The Windfreak SynthUSBII is a 34.4MHz to 4.4GHz software tunable RF signal generator controlled and powered by a PC running Windows XP, Vista, Windows 7 or 8 via its USB port.

The SynthUSBII also has nonvolatile on board memory so it can be programmed to fire up by itself on any frequency, power, sweep or modulation setting. This makes for a highly mobile, low power and light weight solution for your RF signal generation needs.
Please scroll down for more info on the powerful hardware and software features. 

SynthUSBII Low Cost RF Signal Generator

Use this device as a generic RF signal generator in your test setup, or use it as a high quality local oscillator in your RF / microwave communication system.
Shown below, the software is eloquently engineered giving professional performance at fractions the cost of a bench top generator.
You may enter data either with the touch pad, knob, directly with the PC keyboard, and also by clicking on arrows next to the controls.