Method and RFID reader for detecting a delimiter pattern in a signal stream

An contact-less communication device comprising control means with an arithmetic-logic unit and a memory, wherein the contact-less communication device is adapted to process a computer program product and being configured to detect a delimiter pattern in a signal stream, wherein the signal stream contains a carrier or subcarrier modulated by the delimiter pattern, wherein the contact-less communication device is configured to perform the method comprising:

• specifying an expected delimiter occurrence time of an occurrence of the delimiter pattern and a tolerance zone within which the expected delimiter occurrence time may jitter;
• rectifying or demodulating the signal stream to obtain a data stream and performing a zero detection by approximation, within the tolerance zone, to find a zero of the cross correlation function (CCF) of the data stream within the delimiter pattern;
• calculating a first maximum of the cross correlation function (CCF) within the tolerance zone by use of the approximated zero;
• calculating all other maxima of the cross correlation function (CCF) within the tolerance zone;
• detecting a highest maximum among the calculated maxima, which highest maximum is representative for the moment in time of the occurrence of the delimiter pattern.

A method performed on a contact-less communication device for detecting a delimiter pattern in a signal stream, wherein the signal stream contains a carrier or subcarrier modulated by the delimiter pattern (SOF), the method comprising:

• specifying an expected delimiter occurrence time of an occurrence of the delimiter pattern and a tolerance zone within which the expected delimiter occurrence time may jitter;
• rectifying or demodulating the signal stream to obtain a data stream and detecting the phase (φ) of the carrier or subcarrier in respect to an arbitrarily defined reference position within the tolerance zone;
• calculating a first maximum of a cross correlation function (CCF) of the data stream (DS) with the delimiter pattern, within the tolerance zone by use of the approximated phase (φ);
• calculating all other maxima of the cross correlation function (CCF) in the tolerance zone;
• detecting the highest maximum among the calculated maxima, which highest maximum is representative for the moment in time of the occurrence of the delimiter pattern.