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Showing papers on "Frequency-division multiplexing published in 1980"


Journal ArticleDOI
TL;DR: Currently MITRE is developing a variety of TDM techniques for use on coaxial cable, the design of public key crypto systems for application to local networks, integrated data and voice systems, the technical control of local networks and local network protocols.

23 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of multi/demultiplexer using an interference filter and a single graded-refractive-index (g.r.i.n.) rod lens is described.
Abstract: Wavelength division multiplexing (w.d.m.) techniques, which transmit light signals with different wavelengths through a single optical fibre, are required to increase transmission capacity. The letter describes a new type of multi/demultiplexer using an interference filter and a single graded-refractive-index (g.r.i.n.) rod lens. It has a simple structure and a low near-end crosstalk (less than −50 dB).

11 citations


Patent
25 Aug 1980
TL;DR: In this paper, a modular arrangement of directional RF filters was proposed to provide frequency multiplexing of signal sources at earth stations which are transmitting on two orthogonal polarizations.
Abstract: A modular arrangement of directional RF filters provides frequency multiplexing of signal sources at earth stations which are transmitting on two orthogonal polarizations. Each of the modules consist of a pair of 3 dB hybrid couplers coupled to each other through identical bandpass filters such that a signal applied to one of two input ports is output exclusively through an associated one of two output ports. The passbands of each of the modules are mutually exclusive. The output ports of each module are coupled to an output port of two adjacent modules, and two main outputs are taken from the two outer modules. The signals from the two main outputs are applied to two antennas having mutually orthogonal polarizations. The present invention may also be used as a demultiplexing receiver.

11 citations



Journal ArticleDOI
TL;DR: Reducing the number of amplifiers in cascade and the use of coherent carrier systems makes it possible for extended bandwidth cable systems to handle the additional channel loading with no more distortion than in present 35 channel systems.
Abstract: The need for extended bandwidth in cable communications systems is obvious. The rapid growth of cable systems in the U.S.A. is encouraging the proliferation of program services for cable distribution. The tree structured broad-band nature of cable systems means that capacity must be provided for all of the service to be distributed irrespective of relative popularity. Cable losses follow a square root of frequency law which makes bandwidth extension attractive as a means of increasing channel capacity. Reducing the number of amplifiers in cascade and the use of coherent carrier systems makes it possible for extended bandwidth cable systems to handle the additional channel loading with no more distortion than in present 35 channel systems.

3 citations




Journal ArticleDOI
TL;DR: A review of the available signal processing techniques to solve some of the EMI and EMC problems in Radar and Communication environment is presented in this article, where signal resolution, orthogonality, Orthogonal and FEC codes are discussed and their applications in different systems shown.
Abstract: The paper presents a review of the available signal processing techniques to solve some of the EMI and EMC problems in Radar and Communication environment. The signal resolution, orthogonality, orthogonal and FEC codes are discussed and their applications in different systems shown. Advantages of using Interference blankers in Radar, and FEC and SSMA in mobile and Satellite communication have been discussed and recent results presented. It is predicted that Radar and Communication will have to use larger and larger channel bandwidth for their co-existence and survival.

1 citations




Journal ArticleDOI
TL;DR: An error to equation (25) in the above-named work (ibid., vol. COM-27, pp. 1519-1527, Oct. 1979) is corrected.
Abstract: An error to equation (25) in the above-named work (ibid., vol. COM-27, pp. 1519-1527, Oct. 1979) is corrected.