Pub Date : 1900-01-01DOI: 10.1002/9781119602019.ch7
N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev
There are two main types of optical signals propagating in wired or wireless communication links: time continuously varied or analog, which corresponds to narrowband channels, and time discrete varied or pulse‐shaped, which corresponds to wideband channels. Therefore, there are different types of modulation that are usually used for such types of signals. This chapter defines the process of modulation and demodulation. It describes the main principle of both kinds of modulation, analog and digital, and provides some examples of the most useful types of modulation adapted for both kinds of channels, narrowband and wideband. There are three types of modulation, depending on what characteristic is time varied in the modulating signal – amplitude modulation, phase modulation, and frequency modulation. There are three kinds of digital modulation: amplitude shift keying, frequency shift keying, and phase shift keying.
{"title":"Modulation of Signals in Optical Communication Links","authors":"N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev","doi":"10.1002/9781119602019.ch7","DOIUrl":"https://doi.org/10.1002/9781119602019.ch7","url":null,"abstract":"There are two main types of optical signals propagating in wired or wireless communication links: time continuously varied or analog, which corresponds to narrowband channels, and time discrete varied or pulse‐shaped, which corresponds to wideband channels. Therefore, there are different types of modulation that are usually used for such types of signals. This chapter defines the process of modulation and demodulation. It describes the main principle of both kinds of modulation, analog and digital, and provides some examples of the most useful types of modulation adapted for both kinds of channels, narrowband and wideband. There are three types of modulation, depending on what characteristic is time varied in the modulating signal – amplitude modulation, phase modulation, and frequency modulation. There are three kinds of digital modulation: amplitude shift keying, frequency shift keying, and phase shift keying.","PeriodicalId":345187,"journal":{"name":"Fiber Optic and Atmospheric Optical Communication","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125176450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1002/9781119602019.ch11
N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev
This chapter focuses on the effects of the troposphere on optical wave propagation starting with a definition of the troposphere as a natural layered air medium consisting of different gaseous, liquid, and crystal structures. In optical communication, the dense aerosol/dust layers, as part of the wireless atmospheric communication channel, can cause signal power attenuation, as well as temporal and spatial signal fluctuations. Atmospheric turbulence is a chaotic phenomenon created by random temperature, wind magnitude variation, and direction variation in the propagation. The chapter shows that atmospheric turbulences due to their motion can cause strong frequency‐selective or flat fast fading. It analyzes some effects of the turbulent structures on optical signals/rays passing gaseous turbulent irregular atmosphere. The chapter summarizes that for all effects of hydrometeors, as well as fast fading caused by atmospheric turbulences, multipath phenomena due to atmospheric inhomogeneities and diffuse scattering should be taken into account in land–atmospheric, or atmospheric–atmospheric optical communication links. .
{"title":"Atmospheric Communication Channels","authors":"N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev","doi":"10.1002/9781119602019.ch11","DOIUrl":"https://doi.org/10.1002/9781119602019.ch11","url":null,"abstract":"This chapter focuses on the effects of the troposphere on optical wave propagation starting with a definition of the troposphere as a natural layered air medium consisting of different gaseous, liquid, and crystal structures. In optical communication, the dense aerosol/dust layers, as part of the wireless atmospheric communication channel, can cause signal power attenuation, as well as temporal and spatial signal fluctuations. Atmospheric turbulence is a chaotic phenomenon created by random temperature, wind magnitude variation, and direction variation in the propagation. The chapter shows that atmospheric turbulences due to their motion can cause strong frequency‐selective or flat fast fading. It analyzes some effects of the turbulent structures on optical signals/rays passing gaseous turbulent irregular atmosphere. The chapter summarizes that for all effects of hydrometeors, as well as fast fading caused by atmospheric turbulences, multipath phenomena due to atmospheric inhomogeneities and diffuse scattering should be taken into account in land–atmospheric, or atmospheric–atmospheric optical communication links. .","PeriodicalId":345187,"journal":{"name":"Fiber Optic and Atmospheric Optical Communication","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129542517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1002/9781119602019.ch1
N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev
An optical communication system transmits analog and digital information from one place to another using high carrier frequencies lying in the range of 100—1000 THz in the visible and near‐infrared region of the electromagnetic spectrum. This chapter describes the basic elements of the optical communication channel, including the transmitter, as a source of light, and the receiver, as the detector of light. The photodetectors do not affect the propagation properties of the optical wave but certainly must be compatible with the rest of the system. The transmitter includes a modulator, a driver, a light source, and optics. The receiver includes optics, a filter, a polarizer, a detector, a trans‐impedance amplifier, a clock recovery unit, and a decision device. The atmospheric channel attenuates the power of the optical signal and widens and spreads it in the spatial, temporal, angular, and polarization domains.
{"title":"Basic Elements of Optical Communication","authors":"N. Blaunstein, S. Engelberg, E. Krouk, M. Sergeev","doi":"10.1002/9781119602019.ch1","DOIUrl":"https://doi.org/10.1002/9781119602019.ch1","url":null,"abstract":"An optical communication system transmits analog and digital information from one place to another using high carrier frequencies lying in the range of 100—1000 THz in the visible and near‐infrared region of the electromagnetic spectrum. This chapter describes the basic elements of the optical communication channel, including the transmitter, as a source of light, and the receiver, as the detector of light. The photodetectors do not affect the propagation properties of the optical wave but certainly must be compatible with the rest of the system. The transmitter includes a modulator, a driver, a light source, and optics. The receiver includes optics, a filter, a polarizer, a detector, a trans‐impedance amplifier, a clock recovery unit, and a decision device. The atmospheric channel attenuates the power of the optical signal and widens and spreads it in the spatial, temporal, angular, and polarization domains.","PeriodicalId":345187,"journal":{"name":"Fiber Optic and Atmospheric Optical Communication","volume":"392 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127590571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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