Adaptive sampling of cardiac waveforms can produce higher quality measurements than uniform sampling at the same average rates. The paper presents the design of a device for real-time adaptive sampling with the fan al...
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Adaptive sampling of cardiac waveforms can produce higher quality measurements than uniform sampling at the same average rates. The paper presents the design of a device for real-time adaptive sampling with the fan algorithm. Design equations define the relationships between system parameters, allowing choices among hardware complexity, speed or accuracy to be evaluated. The design incorporates a parallel architecture, which can be expanded to achieve any desired peak sampling rate. Examples show the system to be flexible and realistic. A major feature of the design is that fan samples are provided to the user at a fixed rate that the user specifies, although they are selected internally at variable rates. Because of this feature, complications in receiving and storing samples at widely varying intervals are entirely avoided, and simple computers such as PCs can be used to collect samples at a rate far below the peak sampling rate. To accomplish fixed-rate transmission, the system itself selects the fan tolerance .epsilon. based on characteristics of the incoming signal. As the signal changes, .epsilon. is varied dynamically to ensure that the fixed rate is never exceeded. Furthermore, the design guarantees that measurements will never be worse than those from uniform sampling at the given fixed rate.
Retrospective studies have established that the fan algorithm is an effective means of acquiring high-quality digital cardiac measurements. A prototype has now been constructed that samples adaptively in real time. Th...
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Retrospective studies have established that the fan algorithm is an effective means of acquiring high-quality digital cardiac measurements. A prototype has now been constructed that samples adaptively in real time. The prototype uses two Texas Instruments TMS32010 signal processors and 79 additional TTL integrated circuits, at a component cost of approximately US$1000. The device acquires transient samples of the incoming analogue signal at up to 16,000 samples s-1, selects samples from this input stream according to the fan algorithm, and transmits the samples and the time intervals between them at a fixed permanent rate. The permanent rate is between 100 and 400 samples s-1, as selected by the user. To respond to changing waveforms and repetition rates, while maintaining a fixed transmission rate, the prototype varies the fan tolerance. The lowest fan tolerance that will allow transmission of samples and time intervals at a rate not exceeding the permanent rate is used. If permanent samples at uniform intervals result in lower peak error than the fan samples, the prototype transmits the uniformly spaced samples instead of the fan samples. Results with test and real signals show that the device performs as designed and can accurately measure fast waveforms at low average sampling rates. For example, bipolar pulses 350 .mu.s in duration were recorded with permanent rates of only 400 samples s-1, and cardiac signals were measured with 10-390 times lower peak error than would have resulted from uniform sampling at the same average rates.
The fan is a method of adaptive sampling that selects samples from electrocardiograms more rapidly during periods of rapid waveform change and more slowly otherwise. One attribute of the fan is the guarantee that the ...
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The fan is a method of adaptive sampling that selects samples from electrocardiograms more rapidly during periods of rapid waveform change and more slowly otherwise. One attribute of the fan is the guarantee that the original waveform can be reconstructed within tolerance .epsilon.. Many questions about the particulars of the fan''s performance on human ECGs have been undocumented, e.g. what .epsilon. choice leads to good quality, and what average sampling rates occur? The paper provides answers to these and other questions. It is based on retrospective analysis of 20700 human ECG waveforms from subjects of all ages. The results show, for example, that .epsilon. = 10 .mu.V leads to high quality waveforms sampled at an average rate of 266 samples s-1 with maximum errors only 1/24th the maximum errors using uniform sampling at 250 samples s-1, and that .epsilon. = ***.V leads to waveforms showing all deflections at an average rate of 45 samples s-1 with maximum errors only 1/57th of the maximum errors from uniform sampling at 45 samples s-1.
A new test set compaction method that uses multiple frame vectors to test fully scanned sequential circuits is proposed. The PAN algorithm is extended to generate compact multiple frame test vectors. The proposed meth...
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A new test set compaction method that uses multiple frame vectors to test fully scanned sequential circuits is proposed. The PAN algorithm is extended to generate compact multiple frame test vectors. The proposed method generates the smallest test sets among all recognised full scan test set compaction algorithms.
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