The PA-41 is a handheld frame/signalling analyzer for use on 2 Mbit/s digital primary multiplex networks. The instrument has one transmitter and two receivers conforming to ITU-T Recommendation G.703. The user interface is via an LCD screen and membrane keyboard. The menu-driven software is structured for ease of operation and clarity of information. The user interface may be etended to a remote VDU terminal via the V.24 port which can also be used to drive a printer to provide hard copy of setups and results. A memory card interface provides for mass setup and results storage and the means to install software options. The instrument provides two modes of operation: Bit Error Ratio Testing (BERT) PCM and frame analysis (PCM) The PA-41 has many applications for digital primary multiplex testing in the field including: Framed monitoring in both directions simultaneously Framed end to end analysis Drop and Insert testing Digital Cross Connect Testing Automatic protection switch testing Unframed end to end testing