Advantages of the One-Jumper Reference Method 15 July The Advantages of the One-Jumper Reference Method Over the Two-Jumper Reference Method when Measuring Link Insertion Loss

Advantages of the One-Jumper Reference Method 15 July Why is the One-Jumper Reference Method So Important? It is specified in TIA-568 and ISO It eliminates the insertion loss measurement error of about 0.5 dB caused by the two-jumper method. Insertion loss measurement accuracy is critical when certifying multimode Gigabit Ethernet links, which have maximum channel loss requirements of only 3.2 to 4.0 dB.

Advantages of the One-Jumper Reference Method 15 July An optical fiber link comprises one (or more) sections of fiber plus an input and an output connection. Input Connection Output Connection Network Equipment Link Optical Fiber * * May comprise multiple fiber sections joined by other connections and splices.

Advantages of the One-Jumper Reference Method 15 July Measured optical fiber link insertion loss* must include the loss of both the input and output connections. Input Connection (0.5 dB) Output Connection (0.5 dB) Network Equipment Link Insertion Loss = 3.0 dB Optical Fiber (2.0 dB) * Insertion loss will be shortened to simply “loss” for the rest of the presentation.

Advantages of the One-Jumper Reference Method 15 July To measure link loss you need to know the power entering the near-end connection (P IN ) and exiting of the far-end connection (P OUT ). P IN (dBm) P OUT (dBm) Loss (dB) = P IN (dBm) – P OUT (dBm) Input patch cord or test jumper Output patch cord or test jumper Link

Advantages of the One-Jumper Reference Method 15 July Example: P IN = -20 dBm P OUT = -23 dBm Loss = -20 dBm - (-23 dBm) = 3.0 dB Link under test Light Source Optical Power Meter (in dB loss mode) 3.0 dB

Advantages of the One-Jumper Reference Method 15 July When making a link loss measurement, P IN is the output of the light source jumper Link under test Light Source P IN = -20 dBm

Advantages of the One-Jumper Reference Method 15 July Light Source Optical Power Meter (set reference mode) - 20 dBm The transmit jumper has negligible loss. Using the one-jumper method, the reference level stored by the power meter is P IN. There is no loss at the power meter detector. Therefore, the reference level stored by the power meter is P IN. REF

Advantages of the One-Jumper Reference Method 15 July So measured loss is correct ! P IN = -20 dBm P OUT = -23 dBm Measured Loss = -20 dBm - (-23 dBm) = 3.0 dB Link under test Light Source Optical Power Meter (dB loss mode) 3.0 dB

Advantages of the One-Jumper Reference Method 15 July But using the two-jumper method the reference level stored by the power meter is P IN minus the loss of one connection. Reference level stored by the power meter is P IN minus 0.5 dB. Light Source Optical Power Meter (set reference mode) dBm REF One connection loss (about 0.5 dB)

Advantages of the One-Jumper Reference Method 15 July So measured loss is understated by one connection loss or about 0.5 dB. P OUT = -23 dBm Measured Loss = dBm - (-23 dBm) = 2.5 dB  Link under test Light Source Optical Power Meter (dB loss mode) 2.5 dB But the power meter reference level is dBm! P IN = -20 dBm

Advantages of the One-Jumper Reference Method 15 July Measured loss should be less than or equal to the typical loss of one connection, as specified by the connector manufacturer. Light Source Optical Power Meter (dB loss mode) 0.5 dB One Final Point: After you have referenced your power meter and light source using the one- jumper method, you should always check the receive and transmit jumpers before making loss measurements, as shown below: Transmit Jumper Receive Jumper Adapter

Advantages of the One-Jumper Reference Method 15 July Summary of One Jumper Method 1.Attach the transmit jumper to the light source. 2.Connect the free-end of the transmit jumper to the optical power meter. 3.Remove the free-end of the transmit jumper from power meter without disturbing the end connected to the light source. 4.Attach the receive jumper to the power meter. You may change the adapter cap on the power meter at this point to accommodate the connector type on the receive jumper. 5.Connect the transmit and receive jumpers using a mating adapter. 6.Verify that loss is less than the typical loss of one connection. 7.Keeping the transmit jumper attached to light source and receive jumper attached to power meter, you can now measure insertion loss. 8.Re-reference your light source and power meter about once per day.