System and method for combining frames to generate electrical signals

Abstract

A system is provided for combining frames in a plurality of ways to provide as output a new frame comprising a function of the combined frames. A system is also provided for combining a plurality of frames to provide as output a new frame that generates a specified average period as a function of the periods of the combined frames.

Claims

1. A system for combining frames to generate electrical signals, comprising: an input for receiving a plurality of frame definitions, including a first frame definition and a next frame definition; a processor for combining the first frame definition with the next frame definition to provide a new frame definition; and an output to provide the new frame definition to a signal generator configured to generate electrical signals representing the new frame definition.

2. The system of claim 1, wherein the frames are combined by concatenating first frame with a second frame.

3. The system of claim 1, wherein a frame is concatenated with itself.

4. The system of claim 1, wherein the first frame is added to a second frame.

5. The system of claim 4, wherein lengths of the first and second frames are determined before adding the two frames.

6. The system of claim 5, wherein if the first and second frames are of different lengths, the length of one frame is adjusted to be the same length as the other frame.

7. A system for combining a plurality of frames to generate electrical signals, comprising: an input for receiving a specified average frame period for a specified number (N) of frame periods and a first frame period not equal to the specified average frame period; a processor for providing a number N of frame periods that have the specified average frame period; and an output to provide the plurality N of frame periods to a signal generator for generating electrical signals having a specified average period.

8. The system of claim 7, wherein the specified average period is an integer.

9. The system of claim 8, wherein the specified average period is a factor of 60,000.

10. The system of claim 8, wherein the specified average period is a factor of an integer multiple of 60,000.

11. A system for combining a plurality of frames to generate electrical signals, the system comprising: an input for receiving a specified average frame rate for a specified number (N) of frame periods and a first frame rate not equal to the specified average frame rate; a processor for providing a number N of frame periods that have the specified average frame rate; an output to provide the plurality N of frame periods to a signal generator for generating electrical signals having a specified average rate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a block diagram of an embodiment of a physiological electrical signal simulator of the present invention;

(2) FIG. 2 illustrates an embodiment of the remote control panel and display which is part of the simulator of FIG. 1;

(3) FIG. 3 is a table representing one possible arrangement of data fields displayed on the panel of FIG. 2; and

(4) FIG. 4 is a table representing another possible arrangement of data fields displayed on the panel of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Definitions

(5) To aid in understanding the present invention, the following list of terms and their meanings is included. The meaning of the terms, as set forth below, is the intended meaning whenever the term is used herein, unless another meaning is believed to be clear from the context.

(6) Amplitude: The vertical interval in specified units from a baseline such as the x-axis in an x-y coordinate system; for applications herein, the intervals are typically represented by dimensionless numbers that are expected to be scaled using whatever units are appropriate for the application such as, for example, electrical units for voltage and current.

(7) Field: A part of a data base record representing an item of data, as for example, the data in a cell identified by the intersection of a row identified for a Frame and of a column identified for the field.

(8) Frame: (noun) A supporting structure that contains parts with spaces between them and used to build something; a single cycle of shapes in a string of repeated shapes; (verb) to construct or compose a statement or code used to generate a waveform sequence; formulate the essentials of a complex thing, idea, etc.

(9) Period: An interval during which an event of interest occurs; the time required for one repetition of a shape; if the shape has a specified width, the shortest period for one repetition is the specified width; the longest period is limited by the system that generates it.

(10) Shape: Something such as a mold or pattern used to give or determine form; when applied to generating waveforms herein, it is understood that an identified shape inherently includes values for amplitude and width which are expected to be multiplied by scaling factors chosen to produce desired results for generated waveforms.

(11) Width: The horizontal interval in specified units in an x-y coordinate system from the beginning to the end of a shape identified by a shape value; as applied herein, horizontal intervals are typically represented by dimensionless numbers that are expected to be scaled using whatever units are appropriate for the application such as, for example, length, time, or frequency.

