Method and apparatus for correcting frequency offset and storage medium storing control program therefor

An apparatus for correcting frequency offset of a local oscillator in a direct sequence spread spectrum receiver wherein received signals include a plurality of sequential slots of data, at least one of which includes synchronization data, said apparatus comprising:

• means for performing a first correlation between said received data and a locally stored synchronization code;
• means for adjusting the phase of said received data by a predetermined phase step;
• means for performing a second correlation between said phase adjusted data and said stored synchronization code;
• means for determining the largest correlation peak in each of said first and second correlations;
• means for storing a signal corresponding to said largest correlation peak;
• means for estimating the phase offset to be applied to said local oscillator from said signal;
• and
• means for applying said estimated offset to said local oscillator.

A storage medium storing a control program to cause a computer to carry out a method for correcting frequency offset of a local oscillator in a direct sequence spread spectrum receiver wherein received signals include a plurality of sequential slots of data, at least one of which includes synchronization data, said method comprising the steps of:

• performing a first correlation between said received data and a locally stored synchronization code;
• adjusting the phase of said received data by a predetermined phase step;
• performing a second correlation between said phase adjusted data and said stored synchronization code;
• determining which of said first and second correlations gives the largest correlation peak;
• storing a signal corresponding to said largest correlation peak;
• estimating the phase offset to be applied to said local oscillator from said signal;
• and
• applying said estimated offset to said local oscillator.