optical loss budget (OLB)
The attenuation budget (OLB) applies equally to wireline transmission systems with metallic conductors and optical conductors, as well as to wireless high- frequency transmission. The calculation of the attenuation budget is used to determine all existing level values in a transmission system, specifically the power budget, to determine the receive level present at the receiver.
In an optical fiber transmission system, the attenuation budget, also referred to as the optical loss budget (OLB), is composed of the difference between the coupled transmit power and the limiting sensitivity of the optical receiver. This value is the available attenuation budget and is set in relation to the total link attenuation, which is the sum of all losses occurring between source and sink.
In particular, the following must be taken into account: the coupling losses of the laser diode or the light-emitting diode, the added attenuation of all the optical fibers used between the transmitter and the receiver, and the attenuations of all the plug connections and splices. If these values exceed the available attenuation budget, appropriate measures must be taken, for example in the form of active components.
The budget is calculated by adding and subtracting the dB values for the gain and attenuation of the individual components. Example: An amplifier has an input signal of -2 dBm and the gain is 8 dB, then the output level of the amplifier is 6 dBm.