(12) The described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

(13) The present invention provides an apparatus and method for simulating or stimulating physiological electrical signals, such as electrocardiograph (ECG) signals. FIG. 1 is a block diagram of an embodiment of a physiological electrical or biological signal simulator 100 of the present invention. The simulator 100 generally includes a control and display panel 200, and a function generator 300 for outputting signals to a system under test (SUT) 400, such as an ECG or other biological signal monitor. The panel 200 and function generator 300 may be connected through a wired connection or, preferably, wirelessly using methods such as that provided by WiFi and Bluetooth technology. In such a configuration, the panel 200 may thus be used remotely.

(14) The function generator 300 may include a communication (comm) port 302 configured to receive programming signals from the control panel 200, a memory 304 configured to store instructions and predetermined values, a processor 306 configured to process the programming and predetermined values according to the instructions stored in the memory, a digital-to-analog converter (DAC) 308 configured to convert the processed values into analog output signals, and an output port 310 configured to make the analog output signals available to the SUT 400. As will be described in more detail, the function generator 300 may also include an input port 310 to receive signals from the SUT 400 and a comparator 314 configured to compare the signals from the SUT 400 against the signals from the DAC 308. A comparison of the signals may then be displayed on the panel 200.

(15) The panel 200 may be part of any appropriate input product, such as a computer, tablet computer, or smart phone, to receive programming values from a user, output programming signals to the function generator 300, and receive signals for display from the function generator 300. Referring to FIG. 2, the panel 200 may include a processor 204, configured to receive signals from the touch screen 202 and convert them into programming signals, and a comm port 206, configured to transfer the programming signals to the comm port 302 of the function generator 300. The processor 204 is also configured to receive signals from the comm port 302 of the function generator 300 for display on the panel 200. Preferably, the panel 200 will include a touch screen 202 which is configured to display frames 210, accept input values from a user, and display information from the function generator 300. In some embodiments, information from the function generator 300 may be displayed on a screen or hard-copy printout separate from the panel 200. In some other embodiments, some or all of the operations of the function generator 300 may be incorporated into components of the panel 200.

(16) TABLE I of FIG. 3 is a representation of one possible arrangement of frames 210 displayed on the panel 200 of FIG. 2. TABLE II of FIG. 4 is a representation of another possible arrangement of frames 210 displayed on the panel 200 of FIG. 2. Although the frames 210 are shown in table format, they may also be presented or displayed to a user in any other appropriate format.

(17) When the panel 200 includes a touch screen 202, each of the displayed fields may be configured as a button which the user may select, then edit information using a keypad or, alternatively, make a selection from a drop-down list or scrollable wheel of possible entries.

(18) Referring to TABLE I of FIG. 3, each entry in the SHAPE column represents a value identifying a predefined shape that is stored in the memory 304. In addition to being defined by the type of shape itself (e.g., sine, triangular, etc.), each predefined shape has an inherent default amplitude and width. TABLE I may provide frames 210 in which values for the amplitude and width may be edited to preferred values for the width and amplitude of the shape. The PERIOD defines the time interval during which one repetition of the shape is generated. RATE is defined as the number of times the shape is generated during a specified interval of time and is inversely proportional to the PERIOD. If the shape represents one event such as one heart beat, the rate may be calculated in units of beats-per-minute (BPM) from Rate (in BPM)=60,000/Period (in milliseconds). The REPS (repetitions) define the number of times the Period will be repeated for the Frame.

