The impacts of beat noise,multi-access interference ( MAI),shot noise and thermal noise in coherent OCDMA are studied in this paper.

The impact of optical beat interference on the performances of optical fast frequency hopping CDMA networks was analyzed.

Multiple-access interference(MAI) and beat noise(BN) in coherent time-spreading optical code-division multiple access(OCDMA) system are analyzed according to aperiodic cross-correlation function.

The concept of self beat noise induced by inter symbol interference(ISI) is proposed.

In this thesis, we investigate an OSNR monitoring using receiving electrical beat noise , First we reviewed several OSNR monitoring techniques and explored the OSNR monitoring technique using electrical beat noise measurement at the low frequencies where no signal is present.

Then the supersonic ejector is used,the high frequency noise will take place when the pressure in store tanks decreases to a specific value,and the environment of .

Besides, the influence of receiving condition upon data acquisition are studied by analysing geophone and its coupling to ground, and the effect of high frequency noise on data acquisition is a.

In order to prevent the high frequency noise interference from high voltage direct current (HVDC) converter to power line carrier (PLC) communication, the conventional method is that PLC noise filters are installed both on AC and DC sides of a converter, but sometimes, PLC noise filter faults caused the HVDC outages.