Wireless sensor reader with multiple fixed excitation frequencies

A system comprising:

• a sensor configured to be implanted into a patient;
• a sensor reader comprising:
• a transmit circuit configured to excite a resonant circuit within the sensor to resonance at a frequency proportional to a measured parameter;
• a receiver circuit receiving a continuous wave at the frequency;
• and
• a circuit that determines a response frequency of said resonance, wherein the sensor reader selects the frequency from a plurality of discrete narrowband frequencies and wherein the selection takes place before determination of the response frequency;
• wherein the sensor reader obtains a plurality of samples of the continuous wave over a measurement time interval;
• wherein a frequency of each of the plurality of samples of the continuous wave is determined by the circuit for determining frequency;
• and
• wherein each of the plurality of samples is initiated by an energizing pulse at a same transmit frequency throughout the measurement time interval.

A method to ascertain a resonance frequency of a sensor, the method comprising:

• transmitting a wireless energizing pulse at a transmit frequency to the sensor via a sensor reader;
• exciting a resonant circuit within said sensor to resonance at a frequency proportional to a measured parameter;
• receiving a response signal from said sensor, said response signal being a continuous wave at the sensor resonance frequency;
• and
• determining the frequency of said sensor response signal, wherein the sensor reader selects the transmit frequency of the energizing pulse from a plurality of discrete narrowband frequencies, the selection taking place before determination of the frequency of the sensor response signal;
• obtaining a plurality of samples of the sensor response signal over a measurement time interval, wherein the frequency of each of the plurality of samples of the sensor response signal is determined by a circuit of the sensor reader for determining frequency;
• and
• wherein each of the plurality of samples of the sensor response signal is initiated by an energizing pulse at a same frequency as the transmit frequency throughout the measurement time interval.