Another variation of the embodiment of FIG. 9C is one in which target device 930 further comprises an automatic frequency control circuit (AFC) to compensate for any drift in the frequency generated by one or more oscillators onboard the target device (e.g., oscillator 932). The AFC circuit may be configured to sense the difference between the actual oscillator frequency and the frequency that is desired and produces, based on this sensed difference, a control voltage proportional to the difference. In turn, the control voltage may be used to compensate for any drift in the frequency generated by one or more oscillators onboard the target device, which drift may result from variations in temperature, loading, and/or for any other reason. Any suitable AFC circuit may be used as part of target device 930, as aspects of the technology described herein are not limited in this respect. Additionally, in some embodiments, any suitable AFC circuit may be used as part of an interrogator that interrogates target device 930.
