ISR Packet Protocol for CRC Integrity and Time Synchronization
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Solution Overview
Problem
ISR systems face limitations in data integrity and time synchronization due to physical network interface restrictions and non-standard processor configurations, which hinder the use of common architectural elements and algorithms across multiple airborne platforms.
Innovation Solution
A multi-processor computer system with a remote node and control node, utilizing co-processors for data acquisition and analysis, packet headers with CRC values for integrity verification, and high-speed serial interfaces for synchronization, enabling data integrity and time synchronization across multi-domain operational platforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If physical network interfaces are used to connect processors, then data transmission can be achieved, but the available locations of processors are restricted and timing synchronization is limited
Solution Approach 1:
The packet protocol is designed to be universally applicable across different processor architectures and network configurations. The standardized packet format with universal headers (timestamps, CRC, control data) enables the same communication mechanism to work across diverse platforms, eliminating the need for platform-specific adaptations and thereby achieving processor location flexibility without being constrained by specific network interface implementations.
2Productivity
If non-standard processor configurations are used, then platform-specific optimizations are possible, but common architectural elements and algorithms cannot be used
Solution Approach 1:
The system enforces homogeneity in the communication protocol layer by using standardized packet formats, fixed field structures, and uniform CRC calculation methods across all processors. This homogeneous approach to data communication enables different processor configurations to interoperate seamlessly, allowing platform-specific optimizations at the hardware level while maintaining architectural compatibility through the standardized protocol interface.
3Reliability
If data is transmitted without integrity verification, then transmission speed is faster, but data integrity cannot be ensured
Solution Approach 1:
The CRC (Cyclic Redundancy Check) value acts as an intermediary mechanism for integrity verification. Instead of complex error detection algorithms, the system uses the compact CRC checksum as a mediator to verify data integrity efficiently. The CRC value is calculated from the control data and transmitted alongside it, providing reliable integrity checking with minimal computational overhead, thus ensuring data reliability without significantly increasing system complexity.
4Loss of time
If timestamps are not included in packets, then packet size is smaller, but time synchronization cannot be achieved
Solution Approach 1:
The packet protocol includes only the essential timestamp fields needed for synchronization without adding excessive time-related data. The master timestamp and remote timestamp fields provide sufficient information for time synchronization while keeping the packet size manageable. This partial inclusion approach achieves the necessary synchronization accuracy without the overhead of comprehensive time-stamping mechanisms, balancing synchronization needs against packet size constraints.
Data Source
AI summary
A computer system is provided that includes devices configured to acquire input data. The system further includes a remote node (RN) configured to receive a first packet from a control node (CN). The first packet includes a packet header including a master timestamp, first control data and a CRC. The RN is also configured to verify integrity of the first control data based on the received CRC, generate and transmit to the CN a second packet. The second packet includes a packet header which includes a remote timestamp. The system also includes a CN connected with the RN via high-speed serial interfaces. The CN is configured to receive the second packet, determine status of the first packet based on the control data included in the second packet and configured to retransmit the first packet or generate and transmit a third packet based on the determined status of the first packet.