generate one or more outputs to an electrical output connector or other signal receiving unit. 
     Measurement domains refers generally to measurement functions typically handled by different measurement instruments, such as volt meters, audio measurement, power supplies, waveform generators, optical measurements, communication analyzers, PID controllers etc. These are examples of instruments that work in different measurement domains. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     With the availability of flexible user interfaces, graphical screens and fast signal processors, new possibilities arise in the design of test and development equipment. 
     The traditional test and measurement instruments are mostly dedicated devices within each measurement domain such as; oscilloscopes, digital multi-meters, signal generators, PID controllers, electronic loads, power supplies, optical power meters, temperature meters etc. 
     By analyzing the hardware in many of these devices it was observed that the same signal input hardware and in some cases output hardware is present in many of them. The device presented here has flexible input measurement hardware and optionally output generation capabilities, and by designing the underlying hardware in a specific way the same instrument can support most of these measurement and signal generation types. 
     For each measurement type, software application code controls the available hardware in a specific way. These software applications can interact with the hardware to fit the specific function required. An application selector will enable the user to select which one of the measurement applications is running and controlling the measurement and signal generation hardware, and the graphical display in the device will show values, parameters, and user selections specific to that measurement application. 
     Of the instruments in existence today the digital multi-meter is well known. However, this type of instrument has fixed selectors for the measurement types and fixed measurement types on small dedicated displays. It does not have a flexible application selector that can be upgraded or modified. Further they only support signal measurement, not signal generation or any other more advanced type of signal processing. 
     The described approach with an application selector is very flexible, and one instrument will be able to support and replace many dedicated test and measurement instruments. Further enhancing flexibility is the support for uploading new measurement applications from a host. A user requiring a special measurement or signal generation type could upload a new instrument definition that will be present in the application selector and re-use the underlying hardware. 
     Some approaches to this are signal acquisition cards or modules that can be configured by a host to perform a measurement or control job, but these instruments lack the flexible application selector, graphical screen and self-contained operation of the instrument described here. 
     Examples of measurement types and instruments that can be supported with just one available input;
         Standard voltage and current measurements   Panel meters   Oscilloscopes   Data loggers   Thermometers       

     Multiple inputs can support multi-channel operations or more advanced measurement and signal processing applications. 
     Typical instrument types with an output could be:
         Power supplies   Signal generators   PID controllers   Audio analyzers   Power drivers   Battery chargers/analyzers       

     These are just examples of typical instruments that can be designed and selected in an application selector based on the same hardware. 
     For multi-channel units each channel can run the same software and applications, but have individual application selectors and in some implementations individual processing units thereby running different measurement and test applications in the same physical device. 
     The physical implementation of these devices can be in the form of hand-held battery operated units, desktop units for R&amp;D purposes, industrial type units for rack mounting or any other form factor that is required. 
    
