Showing papers on "Optical Carrier transmission rates published in 1980"
TL;DR: In this paper, the error rate characteristics of various optical modulation-demodulation schemes are studied and a coherent optical transmission system is employed in place of the presently available amplitude-shift-keyed (ASK) baseband direct detection system.
Abstract: Error rate characteristics of various digital optical modulation-demodulation schemes are studied. The main concern is whether we can improve receiving power levels to achieve a prescribed error rate by employing a coherent optical transmission system in place of the presently available amplitude-shift-keyed (ASK) baseband direct detection system. The receiving power level reduction in various modulation-demodulation schemes is calculated by taking into account the optical carrier wavelength, data rate, photodetector performance, local oscillator power level, and number of levels in multilevel codes. The phase-shift-keyed (PSK) homodyne detection system requires the least receiving power. The improvement in the receiving power level compared to the conventional ASK baseband direct detection system is expected to be 16-22 dB at the carrier wavelength of \lambda_{c} = 0.5-3 \mu m, 31-36 dB at \lambda_{c} = 3-5 \mu m, and 35-40 dB at \lambda_{c} = 5-10 \mu m.
137 citations
TL;DR: The cutoff rate is derived for a digital communication system employing an optical carrier and direct detection and the coordinated design of the encoder, optical modulator, and demodulator is studied using the cutoff rate as a performance measure rather than the more commonly employed error probability.
Abstract: The cutoff rate is derived for a digital communication system employing an optical carrier and direct detection. The coordinated design of the encoder, optical modulator, and demodulator is then studied using the cutoff rate as a performance measure rather than the more commonly employed error probability. Modulator design is studied when transmitted optical signals are subject simultaneously to average-energy and peak-value constraints. Pulse-position modulation is shown to maximize the cutoff rate when the average-energy constraint predominates, and the best signals when the peak-value constraint predominates are identified in terms of Hadamard matrices. A time-sharing of these signals maximizes the cutoff rate when neither constraint dominates the other. Problems of efficient energy utilization, choice of input and output alphabet dimension, and the effect of random detector gain are addressed.
45 citations
Patent•
07 Oct 1980
TL;DR: In this paper, an array with space-division switching by directional couplers without signal memorization is presented, which includes an array (1) with space division switching by a directional coupler and a receiver (2) connected to a processor which controls the switching of the coupler via an interface circuit.
Abstract: The switching device includes an array (1) with space-division switching by directional couplers without signal memorization, directional couplers (2 1 , . . . 2 r ), detectors (3 1 , . . . 3 r ) and receivers (4 1 , . . . 4 r ) connected to a processor which controls the switching of the couplers of the array (1) via an interface circuit (6). The processor reinserts in the output channels switching control signals and synchronization signals via converters (8 1 , . . . 8 s ) and couplers (7 1 , . . . 7 s ).
7 citations
Patent•
13 Feb 1980
TL;DR: In this article, the optical carrier wave of different wavelengths are branched through optical branching filters 12-12'', carrying out the exchange directly in the form of light wave multiplication through a simple method.
Abstract: PURPOSE:To realize the selection of the output paths by branching the optical carrier wave by the branching filter and thus to simplify the hardware and software necessary for selection of the output path as well as to realize the direct exchange in the form of the light wavelength multiplication with no light-electricity or electricity-light conversion applied. CONSTITUTION:Optical carrier waves of wavelengths lambda1-lambda4 supplied to optical transmission line 13 is applied to optical branching filter 12 of repeating exchange 11, and wavelength lambda1 is branched among lambda1-lambda4. And the branched output is supplied to exchange 17 which performs the exchange with every call via intra- office optical transmission line 14'. At the same time, optical carrier waves of wavelength lambda2-lambda4 are introduced with wavelength division to optical repeating exchange 11' which is positioned in a higher rank via inter-office optical transmission line 14. Then wavelength lambda2 is branched via optical branching filter 12' of exchange 11' and then led into exchange 17' via intra-office optical transmission line 15' to transmit the carrier waves of lambda3 and lambda4 to next exchange 11''. Thus the optical carrier waves of different wavelengths are branched through optical branching filters 12-12'', carrying out the exchange directly in the form of light wave multiplication through a simple method.
1 citations