Pengaruh Penggunaan Filter Butterworth pada Penentuan Waktu Tiba Gelombang P

Abstract

Penentuan waktu tiba gelombang P cukup sulit apabila Signal to Noise Ratio (SNR) rendah. Pemfilteran sinyal dengan rentang frekuensi yang sesuai dapat meningkatkan SNR, namun apabila rentang frekuensi tidak sesuai, fase gelombang P akan terdistorsi dan 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.

Global Maritime Fulcrum: Indonesia’s Middle Power Strategy Between Belt And Road Initiatives (BRI) and Free-Open Indo Pacific (FOIP)

“…Several strategic sea-lanes of communication under Indonesian jurisdiction could support China's global maritime connections. 48 Xi Jinping and Joko Widodo even acknowledged that China's BRI and Indonesia's GMF were highly complementary because both focused on connectivity, especially maritime connectivity. 49 Despite its positive responses to the BRI, Indonesia has refrained from fully engaging with this China-led initiative.…”

“…63 These efforts are supported by the Chinese Foreign Minister, Wang Yi, who stated that Indonesia's GMF and China's BRI aim to strengthen maritime connectivity and enhance the capacity of Southeast Asian countries to maximise security and the management of their maritime resources. 64 The GMF was therefore an important instrument for Indonesia to use to strengthen its middle power capabilities and thus to increase Indonesia's constructive role in the region's security.…”