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing and other features and advantages of the present disclosure will be more readily appreciated as the same become better understood from the following detailed description when taken in conjunction with the following drawings, wherein: 
         FIG. 1  is a block diagram of a test and measurement system formed in accordance with the present disclosure; 
         FIG. 2  is a block diagram of another example of a test and measurement system formed in accordance with the present disclosure; 
         FIG. 3  illustrates an application selector menu for use with the systems of  FIGS. 1 and 2 ; 
         FIG. 4  illustrates an application selected by the application selector of  FIG. 4 ; 
         FIG. 5  illustrates a power supply application selected by the application selector of  FIG. 4 ; 
         FIG. 6  shows an example implementation of an handheld device formed in accordance with the present disclosure; and 
         FIG. 7  illustrates a representative R&amp;D type instrument with two channels formed in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures or components or both associated with measurement and test devices, including multi-meters, signal generators, and the like have not been shown or described in order to avoid unnecessarily obscuring descriptions of the embodiments. 
     Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and variations thereof, such as “comprises” and “comprising” are to be construed in an open inclusive sense, that is, as “including, but not limited to.” The foregoing applies equally to the words “including” and “having.” 
     Reference throughout this description to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
       FIG. 1  is a block diagram that shows a representative example of an overall test and measurement system  10  that includes an application selector  12 , an application processor  14 , a graphical display  16  and a measurement front-end  18 ,  20 ,  22 , and  24 . In this embodiment each channel has a controller  14  and a display  16  to show the application selector  12  and applications  26 . Four channels are shown. 
     The device may have communication interfaces  28  and battery operation provided by batteries  30 . 
     The hardware front end typically consists of electrical isolation  32 , analog to digital converters and digital to analog converters  34 , input buffers, amplifiers and attenuation  36 , input(s)  38  and output(s)  40 . 
       FIG. 2  shows another example of the overall test and measurement system  42  concept with an application selector  44 , an application processor  46 , a graphical display  48  and a measurement front-end  50 . In this embodiment a common processor controls multiple channels, but uses only one graphical display  48  for displaying multiple of application selectors  44  and applications  52 . 
     Also shown are a user input  54 , communication interfaces  56 , and a source of stored power, such as a battery  58 . Electrical isolation  60  is also provided between the instrument controller/processor  46  and the measurement hardware  50 . As in the first example system, inputs  62  and an out  64  are provided that connect to the input buffers, amplifiers, and attenuation devices  66 . Four measurement channels  68  are shown in this system to correspond to the four applications  42 . 
       FIG. 3  shows a typical application selector menu  70 ; this can be based on text, graphical symbols or a combination thereof. 
       FIG. 4  shows a typical application  72  selected by the application selector. In this case a PID controller application is shown. 
       FIG. 5  shows another typical application, in this case a power supply application  74 . 
       FIG. 6  shows an example implementation where the device is built in a handheld format  76 . 
       FIG. 7  shows an example of a R&amp;D type instrument  78  with two channels  80 ,  82  showing two different applications  84 ,  86  running the same overall software. 
     This systems and devices shown and described herein are unique in their approach because they are not limited to specific test and measurement applications, such as DMMs, oscilloscopes, signal generators, temperature controllers, programmable logic controllers etc. These systems and devices can perform all these functions, in a self-contained instrument, only limited by the available inputs, outputs, and the design of the hardware front-end. The hardware front-end is designed to be generic and cover a wide range of input specifications, samples rates and resolutions. The application selector selects the application and the selected application controls the front-end hardware to determine the specific test and measurement function. This approach offers almost unlimited flexibility. 
     When an application is running it takes complete control of the available measurement and signal generation hardware, as well as external inputs and outputs. The application can perform any function within the constraints of the implemented hardware. 
     The representative systems and devices described here use a graphical display for displaying the application selector and measurement and signal generation applications. The graphical display can be of types such as TFT, LCD, OLED, VFD or other types of graphical displays in monochrome, grayscale or color. An embedded computer such as a microcontroller, signal processor or application processor can control the pixels on the display to show text and graphical data in the form of graphs, curves, trends and other graphical representations. 
     The application selector is software defined and can be updated and changed by upgrading the software, or a remote computer can update the application selector to add or remove applications on the device. Each application selector item corresponds to a software defined application that performs measurement functions, signal generation functions, signal processing and transformation as well as user interaction. The applications can optionally be remotely updated to allow changes or new functionality. 
     The application selector can be implemented in various ways, but will typically be a list or a grid of text or icons, or a combination thereof, that describe or illustrate the test and measurement application. 
     When a measurement or signal generation application is selected the display shows values and data related to this application. These values can be measurement of input data, processed data, scaled data, filtered data or any other signal processing function as well as graphical data or any other representation. 
     The devices described herein are multi-purpose devices and will have at least two different measurement applications, but typically many more applications that perform different functions and displays different measurement or signal generation data. Applications will typically be spread over different measurement domains, such as industrial, audio, precision measurement, sensor reading etc., but they may also have variations of different applications within the same domains. 
     The user can select between these applications on a touch screen or with a rotary dial or other selection means. The embedded controller receives this input and shows a corresponding software defined application on the display. These devices can have multiple channels each with an independent application selector for performing measurements and signal generation on each channel. 
     At least one measurement input is provided, and will typically have two or more measurement inputs for performing more advanced measurements and can optionally have one or more signal generation outputs for generation of waveforms or for outputting signals related to the input. 
     In a preferred embodiment there are two high resolution measurement inputs that can sample with very high precision, using an analog to digital converter, with typically 16, 24, or 32-bits resolution and with sample rates from a few samples per second to millions of samples per second. Two additional analog to digital converters on the same two inputs can sample with lower resolution such as 8-bits, 10-bits or 12-bits with higher resolution such as 10 Msamples/sec, 100 Msamples/sec or 1 Gsamples per sec or higher to broaden the measurement functions. The inputs can have comparators for high speed digital input functions and buffers and attenuation hardware for minimal load of the input source. 
     In a preferred embodiment there are one or more outputs for signal generation as well. These outputs can be controlled using digital to analog converters and they can be amplified to source signal level currents or high current applications. In a typical preferred embodiment these outputs will supply 10 mA to 25 A. These outputs can be amplified outputs for DC sourcing such as a power supply, or as a driver for waveform generation for driving coils, motors, LEDs, lasers, or any other device. 
     The inputs will in the preferred embodiment have electrical isolation between the measurement front end and the embedded processor, so that the measurement inputs and signal generation outputs are not affected by ground levels or the electrical potential of other channels. This ensures that the measurement input/outputs can be safely connected to any circuit. 
     In the preferred embodiment the inputs can act as differential or single ended inputs to increase versatility. Used as single end inputs, each input can measure individually, whereas in differential mode they can act as sense inputs in power supply applications etc. 
     Examples of different measurement and signal generation functions:
         Digital Multi-meter, voltage measurement, current measurement, resistance measurement.   Oscilloscope, dynamic voltage measurement.   Signal generator/waveform generator   Temperature measurement from thermocouples, NTCs, PTCs, semiconductors, PT 100 or other sensors.   Power supply, voltage driver, current driver, power driver   PID controller   Programmable amplifier   Programmable filter   Lock in amplifier   Device characterization with sweeping functions, such as testing I/V relations of semiconductors.   Driver for LEDs and laser sources   Coil driver, drivers, speakers, solenoids, galvanometers etc.   Motor driver for DC motors, step motors, brushless motors and other motor types with encoder inputs.   Programmable thermostat   Oscilloscope amplifier and measurement front end with differential inputs   Programmable logic controller for industrial control   Programmable industrial test controller   Production monitoring and documentation   Battery chargers, analyzer, characterization tool for multi-battery chemistry   Characterization of power supplies   Programmable electronic load   Programmable advanced load with capacitive, inductive, resistive and other modes.   Communication line characterization and test and evaluation   Driver and controller for oven heating elements and temperature sequencing   Production monitoring with alarm and stop functions for production lines.   Data logging and trend logging with non-volatile memory   Sensor measurement, such as strain gauges, hygrometers, mems sensors, accelerometers, photo diodes, PH sensors, Hall sensors etc.   Driver for peltier elements with temperature control.   Digital I/O driver with communication interface simulation, such as SPI, I2C, UART etc.   Pulse generator and pulse capture function.   Power analyzer, efficiency, watts consumed, energy etc.   Energy meters, short or long term energy measurement for AC or DC sources.   Drivers, converters and loads for solar panels.   High current measurement.   Environmental measurement station.   High current light source (laser Led etc) driver with feedback and control.   Audio analyzer   Panel meter   Insulation and short circuit tester.   Fan controller   LCR meter       

