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Advanced DSP and Noise reduction P13

TRANSIENT NOISE PULSES 13.1 Transient Noise Waveforms 13.2 Transient Noise Pulse Models 13.3 Detection of Noise Pulses 13.4 Removal of Noise Pulse Distortions 13.5 Summary ransient noise pulses differ from the short-duration impulsive noise studied in the previous chapter, in that they have a longer duration and a relatively higher proportion of low-frequency energy content, and usually occur less frequently than impulsive noise. The sources of transient noise pulses are varied, and may be electromagnetic, acoustic or due to physical defects in the recording medium. Examples of transient noise pulses include switching noise in telephony, noise pulses due to adverse radio transmission environments,. | 13 Advanced Digital Signal Processing and Noise Reduction Second Edition. Saeed V. Vaseghi Copyright 2000 John Wiley Sons Ltd ISBNs 0-471-62692-9 Hardback 0-470-84162-1 Electronic TRANSIENT NOISE PULSES 13.1 Transient Noise Waveforms 13.2 Transient Noise Pulse Models 13.3 Detection of Noise Pulses 13.4 Removal of Noise Pulse Distortions 13.5 Summary Transient noise pulses differ from the short-duration impulsive noise studied in the previous chapter in that they have a longer duration and a relatively higher proportion of low-frequency energy content and usually occur less frequently than impulsive noise. The sources of transient noise pulses are varied and may be electromagnetic acoustic or due to physical defects in the recording medium. Examples of transient noise pulses include switching noise in telephony noise pulses due to adverse radio transmission environments noise pulses due to on off switching of nearby electric devices scratches and defects on damaged records click sounds from a computer keyboard etc. The noise pulse removal methods considered in this chapter are based on the observation that transient noise pulses can be regarded as the response of the communication channel or the playback system to an impulse. In this chapter we study the characteristics of transient noise pulses and consider a template-based method a linear predictive model and a hidden Markov model for the modelling and removal of transient noise pulses. The subject of this chapter closely follows that of Chapter 12 on impulsive noise. Transient Noise Waveforms 379 13.1 Transient Noise Waveforms Transient noise pulses often consist of a relatively short sharp initial pulse followed by decaying low-frequency oscillations as shown in Figure 13.1. The initial pulse is usually due to some external or internal impulsive interference whereas the oscillations are often due to the resonance of the communication channel excited by the initial pulse and may be considered as the response of .