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offers GPS time and frequency systems that support GSSIP.
+-----------------------------------+ +------------------------------------+ | Military GPS Receiver (UE) | Serial | Host System | | - GB-GRAM / DAGR | Interface | - SINCGARS Tactical Radio | | - SAASM / M-Code Security Core | ----------> | - Weapon / Survey System | | - Generates Time & Status Data | (153 Protocol)| - Command & Control Network | +-----------------------------------+ +------------------------------------+ Physical and Data Link Layer Specifications
) identifies the request and replies with a standardized data burst. The Result
The (Interface Control Document GPS 153) is a specialized, military-grade data communication standard used primarily by U.S. Department of Defense (DoD) and allied military systems to interface host applications with military Global Positioning System (GPS) receivers. Unlike civilian GPS protocols like NMEA-0183 or ASCII text streams, ICD-GPS-153 dictates a secure, highly controlled serial interface protocol—often implemented as part of the GPS Standard Serial Interface Protocol (GSSIP) —to transmit critical Position, Navigation, and Timing (PNT) data to communication networks, tactical systems, and inertial navigation systems. Because it governs the output of secure hardware like SAASM (Selective Availability Anti-Spoofing Module) and newer M-Code military GPS receivers, the full technical manual requires specific DoD clearance or an approved request form from agencies like the U.S. Coast Guard Navigation Center . Core Purpose and Role in Military GPS
The protocol ensures the 1 Pulse Per Second (1 PPS) signal aligns perfectly with the time information in the binary messages. icd-gps-153 protocol
The primary role of the ICD-GPS-153 protocol is to manage the hardware and software boundaries between a military GPS receiver—such as a Ground-Based GPS Receiver Application Module (GB-GRAM) or a Defense Advanced GPS Receiver (DAGR)—and its host vehicle, weapon system, or tactical network.
The P(Y) code was designed in the 1970s-80s. Engineers realized that the civilian C/A code was vulnerable to:
The three essential message types are:
The logical wrapper utilizing ICD-GPS-153 framing rules is often referred to as the . GSSIP formalizes how binary or structured ASCII blocks move through communication ports to provide reliable Positioning, Navigation, and Timing (PNT) updates. The Role of ICD-GPS-153 in Military PNT offers GPS time and frequency systems that support GSSIP
Unlike common civilian protocols (e.g., NMEA-0183), the ICD-GPS-153 protocol handles specialized requirements: ICD-GPS-153 Supports SAASM/Encrypted Data Application Military / Defense (DAGR, PLGR) Civilian Marine / Commercial Data Focus High-precision time and status Position, Course, Speed Interface RS-232 / RS-422 RS-422 / Serial 5. Obtaining the Protocol Document
Transmitted at 1 Hz; provides the receiver's operational health and status. Time Transfer (Message 5101):
provides technical specifications for systems using this protocol.
The protocol originated with the (affectionately called "Plugger"), a handheld military GPS receiver. It was later used by the DAGR (Defense Advanced GPS Receiver). However, the ICD-GPS-153 messaging structure has become the de facto standard for embedded military GPS engines, such as the GB-GRAM (Ground-Based GPS Receiver Application Module) and future MGUE (Military GPS User Equipment). Department of Defense (DoD) and allied military systems
Commonly known as the , this standard defines how standard military GPS receivers communicate with host platforms like tanks, aircraft, and handheld devices. What is ICD-GPS-153?
The alarm was a low, humming thrum that vibrated through the hull of the Odysseus , a sound less like a siren and more like a sick heart. Commander Elara Vahn’s hand flew to the interface panel. The red letters pulsed with a sickly glow:
: When emulating a SINCGARS interface for timing purposes, position and velocity vectors are often zeroed out to omit controlled data fields while keeping the timing loop intact. 2. Time Transfer (Message 5101) Transmission Rate : 1 Hz (once per second).