Device and method for reducing number of data sample points sent to a video display system
First Claim
1. A device for converting an input digital electrocardiograph (ECG) signal sampled at a first rate to an output digital ECG signal sampled at a second rate where the first rate is higher than the second rate, the output signal made of a series of representative amplitude values for further processing or display, the output signal being representative of the input signal presented to the device, the input signal made up of a series of N sampled input amplitude values Xn (n-1 to N), the output signal preserving the maximum and minimum amplitudes of the input signal on the range of the sampled input amplitude values Xn, the output signal presented to an output terminal, the device comprising:
- a) means for extracting seriatim N sample amplitude values Xn from an input signal and storing said sample input amplitude values Xn in an electronic memory means, said N sampled input amplitude values Xn having a first amplitude end point and a second amplitude end point at X1 and XN, respectively, and a middle sample;
b) means, implemented on a central processing unit, for determining the shape of a curve formed by plotting said sample input amplitude values versus an indicia representing the order that the sampled input amplitude values were sampled and thereafter sequentially connecting said plotted input amplitude values;
c) means for transferring the amplitude value of said middle sample to the output terminal if both the maximum and minimum amplitude values of said sample group appear at said first and second end points, regardless of order;
d) means for transferring the minimum amplitude value of said sample group to the output terminal if said curve is concave shaped; and
,e) means for transferring the maximum amplitude value of said sample group to the output terminal if said curve is convex shaped.
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Accused Products
Abstract
A device is provided for reducing the number of ECG data sample points presented to a video display system to avoid overwhelming the video display screen with a number of ECG sample points and to present several seconds of data on the screen at the same time. The device ensures that the maximum and minimum values of the original ECG signal are displayed. A collection of consecutive points is broken into sub-groups which are each processed to produce representative amplitude values for each sub-group which representative values are then displayed on the display screen.
In the preferred embodiment, the device includes a microprocessor with electronic memory which calculates a representative amplitude value for each sub-group. The representative amplitude value is chosen depending on whether the sub-group contains a local maximum or a minimum in the values of consecutively sampled points or whether the data points of the sub-group are part of a curve leading to a local maximum or minimum. If the local minimum or maximum value of the sub-group appear between the end points of the sub-group, the maximum or minimum value of the sub-group is passed to the output depending on whether the curve is convex or concave shaped respectively.
22 Citations
23 Claims
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1. A device for converting an input digital electrocardiograph (ECG) signal sampled at a first rate to an output digital ECG signal sampled at a second rate where the first rate is higher than the second rate, the output signal made of a series of representative amplitude values for further processing or display, the output signal being representative of the input signal presented to the device, the input signal made up of a series of N sampled input amplitude values Xn (n-1 to N), the output signal preserving the maximum and minimum amplitudes of the input signal on the range of the sampled input amplitude values Xn, the output signal presented to an output terminal, the device comprising:
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a) means for extracting seriatim N sample amplitude values Xn from an input signal and storing said sample input amplitude values Xn in an electronic memory means, said N sampled input amplitude values Xn having a first amplitude end point and a second amplitude end point at X1 and XN, respectively, and a middle sample; b) means, implemented on a central processing unit, for determining the shape of a curve formed by plotting said sample input amplitude values versus an indicia representing the order that the sampled input amplitude values were sampled and thereafter sequentially connecting said plotted input amplitude values; c) means for transferring the amplitude value of said middle sample to the output terminal if both the maximum and minimum amplitude values of said sample group appear at said first and second end points, regardless of order; d) means for transferring the minimum amplitude value of said sample group to the output terminal if said curve is concave shaped; and
,e) means for transferring the maximum amplitude value of said sample group to the output terminal if said curve is convex shaped. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for converting an input digital electrocardiograph (ECG) signal sampled at a first rate to a digital ECG output signal sampled at a second rate where the first rate is higher than the second rate, the output signal made of a series of representative amplitude values for further processing or display, the output signal being representative of the input signal presented to the device, the input signal made up of a series of N sampled input amplitude values Xn (n-1 to N), the output signal preserving the maximum and minimum amplitudes of the input signal on the range of the sampled input amplitude values Xn, the output signal presented to an output terminal, the method comprising the steps of:
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a) extracting seriatim N sample input amplitude values XN from an input signal and storing said sample input amplitude values Xn in an electronic memory means, said N sampled input amplitude values having a first and a second end point at X1 and XN, respectively, and a middle sample; b) determining, on a central processing unit, the maximum and the minimum amplitude values of the N sampled input amplitude values; c) determining, on a central processing unit, the shape of a curve formed by plotting said sample input amplitude values versus an indicia representing the order that the sampled input amplitude values were sampled and thereafter sequentially connecting said plotted input amplitude values; d) transferring the amplitude value of said middle sample to the terminal if both the maximum and minimum amplitude values of said sample group appear at said first and second end points, regardless of order; e) transferring the minimum amplitude value of said sample group to the terminal if said curve is concave shaped; and
,f) transferring the maximum amplitude value of said sample group to the terminal if said curve is convex shaped. - View Dependent Claims (18, 19)
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20. A device for converting an input electrocardiograph (ECG) signal to an output ECG signal made of a series of representative amplitude values for further processing or display, the output signal being representative of an input ECG signal presented to the device, the input ECG signal made up of a series of N sampled input amplitude values Xn (n-1 to N), the ECG output signal preserving the maximum and minimum amplitudes of the ECG input signal on the range of the sampled input amplitude values Xn, the output signal presented to an output terminal, the device comprising:
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a) an analog to digital converter for sampling seriatim an input analog ECG signal and for producing N pieces of digital sample input amplitude values Xn from the input ECG signal, the N pieces of sampled input amplitude values Xn having a first and a second end point at X1 and XN, respectively, and a middle sample; b) random access memory means for storing the digital sample input amplitude values Xn, for preserving the order of the sampled input values, and for identifying the middle sample; c) means, implemented on a central processing unit, for examining the sampled input amplitude values Xn and selecting therefrom a maximum and a minimum amplitude value of the sampled input amplitude values Xn ; d) means, implemented on a central processing unit, for determining whether a curve, formed by plotting amplitude values of the sample input amplitude values versus the order the sample input amplitude values were sampled and thereafter sequentially connecting the sample input amplitude values, is concave, convex or straight; e) means for; i) transferring the amplitude value of the middle sample to the output terminal if both the maximum amplitude value and the minimum amplitude value of the sample input amplitude values appear at the first and second end points, X1 and XN, respectively, regardless of order; ii) transferring the minimum amplitude value of the sample input amplitude values to the output terminal if the means for determining whether a curve formed determines that the curve formed is concave shaped; and
,iii) transferring the maximum amplitude value of the sample input amplitude values to the output terminal if the means for determining whether a curve formed determines that the curve formed is convex shaped.
