FEASIBILITY MODEL DEVELOPMENT DROP AND INSERT EQUIPMENT FOR MULTIPLEX

摘要

The principal aim of the work described herein was the development and construction or a practicable single channel Drop and Insert Multiplex System having a twelve-channel selection capability in the "B" group from 60KC to 108KC.nSecondary aims were analytical verification of design feasibility as applied to "A" group frequencies from 12KC to 60KC and investigation of state-of-the-art miniaturization techniques in circuitry and packaging.nA single-step modulation and demodulation plan was used with band stop - band pass filters operating at group channel frequencies. Iden¬tical phase and amplitude equalizers were installed in the drop circuitry and in the insert path. Out-of-band signalling facilities were included.nEngineering feasibility model consisted of a relay rack mounted, ex¬ternally powered, full duplex common equipment unit (voice frequency and signalling circuitry) with 12 sets of plug-in band stop - band pass filter and carrier oscillator subassemblies.nFinal system tests indicated some improvement is desirable in pass band ripple particularly in the higher frequency channels. Crosstalk, carrier suppression, distortion and other transmission characteristics were satisfactory.nThe design, construction and finally the testing of the full duplex Drop and Insert Equipment to RADC and CCITT recommended specifications has demonstrated the feasibility of the concept both from an operational point of view as well as from a practical production viewpoint. Although not all specifications were met or widely exceeded, the system was fully opera¬tional on all Group "B" channels and equipped for ease of installation into existing carrier terminal or repeater station equipment such that effective evaluation would present no unusual problems.