# US 10,484,217 B2 · Method of detecting FSK-modulated signals, corresponding circuit, device and computer program product > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,484,217 B2 - Document ID: US10484217B2 - Status: Granted - Kind: B2 - Application number: 15/606,979 - Filed: 2017-05-26 - Published: 2018-05-10 - Granted: 2019-11-19 - Earliest claimed: 2016-11-04 - Assignees: STMicroelectronics Design and Application S.R.O.; STMicroelectronics S.r.l. - Applicants: STMicroelectronics Design and Application s.r.o.; STMicroelectronics S.r.l. - Inventors: Eusebio Dicola; Elena Salurso; Jan Milsimer - Web page: https://patentgrep.com/patent/US10484217B2 ## CPC - H04L 27/144: with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements - G01R 29/0273: {the pulse characteristic being duration, i.e. width (indicating that frequency of pulses is above or below a certain limit)} - H04L 1/206: {for modulated signals} - H04L 27/10: Frequency-modulated carrier systems, i.e. using frequency-shift keying (H04L27/32 takes precedence) - H04L 27/156: with demodulation using temporal properties of the received signal, e.g. detecting pulse width - H04L 27/1563: {using transition or level detection} - H04L 1/1835: {Buffer management} - H04L 25/069: {by detecting edges or zero crossings} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract An occurrence of a first set of n periods of a frequency-shift-keying (FSK)-modulated waveform is counted, where n is an integer number. The n periods of the FSK-modulated waveform in the first set have a first time duration. An occurrence of a second set of n periods of the waveform is counted. The n periods of the waveform in the second set have a second time duration. The first time duration is determined based on the counting of the first set of n periods. The second time duration is determined based on the counting of the second set of n periods. A difference between the first time duration and the second time duration is compared to a threshold. Changes in frequency of the waveform are detected based on the comparing of the difference between the first time duration and the second time duration to the threshold. ## Claims ### Claim 1 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 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. ### Claim 2 (depends on 1) The method of claim 1 wherein said first set of n periods and said second set of n periods are neighboring sets of periods in said FSK-modulated waveform. ### Claim 3 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. ### Claim 4 (depends on 3) The method of claim 3, comprising: cyclically counting occurrences of sets of n periods of said FSK-modulated waveform over sequential time windows wherein: 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. ### Claim 5 (depends on 1) The method of claim 1, comprising: adjusting said number n of periods of said FSK-modulated waveform. ### Claim 6 (depends on 1) The method of claim 1, comprising: adjusting said threshold. ### Claim 7 (depends on 1) The method of claim 1, comprising: 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. ### Claim 8 (depends on 7) The method of claim 7, comprising: buffering information bits of said recovered digital modulation signal. ### Claim 9 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. ### Claim 10 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. ### Claim 11 (depends on 10) The device of claim 10 wherein the frequency-shift detecting circuitry, in operation, compares differences between time durations of neighboring sets of n periods in said FSK-modulated waveform to the threshold difference. ### Claim 12 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. ### Claim 13 (depends on 12) The device of claim 12 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. ### Claim 14 (depends on 10) The device of claim 10 wherein n is adjustable. ### Claim 15 (depends on 10) The device of claim 10 wherein the threshold difference is adjustable. ### Claim 16 (depends on 10) The device of claim 10, comprising: 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. ### Claim 17 (depends on 10) The device of claim 10, wherein the frequency-shift detecting circuitry, 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. ### Claim 18 (depends on 17) The device of claim 17 wherein the one or more memories comprise a buffer, which, in operation, buffers information bits of said recovered digital modulation signal. ### Claim 19 (depends on 18) The device of claim 18 wherein the frequency-shift detecting circuitry, in operation, generates 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. ### Claim 20 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. ### Claim 21 (depends on 20) The system of claim 20, including a buffer, which, in operation, stores information bits of the recovered digital modulation signal. ### Claim 22 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. ### Claim 23 (depends on 22) The system of claim 22 wherein the decoding circuitry, in operation, decodes at least one of a differential by-phase encoded signal and a Manchester-encoded signal. ### Claim 24 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. ### Claim 25 (depends on 24) The non-transitory, computer-readable medium of claim 24 wherein the signal processing circuit comprises one or more memories and one or more processing cores. ### Claim 26 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.