     This is a list of examples of general measurement and signal generation applications that can be implemented within the same device. This flexibility in combination with multiple independently operating channels gives tremendous flexibility and functionality as it reduces the need to invest in multiple instruments. 
     Other than generic measurement and signal generation functions, very specific functions can be created in separate applications by adding a minimum of hardware to the generic inputs/outputs. A few examples of this could be:
         Machine coordinate display   Power quality meter   Weight scale based on strain gauge   IR thermometer based on pyrometers or thermo electric cells.   Color detector/calibrator   Sound level meter.   Controller for optical scanner.       

     Different measurement domains, such as electrical measurement, optical measurements, sensor measurements, drivers, PID controllers, digital control functions, audio, battery are all combined into one instrument with readout in the units that correspond to the measurement domain for clear and easy interpretation. 
     A host based or internal application generator can be used to create new or derived applications. As an example, if a PID controller with a temperature input is required to stabilize a heat plate, the important parameter could be the temperature of the heat plate, or the power required to the heat plate or a derived temperature measurement in another location in the test setup. By creating a new derived application from a PID controller application other display values can be added or logged into non-volatile memory, thereby adding a customized application to the application selector without changing any of the other existing applications and measurement capabilities. 
     A community of user derived applications could be uploaded and managed in an online database and reused by other users of the device, much like software on generic computers, but relying on well-defined measurement and signal generation hardware. 
     In signal generation applications output waveforms may be simple square wave, sine, triangle and other standard waveforms, but may also be much more complex waveforms either computed or derived from input measurements. An example of this could be a PID controller that bases its output on a reference and a feedback input, or advanced filtering of inputs with simple filters or complex filters. 
     A non-volatile memory in the device, such as EEPROM, flash, battery backed up RAM, hard disk drive or other type of memory may be used to save measurement values for later display or processing. In a typical data-logger application samples are measured at regular intervals and display in a compressed graph later or uploaded to a host system. With the integration of non-volatile memory the device can be powered off and moved to a new location without losing measurement data. 
     In a preferred embodiment the device will typically have a number of host interfaces such as USB, Ethernet, CAN or other communication interfaces that will enable upload of measurement data to a host or download of new or revised applications on the device or pre-defined measurement data. 
     These interfaces are optional and the device will be able to operate independently displaying its data on the graphical screen and the device can, for complete self-containment, have an internal power source, such as a lithium ion, lithium polymer, NiMh, NiCd or other type of battery, that may be embedded in the device. Unlike other host controlled sampling and measurement devices, this device will be able to work completely self-contained. 
     The host communication hardware may also be used for inter-device communication and exchange of data, enabling one device to send measurement data to another device. This could prove very useful if the number of inputs or outputs required for a measurement application exceed the number of inputs/outputs available on one device. 
     Another feature that may be implemented is a time synchronization feature that will enable multiple measurement channels to acquire synchronized measurement data. In a typical 16-channel input measurement application, 8 measurement channels with 2 inputs on each could be synchronized to sample at the same time. This synchronization feature could be implemented via a simple trigger signal or as part of a CAN interface or Ethernet interface with time syncing features or other similar ways. 
     The device may be designed in various physical formats. In a preferred embodiment, the device will be a two channel desktop device with one graphical screen to control both channels, but with two independent application selectors. The device and technology are not limited to a specific physical implementation. One unit could have eight channels in a desktop device, another could be a small hand-held device for field service and diagnostic, yet again other implementations may include rack mounted unit or DIN rail device with one or more channels. 
     These devices may be used in many locations such as in R&amp;D labs, production lines, industrial control, field service, home use, remote sensing or any other location. 
     In all embodiments the application selector and the applications themselves are software defined. In some embodiments the application selector and applications can be upgraded, deleted, modified or otherwise changed to suit a specific measurement application either remotely or by using a local feature. 
     The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, application and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.