Wireless data and power transfer over an inductive telemetry link
View Patent ↗A telemetry device includes a resonant inductive link with a primary LC tank and secondary LC tank configured to resonate at a carrier frequency. A modulator assembly in communication with the secondary LC tank implements data-synchronized cyclic on-off keying modulation (COOK) to periodically create a short across the secondary LC tank in response to a pulse from a phase selector and phase-locked loop. During the full cycle-length of the short, data can be transmitted across the inductive link while the charge across the secondary LC tank is preserved. Power may be transferred across the link during non-shorted cycles.
1. A telemetry device, comprising:
an inductive link comprising an external LC tank and an internal LC tank, wherein the inductive link is resonant at a carrier frequency comprising a plurality of cycles;
a switch configured for shorting the internal LC tank in response to a data-synchronized modulation signal; and
a modulator assembly configured to implement cyclic on-off keying to open and close the switch, wherein the switch is closed for data transmission and open for power transfer, the modulator assembly comprising:
a full wave rectifier;
a clock-recovery comparator;
a phase-locked loop configured for generating a plurality of pulses; and
a phase selector configured to select at least one pulse from the plurality of pulses for input to the rectifier.
2. The telemetry device of claim 1 , wherein the modulator assembly causes the switch to close for a full cycle within the plurality of cycles.
3. The telemetry device of claim 1 , wherein the carrier frequency is 13.56 MHz.
4. The telemetry device of claim 1 , wherein data transmission occurs at a data bit rate on the order of one half of the carrier frequency.
5. The telemetry device of claim 1 , wherein the phase selector uses feedback phase selection.
6. The telemetry device of claim 1 , wherein the phase selector selects a first pulse for closing the switch and a second pulse for opening the switch.
7. The telemetry device of claim 1 , further comprising a data decoder configured for receiving an input data transmission, the data decoder comprising a peak detector and a comparator.
8. The telemetry device of claim 7 , wherein the data decoder further comprises a peak-aligning diode configured to set a threshold voltage at the external LC tank.
9. A telemetry device, comprising:
a resonant inductive link comprising a primary LC tank and secondary LC tank configured to resonate at a carrier frequency comprising a plurality of cycles;
a modulator assembly in communication with the secondary LC tank and configured to implement cyclic on-off keying modulation to periodically create a short across the secondary LC tank in response to a pulse, wherein data is transmitted across the inductive link when the secondary LC tank is shorted and power is transferred across the inductive otherwise, and wherein the modulator assembly comprises:
a switch configured for creating the short;
a full wave rectifier configured for controlling the switch;
a phase-locked loop configured for generating a plurality of pulses;
a clock-recovery comparator configured to provide an input to the phase-locked loop; and
a phase selector configured to select at least one pulse from the plurality of pulses for input to the rectifier.
10. The telemetry device of claim 9 , wherein the modulator assembly causes the switch to close for a full cycle within the plurality of cycles.
11. The telemetry device of claim 9 , wherein the data has a bit rate on the order of one-half of the carrier frequency.
12. The telemetry device of claim 9 , wherein the phase selector uses feedback phase selection.
13. The telemetry device of claim 9 , wherein the phase selector selects a first pulse for closing the switch and a second pulse for opening the switch.