Modem design for wireless power transfer
A power transmitter is provided. The power transmitter may synchronize a sampling start time to a pulse-width modulation signal. The power transmitter may determine an average sampling rate for sampling a power carrier signal. The power transmitter may sample the power carrier signal to obtain sample values. The power transmitter may process the sampled values. The average sampling rate may be N times a data rate. The power transmitter may process the sampled power carrier signal using two digital match filters to produce two separate digital match filter outputs. The power transmitter may determine an amplitude of peaks for the two separate digital match filter outputs. The power transmitter may determine an interval between bits for the two separate digital match filter outputs. The power transmitter may determine whether a transmitted bit is a ‘0’ or ‘1’.
1. A power transmitter executing communication with a power receiver, the power transmitter configured to:
synchronize a sampling start time to a pulse-width modulation (PWM) signal;
determine an average sampling rate for sampling a power carrier signal, wherein the power carrier signal is generated by the PWM signal;
sample the power carrier signal to obtain sample values;
limit an amplitude above or below an average of the sampled values to produce limited sampled values;
send the limited sample values to a 0 match filter and a 1 match filter;
search outputs of the 0 match filter and 1 match filter for peaks;
determine a current modem state; and
process the outputs of the 0 match filter and the 1 match filter based on the determined current modem state.
2. The power transmitter of claim 1 , wherein the average sampling rate is N times a data rate of the power carrier signal, wherein N is an integer larger than zero.
3. The power transmitter of claim 1 , wherein the power transmitter is configured to sample the power carrier signal based on the synchronized sampling start time and the determined average sampling rate.
4. The power transmitter of claim 1 , wherein the power transmitter is configured to directly sample the power carrier signal.
5. The power transmitter of claim 1 , wherein the power transmitter is configured to skip a cycle for sampling, such that sampling is not performed for every cycle.
6. A method implemented by a power transmitter that communicates with a power receiver, the method comprising:
synchronizing a sampling start time to a pulse-width modulation (PWM) signal;
determining an average sampling rate for sampling a power carrier signal;
sampling the power carrier signal to obtain sample values;
limiting an amplitude above or below an average of the sampled values;
for producing limited sampled values;
sending the limited sample values to a 0 match filter and a 1 match filter;
searching outputs of the 0 match filter and 1 match filter for peaks;
determining a current modem state; and
processing the outputs of the 0 match filter and the 1 match filter based on the determined current modem state.
7. The method of claim 6 , wherein the sampling rate is N times a data rate of the power carrier signal, wherein N is an integer larger than zero.
8. The method of claim 6 further comprising sampling the power carrier signal based on the synchronized start sampling start time and the determined average sampling rate.