Agilent/Keysight 3561A

The Agilent/Keysight 3561A is a single-channel Dynamic Signal Analyzer engineered for low-frequency measurements spanning 0.000125 Hz to 100 kHz. It delivers real-time spectrum analysis, network analysis, waveform recording, and 1/3 and 1/1 octave analysis with exceptional resolution and dynamic range. The instrument combines analog signal processing with digital storage capabilities, making it ideal for vibration analysis, acoustics, and electronics testing where transient characterization and harmonic content demand precision.

Technical Specifications

Frequency Range: 0.000125 Hz to 100 kHz Resolution:

• Bandwidth resolution up to 640 µHz


• 0.25% of frequency span


• Amplitude: 0.01 dB resolution


• Phase: 0.1 degree resolution Amplitude and Dynamic Range:


• Accuracy: ±0.15 dB


• Amplitude range: +27 dBV to −120 dBV or +27 dBV to −51 dBV


• Dynamic range: 80 dB Real-Time Bandwidth:


• Single display: 3.0 kHz typical


• Fast average display: 7.5 kHz typical Input Characteristics:


• Impedance: 1 MΩ ± 5% shunted by 95 pF maximum


• Input isolation: Low can float up to 30 Vrms (42 V peak) above ground


• Coupling: AC or DC; AC mode low frequency 3-dB point < 1 Hz


• ICP current source: 4 mA nominal for piezoelectric accelerometers Output Source:


• Band-limited, band-translated, pseudo-random, random, or impulse signals


• TTL synchronization output available


• Level: 0.7 to 0.007 Vrms nominal


• Output impedance: 50 Ω Display: Monochrome CRT with three-dimensional spectral mapping, time waveforms, and full annotation Memory:


• Internal non-volatile: 2 traces and 6 states


• Volatile: 40 time records (40k sample buffer)


• Optional bubble memory: 127 traces and states Power Requirements: 100/120/220/240 Vac (±5%/−10%), 48–440 Hz; requires safety earth ground Physical: 197 mm H × 335 mm W × 595 mm D; 33–50 lb

Key Features

• Harmonic analysis with automatic THD computation (percent or dB)


• Band markers for RMS level or average power within frequency bands


• Sideband markers for modulation analysis


• Magnitude and phase measurement


• Time-domain digital storage oscilloscope functionality


• A-weighting filter per ANSI S 1.4-1971 (R1976)

Interfaces & Integration HP-IB interface for instrument control and data transfer.