Digital transmission evaluation project universal loop multiplexer ULM-101

Testing of the ULM-101 loop multiplexer was initiated to establish a data base and assessment of the continuous variable slope delta (CVSD) and log CVSD modulation techniques and to evaluate its ability to interface with existing signals typical of those in use in the Defense Communications System (DCS). Twelve tests of voice channel performance were conducted and in general the minimum DCS performance specifications for voice channels were met by the ULM-101 when operating at 32 KBPS and 64 KBPS sampling rates. Performance was marginal at 16 KPBS and unsuitable at 8 KBPS. Ability of the ULM-101 to interface with VFCT, SF signalling and MF signalling equipment was evaluated to be marginal.