{"id":1170,"date":"2024-10-02T20:11:05","date_gmt":"2024-10-02T13:11:05","guid":{"rendered":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/?p=1170"},"modified":"2024-10-02T20:13:35","modified_gmt":"2024-10-02T13:13:35","slug":"menghitung-spektrum-data-seri-waktu-menggunakan-fft-macro-excel","status":"publish","type":"post","link":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/2024\/10\/02\/menghitung-spektrum-data-seri-waktu-menggunakan-fft-macro-excel\/","title":{"rendered":"Menghitung spektrum data seri waktu menggunakan FFT-Macro (Excel)"},"content":{"rendered":"

Dengan menggunakan fungsi FFT di Excel dan menggunakan Macro Excel, kita dapat menghitung spektrum dari data seri waktu (time series). Sintaks Macro nya dapat dilihat sbb:<\/p>\n

———————— fft-macro ——————————<\/p>\n

Sub uji()
\nDim f(512), ff(512), A(512)
\nApplication.Run “ATPVBAEN.XLAM!Fourier”, _
\nActiveSheet.Range(“$B$2:$B$513”), _
\nActiveSheet.Range(“$C$2:$C$513”), _
\nFalse, False<\/p>\n

Range(“D3”).Select
\nApplication.CutCopyMode = False<\/p>\n

ActiveCell.FormulaR1C1 = “=IMREAL(RC[-1])”
\nRange(“D3”).Select
\nSelection.Copy
\nRange(“C3”).Select
\nSelection.End(xlDown).Select
\nRange(“D513”).Select
\nRange(Selection, Selection.End(xlUp)).Select
\nActiveSheet.Paste
\nCells(2, 5) = “period”
\nCells(2, 6) = “PSD”<\/p>\n

Cells(2, 7) = “period”
\nCells(2, 8) = “PSD”<\/p>\n

Cells(2, 9) = “period”
\nCells(2, 10) = “PSD”
\nL = 252
\nFor i = 1 To L
\nh = i
\nf(i) = h \/ L * 0.5
\nCells(2 + i, 5) = 1 \/ f(i)
\nCells(2 + i, 6) = Abs(Cells(2 + i, 4)) ^ 2 \/ L
\nNext
\nFor i = 2 To L
\nIf Cells(2 + i, 6) > Cells(1 + i, 6) Then
\nIf Cells(2 + i, 6) > Cells(3 + i, 6) Then
\nCells(2 + i, 7) = Cells(2 + i, 5)
\nCells(2 + i, 8) = Cells(2 + i, 6)
\nEnd If
\nEnd If
\nNext
\nj = 1
\nFor i = 2 To 255
\nIf Cells(2 + i, 6) > Cells(1 + i, 6) Then
\nIf Cells(2 + i, 6) > Cells(3 + i, 6) Then
\nCells(2 + j, 9) = Cells(2 + i, 5)
\nCells(2 + j, 10) = Cells(2 + i, 6)
\nj = j + 1
\nEnd If
\nEnd If
\nNext
\nEnd Sub<\/p>\n

———————— fft-macro ——————————<\/p>\n

Tampilan excel FFT-macro adalah sebagai berikut,<\/p>\n

\"\"<\/a><\/p>\n

Dimana kolom B menunjukkan data seri hujan harian. Dengan menjalankan program macro ini maka akan didapat hasil berupa spektrum hujan.<\/p>\n

Hasil uji FFT-Macro dapat dilihat pada gambar screen shoot berikut,<\/p>\n

\"\"<\/a><\/p>\n

Gambar atas merupakan data seri hujan harian (domain waktu). Gambar di bawahnya merupakan spektrum hujan harian (domain frekuensi).<\/p>\n

File program di atas dapat didownload dari Link ini<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Dengan menggunakan fungsi FFT di Excel dan menggunakan Macro Excel, kita dapat menghitung spektrum dari data seri waktu (time series). Sintaks Macro nya dapat dilihat sbb: ———————— fft-macro —————————— Sub … Continue Reading →<\/a><\/p>\n","protected":false},"author":21,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1170","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/posts\/1170"}],"collection":[{"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/users\/21"}],"replies":[{"embeddable":true,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/comments?post=1170"}],"version-history":[{"count":3,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/posts\/1170\/revisions"}],"predecessor-version":[{"id":1175,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/posts\/1170\/revisions\/1175"}],"wp:attachment":[{"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/media?parent=1170"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/categories?post=1170"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dosen.unila.ac.id\/ahmadzakaria\/wp-json\/wp\/v2\/tags?post=1170"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}