The TC9400 converts the analog input (Vin) ito frequencies (10Hz to 100KHz) which can be used to modulate an RF transmitter in a telemetry system. At the other end, The RF signal is picked up by receiver and it’s demodulated back into the 10Hz to 100KHz spectrum.

TELEMETRY1 circuit schematic

A count linearly proportional to the original analog voltage (Vin) is given by connecting this signal to a frequency counter. The counter can be replaced by a TC9400 used in the F/V mode if a linearly-proportional analog output voltage is required. [System’s block diagram source: Microchip Application Note]