| || Software-based Solution for Analysis and Decoding of FSK-2 Modulated, Baudot-coded Signals
Author : Malhotra, Mukesh;Gupta, Neena;Prasad, R.S.
Source : Defence Science Journal ; Vol:56(2) ; 2006 ; pp 259-268
Subject : 681.3:355 Computer Applications in Defence;681.3 Computer Science
Keywords : Frequency shift keying;Fast Fourier transform;Autocorrelation;Sliding window;Hopping window;FSK;FFT
Abstract : In the present-day scenario, digital communication has become predominant choice over analog communication worldwide. Digital modulation schemes form the main block of the digital communication. Among these, frequency shift keying (FSK-2) is a widely used technique employed for Baudot-coded english text transmission. A Baudot-coded-FSK-2 modulated signal was simulated corresponding to an english text file. A technique has been developed for its analysis and decoding in the MATLAB environment. This technique does the signal analysis, its parameter extraction, and then digital demodulation, to retrieve its corresponding composite bit-stream. An efficient method for edge detection using the number of zero-crossings has been devised and implemented successfully. From the composite bit-stream, overhead bits were removed and decoding was performed to get back the text output.
| || Hardware Realization of a General Purpose FFT Processor in a Distributed Processing Configuration
Author : Veerabhadriah, S. ;Dhurkadas, A.;Govardhanarajan, T.S.;Ganesan, K.
Source : Defence Science Journal ; Vol:32(1) ; 1982 ; pp 41-46
Subject : 681.3 Computer Science
Keywords : INTEL ;FFT;Hardware
Abstract : An efficient hardware implementation of a 1024-point sequential FFT processor is described. The processor has been configured in a distributed processing system with an INTEL 8086 microprocessor. In case of real signals, it performs a 1024-point transform of two real signals, simultaneously within the same period and subsequently does spectral separation 2.6 msec. Its general purpose capability and the case of interfacing it with standard mini/micro computers are highlighted with a specific illustrations using the INTEL 8086 microprocessor.