NCJ Number
85876
Date Published
1974
Length
51 pages
Annotation
This study investigates the techniques of Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) for cost savings in the present National Law Enforcement Telecommunications System (NLETS), comparing multiplexed and nonmultiplexed costs for 13 illustrative cases.
Abstract
The analysis employed FDM in the first 6 cases, TDM in cases 7-12, and TDM use with asynchronous terminals only in case 13. Maps permit the reader to identify the States involved in each case. The study used popular manufacturers for typical costs and unit list prices, although quantity discounts and Government discounts would improve savings. Following a summary of its methodology, the study presents tables showing the following features of each case: type of muliplexing, manufacturer, the multiplex configuration, its costs, the costs without multiplexing which is the present NLETS configuration, and differences between the two. In all cases, multiplexing resulted in dollar savings with the most dramatic benefits occurring in the eastern United States. Purchasing modems could produce additional savings, but nothing as great as with line multiplexing. The study did not recommend investment in FDM equipment, since NLETS asynchronous terminals as they upgrade to become synchronous terminals will drop off the FDM channel and reduce its efficiency. It also concluded that savings were significant when large numbers of geographically close terminals are served and that the purchase of multiplexer with the lease of Bell 209 modems was attractive. Details given with each case allow the reader to extrapolate the technique to other situations. The appendixes provide detailed cost breakdowns for the 13 cases as well as costs for dial backup configurations. The latter offers a low cost alternative to cover private line or equipment failures in multiplexed networks. (Author abstract modified)