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A Cd-Rom Based Agricultural Information Retrieval System, H W. Beck, P H. Jones, Dennis G. Watson
A Cd-Rom Based Agricultural Information Retrieval System, H W. Beck, P H. Jones, Dennis G. Watson
Articles
An information retrieval system for agricultural extension was developed using CD-ROM technology as the primary medium for information delivery. Object-oriented database techniques were used to organize the information. Conventional retrieval techniques including hypertext, fulltext searching, and relational databases, and decision support programs such as expert systems were integrated into a complete package for accessing information stored on the CDROM. A multimedia user interface was developed to provide a variety of capabilities including computer graphics and high-resolution digitized images. Information for the disk was gathered and entered using extension publications which were tagged using an SGML-based document markup language. The fully …
Fast Tcm Decoding: Phase Quantization And Integer Weighting, Frank Carden, Michael D. Ross, Brian T. Kopp, William P. Osborne
Fast Tcm Decoding: Phase Quantization And Integer Weighting, Frank Carden, Michael D. Ross, Brian T. Kopp, William P. Osborne
Articles
TCM, combining modulation and coding, achieves coding gains over conventional uncoded multilevel modulation without the attendant bandwidth expansion. Since TCM was proposed Ungerboeck (1982, 1987) substantial work has done in this area. A large portion of the TCM work has been in the area of high-speed data transmission over voice grade modems using quadrature amplitude modulation, QAM. QAM, not having a constant envelope, is unattractive for employing a TWT with its nonlinear behavior as the power stage. Additional work has been done in utilizing M-ary PSK with TCM. Simulations by Taylor and Chan (1981) utilizing a 4-state convolutional code demonstrated …
Performance Study Of Maximum Likelihood Receivers And Transversal Filters For The Detection Of Direct Sequence Spread Spectrum Signal In Narrowband Interference, Arif Ansari, R. Viswanathan
Performance Study Of Maximum Likelihood Receivers And Transversal Filters For The Detection Of Direct Sequence Spread Spectrum Signal In Narrowband Interference, Arif Ansari, R. Viswanathan
Articles
Linear least squares estimation techniques can be used to enhance suppression of narrowband interference in direct sequence spread spectrum systems. Nonlinear techniques for this purpose have also been investigated recently. In this paper, we derive maximum likelihood receivers for direct sequence signal in Gaussian interference with known second order characteristics. It is shown that if the receiver uses samples from outside the bit interval, then the receiver structure is nonlinear. The bit error rate performances of these receivers are compared to those of linear receivers employing one-sided and two-sided least squares estimation filters, for the case of Gaussian autoregressive interference. …