System and method for reducing intra-channel interference
AssigneeEntropic Communications, Inc.
InventorsDean Satoda, Darren Smith
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Abstract
The present invention provides a method for determining a local oscillator frequency for a baseband converter, comprising obtaining characteristics of a channel comprising a plurality of radio signals at corresponding radio frequencies; using the channel characteristics to select a local oscillator frequency to use in baseband conversion of the plurality of radio signals of the channel to form a first baseband converted signal and a second baseband converted signal; and programming a local oscillator to operate the selected local oscillator frequency; wherein the local oscillator frequency is selected such that an image rejection ratio of the baseband converted second signal to an image of the baseband converted first signal is above a predetermined threshold.
Claims20
A method for determining a local oscillator frequency for a baseband converter, comprising:
- obtaining properties of a channel comprising a plurality of radio signals at o s londing radio frequencies;
- using the channel properties to select a local oscillator frequency to use in baseband conversion of the plurality of radio signals of the channel to form a first baseband converted signal and a second baseband converted signal;
- and programming a local oscillator to operate using the selected local oscillator frequency;
- wherein the local oscillator frequency is selected such that an image rejection ratio of the second baseband converted signal to an image of the first baseband converted signal is above a predetermined threshold.
A method of receiving a channel, comprising:
- receiving a radio signal comprising a plurality of channels, a channel of the plurality comprising a first signal and a second signal;
- converting the radio signal to a baseband signal using a local oscillator having a local oscillator frequency that is selected such that an image rejection ratio of the baseband converted second signal to an image of the baseband converted first signal is above a predetermined threshold;
- and
- shifting the frequency of the baseband signal by an amount approximately equal to the difference between a channel center frequency and the local oscillator frequency.
The method claime 8, wherein the channel occupies a 6 MHz range of radio spectrum between 30 MHz and 900 MHz the potential local oscillator frequency comprises a frequency approximately 3 MHz greater than a lowest frequency of the channel, and the selected local oscillator frequency comprises a frequency 0.25 MHz less than the potential local oscillator frequency.
An apparatus for channel tuning, comprising:
- a signal receiver configured to receive a radio signal comprising a plurality of channels, a channel of the plurality comprising a first signal and a second signal;
- a local oscillator configured to provide a local oscillator frequency that is configured such that an image rejection ratio of the baseband converted second signal to an image of the baseband converted first signal is above a predetermined threshold;
- a baseband converter coupled to the antenna and the local oscillator and configured to output a baseband converted radio signal comprising the baseband converted first signal and the baseband converted second signal;
- and
- a phase rotator configured to shift the baseband converted radio signal by an amount approximately equal to the frequency difference between the local oscillator frequency and a center channel frequency.
Dependencies are inferred from the claim text.