4-10
Extech Reporter
UNIT 4
Splice Loss
Definition: during the calculation of an optical loss budget, the amount of optical loss attributed to splices
in the link under test. Splice loss is specified by cabling standards that base link budget calculation on the
passive components of the link under test; examples of this type of standard are the TIA-568 and the ISO
IEC 11801. Splices can be either mechanical or fusion, and can be located anywhere along the link under
test.
Units: dB per splice
Calculation: (number of splices) x (dB loss per splice)
Patch
Panel
Link Under Test
Patch
Panel
Splice
NOTE: some connectors use mechanical
splice technology for fiber termination,
®
such as the Unicam -compatible. These
connectors should be considered splices
when calculating optical loss budgets.
System Overhead
Definition: the difference between the Measured Power and the Minimum Required Power. System
Overhead is also known as headroom. With a PASS rating, System Overhead shows how much
additional loss a link can bear before it will fail. With a FAIL rating, System Overhead shows how much
optical loss must be overcome before it will pass.
Units: dB
Calculation: (Measured Power) - (Minimum Required Power)
Total Allowable System Loss
Light
Source
Reference
Power (dBm)
INVALID
OPERATING
MARGIN **
Minimum
Required
Power (dBm)
Measured
Power (dBm)
PASS
Optical Loss
FAIL
OPERATING MARGIN
or
SYSTEM OVERHEAD
Interpreting Extech Reporter Screens and Reports, cont.
