The Astronics / EADS / Racal 2461-CF is a C-size VXIbus Universal Counter Timer card engineered for precision timing and frequency measurements in automated test equipment and data acquisition systems. This module delivers comprehensive measurement capabilities including frequency, period, time interval, pulse width, rise/fall time, and phase analysis. The CF designation denotes an Oven Controlled Crystal Oscillator (OCXO) timebase, providing exceptional stability for demanding metrology applications.
## Technical Specifications
**Measurement Performance**
• Frequency range: 0.01 Hz to 200 MHz with 9-digit resolution
• Time interval resolution: 1 ns (single shot), 100 ps (averaged mode)
• Time interval range: 100 ns to 1000 s
• Trigger resolution: 2.5 mV
• Input impedance: 1 MΩ // 20 pF (AC/DC coupled, selectable)
• Maximum input voltage: 5 Vrms
• Selectable 50 kHz low-pass filter per channel
**Timebase Stability (OCXO)**
• Aging: ±1 ppm/day, ±1 × 10⁻⁷/yr
• Temperature stability: ±1 × 10⁻⁷ (0°C to 50°C)
• Adjustment range: ±2 × 10⁻⁶
• Warm-up: ±1 × 10⁻⁶ in 45 s, ±1 × 10⁻⁷ in 3 minutes
**Physical & Environmental**
• Form factor: C-size VXI module (8.75″ W × 2.625″ H × 12.5″ D)
• Weight: 8.5 lbs
• Operating temperature: 0°C to 50°C
• Storage temperature: -40°C to 70°C
## Key Features
• Dual-channel configuration (standard)
• Frequency, period, time interval delay, and totalize measurements
• Rise time, fall time, positive/negative pulse width analysis
• Frequency ratio and phase measurements (channel-to-channel)
• Peak detection (positive, negative, mid-range)
• DC voltage measurement capability (MAX, MIN, DC values)
• Nine arming modes via external input and VXI TTL trigger lines
• Continuous, single-shot, and external trigger modes
## Typical Applications
• Frequency and timing validation in production test systems
• Precision phase measurement in communications test
• Pulse characterization and waveform analysis
• Time-interval and jitter measurement in digital systems
• Multi-channel synchronized measurement in automated test environments
## Compatibility & Integration
Designed for integration into C-size VXIbus chassis systems. Compatible with VXIbus standard interfaces and modular test architectures supporting up to 3 function cards per C-size slot configuration.
