A portable telegraph bias and distortion measuring instrument

IN THE modern telegraph system, signals are transmitted over various trunk facilities derived from wire lines or radio relay systems. The trunk telegraph channels furnish facilities between a number of switching centers located at strategic points throughout the country. These centers then distribute traffic to the local points of destination. In addition, various other services must be accommodated by suitable network configurations. These services comprise such arrangements as are involved in leased network circuits, private switching systems, etc. It is necessary that flexibility be maintained in this complex network of circuits so that circuit patching and routing may be accomplished without making undue alignment changes in the circuits themselves.