Intelligent tracking system and methods and systems therefor

1. A passive tracking device comprising:

a first antenna that transmits response signals in a first frequency band;

a second antenna that receives energizing signals in a second frequency band;

an energy harvest module that receives an energizing signal from a remote device via the second antenna and converts the energizing signal from RF electrical energy to DC electrical energy that energizes the passive tracking device; and

a transmission module that modulates a response signal for transmission in the first frequency band and outputs the modulated response signal to the first antenna for transmission in accordance with a communication protocol, the response signal including a message indicating a device identifier of the passive tracking device, wherein the transmission module includes a bulk acoustic wave reference oscillator that produces an output frequency, the bulk acoustic wave reference oscillator including a bulk acoustic wave delay reference, and wherein the transmission module modulates the response signal such that the modulated response signal has a carrier frequency based on the output frequency of the bulk acoustic wave reference oscillator.

2. The passive tracking device of claim 1 , wherein the bulk acoustic wave reference oscillator includes a master clock, a time difference detector, a phase frequency detection module, and a loop filter.

3. The passive tracking device of claim 2 , wherein:

the master clock outputs the output frequency to other components of the transmission module for use as a carrier frequency reference and outputs the output frequency to the time difference detector;

a time difference detector that detects a plurality of echoes of the bulk acoustic wave delay reference, generates a first echo signal and a second echo signal based on a first echo and a second echo of the plurality of echoes, respectively, compares the first echo signal to the output frequency to generate an end pulse, and outputs both the end pulse and the second echo signal to the phase frequency detection module;

a phase frequency detection module that compares a phase of the end pulse to a phase of the second echo signal, generates a pump pulse, and generates a current based on the pump pulse; and

a loop filter that amplifies the current and outputs the amplified current to the master clock, thereby forming a feedback loop and correcting the output frequency.

4. The passive tracking device of claim 3 , wherein:

the pump pulse is a pump-down pulse when the phase of the end pulse is earlier than the phase of the second echo signal, and

the phase frequency detection module generates negative current based on the pump-down pulse.

5. The passive tracking device of claim 3 , wherein:

the pump pulse is a pump-up pulse when the phase of the end pulse is later than the phase of the second echo signal, and

the phase frequency detection module generates positive current based on the pump-up pulse.

6. The passive tracking device of claim 3 , wherein:

the time difference detector includes a temperature compensation module that receives a temperature reading and outputs a temperature adjustment signal to the time difference detector based on the temperature reading; and

the time difference detector adjusts one or both of the first echo signal and the second echo signals and the end pulse based on the temperature adjustment signal.

7. The passive tracking device of claim 1 , wherein the transmission module modulates the response signal such that the modulated response signal has a carrier frequency substantially equal to a factor of the output frequency of the bulk acoustic wave reference oscillator.

8. The passive tracking device of claim 1 , wherein the transmission module is a first transmission module, the response signals are first response signals, the energizing signals are first energizing signals, the communication protocol is a first communication protocol, the message is a first message, and the device identifier is a first device identifier.

9. The passive tracking device of claim 8 , further comprising:

a third antenna that both transmits second response signals and receives second energizing signals in a third frequency band;

a second transmission module that prepares a second response signal for transmission in the third frequency band and facilitates transmission of the prepared second response signals by toggling impedance of the third antenna when the passive tracking device operates in a second mode in accordance with a second communication protocol, and wherein the prepared second response signal includes a second message indicating a second device identifier of the passive tracking device; and

a mode selection module that determines whether the passive tracking device is to operate in the first mode or the second mode based on a received energizing signal from a remote device via the second antenna and/or the third antenna.

10. The passive tracking device of claim 9 , wherein the first frequency band is equal to the second frequency band.