Comb generators, or harmonic comb generators, emit multiple, harmonically-connected CW signals spaced out over an oscillating frequency. Due to the consistency of the harmonic amplitudes, comb generators can be used to calibrate frequency and amplitude, providing a reliable baseline for measuring how well a system is working. Comb generators are used in electromagnetic interference and radio frequency interference testing to simulate the RF emissions of devices, especially consumer electronics. When performing compliance testing for standards like MIL-STD-461, FDA, FAA, and FCC, comb generators are placed in semi-anechoic test chambers to isolate their signals.