Transmission Plan for General Purpose Wideband Services

A transmission plan is described for interconnecting type 303 wideband data stations via facilities of the Bell System national network and those of connecting companies. Transmission signals are binary at digital rates up to 250 kb/s. The data station provides dc restoration of the polar signal to relieve the difficult requirement for adequate transmission close to zero frequency. The plan admits widespread use of the available, frequency-division, analog types of facility as well as the newer digital transmission facilities. Discussion is concentrated on 50 kb/s service in the 48 kc/s bandwidth ordinarily assigned to 12 telephone channels. A wideband network is predicated as a reasonable model for defining transmission limitations.