A state-of-the-art, self-calibrating 3585A Spectrum Analyzer with a fully synthesized local oscillator and HP-IB controllable. Outstanding low frequency performance from 20Hz to 40.1MHz. Within 0.4 dB overall measurement accuracy is maintained by an internal calibration routine, performed by an internal microprocessor. Frequency Span range includes the entire frequency range with 0.1Hz resolution. Resolution Bandwidths of 3Hz to 30kHz in 1-3-10 sequence. Amplitude Measurement range from -137 dBm to +30 dBm (50 or 75 ohms) or 31 nV to 22 V (1 Mohm). A dynamic range of better than -80 dB. The built-in tracking generator provides output levels from 0 dBm to -11 dBm with a single turn knob. The 3585A's CRT readout and microprocessor based controls and internal microcomputer provides for CRT readout of all control settings, digitally stored and refreshed trace, and autoranging input attenuator.