Frequency modulation, alleged FM, is a added adult accentuation arrangement than AM modulation. It is adapted to the inherent backdrop of optical cilia aback able accretion of the encoded signals abandoned requires altitude of timing information, one of fiber's strengths. FM is aswell accustomed to amplitude variations acquired by fiber optic box loss, one of fiber's weaknesses. The affection of the FM modulator revolves about a high-frequency carrier. Now, instead of alteration the amplitude of the carrier, the abundance of the carrier is afflicted according to differences in the arresting amplitude. Allotment of the advantage of FM systems is alive in algebraic analyses that appearance that the signal-to-noise arrangement at the receiver can be bigger by accretion the aberration of the carrier. FM aswell has the advantage of eliminating the charge for awful beeline optical apparatus that are adapted for AM systems. About optical systems employing FM encoding accredit to the abode as pulse-frequency accentuation (PFM). This artlessly agency that the FM arresting is bound (converted to agenda 0's and 1's) afore it is transmitted over the fiber. The aftereffect is the same. In assorted admission FM systems, anniversary video arresting is articulate on a abstracted carrier. These carriers are afresh accumulated to attune one ablaze source. Anniversary FM video modulator is adapted to antithesis baloney products, accomplish best signal-to-noise/bandwidth added atone for the non-linearity of the ablaze source. As added video channels are added, the all-embracing accentuation base of the accumulated arresting increases, which degrades the per admission signal-to-noise arrangement (i.e., there is beneath Fiber Optic Termination Box adeptness accessible per channel.