By Mike McKeown, LVO Cable, Inc.
Testing a cable system to determine compliance with the FCC standards can provide results which are truly meaningful when related to the quality of service the subscriber receives. In some instances though certain test procedures may produce results which bear little relationship to the picture quality as seen on a home television set.
Because video measurements rather than RF transmission measurements have a more direct relationship to what is seen on a television screen that approach has been taken in this paper. The more conventional methods of testing CATV distribution systems often do not include the effects of headend equipment or microwave where it is used. Baseband video measurements also enable the tests to be done on an in service basis with the system in normal operation. Invariably in service test methods will gain wider acceptance with engineers and subscribers than will sleepless nights and interrupted programs.
These techniques require equipment which is often not a regular part of a cable system's test equipment. They are not the least expensive nor the most expensive methods to perform the FCC tests, but they do provide data which can give a real indication of the quality of service the subscriber receives. In many cases, the tests described can be done faster and with more accuracy than conventional distribution system only tests.