estimate a n furthermore the magnitude of sample g n is limited in step 259 to a value which is less than or equal to the value d u00d7 a n and placed into output sample g 39 n while preserving its original sign if h is less than zero the hold state does not exist and a n 1 is set equal in step 260 to a weighted combination of a n and the magnitude of the trace sample g n at sampling time n furthermore the sample g n is passed through in step 261 as output sample g 39 n unchanged the form of the equation in step 260 will be recognized as that of a single pole auto regressive filter with a time constant of u03b1 the limit threshold t n 1 for the next sampling time is then calculated from a n 1 by multiplication step 262 by threshold multiplier parameter c sampling time index n is incremented in step 263 and compared in step 264 to the number of sampling times n if n is less than or equal to n the sequence returns to the top in step 252 of the sample processing loop from which point the above process is repeated for the next sample otherwise the processing of trace g n.