Method of detecting FSK-modulated signals, corresponding circuit, device and computer program product

A method, comprising:

• counting an occurrence of a first set of n periods of a frequency-shift-keying (FSK)-modulated waveform, where n is an integer number, said n periods of said FSK-modulated waveform in said first set having a first time duration, wherein a period of the FSK-modulated waveform varies as a function of a level of a digital modulation signal;
• counting an occurrence of a second set of n periods of said FSK-modulated waveform, said n periods of said FSK-modulated waveform in said second set having a second time duration;
• determining, based on the counting of the first set of n periods, the first time duration;
• determining, based on the counting of the second set of n periods, the second time duration;
• comparing a difference between said first time duration and said second time duration to a threshold;
• and
• detecting a change in a frequency of said FSK-modulated waveform indicative of a change in the level of said digital modulating signal based on the comparing of the difference between the first time duration and the second time duration to the threshold, wherein the method comprises:
• recovering said digital modulation signal as a function of detected changes in the frequency of said FSK-modulated waveform based on a series of comparisons of differences between durations of sets of n periods to the threshold;
• detecting a discontinuation of reception of the FSK-modulated waveform;
• and
• generating an interrupt signal in response to the detection of the discontinuation.

A method, comprising:

• counting an occurrence of a first set of n periods of a frequency-shift-keying (FSK)-modulated waveform, where n is an integer number, said n periods of said FSK-modulated waveform in said first set having a first time duration, wherein a period of the FSK-modulated waveform varies as a function of a level of a digital modulation signal;
• counting an occurrence of a second set of n periods of said FSK-modulated waveform, said n periods of said FSK-modulated waveform in said second set having a second time duration;
• determining, based on the counting of the first set of n periods, the first time duration;
• determining, based on the counting of the second set of n periods, the second time duration;
• comparing a difference between said first time duration and said second time duration to a threshold;
• and
• detecting a change in a frequency of said FSK-modulated waveform indicative of a change in the level of said digital modulating signal based on the comparing of the difference between the first time duration and the second time duration to the threshold, wherein the method comprises:
• recovering said digital modulation signal as a function of detected changes in the frequency of said FSK-modulated waveform based on a series of comparisons of differences between durations of sets of n periods to the threshold;
• buffering information bits of said recovered digital modulation signal;
• and
• generating an interrupt signal in response to at least one of:
• a number of said buffered bits reaching a threshold number of bits;
• and
• a buffer overflow.

A device, comprising:

• one or more memories;
• and
• frequency-shift detection circuitry, which, in operation:
• counts occurrences of sets of n periods of a received frequency-shift-keying (FSK)-modulated waveform, where n is an integer number;
• determines, based on the counting, time durations corresponding to respective sets of n periods;
• compares differences between time durations corresponding to respective sets of n periods to a threshold difference;
• and
• generates one or more signals indicative of variations in frequency of the FSK-modulated waveform based on the comparing of the differences between time durations to the threshold difference, wherein the frequency-shift detecting circuitry, in operation:
• cyclically counts occurrences of sets of n periods of said FSK-modulated waveform over sequential time windows wherein:
• a first set of n periods includes a set of n periods of said FSK-modulated waveform during a current time window;
• a second set of n periods includes a set of n periods of said FSK-modulated waveform during a previous time window;
• and
• a difference between a time duration corresponding to the first set of n periods and a time duration corresponding to the second set of n periods is compared to the threshold difference.

A device, comprising:

• one or more memories;
• and
• frequency-shift detection circuitry, which, in operation:
• counts occurrences of sets of n periods of a received frequency-shift-keying (FSK)-modulated waveform, where n is an integer number;
• determines, based on the counting, time durations corresponding to respective sets of n periods;
• compares differences between time durations corresponding to respective sets of n periods to a threshold difference;
• and
• generates one or more signals indicative of variations in frequency of the FSK-modulated waveform based on the comparing of the differences between time durations to the threshold difference, wherein the frequency-shift detecting circuitry, in operation:
• detects discontinuations of reception of the FSK-modulated waveform;
• and
• generates an interrupt signal in response to detection of a discontinuation.

A system, comprising:

• receiving circuitry, which, in operation:
• counts occurrences of sets of n periods of a received frequency-shift-keying (FSK)-modulated waveform, where n is an integer number;
• determines, based on the counting, time durations corresponding to respective sets of n periods;
• compares differences between time durations corresponding to respective sets of n periods to a threshold difference;
• and
• generates one or more signals indicative of variations in frequency of the FSK-modulated waveform based on the comparing of the differences between time durations to the threshold difference;
• and
• decoding circuitry, which, in operation, recovers a digital modulation signal based on the one or more signals indicative of variations in frequency of the FSK-modulated waveform generated in response to a series of comparisons of differences between durations corresponding to sets of n periods to the threshold difference, wherein the decoding circuitry, in operation, decodes at least one of a differential by-phase encoded signal and a Manchester-encoded signal.

A system, comprising:

• receiving circuitry, which, in operation:
• counts occurrences of sets of n periods of a received frequency-shift-keying (FSK)-modulated waveform, where n is an integer number;
• determines, based on the counting, time durations corresponding to respective sets of n periods;
• compares differences between time durations corresponding to respective sets of n periods to a threshold difference;
• and
• generates one or more signals indicative of variations in frequency of the FSK-modulated waveform based on the comparing of the differences between time durations to the threshold difference;
• decoding circuitry, which, in operation, recovers a digital modulation signal based on the one or more signals indicative of variations in frequency of the FSK-modulated waveform generated in response to a series of comparisons of differences between durations corresponding to sets of n periods to the threshold difference;
• and
• power control circuitry, which, in operation, controls a charging process based on the recovered digital modulation signal.

A non-transitory, computer-readable medium having contents which cause a signal processing circuit to perform a method, the method comprising:

• counting occurrences of sets of n periods of a received frequency-shift-keying (FSK)-modulated waveform, where n is an integer number;
• determining, based on the counting, time durations corresponding to respective sets of n periods;
• comparing differences between time durations corresponding to respective sets of n periods to a threshold difference;
• generating one or more signals indicative of variations in frequency of the FSK-modulated waveform based on the comparing of the differences between time durations to the threshold difference;
• recovering a digital modulation signal based on the one or more signals indicative of variations in frequency of the FSK-modulated waveform generated in response to a series of comparisons of differences between durations corresponding to sets of n periods to the threshold difference;
• and
• controlling a charging process based on the recovered digital modulation signal.

A non-transitory, computer-readable medium having contents which cause a signal processing circuit to perform a method, the method comprising:

• counting an occurrence of a first set of n periods of a frequency-shift-keying (FSK)-modulated waveform, where n is an integer number, said n periods of said FSK-modulated waveform in said first set having a first time duration, wherein a period of the FSK-modulated waveform varies as a function of a level of a digital modulation signal;
• counting an occurrence of a second set of n periods of said FSK-modulated waveform, said n periods of said FSK-modulated waveform in said second set having a second time duration;
• determining, based on the counting of the first set of n periods, the first time duration;
• determining, based on the counting of the second set of n periods, the second time duration;
• comparing a difference between said first time duration and said second time duration to a threshold;
• and
• detecting a change in a frequency of said FSK-modulated waveform indicative of a change in the level of said digital modulating signal based on the comparing of the difference between the first time duration and the second time duration to the threshold, wherein:
• the method comprises cyclically counting occurrences of sets of n periods of said FSK-modulated waveform over sequential time windows,
• said first set of n periods includes a set of n periods of said FSK-modulated waveform during a current time window, and
• said second set of n periods includes a set of n periods of said FSK-modulated waveform during a previous time window.