Passive inter-modulation fault location technology based on the reference signal is researched.The technology has one more reference channel than the traditional passive inter-modulation measurement techniques

to provide a reference signal

to demodulate phase response of the inter-modulation signal

while introducing calibration technology in the measurement port to build the reference plane

Obtained Time domain response relative to the reference plane By the time-frequency conversion and effective troubleshooting.Based on this

the fault location test is simulated to prove the validity of theory

and the phase reference board is designed and fabricated

the experimental results and the actual value showed that:Absolute value of the difference between the actual value and the measured value of two fault location on the cables are 1m

the actual relative error of approximately 5.1%

2.4%

proves the correctness and feasibility of this approach.The technology will overcome the shortcomings of traditional fault location

adapts to the nasty geographical environment.