Tandem Connections of Wideband and Narrowband Speech Communications Systems: Part 1 - Narrowband-to-Wideband Link

Agencies of the United States government are currently formulating plans for an extensive digital secure voice communication network. In this network, a substantial fraction of the signals will be transmitted over "wideband" circuits at 16 kb/s. Owing to severe bandwidth constraints in some parts of the network, however, there will also be "narrowband" speech links in which the transmission rate is 2.4 kb/s. In preliminary plans, the wideband code format is CVSD (Continuously Variable Slope 1701 INPUT OUTPUT Fig. 1--Narrowband-to-wideband link.