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No matter the active sonar or passive sonar, when receiving the acoustic signal reflected from the target, the information included in the signal can not be directly collected and used without technical signal processing. To extract the efficient and useful informations from the mixed signal, some steps should be taken to transfer sonar data from raw acoustic data reception to detection output. Thus, for the active sonar, six steps are needed during the signal processing system. centre centre == Signal generation == To actually generate in hardware as signal pulse typical analog implementations are oscillators and voltage controlled oscillators (VCO) which are followed by modulators. Amplitude modulation is used to weight the pulse envelopes and to translate the signal spectrum up to some suitable carrier frequency for transmission. First, in sonar system, the acoustic pressure field can be represented as . The field function include four variables: time and spatial coordinate as elemental signal, for the reason that any 4-D can be generated by taking a linear combination of elemental signals. Obviously, the direction of gives the direction of propagation of waves, and the speed of the waves is right The wavelength is 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sonar signal processing」の詳細全文を読む スポンサード リンク
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