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21. A method for converting, a digital electrocardiograph (ECG) signal sampled at a first rate to an ECG signal sampled at a second rate where the first rate is higher than the second rate and for preserving the maximum and minimum amplitudes of the digital ECG signal sampled at the first rate in the digital ECG signal sampled at the second rate comprising the steps of:
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receiving, at an input terminal, a digital ECG signal sampled at a first sample rate; examining a seriatim portion of the ECG signal sampled at the first rate and presented to the input terminal, the portion having a beginning endpoint, an ending endpoint and a middle point and determining whether the amplitudes of the portion;
are monotonically increasing in amplitude, are monotonically decreasing in amplitude, have a highest amplitude value located between the beginning and the ending endpoints or have a lowest amplitude value located between the beginning and the ending endpoints;transferring a representative amplitude to an output terminal at a second sample rate that is lower than the first sample rate, the representative amplitude determined in response to the step of determining, the representative amplitude being; i) the middle point amplitude if the step of determining determines that the amplitudes of the portion are monotonically increasing or monotonically decreasing in amplitude; ii) the highest amplitude value if the step of determining determines that the highest amplitude value is located between the beginning and the ending endpoints; iii) the lowest amplitude value if the step of determining determines that the lowest amplitude value is located between the beginning and the ending endpoints; whereby the series of representative amplitudes transferred to the output terminal by the step of transferring a representative amplitude produces a digital ECG signal that preserves the maximum and minimum amplitudes of the digital ECG signal sampled at the first rate.
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22. Apparatus for converting, in real time, a digital electrocardiograph signal sampled at a first rate to an electrocardiograph signal sampled at a second rate where the first rate is higher than the second rate and for preserving the maximum and minimum amplitudes of the digital electrocardiograph signal sampled at the first rate in the digital electrocardiograph signal sampled at the second rate comprising:
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an input terminal for receiving the electrocardiograph signal sampled at the first sample rate; an output terminal for transferring the electrocardiograph signal sampled at the second sample rate to a video display device for display; means, attached to the input terminal, for examining a seriatim portion of the electrocardiograph signal sampled at the first rate, the portion having a beginning endpoint, an ending endpoint and a middle point, and for determining whether the amplitudes of the portion;
are monotonically increasing in amplitude, are monotonically decreasing in amplitude, have a highest amplitude value located between the beginning and the ending endpoints, or have a lowest amplitude value located between the beginning and the ending endpoints;means for transferring a representative amplitude to the output terminal at the second sample rate that is lower than the first sample rate, the second sample rate being the rate required to provide amplitudes to a video display device for display, the representative amplitude determined in response to the determination of the means for examining and determining, the representative amplitude being; i) the middle point amplitude if the means for examining and determining determines that the amplitude of the portion are monotonically increasing or monotonically decreasing in amplitude; ii) the highest amplitude value if the means for examining and determining determines that the highest amplitude value is located between the beginning and the ending endpoints; ii) the lowest amplitude value if the means for examining and determining determines that the lowest amplitude value is located between the beginning and the ending endpoints.
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23. Apparatus for converting analog electrocardiograph (ECG) signals to an ECG signal sampled at a rate compatible with external devices comprising:
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an input terminal for receiving the analog ECG input signal; means for sampling the analog ECG input signal at a first rate and for producing a digital ECG input signal; an output terminal for transferring the digital ECG signal to an external device; means, attached to the means for sampling, for examining a seriatim portion of the ECG signal sampled at the first rate, the portion having a beginning endpoint, and ending endpoint and a middle point, and for determining whether the digital amplitudes of the portion;
are monotonically increasing in amplitude, are monotonically decreasing in amplitude, have a highest amplitude value located between the beginning and the ending endpoints, or have a lowest amplitude value located between the beginning and the ending endpoints;means for transferring a representative amplitude to said output terminal at a second sample rate for transferring the electrocardiograph signal sampled at the second sample rate to an external device for further processing or display, the representative amplitude value determined in response to the determination of the means for examining and determining, the representative amplitude being; i) the middle point amplitude if the means for examining and determining determines that the digital amplitudes of the portion are monotonically increasing or monotonically decreasing in amplitude; ii) the highest amplitude value if the means for examining and determining determines that the highest amplitude value is located between the beginning and the ending endpoints; iii) the lowest amplitude value if the means for examining and determining determines that the lowest amplitude value is located between the beginning and the ending endpoints.
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Specification