SYSTEMS AND METHODS FOR SIGNAL MODULATION AND DEMODULATION USING PHASE

• US 20090154589A1
• Filed: 12/15/2008
• Published: 06/18/2009
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Landis+Gyr Technology, Inc. (Landis+Gyr Group AG)
• Original Assignee: Landis+Gyr Innovations Incorporated (Landis+Gyr Group AG)
• Inventors: Monnerie, Emmanuel
• Granted Patent: US 8,107,551 B2
• Time in Patent Office: Days
• US Class Current: 375/269
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/26524 Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation

Abstract

Certain embodiments provide a system for recovering data from at least one signal. The system can include an analog-to-digital converter (ADC) and in-phase/quadrature (IQ) generator component that can sample a signal recovered from a communication medium to generate a first signal sample and a second signal sample. A Fast Fourier Transform (FFT) component can process the first signal sample to generate a first signal phase and process the second signal sample to generate a second signal phase. A phase difference calculation component can determine a phase difference between the first signal phase and the second signal phase, determine a bit value represented by the signal based on the phase difference, and output the bit value to an end device coupled to the phase difference calculation component.

Claims

1. A system for recovering data from at least one signal, the system comprising:

an analog-to-digital converter (ADC) and in-phase/quadrature (IQ) generator component configured to sample a signal recovered from a communication medium on which the signal is propagating to generate a first signal sample and a second signal sample;

a Fast Fourier Transform (FFT) component coupled to the ADC and IQ generator component, the FFT component being configured to process the first signal sample to generate a first signal phase and process the second signal sample to generate a second signal phase; and

a phase difference calculation component coupled to the FFT component, the phase difference calculation component being configured to;

determine a phase difference between the first signal phase and the second signal phase;

determine a bit value represented by the signal based on the phase difference; and

output the bit value to an end device coupled to the phase difference calculation component.

2. The system of claim 1, wherein the phase difference calculation component is configured to determine the phase difference between the first signal phase and the second signal phase by subtracting the first signal phase from the second signal phase.

3. The system of claim 1, wherein the ADC and IQ generator component is configured to determine a time offset for the first signal sample and the second signal sample based on a number of signal samples generated by the ADC and IQ generator component;

and

wherein the phase difference calculation component is configured to determine the phase difference using a frequency of the signal, a sampling frequency of the ADC and IQ generator component, and the time offset.

4. The system of claim 1, wherein the phase difference calculation component is configured to determine the bit value represented by the signal based on the phase difference by:

identifying a sign of the phase difference;

determining the bit value is a digital 0 if the sign of the phase difference is positive; and

determining the bit value is a digital 1 if the sign of the phase difference is negative.

5. The system of claim 1, wherein the FFT component is configured to process the first signal sample to generate the first signal phase and process the second signal sample to generate the second signal phase by performing an FFT algorithm on the first signal sample to generate the first signal phase and performing the FFT algorithm on the second signal sample to generate the second signal phase.

6. The system of claim 1, further comprising an RF front end component coupled to the ADC and IQ generator component, the RF front end component being configured to amplify the signal recovered from the communication medium and provide an amplified signal to the ADC and IQ generator component.

7. The system of claim 1, wherein the FFT component comprises a first channel and a second channel, the first channel being configured to process the first signal sample and the second signal sample and the second channel being configured to process at least two samples from a second signal to generate at least two phases for the second signal, wherein processing the at least two samples from the second signal at least partially overlaps processing the first signal sample or processing the second signal sample.

8. The system of claim 7, wherein the ADC and IQ generator component is configured to sample the second signal recovered from the communication medium on which the second signal is propagating to generate the at least two samples from the second signal;

and

wherein the phase difference calculation component is configured to;

determine a second signal phase difference between the at least two phases for the second signal;

determine a second signal bit value based on the second signal phase difference; and

output the second signal bit value to an end device coupled to the phase difference calculation component.

