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ABSTRACT
The modern communication systems and software radio based applications demands fully digital receivers, consisting of only an antenna and a fully programmable circuit with digital modulators and demodulators. A basic communication system's transmitter modulates the amplitude, phase or frequency proportional to the signal being transmitted. The revolutions which are coming up in mobile phones are mainly because of usage of SDR (software defined radio) principles. In all communication algorithms we need the carrier. The traditional techniques of analog implementation of carrier and reading its digital value in processor have several limitations. Instead it is possible to generate the carrier on the microcontroller directly by using few algorithms. This paper involves implementation of CORDIC (Co-ordinate Rotation Digital Computer) algorithm on ARM controller for generating high carrier frequency. An efficient solution (that doesn't require large tables/memory) for realizing a carrier source is CORDIC algorithm Finally the generation of SIN and COS output values will are tested for a given input angle (θ) value. The universal modulator will be designed around the CORDIC algorithms which can generate all most all digital modulation schemes such as ASK, PSK, FSK, QPSK. The GNU tool chain will be used to build the application.
KEYWORDS: CORDIC, ASK, PSK, FSK, ARM7.
(ProQuest: ... denotes formulae omitted.)
I. INTRODUCTION TO CORDIC
Carrier signal plays a key role in all communication algorithms. The traditional techniques of analog implementation of carrier and reading its digital value in processor have several limitations. Instead, it is possible to generate the carrier on the microcontroller directly by using an algorithm called CORDIC [2], CORDIC means "Coordinate Rotation Digital Computer" algorithm which avoids the use of function generator which generates a carrier or different wave forms like sine wave, triangular wave, square wave etc. By using CORDIC algorithm, the digital modulation techniques can also be implemented like ASK, FSK, PSK, and QPSK. A carrier generator is generated by using CORDIC algorithm for digital modulation techniques by avoiding hardware complexity at very less power. A constraint low power can be obtained by using ARM7 processor. So by dumping the code into ARM7 processor, generation of a carrier waveform for digital modulation techniques takes place depending on the input given by the user on the control word which is written...