Pengaruh Penggunaan Filter Butterworth pada Penentuan Waktu Tiba Gelombang P
DOI:
https://doi.org/10.23887/jstundiksha.v7i2.13013Keywords:
waktu tiba gelombang P, filter Butterworth, rasio sinyal terhadap bisingAbstract
Penentuan waktu tiba gelombang P cukup sulit dilakukan apabila sinyal memiliki Signal to Noise Ratio (SNR) rendah. Pemfilteran sinyal dapat dilakukan untuk meningkatkan SNR. Pemilihan rentang frekuensi filter harus sesuai dengan kandungan frekuensi gelombang gempabumi karena apabila tidak sesuai akan mendistorsi fase gelombang P dan menyebabkan penentuan waktu tiba gelombang P tidak tepat. Pada penelitian ini dilakukan analisis pengaruh penggunaan 3 jenis filter Butterworth orde 5 pada waktu tiba gelombang P. Jenis filter Butterworth kausal yang digunakan yaitu, filter lowpass 2 Hz, bandpass 2-6 Hz, dan highpass 6 Hz. Hasilnya, secara umum penggunaan filter memberikan efek keterlambatan fase dan pelemahan impuls awal gelombang P yang menyebabkan kesalahan penentuan waktu tiba gelombang P. Jenis filter yang paling bagus digunakan adalah filter bandpass karena kesalahan penentuan waktu tiba gelombang P rata-rata 0.271 detik. Hal ini disebabkan karena gelombang P memiliki frekuensi dominan rata-rata 3.83 Hz. Sementara itu, pemfilteran dengan lowpass dan highpass rata-rata kesalahan masing-masing sebesar 2.183 detik dan 0.347 detik.References
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