9. A system for recovering data from at least two signals, the system comprising:

an analog-to-digital converter (ADC) and in-phase/quadrature (IQ) generator component configured to sample a first signal modulated by a first technique to generate a plurality of first signal samples and sample a second signal modulated by a second technique to generate a plurality of second signal samples, the first signal and the second signal being recovered from a communication medium on which the first signal and the second signal are propagating;

a Fast Fourier Transform (FFT) component coupled to the ADC and IQ generator component, the FFT component being configured to process the plurality of first signal samples to generate at least two first signal phases and process the plurality of second signal samples to generate at least two second signal phases, wherein processing the plurality of first signal samples at least partially overlaps processing the plurality of second signal samples;

a phase difference calculation component coupled to the FFT component, the phase difference calculation component being configured to determine a first signal bit value based on a phase difference between the at least two first signal phases and output the first signal bit value; and

a demodulator coupled to the FFT component, the demodulator being configured to demodulate the second signal using the at least two second signal phases to determine a second signal bit value and output the second signal bit value.

10. The system of claim 9, wherein the first signal is an FSK modulated signal and the second signal is an OFDM modulated signal;

and

wherein the demodulator is an OFDM demodulator.

11. The system of claim 10, wherein the FFT component is configured to:

provide the at least two first signal phases to the phase difference calculation component by determining the first signal is the FSK modulated signal; and

provide the at least two second signal phases to the OFDM modulator by determining the second signal is the OFDM modulated signal.

12. The system of claim 9, wherein the ADC and IQ generator component is configured to determine a time offset for the plurality of first signal samples based on a number of signal samples generated by the ADC and IQ generator component for the first signal;

and

wherein the phase difference calculation component is configured to determine the phase difference using a frequency of the first signal, a sampling frequency of the ADC and IQ generator component, and the time offset.

13. The system of claim 9, wherein the phase difference calculation component is configured to determine the first signal bit value represented by the first signal based on the phase difference by:

identifying a sign of the phase difference;

determining the first signal bit value is a digital 0 if the sign of the phase difference is positive; and

determining the first signal bit value is a digital 1 if the sign of the phase difference is negative.

14. The system of claim 9, wherein the FFT component is configured to process the plurality of first signal samples to generate at least two first signal phases and process the plurality of second signal samples to generate at least two second signal phases by performing an FFT algorithm on the plurality of first signal samples to generate the at least two first signal phases and performing the FFT algorithm on the plurality of second signal samples to generate the at least two second signal phases.

15. The system of claim 9, wherein the FFT component is configured to determine a phase threshold based on an expected phase difference between the at least two first signal phases, the expected phase difference being based on a difference of a digital 0 signal phase and a digital 1 signal phase;

and

wherein the phase difference calculation component is configured to determine the first signal bit value by comparing the phase difference to the phase threshold.

16. A method for recovering data from at least one signal, the method comprising:

sampling a signal recovered from a communication medium on which the signal is propagating to generate a first signal sample and a second signal sample;

processing the first signal sample to generate a first signal phase;

processing the second signal sample to generate a second signal phase;

determining a phase difference between the first signal phase and the second signal phase;

determining a bit value represented by the signal based on the phase difference; and

outputting the bit value.

17. The method of claim 16, wherein determining the phase difference between the first signal phase and the second signal phase comprises subtracting the first signal phase from the second signal phase.

18. The method of claim 16, further comprising determining a time offset for the first signal sample and the second signal sample based on a number of signal samples generated by sampling the signal;

and

wherein determining the phase difference comprises using a frequency of the signal, a sampling frequency, and the time offset.

19. The method of claim 16, wherein determining the bit value represented by the signal based on the phase difference comprises:

identifying a sign of the phase difference;

determining the bit value is a digital 0 if the sign of the phase difference is positive; and

determining the bit value is a digital 1 if the sign of the phase difference is negative.

20. The method of claim 16, wherein processing the first signal sample to generate the first signal phase comprises performing an FFT algorithm on the first signal sample to generate the first signal phase;

and

wherein processing the second signal sample to generate the second signal phase comprises performing the FFT algorithm on the second signal sample to generate the second signal phase.

21. The method of claim 16, further comprising:

processing the first signal sample and the second signal sample by a first channel of an FFT component;

processing at least two samples from a second signal by a second channel of the FFT component to generate at least two phases for the second signal; and

wherein processing the at least two samples from the second signal at least partially overlaps processing the first signal sample or processing the second signal sample.

22. The method of claim 21, further comprising:

sampling the second signal to generate the at least two samples from the second signal;

determining a second signal phase difference between the at least two phases for the second signal;

determining a second signal bit value based on the second signal phase difference; and

outputting the second signal bit value.