Abstract: A rain sensor includes an emitter, a receiver, a processor, and a printed circuit board (PCB). The emitter projects an incident beam that is reflected, as a reflected beam, by a windshield of a vehicle that includes the rain sensor. The receiver generates, based upon a received intensity of the reflected beam, a rain signal indicating a potential presence of rainwater on the windshield. The processor receives the rain signal and performs a filtering operation on the rain signal to generate a filtered signal. The PCB electronically interconnects the emitter, the receiver, and the processor. The filtering operation comprises filtering noise from the rain signal such that the filtered signal has a signal frequency within a predetermined range of frequencies and related harmonics with respective magnitudes and frequencies that are correlated with a definitive presence of the rainwater on the windshield.