The Safran Navigation & Timing documentation highlights three primary message types utilized in the GSSIP format (specifically version ICD-GPS-153C): A. Current Status (Message 5040) 1 Hz (once per second)
Fixed characters marking the start of a message.
The (also known as the GPS Standard Serial Interface Protocol or GSSIP ) is a specialized military data exchange specification that dictates how encrypted Selective Availability Anti-Spoofing Module (SAASM) and modern M-Code GPS receivers communicate over serial interfaces with military host platforms. Unlike civilian GPS devices that primarily rely on the open NMEA-0183 standard , United States and allied defense systems implement the ICD-GPS-153 architecture to ensure highly secure, jam-resistant, and low-latency transmission of Position, Navigation, and Timing (PNT) data. Because it details tactical military data transfers, the official physical document remains restricted, requiring government authorization via the U.S. Coast Guard Navigation Center website . Core Purpose and Architectural Role icd-gps-153 protocol
There is no "open source" ICD-GPS-153 receiver. Any such product requires a DoD contract and a classified facility.
Monitoring the internal temperature, battery, and hardware status. Unlike civilian GPS devices that primarily rely on
: Messages typically start with a specific header byte (often ) and end with a checksum. Checksum Validation : Most implementations use a
| Feature | ICD-GPS-153 (P(Y) Code) | M-Code (ICD-GPS-240) | | :--- | :--- | :--- | | | Encryption (W-code) | Cryptography + Spreading code separation | | Power | Same as civil (+3 dB) | +20 dB (spot beam) | | Jamming resistance | Moderate | Very High (designed for contested environments) | | Signal structure | Legacy BPSK | BOC (Binary Offset Carrier) | | Backward compatibility | N/A | New receivers required | Core Purpose and Architectural Role There is no
: Unlike standard NMEA messages, this protocol outputs high-fidelity data including Position, Velocity, and Time (PVT) , Pseudorange (PR), Delta Range (DR), and detailed SAASM/satellite status information.