The Agilent/Keysight 3785A is a specialized jitter generation and measurement instrument designed for testing digital transmission terminal and link equipment in CEPT and Bell hierarchies up to DS-3 (34368 kb/s). It performs production testing, field installation, and maintenance across cable, radio, satellite, and fiber optic transmission media. The instrument delivers six distinct jitter measurement types—absolute amplitude in Unit Intervals (UI) peak-to-peak, positive/negative jitter peak, jitter hit count, jitter hit seconds, and hit-free seconds—against CCITT Recommendation 0.171 tolerance masks. Microprocessor control and HP-IB interface enable automated measurement sequencing and bus-controlled operation.
Technical Specifications
• Maximum bit rate handling: Four internal bit rates (up to DS-3, 34368 kb/s)
• Jitter measurement: Absolute amplitude in Unit Intervals (UI) peak-to-peak; positive or negative peak values; hit count with user-defined thresholds; hit seconds and hit-free seconds tracking
• Jitter generation: Sinusoidal phase modulation with manually controlled or swept amplitude and frequency per CCITT Recommendation 0.171
• Measurement filters: Two high-pass and one low-pass filter per bit rate, all CCITT-compliant
• Input capabilities: Clock or data inputs with optional internal filtering
• Jitter source: Internal crystal clock or external data stream modulation
– Key Features
• Transient-free sweeping of CCITT-defined jitter tolerance masks
• Real-time jitter analysis against amplitude thresholds
• Four-rate portable configuration in single unit
• Front-panel frequency display for internal modulation
• Ergonomic front-panel layout with integrated switch and connector arrangement
– Typical Applications
• CEPT and Bell PCM/TDM transmission system validation
• Production testing of digital transmission terminals
• Field installation verification and maintenance diagnostics
• Multi-media link testing: cable, radio, satellite, and fiber optic systems
– Compatibility & Integration
• HP-IB interface for automated control and data sequencing
• Microprocessor-based operation for programmable measurement workflows
