The Telecommunications Option for the TDS Series of Tektronix digitizing oscilloscopes (DSO) provides the user with the capability of comparing various telecommunication signals, within the oscilloscope, against supplied templates which conform to ANSI and CCITT standards. In addition, the Telecommunications Option for the TDS series of Tektronix digitizing oscilloscopes provides the user with the capability of displaying waveforms acquired from the oscilloscope on the screen of an IBM-PC or compatible computer and performing comparisons against the supplied i-Pattern masks. Although related, these test methods are separate in scope and operation and will be discussed individually.