Kalau spektrumnya flat untuk range frekuensi yang lebar, memang cenderung menjadi spike. Tapi kalau flat untuk range frekuensi yang terbatas, biasanya side lobe malah lebih kuat dibandingkan bell shape spectra. Karena itu, dalam seismic processing, jarang orang menggunakan rectangle window, biasanya yang ada zona transisi di kiri dan kanan (Butterworth, trapesium, Kaiser, etc).
LL -----Original Message----- From: Paulus Tangke Allo [mailto:[EMAIL PROTECTED] Sent: Wednesday, March 14, 2007 8:16 PM To: fogri@iagi.or.id Subject: Re: [fogri] Spectral balancing ohh, ini sih maksudnya spectral whitening ngkali.... spectral whitening tentu saja bisa menghilangkan "geologic information"-nya. makanya dikatakan: ".... it is prudent to balance the wavelet amplitude without degrading the geologic information." jadi kalau balancing, yah jangan sampai degrading the geologic information-nya. kenapa perlu whitening? ini kaitannya dgn wavelet overprint. kurang lebih maksudnya, efek wavelet sidelobe. semakin flat spektrum-nya, sidelobe waveletnya makin kecil dan mendekati spike. jadi karena efek sidelobe waveletnya makin kecil maka frequency slice hanya akan berisi informasi thin bed interference dan noise. mudah2an membantu. --pta On 3/14/07, attar kusuma <[EMAIL PROTECTED]> wrote: > makasih atas tanggapannya > > yang saya maksud sebenarnya spectral balancing dalam > Specdecom. > dalam papernya partyka dijelaskan: > The tuning cube has three components: > thin-bed interference, wavelet overprint, > and noise (Figure 7). Since the > geologic response is the most interesting > component for the interpreter, > it is prudent to balance the wavelet > amplitude without degrading the geologic > information. This reduces the > tuning cube to thin-bed interference > and noise. > Common spectral balancing techniques > rely on sparse invariant stationary > statistics. If we assume that the > geologic tuning varies considerably > along any flattened horizon, then we > balance the wavelet spectrum by > equalizing each frequency slice according > to its average amplitude (Figure 8). > After whitening to minimize the > wavelet effect, the tuning cube retains > two main components: thin-bed interference > and noise. > In frequency-slice form, thin-bed > interference appears as coherent > amplitude variations. Random noise > speckles the interference pattern in a > similar fashion to poor quality television > reception. At dominant frequencies, > the relatively high signal-to-noise ratio (SNR) > results in clear pictures of > thin-bed tuning. Movement away > from dominant frequency causes the > SNR to degrade. At frequencies > beyond usable bandwidth, the poor > SNR results in a noise map. > > apakah mungkin spectral balancing tidak akan > menghilangkan "informasi geologic-nya"? > > apa sih sebenarnya "wavelet overprint"? --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] Visit FOGRI Website: http://fogri.or.id FOGRI Archive: http://www.mail-archive.com/fogri%40iagi.or.id/ --------------------------------------------------------------------- --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] Visit FOGRI Website: http://fogri.or.id FOGRI Archive: http://www.mail-archive.com/fogri%40iagi.or.id/ ---------------------------------------------------------------------
