Variable length FFT system and method
AssigneeMediatek Inc.
InventorsJhih-siang Jhang, Jui-Ming Wei, Ming-hung Li
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Abstract
A variable length fast Fourier transform (FFT) system and a method for performing the FFT system in a global navigation satellite system (GNSS) signal acquisition and tracking, which includes a memory and a number of processing elements are disclosed. Based on the GNSS signal tracking, the variable length FFT system performs a first FFT operation together with a first data length. Based on the GNSS signal acquisition, the variable length FFT system is divided into several FFT subsystems to simultaneously perform different operations with various data lengths different from the first data length. Thus, the variable length FFT system can enhance the hardware utility and increase throughputs.
Claims29
A variable length fast Fourier transform (FFT) system, comprising:
- a plurality of cascaded butterfly stages, each containing at least one of processing elements;
- at least one divide switch for dividing the connection of said processing elements or said cascaded butterfly stages according to a bypassing signal to perform either a first data length FFT operation, or a second data length FFT operation, wherein the second data length is shorter than the first data length;
- a mode switch for generating the bypassing signal and a control signal depended on requirements of different data lengths for different FFT operation modes;
- and
- at least one multiplexer which is selectively switched by different levels of the control signal from the mode switch to output either of two different kinds of twiddle factors to a corresponding multiplier interposing between the neighboring butterfly stages for generating a twiddle factor multiplication product.
A method for performing a variable length fast Fourier transform (FFT) system with a plurality of cascaded butterfly stages each containing at least one of processing elements, comprising the following step:
- generating a bypassing signal, based on a requirement of different data length FFT operations;
- dividing a connection between said processing elements or said cascaded butterfly stages according to the bypassing signal, to perform either a first data length FFT operation or a second data length FFT operation, wherein the second data length is shorter than the first data length;
- generating a control signal depended on requirements of different data lengths for different FFT operation modes;
- and
- selectively switching at least one multiplexer by different levels of the control signal to output either of two different kinds of twiddle factors to a corresponding multiplier interposing between the neighboring butterfly stages for generating a twiddle factor multiplication product.
A variable length fast Fourier transform (FFT) system, comprising:
- a plurality of cascaded butterfly stages, each containing a plurality of processing elements;
- and
- at least one divide switch for dividing the connection of said processing elements according to a bypassing signal to perform either a first data length FFT operation, or a second data length FFT operation, wherein the second data length is shorter than the first data length.
A method for performing a variable length fast Fourier transform (FFT) system with a plurality cascaded butterfly stages each containing a plurality of processing elements, comprising the following step:
- generating a bypassing signal, based on a requirement of different data length FFT operations;
- and
- dividing a connection between said processing elements according to the bypassing signal, to perform either a first data length FFT operation or a second data length FFT operation, wherein the second data length is shorter than the first data length.
Dependencies are inferred from the claim text.