HP / Agilent 59551A GPS Measurements Synchronization Module

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.