DEVELOPMENT AND TESTING OF A LOW POWERED COST-EFFECTIVE FREQUENCY MODULATOR FOR APPLICATIONS IN RF TRANSMISSION

Abstract

In this thesis the frequency modulation for different types of modulating circuits was studied and a low-powered, cost-effective modulator was developed. By changing the wave's instantaneous frequency, information is encoded in a carrier wave using frequency modulation. The technology is utilized in computing, signal processing, radio broadcasting, navigation and telecommunications. Three modulating circuits were designed and developed for the study. The performance of Triangular Modulating Circuit, Sawtooth Modulating Circuit and Sinusoidal Modulating Circuit was studied and analyzed in terms of message transmission. To validate the proposed modulating circuit, its performance was compared with MATLAB script, Simulink model and Python script. Its performance was also compared with the modulation done by existing model “EMONA Telecoms- Trainer 101” present at Electrical, Electronic and Communication Engineering lab of MIST. Results of the analysis show that if the modulation is linear, the frequency change is directly proportional to the modulating voltage's amplitude. Parameters of the modulated signal when used in MATLAB, Python and Simulink gave the same modulated signals that validates the modulation done by the proposed circuits. The proposed modulating circuits generate signal with very less noise at the desired voltage level which also matches the performance capacity of microwave VCOs. And so, it can be used effectively to develop a low cost FMCW Radar. The proposed modulating circuits can be used in telemetry, video broadcasting and recording, sound synthesis, medicine, navigation, aviation, radar, analog and digital data transmission and many other fields to a further extent