The HP 37724A is a comprehensive, field-portable SDH/PDH test set for applications up to 622 Mb/s (STM-4), It provides generation and analysis of TU-12 (2 Mb/s) and 140 Mb/s mapped SDH signals, with full control of regenerator section, multiplexer section, and path overhead bytes. Plug-in modules provide connection to a range of optical interfaces. Errors, alarms, and G.783 pointer movement sequences are generated to stress equipment up to and beyond CCITT standards.