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Yupin Suppakhun,Pornchai Supnithi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, we investigate the performance of perpendicular recording channel for dc-full and dcattenuation partial response targets under the environment of electronics noise and jitter noise. We compare the performance of partial-response maximum-likelihood (PRML) and noise-predictive maximum?likelihood (NPML) detector for both types of targets. The NPML system is more suited for dc-attenuation targets, whereas the dc-full targets are suited to PRML system at low jitter noise.
GUI-Based Read Channel Simulation Tools in Magnetic Recording System
Kitiyaporn Boonserm,Pornchai Supnithi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
This paper presents a simulation and visualization tool for the read channel in magnetic recording system based on MATLAB and GUI tools. The system consists of read-back signal generator, low-pass filter (LPF), FIR equalizer, Viterbi detector and Graphical user interface (GUI) structure. Simulation results show the signals of each component in read channel model and users can modify important relevant parameters in each subsystem.
An MMSE Infinite Impulse Response Equalizer for Perpendicular Recording Channels with Jitter Noise
Piya Kovintavewat,Chanon Warisarn,Pornchai Supnithi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
A finite impulse response (FIR) equalizer is practically employed in conjunction with the Viterbi detector for data detection process in magnetic recording channels. However, the FIR equalizer with a large number of taps is required at high density storage channels. It is well-known that an infinite impulse response (IIR) filter with a small number of taps can closely approximate such an FIR filter. In this paper, we propose the IIR filter for perpendicular recording channels, based on a minimum mean-squared error approach, and compare its performance with the FIR equalizer in the presence and in the absence of media jitter noise. Results indicate that the IIR equalizer performs better than the FIR equalizer for all jitter noise levels, especially when the number of equalizer taps is small (e.g., 3 taps) and the normalized recording density is high.
The Variation of Ionospheric Slab Thickness at Thailand Equatorial Latitude Station
Pusit Suvannasang,Noraset Wichaipanich,Nipa Leelaruji,Mamoru Ishii,Pornchai Supnithi 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
This paper presents the study and analysis of ionospheric slab thickness (τ) during the solar minimum in year 2006. The ionospheric slab thickness is obtained from the ratio of the total electron content (TEC) to the peak electron density in the F2 region (NmF2). According to the analysis of the total electron content and the peak electron density in the F2 region, the peak electron density in the F2 region by critical frequency (foF2) are determined by ionosonde technique. In addition, the total electron content are determined by the correlation of different time delay of 2 L - band signals from GPS satellites. All three parameters, critical frequency, total electron content, and peak electron density in the F2 region, are analyzed at the Chumphon campus King Mongkut’s Institute of Technology Ladkrabang station, located at longitude 99.3˚E and latitude 10.7 ˚N. The analyzed results show that there are irregularities of all parameters during the equinox period and the ionospheric slab thickness at low latitude peaks in the pre-sunrise.
Tsujii, Toshiaki,Fujiwara, Takeshi,Kubota, Tetsunari,Satirapod, Chalermchon,Supnithi, Pornchai,Tsugawa, Takuya,Lee, Hungkyu Korean Society of Surveying 2012 한국측량학회지 Vol.30 No.6
Ionospheric anomaly is one of the major error sources which deteriorate the GNSS performance. In the equatorial region, effects of the ionospheric plasma bubbles are of great interest because they are pretty common phenomena, especially in the period of the high solar activity. In order to evaluate the GNSS performance under circumstance of the bubbles, an ionospheric scintillation monitor has been developed and installed in Bangkok, Thailand. Furthermore, a model simulating the ionospheric delay and scintillation due to the bubbles has been developed. Based on these developments, the effects of the simulated plasma bubbles are analyzed and their agreement with the real observation is demonstrated. An availability degradation of the GPS ground based augmentation system (GBAS) caused by the bubbles is exampled in details. Finally, an integrated GPS/INS approach based on the Doppler frequency is proposed to remedy the deterioration.