Method and Apparatus for Calculating an N-Point Discrete Fourier Transform

An apparatus for calculating an N-point discrete Fourier transform having first input configured to receive an even quadrature sample value and an even Phase sample value in a sample period and a second input configured to receive an odd quadrature sample value and an odd phase sample value in a sample period, comprising:

• a) a counter to count the sample periods;
• b) an even sample value scaling circuit having a selectable even scaling factor;
• c) an odd sample value sealing circuit having a selectable odd scaling factor;
• d) an adder to sum the sealed even and odd quadrature sample values;
• e) an adder to sum the scaled even and odd phase sample values;
• f) an accumulator to accumulate the summed even and odd quadrature sample values;
• and
• g) an accumulator to accumulate the summed even and odd phase sample values;
• wherein N is selectable and is either 3 or 4, the even and odd scaling factors are selectable based upon the value of N and the value of the sample period count, and wherein when N is set to 3, the counter counts 3 sample periods, and wherein when N is set to 4, the counter counts 2 sample periods.

A method of calculating an N-point discrete Fourier transform, the method comprising:

• generating, by a quantizer based on a received signal, an even quadrature sample value and an even phase sample value of the received signal, and an odd quadrature sample value and an odd phase sample value of the received signal in a sample period of the quantizer;
• counting, by a counter, a number of sample periods of the quantizer;
• scaling, by at least one scaling circuit, the even quadrature sample value, even phase sample value the odd quadrature sample value, and the odd phase sample value by at least one sealing factor;
• adding, by a first adding circuit, the scaled even quadrature sample value and the scaled odd quadrature sample value;
• adding, by a second adding circuit, the scaled even phase sample value and the scaled odd phase sample value;
• accumulating, by a first accumulator, the added scaled even and odd quadrature sample values;
• accumulating, by a second accumulator, the added scaled even and odd phase sample values;
• wherein N is selectable and is either 3 or 4, the at least one scaling factor is selectable based upon the value of N and the number of sample periods, and wherein when N is set to 3, the counter counts 3 sample periods, and wherein when N is set to 4, the counter counts 2 sample periods.