Icd-gps-153 Protocol Site
ICD-GPS-153 (Interface Control Document GPS-153) is a technical specification maintained by the United States Space Force (and historically the US Air Force Space Command). It defines the standard digital interface between a GPS Receiver Application Module (GRAM) or User Equipment (UE) and a Host Application Equipment (HAE), such as a mission computer, flight controller, or handheld terminal.
The ICD-GPS-153 protocol was first introduced by the U.S. Department of Defense (DoD) in the 1980s as part of the GPS system's development. The document provides a detailed description of the communication protocol used for transmitting data between GPS satellites and user equipment, such as GPS receivers. The protocol defines the format and structure of the data transmitted, as well as the communication channels and signal structures used.
ICD-GPS-153 is extensively used in environments requiring high reliability and security.
How does ICD-GPS-153 compare to other protocols you might encounter in a defense integration lab? icd-gps-153 protocol
For a practical example, Safran's VersaSync and NetClock systems use their ASCII outputs to generate ICD-GPS-153C messages over GSSIP. This allows them to emulate a SAASM GPS receiver for a SINCGARS radio, providing time and 1PPS data as if they were connected to a genuine, secure GPS source.
While the full protocol is controlled, common implementation examples (such as those used in timing systems) utilize specific message subsets: Safran - Navigation & Timing Current Status (Message 5040):
Provides real-time status updates of the GPS receiver, including satellite tracking information, signal lock, and integrity data. B. Time Transfer (Message 5101) Frequency: 1 Hz (once per second) Department of Defense (DoD) in the 1980s as
It serves as a reminder that in the world of critical infrastructure, protocols rarely die—they just get buried under layers of abstraction.
NetClock and other advanced time servers can generate ICD-GPS-153C messages to emulate a SAASM GPS receiver. This allows modern, highly stable network time servers to feed high-precision time (1 PPS) to legacy tactical radios (SINCGARS) or specialized platforms without needing a physical SAASM receiver attached to every piece of equipment.
A 1Hz message crucial for synchronizing external equipment with the GPS time source. M-Code offers improved anti-jam capabilities
The U.S. Department of Defense is currently transitioning from SAASM to (Military Code) on the GPS III satellites. M-Code offers improved anti-jam capabilities, greater power, and better security.
This SAASM receiver supports the ICD-GPS-153 protocol and outputs PVT (Position, Velocity, Time), PR/DR (Pseudo-range/Delta Range), and SAASM status data at rates up to 10 Hz. It is designed for SWaP-constrained applications like UAVs and embedded radios.
The protocol ensures the 1 Pulse Per Second (1 PPS) signal aligns perfectly with the time information in the binary messages.