Network Test System for Spacecraft via SERDES Tapping
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Solution Overview
Problem
Current spacecraft integration and test procedures lack the ability to observe network activity without affecting operational parameters like loading and latency, and they do not provide adequate access to individual network links for testing without disturbing other traffic, which complicates anomaly resolution and extends integration and test timelines.
Innovation Solution
A network test system comprising a SERDES receiver, a SERDES transmitter, and a circuit switch that taps off network activity for passive observation or test signal injection, allowing real-time observation and testing without disturbing the network, using a port that replicates data streams and inserts test signals without modifying packet routing or queuing functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated test ports are added to observe network activity, then observation capability is improved, but device complexity increases
Solution Approach 1:
The circuit switch is integrated within the existing network device structure, nesting the test observation functionality inside the operational network path. The circuit switch taps into the existing data flow between SERDES receiver and transmitter, allowing observation without adding external complexity.
Solution Approach 2:
The circuit switch acts as an intermediary element that copies network traffic to test ports without interfering with the primary data path. It mediates between the operational network and test observation functions, enabling both to coexist without significant interaction or complexity increase.
2Adaptability or versatility
If test traffic is injected into network ports, then testing capability is improved, but network operation is disturbed
Solution Approach 1:
The test traffic injection function is extracted from the main network data path and placed in a separate, parallel path through the circuit switch. This allows test traffic to be injected independently without modifying or disturbing the operational network traffic flow, maintaining network stability while enabling comprehensive testing.
Solution Approach 2:
The network traffic flow is segmented into separate paths: one for operational data and another for test traffic. The circuit switch creates distinct routing paths that allow independent control of test and operational traffic, preventing interference between them.
3Ease of operation
If packet routing tables are modified to route test traffic, then test access is improved, but network loading and latency change
Solution Approach 1:
The circuit switch is pre-configured with dedicated test traffic routing paths that bypass the normal packet routing table lookup processes. Test traffic is routed through predetermined paths established by the circuit switch, eliminating the need for real-time routing table modifications and associated processing delays.
4Difficulty of detecting and measuring
If spacecraft boxes are opened to investigate anomalies, then anomaly detection is improved, but integration time increases
Solution Approach 1:
Test ports and observation capabilities are installed and configured during the normal integration process before final assembly. This preliminary setup of diagnostic infrastructure allows anomalies to be detected and investigated without requiring disassembly of finished spacecraft, enabling rapid troubleshooting during operation.
Solution Approach 2:
Physical disassembly of spacecraft boxes is replaced by electronic/digital observation methods through the circuit switch and test ports. Instead of mechanically opening boxes to inspect hardware, operators can electronically monitor network traffic and inject test signals through the integrated observation system.
Data Source
AI summary
A network test system seeks to improve visibility into the real-time operation of a network system or subsystem of a spacecraft through the use of a port from each relevant network to a spacecraft test interface. The network test system includes a packet switch operatively coupled downstream from a SERDES receiver and operatively coupled upstream from a SERDES transmitter. The packet switch in conjunction with the signal replicator in the SERDES receiver taps off a data stream of the network activity so that the port allows an observation device to passively observe the network activity. The system is adapted to increase real-time observation of network activity without disturbing the network.