Comparison of correlation and modulus difference processing algorithms for the determination of foetal heart rate from ultrasonic Doppler signals
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Microprocessor-based correlation processing is now widely used for the estimation of foetal heart rate from ultrasonic Doppler signals. The paper describes a technique having a, similar performance, to correlation but which will run three times faster on a microprocessor without an onboard hardware multiplier. This speed improvement results from replacing each multiplication operation of the correlation algorithm with a subtraction and a modulus operation. The algorithm, is thus referred to as the modulus difference algorithm. Typical waveforms are presented illustrating the responses of the two processors to continuous wave Doppler foetal heart signals for both wide (50 Hz) and narrow (4 Hz) preprocessor bandwidths. A quantitative comparison is given of the performance of the two methods in estimating the period of a synthetic signal with additive white Gaussian noise. This simulation represents the wideband preprocessor case. A theoretical derivation of the outputs for the narrowband preprocessor case is given, and actual outputs are shown for comparison. A tutorial approach is adopted throughout the paper.
KeywordsCorrelation Foetal heart rate Modulus difference Ultrasonic foetal monitoring
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- Atkinson, P. andWoodcock, J. P. (1982)Doppler ultrasound and its use in clinical measurement. Academic Press.Google Scholar
- Bendat, J. S. andPiersol, A. G. (1980)Engineering applications of correlation and spectral analysis. Wiley.Google Scholar
- Flynn, A. M. andKelly, J. (1977) Evaluation of fetal well-being by antepartum fetal monitoring.Br. Med. J.,1, 936.Google Scholar
- Moorer, J. A. (1974) The optimum comb method of pitch period analysis of continuous digitized speech.IEEE Trans.,ASSP-22, 330–338.Google Scholar
- Neilson, J. M. (1974) High speed anlaysis of ventricular arrhythmias from 24 hour recordings. InComputers in Cardiology. IEEE Computer Society, 55–61.Google Scholar
- Patrick, J. E., Dalton, K. J. andDawes, G. S. (1976) Breathing patterns before death in fetal lambs.Am. J. Obstet. Gynecol.,125, 73.Google Scholar