The Agilent/Keysight 4971A Transmission Impairment Measuring Set (TIMS) is a portable instrument for field measurement of voice, data, and broadcast telecommunications circuits. It delivers noise, level, frequency, and distortion measurements across a 20 Hz to 110 kHz operating range, with harmonic analysis extending to 330 kHz. The unit addresses the complete measurement requirements of field technicians and telecommunications engineers deploying Bell and CCITT standard testing.
Technical Specifications
• Frequency Coverage: 20 Hz to 110 kHz for standard measurements; harmonics measured to 330 kHz
• Voltage Measurement: 300 µV to 300 V rms full scale; 1 mV to 300 V RMS full scale on meter calibrated in dBV and dBm into 600 ohms
• Distortion Measurement: THD as low as 0.0018%, range 0.01% to 100% full scale (-80 dB to 0 dB) across nine ranges
• Noise Measurement: Residual noise below 25 µV; selectable filters include C-message, Psophometric (P.53), 3 kHz flat, 275-3250 Hz flat, 15 kHz flat, 50 kbit, and 1010 Hz notch
• Impulse Noise: 3-level detection with optional quiet setting
• Internal Oscillator: <0.003% distortion
– Key Features
• Relative Level mode establishes 0 dBm reference at any frequency from 10 Hz to 110 kHz
• High-Pass Filter (1 kHz) attenuates frequencies below 400 Hz for hum reduction
• Signal-to-noise ratio and noise-with-tone measurement capabilities
• Peak-to-Average Ratio (P/AR) measurement available on select models
• Noise-to-ground measurement on certain configurations
– Typical Applications
• Digital Data System (DDS) local loop qualification to 56 kb/s
• Telecommunications channel acceptance and performance verification
• Voice and data circuit impairment analysis
– Compatibility & Integration
• 4935A model: Bell standards (BSTR 41009)
• 4936A model: CCITT recommendations
