Background noise in optical communication systems

Atmospheric Optical Communication Systems.

“…We emphasize inclusion of preamtplifter noise since Lu some Instances a detection system may be pre2mplL:1er-woise limiIted, anm noise ealcubations must account for total system noise and not only those sources arising fromn the photodetector ItseIl ()The exteraly induced woise components '.If and ';b are given by r2 -G q2XAc)p 5 F3RL 28 Ns~b 2.Sb where P, refers to either signal power P. averaged over a period 1/13 or backgr-rnnd power N.-F Is an excess noise factor accounting for noise inclaed by the mechanir-m providing the gain G; and B is the electrical bandwidth of the detection system. "Me bmc~rond owe 9 bmay arise from re-flected. or scantered solar radiation from the terrain.…”

“…UNCLASSIFIED ()Tnteral system noise due to dark current id is Oven by .1d = 2qGrB"" (2)(3)(4)(5)(6)(7)(8)(9) Dark current is due to detecor biasing in some instances, and in somue instances it is caused by thermal radiation incident on the phowdetecwar from deector enclosure surtames (usually mi-fzed by cryoenic cooling). Thermual (Johnson) Doise is given by Nt = 4kT3 (2)(3)(4)(5)(6)(7)(8)(9)(10) where k is Bol~ann's coostn± and T the effective detection-systezu temperamre.…”

“…Thermual (Johnson) Doise is given by Nt = 4kT3 (2)(3)(4)(5)(6)(7)(8)(9)(10) where k is Bol~ann's coostn± and T the effective detection-systezu temperamre.…”

“…Using (2 -4) - (2)(3)(4)(5)(6)(7)(8)(9)(10) and (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), an overall signal-to-noise raztn (SNZ can be speciled in the relatively simple form…”

“…brm which (S % T)/N can be speied, i.e., + 1 (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) The iipeciftcation of the oacal. power P in (2-1.3) depends on whetber link detecto-acise ratio is the sigal quantity of ifteret 4 and P corr-spauLds to the average cu'±cal power duin the peelod I/B repardess mf rho tmodulaion, type.…”