Fast realization of the LADT ECG data compression method

The system clock in the authors' Intel 80c31-based Holter recorder is 12 MHz, and thus it takes tens of milliseconds to obtain the d/sub k/ at instant k. Therefore, it is impossible to apply the original linear approximation distance thresholding (LADT) algorithm in real time. With the authors' improved algorithm it takes about one ms to calculate /spl verbar/a/sub adm//spl verbar/=/spl sigma//spl middot/(1+(a/t)/sup 2/)/sup 1/2/. Though it is much faster to fulfill a linear segment approximation by the improved algorithm than by the original one, it is still difficult directly to apply the improved algorithm in a real-time system. However, it takes only two microseconds to get /spl verbar/a/sub adm//spl verbar/ by look-up in the error threshold table. In this way, about one millisecond is needed to complete a linear segment approximating (about 50 points). It can be seen that the fast realization scheme using the error threshold table not only preserves the high compression ratio and low distortion advantages of the LADT algorithm, but also makes possible the application of the LADT algorithm in real-time.<
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