Browsing by Author "Guo, JH"

Now showing 1 - 2 of 2

A DSSS receiver for dual-mode DSSS/OFDM wireless LAN systems
(2005)
Hsiao, FH
;
Guo, JH
;
Lo, SL
;
Hsu, TY
;
資訊工程學系
This paper introduces a DSSS baseband receiver suitable for a dual mode DSSS/OFDM wireless LAN system. Packet synchronizer with a pair of ADCs with dynamic sampling is used for detecting both DSSS and OFDM packets. For differentially encoded symbols, frequency offset and phase offset can be compensated based on their inherent characteristics. For high data rate DSSS based modulations, channel estimation and equalization with receive diversity combining in frequency domain is applied to resolve the multipath distortions. With channel equalization and diversity combining of the DSSS receiver achieved in frequency domain the overall complexity of the dual mode DSSS/OFDM equalization can be realized.
Comparison of the electronic structures of AIN nanotips grown on p- and n-type Si substrates
(2005-12-07)
Chiou, JW
;
Tsai, HM
;
Pao, CW
;
Dong, CL
;
Chang, CL
At and N K-edge x-ray absorption near-edge structure (XANES), scanning photoelectron microscopy (SPEM) and x-ray emission measurements were performed on AIN nanotips grown on p- and n-type Si substrates (p-AIN and n-AIN). Features and intensities in the Al and N K-edge XANES spectra of these AIN nanotips overall are similar. In contrast, the intensities of the valence-band SPEM spectra of p-AIN are apparently larger than those of n-AIN, which indicates that the valence-band density of states of p-AIN exceeds that of n-AIN. This result may be related to the observed enhancement of field-emission intensity of AIN nanotips grown on the p-type Si substrate.