Interface Control Documents (ICDs) & Interface Specifications (ISs)

A 1Hz message providing the current operational state of the SAASM receiver, including satellite tracking status and health. 3. ICD-GPS-153 vs. Other Protocols ICD-GPS-153 (GSSIP) Application Military/Defense Commercial/Marine Security Supports SAASM/Crypto Keys None (Plaintext) Data Format Binary/Specific Hex ASCII String Purpose Precise Time/Pos + Control Basic Position/Velocity Common Use SAASM to SINCGARS GPS to Marine Chartplotter

Today, while newer protocols exist, ICD-GPS-153 remains a cornerstone of legacy and modern Military GPS systems

Many tactical timing systems provide both protocols simultaneously: an ICD-GPS-153 port for secure military data and an NMEA 0183 port for general output.

: It provides a standard messaging format so that different military GPS hardware (like the NavGuard 100

The ICD-GPS-153 protocol defines several message types, each with a unique identifier. Some of the most common message types include:

The ICD-GPS-153 protocol was first introduced by the US Department of Defense (DoD) in the 1990s as part of the GPS (Global Positioning System) modernization effort. The protocol was designed to provide a standardized interface for GPS receivers to communicate with host devices, allowing for the exchange of GPS data, configuration, and control information.

This message is a GPS navigation data message (Message Type 2) that contains the following information:

Provides raw measurement data. Status Messages: Channel, satellite, and SAASM status. Time Mark (8504): Supports precision timing data.

While NMEA-0183 is the standard for commercial marine and civilian GPS devices, it lacks the security and high-accuracy synchronization required for military operations. ICD-GPS-153 (GSSIP) Military/SAASM Commercial/Consumer Security High (Encrypted) Low (Unencrypted) Data Types 1PPS, Detailed Status Standard NMEA Sentences Common Application SINCGARS, Tactical Systems Marine Plotters, Vehicle Nav 5. Accessing the ICD-GPS-153 Specification

The ICD-GPS-153 protocol is not an abstract technical specification—it is actively deployed in cutting-edge military and timing equipment. Here are several key examples: