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.
Highlights
The development of programmable and reconfigurable devices has triggered the use of digital communication techniques in modern communication systems
We are going to overcome this challenge, focus some of the research activity to carry out the implementation of digital modulators such as Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), Phase Shift Keying (PSK) and other digital modulators using Programmable Logic Devices
The register transfer level (RTL) schematic of proposed ASK and QAM modulators are shown in Figure 7 and Figure 8 respectively
Summary
The development of programmable and reconfigurable devices has triggered the use of digital communication techniques in modern communication systems. Joseph Mitola [1,2,3] was the first researcher who introduced the concept of radio-defined software by allowing the implementation of the radio (transceivers) programmable and reconfigurable. This technique is cost effective and presents some advantages like resistivity to the impairments, encryption, security, noise immunity, source coding, multiplexing of video, equalization, error detection and correction. The work of Quadri and Tete [4] presents a summary of some research papers using Xilinx System Generator to implement digital modulator.
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