The A-7550 Spectrum Analyzer is a microprocessor-control1ed } superheterodyne unit which offers ease of operation, while including the most needed features of a spectrum analyzer. 1-2 STANDARD FEATURES The A-7550 Spectrum Analyzer covers a range from 100 kHz to 999.9999 MHz at levels of up to +30 dBm. Signal levels may be directly read on the CRT in either dBm* dByW, dBV, dBmV or dByV. Signals can be stored, recalled, plotted or used for comparison purposes. Standard A-7 5 5 0 input impedance is 50Ω. All operating parameters are set via keyboard o pera ti on . 1-2-1 DISPLAY METHOD The A-7550 display is fully digitized. A VRS™ (Vertical Raster Scan) method is used to form the display. The display has'390 horizontal discrete points and 480 vertical discrete points. Full scan range is from 0 Hz to 1 GHz. Users familiar with other spectrum analyzers may be used to seeing the zero hertz marker displayed anywhere on the display. On the A-7550, the zero hertz marker does not move to the right of the left edge of the display. The microprocessor does not allow a setting that would theoretically allow a "negative11 frequency to the left of the zero hertz marker. The user should note this characteristic when becoming familiar with the A-7550.