I want to retool the classic HC SR04 rangefinder to be able to do ToF gas flow sensing. I need to be able to do ToF on a column of air in both directions, so it benefits me to be able to use the transceiver as both transmit and receive.
Otherwise, I either need a larger diameter tube with a pair of Tx/Rx on either side, or two tubes, neither is optimal.
Is there any reason why I can't just use a mux and alternately use one module as Tx and other as Rx, then switch roles?
Here's a datasheet of what I think is a representative transducer.
How could I even go about telling if the two components are different? They are likely piezoelectric, so resistance won't tell me much.