The 701 Digital Link (701-DL) providesan interface between a computer running EdgeTech's Discover sonar acquisition software and an EdgeTech sonar system (tow vehicle, sonar head). The 701-DL is self-contained, with all interface and power supply electronics housed within. Communication between the computer and the 701-DL is an Ethernet LAN connection using TCP/IP protocols. The data and control interface between the 701-DL and the sonar system is via TCP/IP protocols over the ADSL link using the 701-DL Ethernet connection and ADSL modem. A Sync Trigger port provides an interface with an external TTL trigger. EdgeTech Discover software interfaces with the 701-DL, monitors and controlsthe attached system, and displays and records acquired sonar and sensor data. The 701-DL fits a 19-inch rack and is delivered mounted independently in a rugged 2U-SKB case or mounted with an EdgeTech-provided computer in a rugged 6U case.