Title: Application of binary excitation spread spectrum signals for spectral compensation
Abstract: Ultrasonic probing usually uses pulse signals. Resolution of the ultrasonic imaging depends on the bandwidth of the received signal. It is also important while measuring thin materials. Wide bandwidth and bandwidth flatness is important in ultrasound spectroscopy 1. Bandwidth of the received signal is mainly limited by the ultrasonic transducer. Both bandwidth and SNR improvement can be accomplished by using spread spectrum signals that have been compensated for spectral losses. Yet, such signals require arbitrary waveform generation using digital-to-analog converter and linear power amplifier. Equipment size, cost and efficiency of excitation are an issue in such case. Frequency modulation spread spectrum signals (both linear frequency modulation and nonlinear frequency modulation) explore the amplifier capabilities better, but still suffer for size and efficiency. Essential, that derivation of such signals is an approximate procedure. Rectangular pulses are relatively easy to generate offer small equipment size and low cost. Spread spectrum signals can be generated using arbitrary position and width pulses (APWP) sequences. Unfortunately, linear and nonlinear frequency modulation (chirp) signals have large spectral ripple. Direct derivation of APWP sequences is a lengthy process. Novelty of the approach presented in this paper is that nonlinear frequency modulated and amplitude modulated spread spectrum signal is converted into bipolar APWP sequence and this sequence is used for further optimization to improve the spectral flatness of the received signal.
Publication Year: 2017
Publication Date: 2017-09-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 6
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