Carrier to noise ratio estimations from a received signal
First Claim
Patent Images
1. A method comprising:
- receiving a phase-shift keyed signal with a layered modulation scheme having a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
processing the phase-shift keyed signal through a carrier recovery loop to produce signal points in the second layer relative to ideal signal nodes located in the first layer; and
determining a carrier to noise ratio (CNR) measurement from an average difference between the signal points and the respective ideal signal nodes.
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Abstract
Techniques for measuring the carrier to noise ratio (CNR) in a received digital signal are disclosed. The methods can operate on a received digital signal, such as a layered modulation signal used in a satellite television system. The CNR measurement can be made at the output of a carrier recovery loop or a timing recovery loop in a demodulator. Alternately, the CNR measurement can be made when the received signal is digitized in an analog to digital (A/D) converter at base-band by the demodulator.
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Citations
24 Claims
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1. A method comprising:
- receiving a phase-shift keyed signal with a layered modulation scheme having a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
processing the phase-shift keyed signal through a carrier recovery loop to produce signal points in the second layer relative to ideal signal nodes located in the first layer; and determining a carrier to noise ratio (CNR) measurement from an average difference between the signal points and the respective ideal signal nodes. - View Dependent Claims (2, 3, 4)
- receiving a phase-shift keyed signal with a layered modulation scheme having a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
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5. A method comprising:
- receiving a phase-shift keyed signal with a layered modulation scheme, wherein a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
sampling the phase-shift keyed signal of the second layer at tracked peak symbol times to determine signal point magnitudes of the signal points in the second layer; and determining a carrier to noise ratio (CNR) measurement from the average difference between (a) an average value of the signal point magnitudes and (b) the signal point magnitudes. - View Dependent Claims (6, 7, 8)
- receiving a phase-shift keyed signal with a layered modulation scheme, wherein a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
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9. A method comprising:
- receiving a phase-shift keyed signal with a layered modulation scheme, wherein a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
digitizing the phase-shift keyed signal in the second layer at base-band to determine digitized signal values; and determining a carrier to noise ratio (CNR) measurement from the signal raised to its N-th power by comparing the power ratio between the DC and AC components of the powered signals. - View Dependent Claims (10, 11, 12)
- receiving a phase-shift keyed signal with a layered modulation scheme, wherein a first layer non-coherent with at least a second layer in the phase-shift keyed signal using a demodulator;
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13. An apparatus for measuring a carrier to noise ratio in a received signal, comprising:
a demodulator for receiving a phase-shift keyed signal with a layered modulation scheme having a first layer non-coherent with at least a second layer in the phase-shift keyed signal, for processing the phase-shift keyed signal through a carrier recovery loop to produce signal points in the second layer relative to ideal signal nodes located in the first layer, and for determining a carrier to noise ratio (CNR) measurement from the average difference between an signal points and the respective ideal signal nodes. - View Dependent Claims (14, 15, 16)
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17. An apparatus for measuring a carrier to noise ratio in a received signal, comprising:
a demodulator for receiving a phase-shift keyed signal with a layered modulation scheme having a first layer non-coherent with at least a second layer in the phase-shift keyed signal, for sampling the phase-shift keyed signal of the second layer at tracked peak symbol times to determine signal point magnitudes of the signal points in the second layer, and for determining a carrier to noise ratio (CNR) measurement from an average difference between (a) an average value of the signal point magnitudes and (b) the signal point magnitudes. - View Dependent Claims (18, 19, 20)
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21. An apparatus for measuring a carrier to noise ratio in a received signal, comprising:
a demodulator for receiving a phase-shift keyed signal with a layered modulation scheme, wherein a first layer is non-coherent with at least a second layer of the phase-shift keyed signal, for digitizing the phase-shift keyed signal in the second layer at base-band to determine digitized signal values, and for determining a carrier to noise ratio (CNR) measurement from the signal raised to its N-th power by comparing the power ratio between the DC and AC components of the powered signals. - View Dependent Claims (22, 23, 24)
Specification