Measurement of the Increase in Delay Distortion for ADSL Splitters

A method for measuring the increase in delay distortion caused by asymmetric digital subscriber line (ADSL) splitters is presented in this paper. The procedure employs standard laboratory equipment rather than dedicated instrumentation, which may not be readily available in a test lab. The technique exploits a discrete Fourier transform (DFT)-based phase estimation algorithm to evaluate the group delay of the device under test. Measurements are performed in accordance to the relevant standards of the ADSL technology. Experimental results are reported to validate the method and confirm the theoretical analysis.