Receiver Testing: Why Test Signal Quality Matters

RF and microwave signal generators are essential tools for testing receiver systems and subsystems, yet their performance can significantly affect measurement accuracy. While many signal generators appear suitable at first glance, it's critical to ensure they don't introduce measurement errors due to phase noise or spurious signals. This educational note outlines key performance parameters to consider when selecting a signal generator, ensuring it minimally impacts the receiver-under-test.

A primary challenge in receiver testing is detecting small signals amidst larger ones. Poor performance can lead to issues like dropped calls in smartphones or reduced detection capabilities in automotive radar systems. Key tests, such as sensitivity measurements, assess how well a receiver detects low-level signals near its noise floor and how it handles high-power signals that may generate spurious responses.

Effective testing requires a signal generator with low phase noise, minimal harmonics, and sufficient output power. High phase noise can obscure low-level signals, raising the receiver's noise floor and complicating detection. Thus, the ideal generator provides clear signals, enabling accurate sensitivity assessments.

In real-world applications, receivers must filter out in-band and out-of-band interference. Proper evaluation necessitates ensuring that both the low-level test signals and the high-power signals maintain amplitude accuracy and purity. The right signal generator ultimately enhances testing reliability, ensuring that measured performance truly reflects the receiver's capabilities rather than artifacts from the generator itself.