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US 7,002,946 B2Granted
Frequency discriminator
AssigneeQUALCOMM Incorporated
InventorAndrew Sendonaris
Life of this patent
Estimating the term…
Abstract
A cross product is determined for a received signal. A dot product is also determined for the received signal. If the cross product is greater than a predetermined threshold, the cross product is decremented by the product of the dot product multiplied by a constant value. If the cross product is less than or equal to the predetermined threshold, the cross product is incremented by the product of the dot product multiplied by the constant value. The incrementing or decrementing is continued until the frequency error approaches a minimum value.
Claims23
A method of performing frequency tracking of input signal having a frequency error, the method comprising:
- identifying a cross product and a dot product of the input signal;
- comparing the cross product relative to a predetermined threshold;
- adjusting the cross product by an adjustment amount equivalent to a first product of the dot product times a constant value on the basis of the comparison;
- and
- using the cross product, after adjusting by the adjustment amount, for frequency tracking of the input signal.
2 more elements
A method comprising:
- identifying a cross product and a dot product of a signal comprised of a plurality of symbols;
- multiplying the dot product by a constant value to generate a frequency adjustment product;
- when the cross product is greater than zero, decreasing the cross product by the frequency adjustment product;
- when the cross product is less than zero, increasing the cross product by the frequency adjustment product;
- and
- using the cross product, after decreasing or increasing by the frequency adjustment product, for frequency tracking of the signal.
3 more elements
An apparatus comprising:
- a cross product generator, coupled to an input signal, for generating a cross product of the input signal;
- a dot product generator, coupled to the input signal, for generating a dot product of the input signal;
- a multiplier coupled to the dot product generator for generating a product in response to the dot product and a constant value;
- a first multiplexing device having a first input coupled to the product and a second input coupled to a negative of the product, the first multiplexing device selecting either the first input or the second input in response to the cross product;
- a summer coupled to the cross product generator and the first multiplexing device, the summer generating a summation signal of the cross product and an output of the first multiplexing device;
- and
- a second multiplexing device coupled to the cross product generator and the summer, the second multiplexing device selecting either the cross product or the summation signal in response to the dot product.
4 more elements
A mobile communications device comprising:
- a receiver for demodulating an input signal that was received over a communications channel, the receiver comprising:
- a cross product generator, coupled to the input signal, for generating a cross product of the input signal;
- a dot product generator, coupled to the input signal, for generating a dot product of the input signal;
- a multiplier coupled to the dot product generator for generating a product in response to the dot product and a constant value;
- a first multiplexing device having a first input coupled to the product and a second input coupled to a negative of the product, the first multiplexing device selecting either the first input or the second input in response to the cross product;
- a summer coupled to the cross product generator and the first multiplexing device, the summer generating a summation signal of the cross product and an output of the first multiplexing device;
- and
- a second multiplexing device coupled to the cross product generator and the summer, the second multiplexing device selecting either the cross product or the summation signal in response to the dot product.
5 more elements
A receiver comprising:
- a cross product generator, coupled to an input signal, for generating a cross product of the input signal;
- a dot product generator, coupled to the input signal, for generating a dot product of the input signal;
- a first low pass filter, coupled to the cross product, for generating a filtered cross product;
- a second low pass filter, coupled to the dot product, for generating a filtered dot product;
- a multiplier coupled to the filtered dot product for generating an adjustment product in response to the filtered dot product and a constant value;
- a first multiplexing device having a first input coupled to the adjustment product and a second input coupled to a negative of the adjustment product, the first multiplexing device selecting either the first input or the second input in response to the filtered cross product;
- a summer coupled to the filtered cross product and the first multiplexing device, the summer generating a summation signal of the filtered cross product and an output of the first multiplexing device;
- and
- a second multiplexing device coupled to the first low pass filter and the summer, the second multiplexing device selecting either the filtered cross product or the summation signal in response to the filtered dot product.
6 more elements
An apparatus comprising:
- means for processing a received signal having a frequency error, with a frequency error estimate, to obtain an input signal having a residual frequency error;
- means for determining a cross product of the input signal;
- means for determining a dot product of the input signal;
- means for determining an adjustment amount based on the dot product and a predetermined value;
- means for determining the cross product by the adjustment amount if the cross product is greater than a predetermined threshold;
- means for incrementing the cross product by the adjustment amount if the cross product is less than or equal to the predetermined threshold;
- and
- means for using the cross product, after decrementing or incrementing by the adjustment amount, for frequency tracking of the received signal.
5 more elements
An apparatus comprising:
- a cross product generator, coupled to an input signal, for generating a cross product of the input signal;
- a dot product generator, coupled to the input signal, for generating a dot product of the input signal;
- a first low pass filter, coupled to the cross product, for generating a filtered cross product;
- a second low pass filter, coupled to the dot product, for generating a filtered dot product;
- a multiplier coupled to the filtered dot product for generating an adjustment product in response to the filtered dot product and a constant value;
- a first multiplexing device having a first input coupled to the adjustment product and a second input coupled to a negative of the adjustment product, the first multiplexing device selecting either the first input or the second input in response to the filtered cross product;
- a summer coupled to the filtered cross product and the first multiplexing device, the summer generating a summation signal of the filtered cross product and an output of the first multiplexing device;
- and
- a second multiplexing device coupled to the first low pass filter and the summer, the second multiplexing device selecting either the filtered cross product or the summation signal in response to the filtered dot product.
6 more elements
Dependencies are inferred from the claim text.