In some embodiments, control circuitry 118 may be configured to trigger the waveform generator 110 to generate an RF signal for transmission by the transmit antenna 114. The control circuitry 118 may trigger the waveform generator in response to a command to do so received by external communications interface 120 and/or based on logic part of control circuitry 118.
In some embodiments, control circuitry 118 may be configured to receive RF signals from transmit and receive circuitry 112 and forward the received RF signals to external communications interface 120 for sending to controller 106. In some embodiments, control circuitry 118 may be configured to process the RF signals received from transmit and receive circuitry 112 and forward the processed RF signals to external communications interface 120. Control circuitry 118 may perform any of numerous types of processing on the received RF signals including, but not limited to, converting the received RF signals to from analog to digital (e.g., by sampling using an ADC), performing a Fourier transform to obtain a time-domain waveform, estimating a time of flight between the interrogator and the target device from the time-domain waveform, and determining an estimate of distance between the interrogator 102 and the target device that the interrogator 102 interrogated. The control circuitry 118 may be implemented in any suitable way and, for example, may be implemented as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a combination of logic circuits, a microcontroller, or a microprocessor.