Abstract: An apparatus and method for characterizing a loading pattern of a twisted pair telecommunications transmission line includes a variable frequency signal generator and a measurement receiver connected to the twisted pair line. The signal generator applies a variable frequency signal to the twisted pair line and the measurement receiver acquires magnitude values representative of the impedance of the twisted pair line. A controller, operating under program control, models a plurality of baseline transmission line and twisted pair lines to generate magnitude values representative of the models. Error values are generated between the acquired magnitude values and the modeled magnitude values. The error values are compared to each other to determine the model with the minimum error value which is used as the model for charactering the twisted pair transmission line.

Abstract: A microprocessor controlled test system generates and transmits distorted digital signals to a system under test by expanding a bit pattern, representative of a character to be transmitted, by an integer multiple of expansion. Selected bits of the expanded bit pattern are toggled from one logic level to another under program control to produce a distorted expanded bit pattern. The distorted expanded bit pattern is clocked out of the test system to the system under test at a rate equal to the integer multiple of expansion times the baud rate of the system under test. The resolution of the test signal can be varied by changing the integer multiple of expansion along with the rate at which the test signal is clocked out of the test system. The invention is useful in testing and adjusting a teletypewriter.

Abstract: Apparatus for comparing a stream of data characters with a predetermined string of test characters has an input device for receiving the stream of data characters and a main processor for generating the predetermined string of test characters. A hardware register receives the predetermined string of test characters from the main processor, and a comparator device compares the stream of data characters with the contents of the register device and generates a response in the event that a portion of the stream is identical to the string of test characters generated by the main processor. A second processor receives the response and sends a report to the main processor.