Normalization methods for automatic requency compensation in bluetooth applications
AssigneeAgere Systems Inc.
InventorsWenzhe Luo, Zhigang Ma
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Abstract
An improved automatic frequency compensation (AFC) technique and apparatus is provided for piconet applications, e.g., BLUETOOTH™ applications. In particular, the present invention provides an offset normalizer which normalizes frequency offset against maximum deviations. By normalizing the frequency offset, before determination of an adjustment of a local oscillator, the local oscillator adjustment becomes uncorrelated with respect to gain along the receiving path (including in a demodulator). Thus, extremely precise adjustments can be made to the local oscillator in a piconet device to provide extremely precise automatic frequency compensation.
Claims16
An automatic frequency compensation circuit for a local oscillator, comprising:
- an analog-to-digital converter to digitize a demodulated signal;
- a digital peak detector to determine a maximum positive peak in said demodulated signal and a maximum negative peak in said demodulated signal;
- and
- an offset normalizer to normalize said maximum positive peak and said maximum negative peak, and to provide a signal to control a local oscillator in correspondence with a determined frequency offset;
- whereby frequency offset control of said local oscillator is attained without sensitivity to variable receive gains.
A method for controlling a local oscillator, comprising:
- demodulating a received RF signal;
- determining a maximum positive peak value and a maximum negative peak value in said received RF signal;
- correlating said maximum positive peak value and said maximum negative peak value with a particular normalized frequency offset;
- and
- controlling said local oscillator based on said correlation.
Apparatus for controlling a local oscillator, comprising:
- means for demodulating a received RF signal;
- means for determining a maximum positive peak value and a maximum negative peak value in said received RF signal;
- means for correlating said maximum positive peak value and said maximum negative peak value with a particular normalized frequency offset;
- and
- means for controlling said local oscillator based on said correlation.
Dependencies are inferred from the claim text.