The attitude information acquisition of unresolved space objects, such as micro-nano satellites and GEO objects under the way of ground-based optical observations, is a challenge to space surveillance. In this paper, a useful method is proposed to estimate the SO attitude state according to the simulation analysis of photometric data in different attitude states. The object shape model was established and the parameters of the BRDF model were determined, then the space object photometric model was established. Furthermore, the photometric data of space objects in different states are analyzed by simulation and the regular characteristics of the photometric curves are summarized. The simulation results show that the photometric characteristics are useful for attitude inversion in a unique way. Thus, a new idea is provided for space object identification in this paper.
This article introduces DVD Download specification and Manufacturing On Demand (MOD) system firstly. Then it will
show a designed MOD system and analyze the function of each part in it. In this system, we need to combine two DVD's
files into one disc automatically, so in the last part, the article shows work on this problem and achievement up to now.
A new high efficient DC-free 3-ary run-length limited (RLL) code for 3-level optical recording system is presented. Signal processing techniques, partial-response maximum-likelihood (PRML), which is used for recovery data from readout signal, is discussed.
Multi-level optical storage is a promising approach to increase recording density and data transfer rate significantly without altering optical and mechanical parameters of current optical disc systems. Multi-level amplitude modulation and multi-level run-length limited modulation are two different important recording approaches. In this paper, we discuss and compare these two multi-level modulation principles and corresponding multi-level coding schemes. With advanced coding and signal detection, multi-level run-length limited modulation shows better performances in terms of higher recording density. We present a new 8-ary (1, 3) RLL code constructed by state splitting algorithm for photochromic storage channel. The proposed code has only two coding states and high coding density of 3.0 bits per minimum mark. The encoder/decoder is simple and easy for implementation, which can be applied in future high density multi-level optical storage systems.
4-Level Run-Length Limited (4L-RLL) optical storage based on photo-chromic materials is firstly investigated in this paper to our knowledge. Unlike binary recording, information in Multi-Level Run-Length Limited (ML-RLL) modulation system is carried in both the amplitude and length of the marks. ML-RLL optical storage can increase the recording density and data transfer rate with no changes to the optical/mechanical unit. For photo-chromic materials, different levels of input laser power amplitude give rise to different reflection levels. Using optimal write strategies, a 4 level linear playback signal was obtained and the sigma-to-dynamic range (SDR) of the 4-level signal was calculated. The results show that the SDR is low enough to provide low bits error rate (BER).
Proc. SPIE. 5643, Advances in Optical Data Storage Technology
KEYWORDS: Mathematical modeling, Control systems, Signal processing, Optical tracking, Servomechanisms, Digital video discs, Optical discs, Filtering (signal processing), Process modeling, Device simulation
This paper considers the implementation of compensators for periodic disturbance cancellation, specifically applied to the removal of repeatable runout(RRO) from the position error signal(PES) in the high performance DVD player. The internal model principle is used for rejecting the sinusoidal disturbance caused by eccentric rotation of the disk, and the LQG methodology is used for the servo compensator design to improve the drive performance and meet the stability-robustness specifications in the frequency domain. A mathematical model of radial servo is constructed which forms the basis of a computer simulation. Simulation results are presented to show that LQG design is a viable approach.