(19) The NEXT FRAME value points to the number of the next frame to be inserted into the sequence. NEXT FRAME may be the actual frame number or may be an increment/decrement pointer. For example, in frame 1 of TABLE I, NEXT FRAME equals 3, indicating that the next frame to be inserted into the sequence is frame 3. In frame 3, NEXT FRAME equals +2, indicating that the next frame to be inserted is 3+2=5. Thus, a number with a plus sign (+) would indicate that the next frame is below the current frame in TABLE I; a number with a negative sign () would indicate that the next frame is above the current frame in TABLE I; and, an unsigned number indicates an absolute frame number. If the NEXT FRAME cell, other than in the last frame N, is blank, NEXT FRAME will default to a predetermined value, such as +1. If the NEXT FRAME cell in the last frame N is blank, NEXT FRAME will default to a predetermined action, such as repeat the sequence from frame 1, proceed through the just-ended sequence in the reverse order, stop, or some other action. In TABLE I, NEXT FRAME=1 in the last frame N, indicating that the sequence should return to frame 1 and repeat. In some embodiments, each of the fields may allow a referenced input, as described above with respect to inputs to the NEXT FRAME field, such that the value of a frame may be incremented, decremented, or remain the same with respect to the entry for the previous frame. For example, in TABLE I, the RATE in frame 3 may be entered as 90, indicating that the RATE will be 90 beats per minute less than the RATE of the previous frame (frame 1). In some other embodiments, the value of a field may vary within the frame. For example, the RATE within a frame may vary with each REP of the frame.

(20) The length of a frame may be increased, such as by inserting a specified number of members, each member having a specified value, or may be decreased, such as by removing a specified number of members.

(21) TABLE II of FIG. 4 provides some additional input fields. The WIDTH field allows entry of a desired shape width and the AMPLITUDE field allows entry of the shape amplitude. Additional fields may be included to enter or display notes and statistics for information about the frame such as expected number of detectable events (for example, the number of expected beats), average period, the average signal value, the maximum or minimum amplitude, and the frequency content of signals in the frame.

(22) If desired, a sequence of frames, such as illustrated in the Tables, may be saved as a new defined shape, which may be subsequently entered by name when creating a new sequence. Any parameter of the saved sequence may be modified and either saved with the newly created sequence, saved separately as still another new sequence, or saved as a modification to the originally saved sequence. Additionally, if a parameter in a saved sequence is changed, the change may be applied to each other sequence that incorporates or references the saved sequence.

(23) Frames may be combined in a number of different ways, providing a new frame that is a function of the combined frames. Some examples include: a) combining frames by multiplying their values, whether the frames are of equal or unequal lengths; b) combining frames by a process of convolution; c) combining frames by a process of correlation; d) combining frames by a process of auto-correlation; e) combining a frame with itself to provide a spectrum of the frame; f) combining frames to provide a specified average period of the periods of the individual frames; g) combining frames to provide a specified average rate of the rates of the individual frames; h) combining frames by concatenation; i) concatenating a frame with itself; and j) combining frames by adding their values.

(24) When frames are combined by adding their values, their respective lengths may be determined and, if different, their lengths may be adjusted to be equal to each other prior to adding.

(25) When frames are combined to provide a specified average period, the specified average period may be selected as an integer or a non-integer. For convenient scaling, the specified average period may be an integer or non-integer factor of 60,000.

(26) It is known that a normal, healthy heart beats in a manner that is not perfectly uniform. Without going into detail that is known in the medical field, healthy hearts beat with variations in the period between beats. It is therefore important for an ECG simulator to take into account such variations. An embodiment of the simulator 100, when configured as an ECG simulator, may display a varying heart rate from the function generator 300 with a predetermined average. In one embodiment, an average rate is computed by converting the average of the periods into a rate (in beats-per-minute, as described above). The average may be taken over a specified period of time (such as, for example, four seconds) or over a specified number of beats (such as, for example, four beats).

(27) The simulator 100 may transmit simulated physiological electrical (biological process) signals to a monitor, in place of signals from patient electrodes, for the purpose of evaluating, verifying, and validating various functions of the monitor. When the monitor is an ECG monitor, such functions may include those related to variations in heart rate. As noted above, the comparator 314 is configured to compare the signals from the monitor or SUT 400 against the signals from the DAC 308 and a comparison of the signals may then be displayed on the panel 200. In this manner, the SUT 400 may be evaluated to help decide whether corrective action is required.

(28) The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.