The HP 3561A is a single-channel, real-time spectrum analyzer spanning 0.000125 Hz to 100 kHz. It delivers simultaneous frequency and time domain analysis through digital signal processing, functioning as a spectrum analyzer, network analyzer, and waveform recorder. The instrument supports 1/3 and 1/1 octave analysis with frequency resolution as narrow as 640 µHz and amplitude accuracy of ±0.15 dB across its primary measurement range. A full 80 dB dynamic range with complete alias protection enables precise signal characterization from broadband noise to narrowband tones.
Technical Specifications
Frequency Domain
• Frequency range: 0.000125 Hz to 100 kHz
• Selectable spans: 0.01024 Hz to 100 kHz in 1, 2, 2.5, 5, 10 sequence
• Frequency accuracy: ±0.003% of display center frequency
• Resolution bandwidth: As low as 640 µHz
• Real-time bandwidth: 3.0 kHz (single display); 7.5 kHz (fast average display)
Amplitude Measurement
• Measurement range: +27 dBV (22.4 Vrms) to -51 dBV (2.82 mVrms)
• Dynamic range: 80 dB
• Amplitude accuracy: ±0.15 dB (+27 to -40 dBV); ±0.25 dB (-41 to -51 dBV)
• Display units: RMS volts, V², mW, dBV, dBm (user-selectable impedance), user-defined engineering units
• Level accuracy: ±20% for random source in 0–100 kHz span
Time Domain
• Capture buffer: 40 k samples at 256 kHz A-to-D sampling rate
• Trigger modes: Analog level trigger with positive/negative slope selection
• Pre-trigger: 40 k samples; post-trigger: 1023 k samples
Phase Measurement
• Phase accuracy: ±2° (DC to 10 kHz); ±10° (10 kHz to 100 kHz, signals ≤40 dB below full range)
• Phase resolution: 0.1°
Signal Processing
• Averaging: RMS, RMS exponential weighting, time averaging
• Display formats: Magnitude, phase, time, math traces, spectral map (up to 60 successive spectra)
• Marker functions: Peak tracking, harmonic markers (THD computation), band markers, sideband markers
– Key Features
• Built-in tracking noise source for network analysis measurements
• Magnitude and phase response calculation through trace math
• Harmonic distortion analysis with THD reporting in dB or percent
• Configurable pre- and post-trigger data capture with variable trigger delays
– Typical Applications
• Vibration analysis and acoustic measurements
• Electronics characterization requiring high frequency resolution
• Network and frequency response testing
• Detailed time and frequency domain signal capture and analysis
