Hal, We have seen the same trend. The fact of the matter is that the frequency for TDR test is establshed by the length of the test trace. The shorter the trace, the higher the frequency required. Because of the need for high resolution, most TDR systems employ the sampling principle to achieve the high system bandwidth required by short length traces. A lower system bandwidth (less than 20 Ghz) limits the capability of accurately measuring short length traces. We send a copy of the test results, which includes the resulting frequency under test, to our customers, with a description of the measurement technique and process. To date, our reply has been sufficient. Gary Ferrari Tech Circuits