Investigation of Methods to Detect Weak Signals under Noisy Environment

Chai, Tian Chi (2023) Investigation of Methods to Detect Weak Signals under Noisy Environment. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

The presence of electrical noise has always been a problem in instrumentation and transmission/reception of signals. Noise not only reduces the resolution of an instrument/equipment, it can also reduce the transmission and reception range of a signal or diminish the speed of data transfer. The situation gets even worse when the signal is weak compared to the noise. Methods of reducing noise do exist in instrumentation and transmission/reception of signals. Unfortunately, the various methods of detecting weak signals under noisy environments are not well studied comparatively. Hence, in this project the aim is to investigate four methods of detecting weak signals under noisy environments. The four methods are, using a differential amplifier, step-up transformer, narrow band-pass filter and phase locked loop. Each method is expected to yield a different level of performance and possess different limitations. Lastly, the objective of the research is to investigate the best method of noise reduction in a noisy environment and compare the advantages and disadvantages of the four methods of noise reduction in a noisy environment. After several experiments, the advantage of a differential amplifier method is immunity to external noise in a dynamic range of 6dB and it can apply to both AC and DC voltage detection. The advantage of the step-up transformer method is it will not produce significant thermal noise which is also known as Johnson noise. The narrow band-pass filter is handy and effective for amplifying a single frequency. Finally, the phase locked loop is the most reliable and stable method of removing noise from the signal.