Apparatus and method for frequency calibration between two radios
First Claim
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1. A wireless device, comprising:
- a crystal oscillator configured to generate a reference frequency;
a radio circuit configured to operate according to the reference frequency; and
a frequency offset circuit configured to generate, based on signal quality information in a wireless data signal received from a second wireless device, an offset value to reduce an operating frequency offset between the wireless device and the second wireless device, wherein the frequency offset circuit comprises an accumulator circuit, and wherein an overflow rate of the accumulator circuit represents the operating frequency offset of the radio circuit.
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Abstract
Wireless devices transmit and receive radio signals based upon reference frequencies generated by crystal oscillators. If the reference frequencies of the transmitter and the receiver are different, the radio signals may not be received properly or may not be received at all. A measurement circuit measures the amount of error or signal corruption in the radio signals due to the reference frequency offset between the transmitter and the receiver. A frequency offset circuit generates an offset operating frequency in the transmitter or the receiver to align or calibrate the operating frequencies of the devices.
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Citations
19 Claims
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1. A wireless device, comprising:
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a crystal oscillator configured to generate a reference frequency; a radio circuit configured to operate according to the reference frequency; and a frequency offset circuit configured to generate, based on signal quality information in a wireless data signal received from a second wireless device, an offset value to reduce an operating frequency offset between the wireless device and the second wireless device, wherein the frequency offset circuit comprises an accumulator circuit, and wherein an overflow rate of the accumulator circuit represents the operating frequency offset of the radio circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A frequency calibration method comprising:
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adjusting a first operating transmit frequency on a transmitting device to establish an operating transmission frequency range for wireless data transmissions between the transmitting device and a receiving device; and based on the operating transmission frequency range, generating a second operating transmit frequency for the wireless data transmissions by inputting to an accumulator, a signal representing an instantaneous frequency of the first operating transmit frequency and adjusting an overflow rate from the accumulator to obtain the second operating transmit frequency, wherein the second operating transmit frequency is associated with a reduced amount of carrier-based operating frequency offset between the transmitting device and the receiving device. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A radio system, comprising:
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a radio transmitter configured to transmit a radio transmission according to a transmitter crystal oscillator frequency; a radio receiver configured to receive and process the radio transmission according to a receiver crystal oscillator frequency; a processing element configured to calculate a signal integrity for a received radio transmission; and a frequency offset circuit configured to generate an offset carrier-based operating frequency of the radio transmitter according to the calculated signal integrity, wherein the frequency offset circuit comprises an accumulator circuit, and wherein an overflow rate of the accumulator circuit represents the offset carrier-based operating frequency of the radio transmitter. - View Dependent Claims (17, 18, 19)
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Specification