Non-parametric calibration of a time domain reflectometer

The non-parametric calibration procedure consists in finding the scattering parameters of the line network that connects the reflectometer and the device under test. The scattering parameters are determined by using the S/sub 11/ measurement of the connection cable terminated with three different loads (open, short and load). Since commercial reflectometers digitize only voltages, one has to extent the hardware so that it becomes possible to measure currents. A current to voltage transducer will be applied. This transducer will be parametric calibrated. For each load, the voltage and current reflectogram will be measured and transformed to the frequency domain where the S/sub 11/ equivalent can be calculated. The corrected voltage reflectogram can be obtained through convolution of the excitation pulse with the time domain representation of S/sub 11/. Due to the limited energy at high frequencies of the pulse-like excitation signals, one has to apply a deconvolution technique to visualize the time domain representation of the S/sub 11/ measurement.<
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