NASA Scientific and Technical Aerospace Reports

McKinsey report, August 2001, the market trend for this industry is hard to predict at this point. In general, the telecom
markets have slumped for the last few years. The slowdown was caused by over-capacity and unrealistic forecast. Numerous
start-ups were funded five years ago, but many stocks dropped by 80 percent or more in value since then. Many US companies
have suffered great losses. However, the demand for broad band services is for sure increasing. It is estimated that the growth
rate may reach 25 percent a year. Thus the over-capacity or glut may be absorbed in a few years. It can be safely remarked
that the ‘fiber-radio’ technology is attractive, but it is not a huge mature market yet.
Author
Wireless Communication; Optical Communication; Radio Equipment; Communication Networks
20040047130 Budapest Univ. of Technology and Economics, Budapest, Hungary
Opto-Microwave Signal Processing: Up and Down Conversion Techniques
Berceli, Tibor; Csornyei, Mark; Optics Microwave Interactions; April 2003, pp. 6-1 - 6-17; In English; See also
20040047121; Copyright; Avail: CASI; A03, Hardcopy
This application note introduces the concepts of opto-microwave signal processing used in several communication
systems today. Emphasis is placed on optical-microwave up- and down conversion techniques. In today’s and future mobileor
local area networks (LAN) there is a need for optically supported network technologies with a few sophisticated central
stations serving a big number of quite simple and cheap optical terminals, such as small base-stations in millimeter-wave
optical-wireless local multipoint distribution systems (LMDS), computer or CATV networks. The right answer for all of these
challenges is the subcarrier modulated optical transmission. The subcarrier optical data transmission method offers several
advantages over the generally applied TDMA (time division multiple access) system. In a TDMA system the transmitters of
the stations are operated on a time sharing basis. In the receivers direct optical detection is used. In a high bit rate data
communications network a digital signal processing system with complete capacity should be applied both in the transmitters
and in the receivers. That is a big disadvantage which limits the future enhancement of the network capacity. In case of the
subcarrier type optical data communications the transmission capacity of the network can be increased by applying new
subcarriers, and thus the digital signal processing system can be kept with unchanged bit rate. The transmitters are used in a
continuous operation and in the receivers a heterodyne type detection can be applied which provides a lower noise figure. The
continuous operation of the transmitters makes possible several connections working at the same time. The present method
used for reception is rather complex and therefore somewhat troublesome because it applies a tuned filter. Utilizing an
opto-microwave mixer there is no need for a tuned filter and thus it is suitable for monolithic integration.
Author
Optical Communication; Microwaves; Signal Processing
20040047131 Drexel Univ., Philadelphia, PA, USA
Fiber Optic Distribution Networks for Military Applications
Daryoush, Afshin S.; Optics Microwave Interactions; April 2003, pp. 7-1 - 7-16; In English; See also 20040047121;
Copyright; Avail: CASI; A03, Hardcopy
A number of military applications require ad-hoc wireless communication and networking systems that employ low phase
noise reference signals for up- and down-conversion of communication signals and further processing of data signals. High
performance fiber optic links are important for distribution of signals while phase noise degradation induced by AM-PM
conversion in fiberoptic links impacts phase coherency of local oscillator (LO) signals in distributed systems. This paper
focuses on issues associated with directly and externally modulated fiber optic links and their performance limitations in terms
of gain, noise figure, nonlinearity, and dynamic range. The performance-cost aspects of both types of links are compared and
it is pointed out that directly modulated links meet performance-cost requirements in most applications. Analysis of phase
noise degradation of frequency reference is presented for directly modulated fiber optic distribution networks. SRS induced
fiber nonlinearity is also discussed. Since the response of a Fabry-Perot laser diode can be altered by adding an external
feedback, resulting in a resonance peak, results of a monolithically integrated FP laser are discussed. Finally, opto-electronic
mixing of IF and LO signals are also demonstrated for the mode-locked case.
Author
Communication Networks; Fiber Optics; Optical Communication
20040047132 Thales Airborne Systems, Elancourt, France
Optical Beamforming Networks for Radars and Electronic Warfare Applications
Chazelas, Jean; Dolfi, Daniel; Tonda-Goldstein, Sylvie; Huignard, Jean-Pierre; Optics Microwave Interactions; April 2003,
pp. 9-1 - 9-14; In English; See also 20040047121; Copyright; Avail: CASI; A03, Hardcopy
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