Hardware Implementation of Amplitude Shift Keying and Quadrature Amplitude Modulators Using FPGA

Abstract

In our paper, we present the implementation of two kinds of FPGA-based modulators: ASK and QAM signal modulators. The ASK modulators we implemented are OOK, ASK, and 4ASK, then the QAM modulators implemented are 4QAM and 16QAM. The generation of the sine wave carrier is the main task when implementing any digital transmitter including ASK and QAM modulators. For us to implement these modulators, a sine function with floating-point operation as per IEEE754 standards is used based on Hardware Description Language technique. When the carrier is generated, the digital message modulates the amplitude of the carrier. To implement the QAM modulator, we need two sinusoidal carriers. A cosine function and a sine function are built to get the two carriers. Alongside to this work, ASK and QAM signal modulators are implemented using 26-bit phase accumulator and Look Up Table to generate the sine and cosine functions, then comparison of speed, occupied area and estimated power consume are done with the proposed modulators. Without using DSP builder tools or an Altera system generator, we implemented the whole systems using VHDL on cyclone IV-E-EP4CE115F29C7N of the board DE2-115. In general, the proposed modulator design present low area and power consummation than modulator using LUT or CORDIC.