The Keysight / Agilent / HP 37721A digital transmission analyzer is a portable, lightweight, rugged test set providing bit and code error testing at the European CEPT rates of 704 kb/s, 2, 8, 34, and 140 Mb/s. It measures error performance to CCITT Recommendation G.821, with interfaces to G.703.

A key feature of the HP 37721A is its ease of use: the auto setup facility automatically configures the test set to the incoming data; nine stored setups ensure that required test parameters are instantly available; graphic display of results shows error counts, error seconds, and alarms at a glance; and a range of logging options to an internal or external printer provides customized hard-copy proof of results.

Option 001 provides remote control via RS-232 and HP-IB interfaces and adds the ability to log results to an HP ThinkJet. Multiple outputs in Option 002 enable simultaneous loading of four channels of a multiplexer or digital radio with only one test set. With Option 003, up to 100 ppm of frequency offset is provided at all rates to evaluate clock-recovery circuits.