Investigating noise performance in direct conversion receiver system using Matlab simulink / Nor Hasnifarina Jamadin

Noise is very crucial problem in communication system for data transmission and reception of original signal. Predicting noise performance of RF system is much more complex than for linear ones. Noise which is generated either within the component of the devices can also cause distortion and interference for the system. This paper investigates about noise performance on Direct Conversion Receiver (DCR) system with injected external noise. Naturally, DCR has internal noise in the system. DCR is architecture of choice in most modern receiver because of high level integration and accommodating multi standard radio platform at lower cost. For DCR system, MATLAB simulation is used and the result was obtained in specification for Industrial, scientific and medical (ISM) band frequency. External noise is injected to the system and simulated using MATLAB simulink. The result was specified using bit error rate (BER), scatter plot and spectrum analyzer signal. The suitable filter is investigated and designed to reduce noise that affects the whole DCR system. The most suitable filter for the reduction external noise in DCR system is Butterworth low pass filter. Moreover, by using this filter the receive signal is recovered back approximately the same with transmitted signal. It was also noted that less data error in BER. However, for the scatter plot, suitable software is to be identified to display the scatter plot of the demodulated data.