The Hewlett-Packard Model 3580A Spectrum Analyzer is a low frequency instrument that has been optimized for use in the 5 Hz to 50 kHz range. The 3580A functions as a signal analyzer or as a network analyzer. When used as a signal analyzer, the 3580A provides a graphical display of the spectral components of an input signal. When used as a network analyzer, the 3580A plots the amplitude vs. frequency characteristics of 2-port networks such as amplifiers, attenuators and filters. The major features of the 3580A include a digitally stored display, adaptive sweep, six selectable band-widths (1 Hz - 300 Hz), 30 nV sensitivity and 80 dB dynamic range. These standard features, along with optional balanced inputs and an internal rechargeable battery pack, make the 3580A ideally suited for communications, geophyical, oceanography and metrology applications.