Digital emulation of non-linear and linear distortions caused by Analog/RF devices involved in wireless transmissions.

Background:
By nature, Analog/RF devices are not perfect and show both non-linear distortions in time domain (amplitude and phase of output signal are not exactly following amplitude and phase of input signal) and linear distortions in frequency domain (amplitude and phase frequency response is not perfect).

Such imperfect characteristics constitute a limiting factor to wireless digital transmission systems performances. However, the influence and acceptable limits for those distortion effects are quite difficult to quantify in practise since real Analog/RF devices characteristics cannot simply be tuned on demand for such test purposes.

This is why a digital system capable of emulating and generating adjustable/calibrated distortion effects is of prime interest to quantify digital transmission systems requirements in terms of Analog/RF devices performances and quality.

Objectives:
Objectives

The project consists in developing a real-time digital processing solution which can be inserted between a transmitter and a receiver at baseband level in order to simulate the non-linear and linear distortion effects of various Analog/RF devices (amplifiers, filters, antennas, etc.) having influence on transmission.

A first step is to develop an off-line PC software enabling to create AM-AM (Amplitude-to-Amplitude) and AM-PM (Amplitude-to-Phase) non-linear response curves in time domain through interpolation from user set of points.

A second step is to implement real-time corresponding non-linear distortion block as real/imaginary processing and LUTs (Look-Up-Tables) on an hardware FPGA-based (programmable component) platform.

A third step is to develop an off-line PC software enabling to create amplitude and phase linear response curves in frequency domain, still through interpolation from user points.

A fourth step is to implement real-time corresponding linear distortion block as a parametrizable FIR filter on the hardware platform.

Deliverables:
- Visual C++ modules with graphic user-interface for response curves capture, LUTs coefficients generation and FIR filter coefficients calculation.
- VHDL modules for real-time distortion blocks implementation.
- Final project report (diploma report).