TRC measured less than 50 cm. Set the reference again. - CertiFiber Pro

If you get this error message, you have set the reference incorrectly

When you set a 1-jumper reference for a duplex fiber loss test, it is important to understand the difference between the Reference and the TRC Verification. (TRC stands for Test Reference Cord.)

The first step is to establish our Reference power levels.

This is done with only one cord (or "jumper") between each output and input port, these cords get zeroed out and we establish our reference power levels for both sides of the duplex link.

Because we cannot connect to an installed duplex link with only two test cords, we need to add one more cord to each side of the link before we can run our test, for a total of four cords.

However, the second two cords are not zeroed out like the first two, so we need to take a loss measurement of these cords to check if their values are acceptable - this is the second step which we call "TRC Verification".

When the loss measurement is taken for TRC Verification, the tester also measures the length of the cords. If the measured length is less than 50cm, the error message shown below appears.

This will happen if the user did not set the reference with only one cord in each direction, but rather two cords and a coupler in each direction - or said differently, they did a 2-jumper reference instead of a 1-jumper reference.

1-Jumper Reference:

TRC Verification:

Why not to do a 2-Jumper Reference

The problem with a 2-jumper reference is that all of the cords and the couplers get zeroed out.

If you do this and then remove the couplers before connecting to your installed link, you have removed a zeroed loss factor and skewed your loss measurements to look better than they actually are, or can even create negative loss readings (AKA "gainers").

In summary, always remember that for loss testing on duplex links, you must:

1. Set your reference with only one cord in each direction.
2. Run TRC Verification with two cords in each direction.
3. NEVER set your reference with two cords in each direction.