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Why is the One-Jumper Reference Method So Important?

The Advantages of the One-Jumper Reference Method Over the Two-Jumper Reference Method when Measuring Link Insertion Loss. Why is the One-Jumper Reference Method So Important?. It is specified in TIA-568 and ISO 11801.

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Why is the One-Jumper Reference Method So Important?

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  1. 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 2000

  2. Why is the One-Jumper Reference Method So Important? • It is specified in TIA-568 and ISO 11801. • 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 2000

  3. An optical fiber link comprises one (or more) sections of fiber plus an input and an output connection. Link NetworkEquipment NetworkEquipment Optical Fiber * InputConnection OutputConnection * May comprise multiple fiber sections joined by other connections and splices. Advantages of the One-Jumper Reference Method 15 July 2000

  4. Measured optical fiber link insertion loss* must include the loss of both the input and output connections. Link Insertion Loss = 3.0 dB NetworkEquipment NetworkEquipment Optical Fiber(2.0 dB) InputConnection(0.5 dB) OutputConnection(0.5 dB) * Insertion loss will be shortened to simply “loss” for the rest of the presentation. Advantages of the One-Jumper Reference Method 15 July 2000

  5. To measure link loss you need to know the power entering the near-end connection (PIN) and exiting of the far-end connection (POUT). Link PIN(dBm) POUT(dBm) Input patch cordor test jumper Output patch cordor test jumper Loss (dB) = PIN (dBm) – POUT (dBm) Advantages of the One-Jumper Reference Method 15 July 2000

  6. Link under test Optical Power Meter(in dB loss mode) Light Source Example: POUT =-23 dBm PIN =-20 dBm 3.0 dB Loss = -20 dBm - (-23 dBm) = 3.0 dB Advantages of the One-Jumper Reference Method 15 July 2000

  7. Light Source When making a link loss measurement, PIN is the output of the light source jumper PIN = -20 dBm Link under test Advantages of the One-Jumper Reference Method 15 July 2000

  8. Using the one-jumper method, the reference level stored by the power meter is PIN. The transmit jumper has negligible loss. There is no loss at the power meter detector. Therefore, the reference level stored by the power meter is PIN. - 20dBm REF Light Source Optical Power Meter(set reference mode) Advantages of the One-Jumper Reference Method 15 July 2000

  9. Link under test Optical Power Meter(dB loss mode) Light Source So measured loss is correct ! POUT =-23 dBm PIN =-20 dBm 3.0 dB Measured Loss = -20 dBm - (-23 dBm) = 3.0 dB Advantages of the One-Jumper Reference Method 15 July 2000

  10. But using the two-jumper method the reference level stored by the power meter is PINminus the loss of one connection. One connection loss(about 0.5 dB) Reference level stored by the power meter is PIN minus 0.5 dB. - 20.5dBm REF Light Source Optical Power Meter(set reference mode) Advantages of the One-Jumper Reference Method 15 July 2000

  11. Link under test Optical Power Meter(dB loss mode) Light Source So measured loss is understated by one connection loss or about 0.5 dB. POUT = -23 dBm PIN = -20 dBm But the power meter reference level is -20.5 dBm! 2.5 dB Measured Loss = -20.5 dBm - (-23 dBm) = 2.5 dB  Advantages of the One-Jumper Reference Method 15 July 2000

  12. 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: Adapter Measured loss should be less than or equal to the typical loss of one connection, as specified by the connector manufacturer. TransmitJumper ReceiveJumper 0.5 dB Light Source Optical Power Meter(dB loss mode) Advantages of the One-Jumper Reference Method 15 July 2000

  13. Summary of One Jumper Method • Attach the transmit jumper to the light source. • Connect the free-end of the transmit jumper to the optical power meter. • Remove the free-end of the transmit jumper from power meter without disturbing the end connected to the light source. • 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. • Connect the transmit and receive jumpers using a mating adapter. • Verify that loss is less than the typical loss of one connection. • Keeping the transmit jumper attached to light source and receive jumper attached to power meter, you can now measure insertion loss. • Re-reference your light source and power meter about once per day. Advantages of the One-Jumper Reference Method 15 July 2000

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