The Satellite 931 CSU provides conditioning of T1 service lines. Its transparent operation passes the T1 bitstream unaltered. The Satellite 931 includes bipolar violation (BPV) correction, line build out, front-panel LED status indicators, test jacks, power options, and automatic keep-alive signal generation. It also features a signal monitor to ensure proper pulse density is transmitted to the network.??The Satellite 931 includes regenerators for both the incoming signals from the network, and from local customer equipment toward the network. The BPV detector monitors the Receive line from the network only.