To pass digital pulses in an electronic circuit requires surprisingly better circuitry than for a one on one comparison of a 2 GHz clock compared to a 2 GHz RF continuous wave signal. The key difference is the sharp rise time of the digital pulse. Correspondingly, the continuous wave RF signal rises gradually relative to the digital pulse. So to electronically compare the frequencies between continuous wave and digital pulses it takes a minimum of 5 harmonics of a sine wave. This is shown here. Note how the leading edge of the sine in the first square wave is separated from the leading edge of the square, but by the fifth harmonic shown in the last digital pulse the leading edge of the sine wave is very close to leading edge of the digital pulse.