Cabling
DS3 interconnect cables must be made with true 75 ohm coaxial cable and connectors. Cables or connectors which are 50 ohm or which significantly deviate from 75 ohms will result in signal reflections which will lower the performance of the connection, possibly to the point of not working. GR-139-CORE, Generic Requirements for Central Office Coaxial Cable, defines type 734 and 735 cables for this application. Due to losses, there are differing distance limitations for each type of cable. Type 734 has a larger center conductor and insulator for lower losses for a given distance. The BNC connectors are also very important as are the crimping and cable stripping tools used to install them. Trompeter, Cannon, Amphenol, Kings, and Canare make some of the true 75 ohm connectors known to work. RG-6 or even inexpensive RG-59 cable may work temporarily when properly connectorized, though it does not meet telephony technical standards.
Read more about this topic: Digital Signal 3