According to the rules, this should be measured on all channels at the subscriber terminal. For most systems, this means at the tap and at the output of the converter. With the automated test capabilities available today, tests at the tap are a simple matter of running a carrier survey. Tests at the output of the converter are not so simple because the test must be paused long enough to change channels on the converter.
Here's the way we approach this test. We measure all levels at the tap. If the converter being used is a baseband converter (demod, remod type), the levels at the output of the converter don't change. So, rather than test all channels at the converter's output, we only check the test channels and put a note in the report indicating that the level doesn't change at the output of the converter as demonstrated by the samples. For other converters, we go ahead and run the tests on all channels. We have a simple program to perform the tests using our signal level meter and a notebook computer.