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We propose an imaging sonar-based backtracking method as a navigation strategy for an underwater investigation of AUVs. The purpose of backtracking method is to reduce a drift error caused by the inaccuracy of navigation sensors when an AUV returns to its previous position. The AUV divides the trajectory into several intervals and returns to the previous position while correcting small drift error...
In this paper, we propose a backtracking method of AUV based on optical and acoustic image evaluation. With the proposed method, the vehicle can record useful images on its path, and conduct backtracking efficiently and robustly even in turbid water. At each point during the exploration, AUV chooses better image between optical and acoustic image by feature detection. The chosen image is saved in...
Docking an autonomous underwater vehicle is a critical part of many current and envisioned Navy, commercial, and scientific missions. In the Defense Advanced Research Projects Agency's (DARPA) Tactical Undersea Network Architectures (TUNA) program, docking a vehicle is a key enabler for several of the proposed concepts of operation. To support the program, a series of risk reduction tests were performed...
In this paper, we investigate the impact of timing mismatch among different sub-bands on the performance of a multicarrier spectral-slicing OFDM system with a single coherent receiver, both in the back-to-back configuration and long-distance fiber transmission. Two different timing mismatch models, namely linear timing error and Gaussian timing error, are introduced and investigated. Furthermore,...
Glaucoma is caused due to neuro degeneration of the optic nerve leading to vision loss. The Optic nerve that is responsible for transmission of visual information to the brain can be viewed in a fundus image. In this paper, a new approach for determination of the presence of glaucoma based on the features extracted from the fundus image is proposed. Histogram oriented features (HoG) are extracted...
In optical wireless communications, because of the attenuation of light and the shadowing of the channel, partial erasure channel, which means failing to receive a part of transmitted light steams, may raise. It is of importance to design a system compatible with partial erasure channel. In this paper, a new turbo coded APPM system is proposed. APPM is a modulation technique combining with amplitude-shift...
The high density code-shift-keying (CSK) using Pseudo Noise (PN) codes generated by combining modified pseudo orthogonal M-sequence sets (MPOMs) with biorthogonal code has been proposed. In this paper, synchronous code division multiple access (SCDMA) capability of the proposed system is clarified under the optical-wireless channel. Consequently, simulation results are in good agreement with theoretical...
This paper reports on ex-vivo studies with rabbit eyes using an optical intraocular pressure (IOP) measurement system. The system consists of an optical reader and a miniaturized interferometric pressure sensor integrated onto a standard intraocular lens. The results show that the measurement sensitivity of the sensor is on the order of 22 nm/mmHg with an accuracy of ±0.5 mmHg post implantation. The...
The principle of operation of the optical device for determine the size and velocity of rain and hail drops and measuring the level of meteorological precipitation is described. The estimation of the required parameters of the electronic and optical elements of the device is presented. Two version of the device construction the slit-type diaphragm and arrays of photodiodes were tested and obtained...
Analog Radio-over-Fiber (a-RoF) has been the subject of increased interest in relation to next-generation optical networks due to its spectral efficiency and lower deployment cost. Nonetheless, some complexity arises from electro-optical conversion of the information signal due to the non-linear characteristic of the modulator's transfer function which causes inter-channel interference and poses a...
Reflex Photonics Inc. has developed compact 40G full duplex (4+4) 10Gbps/lane optical fiber transceivers for harsh environment applications such as Aerospace and Defense. These products were made to be embedded on printed-circuit boards in close proximity to high speed electronics in high performance embedded computing systems to optimize their performance [1,2]. Going one step further, the industry...
The support of higher order modulation format such as 16-QAM and 64-QAMis an essential feature of next generation coherent optical transceivers to ensure a spectrally efficient and high capacity optical transmission [1–3]. In previous work, we have proposed an optical QAM transmitter scheme that employs QPSK modulators driven by binary electrical signals [4, 5]. This paper presents the design for...
Optically active Spatial-Spectral (S2) materials are a unique resource for spectrally based optical memory and processing. At cryogenic temperatures, the rare-earth ions in these materials individually exhibit narrow optical resonances on the order of MHz to sub-KHz, but are inhomogeneously broadened over GHz to THz spectral bandwidths providing up to 10^7 resolvable spectral channels. The material...
Photonic reservoir computing is a recent bio- inspired paradigm for signal processing. Despite first successes, the paradigm still faces challenges. We address some of these challenges and introduce our approaches to solve them. In detail, we discuss how integrated reservoirs can be scaled up by injecting multiple copies of the input. Further we introduce a new hardware-friendly training method for...
This paper discusses the effect of ionizing radiation on several commercial transceivers. The changing of current and receiver sensitivity of optical transceivers are discussed and analyzed. Based on the results, the commercial components need to reinforce in order to be suitable for space application.
Multi-access stable radio frequency phase dissemination for 100 km fiber-optic loop link is achieved based on single optical source. Phase jitter of 2.4 GHz signal at the accessing node is reduced to 1.57 ps/1.76 ps.
Optical mapping is a high-throughput sequencing technology which carries long-range genome information at no risk of PCR artifacts. On account of its long span, optical maps leave much fewer gaps when used for genome assembly. However, a high risk of errors poses an enormous challenge to optical map assembly. Here we propose an iterative algorithm for de novo optical map assembly. In any iteration,...
We investigate theoretically and experimentally the factors to influence on the core height when the Mosquito method is applied. Using the simulation analysis, we find a correction method to align the core height accurately.
A 25.78-Gbit/s × 4-ch active optical cable (AOC) with a ultra-compact form factor is proposed. The size of the proposed AOC is 5.2 cm3, which is 45-% smaller than the standard form factor of a pQSFP. By utilizing a gapped ground electrode structure, the proposed AOC demonstrated 25.78-Gbit/s error-free optical transmission under all-channels (4-ch) operation, and improved bit error rate (BER) power...
In this contribution we consider a communication system consisting of a cascade of a passive optical network (PON) link with on/off keying, and a short twisted pair (TP) link with discrete multitone modulation (DMT). Three coding configurations are investigated. In the first configuration (C1), the PON link and the TP link are protected by a Reed-Solomon (RS) code and trellis-coded modulation (TCM),...
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