A loss budget is a predetermined amount of allowed loss, in decibels (dB), for a given fiber optic installation. Losses can be attributed to several factors, including insertion loss due to connectorization, attenuation due to cable length, splicing of cables, and other factors. Loss budgets are used to ensure that the total losses in a fiber optic network remain within acceptable parameters and thus ensure that the network is reliable and performs as expected.
Insertion loss is the amount of energy lost when a signal is transferred through a connector or splice. It is usually expressed as a dB value and is a function of the type of connector used, the quality of the connection, and the frequency of the signal. Attenuation is the amount of signal loss due to the length of the cable. This type of loss is typically expressed in dB/km (decibels per kilometer). Attenuation is a function of the type of cable and the wavelength of the signal.
When designing a fiber optic network, it is important to calculate the total losses due to both insertion loss and attenuation. The sum of these losses should not exceed the predetermined loss budget. If it does, it indicates that the network is not designed optimally and could be improved upon. This could be done by reducing the number of connectors, or by using a different type of cable or connector.
In summary, the loss budget is a predetermined amount of allowed loss, in dB, for a given fiber optic installation. It is used to ensure that the total losses remain within acceptable parameters and that the overall performance of the network is as expected. Properly calculating the total losses due to insertion loss and attenuation, and then staying within the loss budget, is key to a successful fiber optic network.