Free-space optical measurement systems can have a direct impact on evaluation systems operational in propagation paths. During propagation via optical fibers, light suffers scattering or interference, causing some output signal loss with an uncertainty outcome. Therefore, this study aims to explore the instant decisions related to the use of single- and multi-mode fiber optics and how they affect the gathering of data from high-speed optical measurement instrument links. The study also seeks to address a number of design methodology aspects and the empirical outcomes related to a surface topography measurement sensor based on fiber optics capable of surface roughness or step-height measurement. The study suggests that the Fourier transform profilometry method (FTP) can overcome the disadvantages of optical metrology sensors (e.g., bulkiness, challenging set-up, high costs, and low speed). However, despite eliminating vertical height problems, the Fourier transform profilometry (FTP) did have some shortcomings for every outcome related to core variables, including the dispersive optical fiber link sensor. The synthetic wavelength method enabled the dispersive optical fiber link sensor to calculate the vertical step height of the selected sample (1 µm). There was improved step-height repeatability, with satisfactory from 20 to 18 nm outcome improvement range. Additional investigations are necessary to establish the compatibility of single- or multi-mode optical fiber sensors with particular instruments, especially those currently preferred for embedded metrology applications.
Dicode Pulse Position Modulation (DiPPM) has been proposed as an alternative modulation scheme to digital PPM over optical fibre channels. This paper, for the first time, analyses the receiver sensitivity of the DiPPM system on a diffuse indoor Visible Light Communication (VLC). The system operates at a bit rate of 1Gbit/s and = 0.65 m. A mathematical model of the VLC using DiPPM is presented. The results show the degradation in sensitivity as normalized delay spreads increase. It is shown that with a typical delay spread of 5 ns, the DiPPM system can achieve a sensitivity of -36.47 dBm and -37.5 dBm for the error rates of 10 -9 and 10 -6 , respectively. This represents a sensitivity improvement over a comparable digital PPM system by 3.47 dB and 3.5 dB.
The Low Density Parity Check (LDPC) forward error correction code provides significant results that have been very close to Shannon limit. This paper compares the Bit Error Rate (BER) performance of soft decision decoding algorithms of LDPC codes on AWGN channel. Devising soft decision decoding algorithms which are good in BER performance requires a comparison of probabilistic, log domain and Min-Sum methods. Simulations are conducted with different parameters using MATLAB workspace to evaluate the LDPC system performance. Results have shown that Min-Sum has outperformed the algorithms of Log Domain and Prob. Domain with a considerable amount of the Signal to Noise Ratio (SNR). Finally, the optimal LDPC parameter values have been selected based on the achieved results which provide superior results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.