When you are working on your design at the component level, you need to understand how each component will behave when used in its final design. For example, in most transceivers, there are amplifiers to boost LO power to a mixer and there are filters to remove signal harmonics. You may need to measure these components to verify they perform the same as their simulation models. Tracking generators provide a cost-effective way for spectrum analyzer users to expand their testing to cover more component-level characterization. They stretch your instrument budget by expanding the capabilities of your spectrum analyzer and provide effective scalar transmission measurements.