The Marconi IFR Aeroflex 2855S is a portable, battery-operated digital communications analyzer for testing and troubleshooting digital networks across European and North American hierarchies. It generates and receives PCM framing systems up to 140 Mbit/s, supports individual channel testing at 56 kbit/s and 64 kbit/s rates, and provides full data interface testing via RS-232, X.21, RS-449, and V.35. The instrument delivers bit rate measurement to ±2 ppm ±1 count and digital signal level accuracy of ±2 dB across the +3 to -30 dB range, making it essential for fault location in cross-connect switches and international gateway applications.
Technical Specifications
Digital Signal Testing
• Bit rates: 2, 8, 34, and 140 Mbit/s
• PCM framing generation and reception up to 140 Mbit/s (European), 6 Mbit/s (North American)
• Supports T1, 704, 2048, 8448, 34368, and 139264 kbit/s signals
• Tributary testing: 2048 kbit/s within 8448 kbit/s; 2048 and 8448 kbit/s within 34 Mbit/s signals
Channel Testing Capabilities
• Individual channel testing at 56 kbit/s and 64 kbit/s
• n × 64 kbit/s contiguous and non-contiguous channel selection
• Fault location in digital data networks and cross-connect switches
Data Interface Testing
• Interfaces: RS-232, X.21, RS-449 (V.36), V.35
• Codirectional and contradirectional G.703 support
• DTE (standard) and DCE (optional) modes
• Synchronous and asynchronous operation
• EUROCOM D/1 option for European military networks
Measurement Performance
• Bit rate: ±2 ppm ±1 count, updated every second (resolution 1 Hz, 4 Hz at 140 Mbit/s)
• Digital signal level: +3 to -40 dB amplitude range, accuracy ±2 dB (+3 to -30 dB), ±3 dB (-30 to -40 dB)
• G.821 error performance analysis
• Voice frequency input/output for framed signals
Signal Generation
• PRBS patterns: 2^15-1, 2^18-1 at 34 and 140 Mbit/s
• All zeros, all ones, alternating 10, user-programmable word patterns
• Multiple line code support
– Key Features
• Hybrid and mixed-rate versions for global European/North American testing
• Portable battery operation for field deployment
• G.703 interface flexibility for international applications
– Typical Applications
• International gateway testing
• Digital hierarchy cross-connect verification
• Tributary signal isolation and fault diagnosis
• PCM network commissioning and maintenance
– Compatibility & Integration
Supports both European (E1) and North American (T1) digital hierarchies with optional configurations for military and specialized telecommunications networks.
