By Clifford B. Schrock, Tektronix, Inc.
In view of the present FCC standards for CATV·, there has been much discussion as to the validity of inexpensive test techniques; specifically subjective testing. A systematic study into test techniques and results was performed in an attempt to open up this needed field of testing. The goal was to provide the smaller or financially burdened operator with simple, inexpensive, repeatable, and valid alternatives to known, expensive instrumentation test techniques.
We chose to study three areas felt to be the most restrictive financially for the small operator; lntermodulation, Co-channel Interference, and Signal-to-Noise ratio. Using the technical standards suggested by the FCC in §76.605 (now partially suspended) we performed a comparison between an elaborate $11,000 test set, and a test set consisting of simple equipment and a TV set. The results we feel substantiate our theory, that subjective testing can be valid, and in some cases superior to other techniques.