1. Backend System Requirements
System Requirements Specification
EVLA Correlator Backend
Project Document A25251N0000
Revision 2.0
May 10, 2002
14-15 May, 2002
Backend System Requirements

2. Backend System Requirements
Assumptions
Correlator Handles Packetization of Lag Frames
Lag Frames Will Not Necessarily Arrive in Lag Set Order
Lag Frame Delivery a One-Time Shot
Lag Set Length Always Power of 2
Timely Delivery of Indirect Data
e2e Capable of Handling Output Rates and Volumes
14-15 May, 2002
Backend System Requirements

3. Backend System Requirements
Constraints
Critical Component in the Astronomical Data Path
Operations Performed Shall be Reversible
Performance Limits Set by Technology and Budget
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Backend System Requirements

4. Backend System Requirements
Input Data
Lag Frames
State Counts
Data Valids
Meta-data
Observational Mode
Data Processing Parameters
Status Requests
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Backend System Requirements

5. Backend System Requirements
Output Data
Formatted Observational Output
Status Reports
Error Reports
Warning Reports
Failure Reports
Recovery Reports
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Backend System Requirements

6. Backend System Requirements
Correlator Interface
Receive Lag Frame Data Packets
All Backend Processors Have Paths to All Correlator Outputs
Sufficient Bandwidth to Meet Performance Requirement
All Frames For Same Baseline Routed to Same BE Processor
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Backend System Requirements

7. Monitor & Control Interface
Receive Non-Lag Frame Data
Receive Status and Queries
Send Query Responses and Internally Generated Messages
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Backend System Requirements

8. Backend System Requirements
End-to-End Interface
Transfer Formatted Data
All Backend Processors Have a Path to the e2e System
Sufficient Bandwidth to Meet Performance Requirement
14-15 May, 2002
Backend System Requirements

9. Backend System Requirements
Data Processing
Lag Set Assembly
Normalization
Coarse Quantization Correction
Time Stamp Adjustment
Interference Removal/Reduction
Windowing
Fourier Transform
Integration
Output Formatting
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Backend System Requirements

10. Internal Monitor and Control
No User Interface of Its Own
Respond to Outside Queries
Selectable Internal Test Modes
Self Monitoring
Self Recovery
Problem Reporting
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Backend System Requirements

11. Backend System Requirements
Performance
Maximum Aggregate Input Rate of 1.6 Gbytes/sec
Maximum Aggregate Output Rate of 25 Mbytes/sec
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Backend System Requirements

12. Backend System Requirements
Reliability
Detect and Recover From Processor Failures
Detect and Recover From Process Failures
Detect and Recover From Internal Network Failures
No Total System Reboots Between Maintenance Windows (Goal)
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Backend System Requirements

13. Backend System Requirements
Scalability
Total System Extensible to Higher Rates of Input, Output, and Data Processing
Hardware Extensible in a Manner That is Transparent to Software and Vice Versa
Upgrades Meet Seamlessly With Unchanged Components
14-15 May, 2002
Backend System Requirements