We present a feature extraction method for a feedforward-type neural network (FNN) designed to realize a distributed acoustic sensing (DAS) technique that suits conventional optical fiber. This is, to the best of our knowledge, the first trial in which an FNN is used to interpret the field communication infrastructure type surrounding optical cables. Three classes are taken to represent the field environment: the cable tunnel (class 1), circular duct (class 2), and overhead area (class 3). We investigate and compare frequency- and time-domain feature extraction. We also show that the frequency-domain features yielded by spectral envelope shape (SES) processing have better performance than simple fast Fourier transform features. Two types of time-domain features are verified: one is the short-time maximum magnitude (STMM), which shows the largest value in the time frame, and the other is the short-time average magnitude (STAM), which indicates the average value in a time frame. Note that all features are optimized for multi-class classification. In this paper, we present the suitable number of both features and the number of training iterations. An accuracy rate of 79.0% is achieved using FNN analysis with the features studied here. Furthermore, by considering the similarity of neighboring classes, classes are refined into higher probability classes. As a result, accuracy is improved to 87.2%.

We investigate a machine learning algorithm that interprets distributed vibration in a telecommunication facility environment. This is the first evaluation on the accuracy of a classification algorithm using field data in a cable tunnel.

We can automate inspection work of infrastructure facilities by analyzing the characteristics of 3D structure information obtained through 3D structure visualization using a point cloud. The safety level of equipment can then be diagnosed quantitatively. In this paper, we investigate the modeling of wire structures such as overhead communication cables between utility poles, which are close to the ground, have many obstructions, and have a complex structure. We evaluate the accuracy of cable models and compare them to the correct model. We use three modeling methods: a machine-learning method based on the extruded surface of a point cloud as a feature, a rule-based method involving principal component analysis, and models generated from a combination of these models. In addition, we focus on modeling overhead cables from field data (urban and suburban). Results show the practicability of modeling overhead cables with a cable length of 10–70 m regardless of the area type. We find that the best cable modeling rate with the precision and recall of 80.76% and 83.84%, respectively, can be obtained using the machine-learning method and by specifying the cable reproduction rate to be 2 m. Article highlights This study is useful in determining the practicality of 3D visualization of communication cables based on a 3D point cloud. Precision and recall are presented as indices to determine the practicality of 3D cable modeling. This study provides 3D cable modeling for actual field data (in suburban, bridges, and urban areas).

This letter describes a novel configuration and theory for the degree of coherence measurement based on the statistical speckle analysis in coherent optical frequency domain reflectometry. The difference from the previous letter is using a standard phase modulator instead of a single-sideband modulator, which not only simplifies the system configuration, but also yields modulation efficiency, resulting in the operation with lower light source power. A novel theory is presented to describe the operation of the proposed configuration, and experimental results show the validity of the new configuration and theory.

Phase error variance is an important figure in many laser applications such as coherent optical communication and interferometric optical diagnosis and is directly related to system performance. In this letter, we show that the phase error variance of a single-mode laser with a narrow linewidth can be measured as a function of relative delay without using any reference (local) beam. In addition, the results are in good agreement with those measured using the beat note of two identical lasers, one of which acts as a local beam. The new method, uniquely we believe, enables us to evaluate the phase error variance of lasers at continuous delays without using any reference (local) beam.

We propose a novel technique for characterizing laser phase noise using parallel linear optical sampling. The high bandwidth of the linear optical sampling relaxes the bandwidth limitation, which is the critical problem in phase noise characterization using a digital coherent receiver.

The modulus of the degree of coherence (DOC) of a kHz-linewidth laser is fully characterized for the first time by using a single test laser. By employing the obtained DOC, the power spectrum is reconstructed, and the phase-error variance for a short delay is analysed, which is important in coherent communication.

The measurement of the spectral broadening, or temporal coherence property of very narrow linewidth lasers is not an easy task, while such a measurement is essential in any interferometric applications of the lasers. The beat note between two assumingly identical lasers only provides the convolutional spectral profile of the two lasers, but not characterizes the single laser. The delayed self-heterodyne interferometer (DSHI) would not be effective for kHz linewidth range because the finite delay cannot realize complete de-correlation. Here, we demonstrate, for the first time to our knowledge, the complete characterization of the modulus of the degree of coherence (DOC) of kHz linewidth lasers, with a self-referenced fashion where any other reference beam is not used, accordingly, characterize the spectral profile. The method is based on speckle statistical analysis of the Rayleigh scattering in the coherent fiber reflectometry, and would be a novel strong tool to characterize very narrow linewidth lasers.

A novel method for characterizing the amplitude of a coherence function with respect to a delay between two optical waves is proposed and demonstrated by using a distributional Rayleigh speckle analysis based on C-OFDR. This technique allows us to estimate both the coherence time of the laser and that of the spectral profiles from the measured amplitude of the coherence function, if the symmetry of the spectrum can be assumed. The spectral width obtained in the experiment agrees roughly with that obtained using a delayed self-heterodyne method.

ScanningVolume 4, Issue 3 p. 155-158 Short NoteFree to Read Addition of surface information to STEM image by signal processing J. Hosoi, J. Hosoi JEOL Ltd, 1418 Nakagami, Akishima, Tokyo 196, JapanSearch for more papers by this authorM. Inoue, M. Inoue JEOL Ltd, 1418 Nakagami, Akishima, Tokyo 196, JapanSearch for more papers by this authorY. Kokubo, Y. Kokubo JEOL (USA) Inc., 11 Dearborn Road, Peabody, MA 01960, USASearch for more papers by this authorK. Hama, K. Hama Department of fine morphology, Institute of Medical Science, University of Tokyo, 4-6-1 Shiroganedai, Minato-ku, Tokyo 108, JapanSearch for more papers by this author J. Hosoi, J. Hosoi JEOL Ltd, 1418 Nakagami, Akishima, Tokyo 196, JapanSearch for more papers by this authorM. Inoue, M. Inoue JEOL Ltd, 1418 Nakagami, Akishima, Tokyo 196, JapanSearch for more papers by this authorY. Kokubo, Y. Kokubo JEOL (USA) Inc., 11 Dearborn Road, Peabody, MA 01960, USASearch for more papers by this authorK. Hama, K. Hama Department of fine morphology, Institute of Medical Science, University of Tokyo, 4-6-1 Shiroganedai, Minato-ku, Tokyo 108, JapanSearch for more papers by this author First published: 1981 https://doi.org/10.1002/sca.4950040306AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume4, Issue31981Pages 155-158 RelatedInformation