Methods and systems of phase aligning a replica carrier signal for use in demodulating a subcarrier signal

A test and measurement system, comprising:

• a proximity coupling device configured to transmit a modulated carrier signal;
• a proximity integrated circuit card configured to load modulate the transmitted modulated carrier signal to generate a modulated subcarrier signal on the transmitted wireless carrier;
• and
• a test and measurement instrument including one or more processors configured to acquire the modulated carrier signal and including a phase-aligned subcarrier demodulator, the phase-aligned subcarrier demodulator configured, in order to demodulate the modulated subcarrier signal, to:
• detect commands and responses contained in the modulated carrier signal;
• remove the detected commands to generate a response vector including the removed commands and the detected responses;
• identify a correlation index for each response in the response vector, each correlation index indicating a phase of a modulated carrier signal of the corresponding response relative to a replica carrier signal;
• adjust a phase of the replica carrier signal based on the correlation index for each response in the response vector to phase align the replica carrier signal and modulated carrier signal for the response;
• demodulate each response in the response vector using the replica carrier signal having the corresponding adjusted phase to generate a demodulated response vector including a plurality of demodulated responses;
• and
• low pass filter the demodulated response vector to generate a decoded response vector.

A test and measurement system, comprising:

• a proximity coupling device configured to transmit a modulated carrier signal;
• a proximity integrated circuit card configured to load modulate the transmitted modulated carrier signal to generate one of an OOK and a BPSK modulated subcarrier signal on the transmitted wireless carrier;
• and
• a test and measurement instrument configured to acquire the modulated carrier signal, the test and measurement instrument including a phase-aligned subcarrier demodulator configured to demodulate the modulated subcarrier signal, the phase-aligned subcarrier demodulator configured to:
• detect commands and responses contained in the modulated carrier signal;
• remove the detected commands to generate a response vector including the removed commands and the detected responses;
• identify a correlation index for each response in the response vector, each correlation index indicating a phase of a modulated carrier signal of the corresponding response relative to a replica carrier signal;
• adjust a phase of the replica carrier signal based on the correlation index for each response in the response vector to phase align the replica carrier signal and modulated carrier signal for the response;
• down convert each response in the response vector using the replica carrier signal having the corresponding adjusted phase to generate a modulated subcarrier signal for each response in the response vector;
• and
• low pass filter the modulated subcarrier signals to generate a decoded response vector.