There are many uses for a spectrum analyzer to troubleshooting wifi signals to evaluating cell signals.
They are used by EMC/RF technicians along with other equipment to examine Cellular, Bluetooth, Wlan and so on.
Every spectrum analyzer comes with its own unique features and price ranges, what works for one person may not work for the next.
In the past bench-top analyzer were the main spectrum analyzers used.
They now come in many portable handheld forms and can use USB to communicate information back to computer.
Handheld Spectrum Analyzers
RF Explorer Handheld Spectrum Analyzer 6G Combo
RF Explorer and Handheld Spectrum Analyzer 3G Combo
RF Explorer – ISM Combo and Handheld Spectrum Analyzer 240 – 960 MHz and 2.35 – 2.55 GHz