The HP 3784A is a portable error performance/jitter test set, offering standard telecom interfaces at 704 kb/s, 2, 8, and 34 Mb/s. In addition it has binary TTL/ECL interfaces for measurements up to 50 Mb/s using internal clock synthesizer.  The HP 3784A is easy to use with measurement presets, automatic receiver setup and error performance pass/fail thresholds.  Automatic jitter tolerance and transfer plotting routines are provided for fast accurate testing up to and beyond CCITT limits.  Through data mode allows jitter to be added to a structured signal for jitter tolerance testing of demultiplexers.