The HP/Agilent 59551A GPS Measurements Synchronization Module delivers precise timing and frequency references for distributed measurement systems using GPS satellite signals. It automatically maintains synchronization during signal loss via holdover mode, sustaining accuracy for up to 24 hours. The module interfaces with external instruments and computers through dual RS-232C ports and outputs multiple time-reference formats: 1 PPS (One-Pulse-Per-Second), programmable pulse signals, IRIG-B time-code, 10 MHz frequency reference, and TTL time-tag inputs. Four front-panel LED indicators display power status, GPS lock condition, holdover mode activation, and system alarms.
## Technical Specifications
• **Synchronization Source:** GPS satellite signals
• **Primary Timing Output:** 1 PPS (One-Pulse-Per-Second) continuous signal
• **Holdover Duration:** Up to 24 hours with accuracy degradation
• **Frequency Reference Output:** 10 MHz
• **Power Input:** 90–132 VAC or 198–264 VAC AC Jack
• **Option 002:** One-Pulse-Per-Two-Seconds (PP2S) output synchronized to even GPS time seconds
## Key Features
• Four front-panel LEDs: Power, GPS Lock, Holdover, Alarm indicators
• Dual RS-232C serial interfaces—DB-25 (rear panel) and 9-pin (front panel) connectors
• Programmable pulse output for user-defined timing requirements
• IRIG-B formatted time-code output for time distribution and magnetic tape annotation
• Alarm BITE relay output for external device signaling
• TTL time-tag input connectors for conditioned time signals
• N-type (female) GPS antenna connector
• Remote control, monitoring, and firmware identification via RS-232C using standard SCPI commands (*IDN?)
## Typical Applications
• Telecommunications network synchronization
• Aerospace and research timing systems
• Utility substation and power plant frequency references
• Multi-site coordinated data acquisition
• Magnetic tape annotation and time distribution networks
## Compatibility & Integration
The 59551A integrates with measurement systems requiring distributed GPS-disciplined timing through industry-standard serial interfaces and multiple output formats. RS-232C connectivity enables PC-based remote operation and firmware management.
