Agilent-Keysight 8594A en Lake Mary, Florida, USA

Agilent Technologies 8594A 9 kHz to 2.9 GHz Portable Spectrum Analyzer
Resolution BW 1 kHz to 3 MHz
Amplitude -112 to +30 dBm. Reads 32K memory cards.
Built-in frequency counter and clock/calendar.
The Agilent Technologies 8594A spectrum analyzer is a wide band, very sensitive receiver. It works on the principle of "super-heterodyne receiver" to convert higher frequencies (normally ranging up to several 10s of GHz) to measurable quantities. The received frequency spectrum is slowly swept through a range of pre-selected frequencies, converting the selected frequency to a measurable DC level (usually logarithmic scale), and displaying the same on the CRT of the Agilent Technologies 8594A. The CRT displays received signal strength (y-axis) against frequency ( x-axis).