نتایج جستجو برای: شبکه fft
تعداد نتایج: 41640 فیلتر نتایج به سال:
یکی از مهم ترین مشکلات سیستم های ofdm عدم توانایی این سیستم ها در حذف سیگنال تداخل در باند فرکانسی سیگنال مطلوب می باشد. برای حذف این تداخلات از روش های شکل دهی پرتو استفاده می شود. دو روش مرسوم شکل دهی پرتو، روش pre-fft (شکل دهی پرتو در حوزه زمان) و روش post-fft (شکل دهی پرتو در حوزه فرکانس) می باشند. برای به روزرسانی وزن ها در هر دو روش راه حل های مختلفی پیشنهاد شده است که می توان همه آن ها ر...
A radix-16 fast Fourier transform (FFT) algorithm suitable for multiply-add instruction is proposed. The proposed radix-16 FFT algorithm requires fewer floating-point instructions than the conventional radix-16 FFT algorithm on processors that have a multiplyadd instruction. Moreover, this algorithm has the advantage of fewer loads and stores than either the radix-2, 4 and 8 FFT algorithms or t...
OBJECTIVE To investigate the effects of frontal facial type (FFT) and sex on preferred chin projection (CP) in three-dimensional (3D) facial images. METHODS Six 3D facial images were acquired using a 3D facial scanner (euryprosopic [Eury-FFT], mesoprosopic [Meso-FFT], and leptoprosopic [Lepto-FFT] for each sex). After normal CP in each 3D facial image was set to 10° of the facial profile angl...
The FFT processor is a critical block in all multi-carrier systems used primarily in the mobile environment. The portability requirement of these systems is mainly responsible for the need of low power FFT architectures. In this study, an efficient addressing scheme for radix-4 64 point FFT processor is presented. It avoids the modulo-r addition in the address generation; hence, the critical pa...
The original Cooley-Tukey FFT was published in 1965 and presented for sequences with length N equal to a power of two. However, in the same paper they noted that their algorithm could be generalized to composite N in which the length of the sequence was a product of small primes. In 1967, Bergland presented an algorithm for composite N and variants of his mixed radix FFT are currently in wide u...
in this study, an intelligent system for sorting closed shell and open shell pistachio nuts, was designed and developed based on combined acoustic and artificial neural network (ann) techniques. the system included a microphone, pc, material handling equipment and an air reject pneumatic mechanism. the microphone, placed under the steel plate, received sound signals generated by the pistachio n...
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In digital signal processing applications, we usually use DFT (discrete Fourier transform) to transfer signal from time-domain to frequency-domain. In past decades, there were many papers discussing and exploiting FFT (fast Fourier transform) architectures for hardware implementation. In this paper, we proposed a novel VLSI FFT processor based on parallel-pipelined constant geometry algorithm (...
A parallel and pipelined Fast Fourier Transform (FFT) processor for use in the Orthogonal Frequency division Multiplexer (OFDM) and WLAN, unlike being stored in the traditional ROM. The twiddle factors in our pipelined FFT processor can be accessed directly. A novel simple address mapping scheme and the modified radix 4 FFT also proposed. FPGA was majorly used to develop the ASIC IC’s to which ...
This paper describes in detail the design of a CMOS custom fast Fourier transform (FFT) processor for computing a 256-point complex FFT. The FFT is well-suited for realtime spectrum analysis in instrumentation and measurement applications. The FFT butterfly processor reported here consists of one parallel–parallel multiplier and two adders. It is capable of computing one butterfly computation e...
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