A ultra-low frequency (μ Hz-10 kHz) high stability signal source designed specifically for fields such as power systems, seismic exploration, structural modal testing, biomedical research, and sensor calibration. Can replace the blank space of traditional function generators in the "millihertz" band, providing low distortion, high amplitude, programmable voltage/current/charge signals. Typical applications: low-frequency oscillation traceability, PSS parameter tuning, synchronous phasor calibration. Sensor/accelerometer 0.1 Hz -500 Hz amplitude frequency characteristic test. High rise buildings, bridges, and wind turbine blades subjected to 0.01 Hz modal excitation. ECG/EEG simulation, neural stimulation pulse sequence. Low frequency creep test of 0.05 level electric energy meter and 0.1 Hz error test of transformer.