Receiver

The Receiver side of my system includes 4 Op-Amps, from right to left, an amplifier, a bandpass filter, another amplifier, and a comparator.

Amplifier 1 (IC1A)

The first amplifier is used to amplify the signal received directly from the second transducer. with a gain of ~6.

Bandpass Filter (IC1B)

The amplified signal is then sent through a bandpass filter centered at 40kHz. The bandpass also has a gain so the signal is boosted.

Amplifier 2 (IC1C)

The second amplifier boosts the filtered signal with a gain of ~7.

Comparator (IC1D)

Finally the signal is compared to 500mV, if it exceeds that limit the transistor is turned on and a +5V signal is sent to the base station. Using timer 14 we can measure the time when the pulses are sent to the time the first stop pulse is seen to get the distance the sound wave traveled.