Abstract: A measuring device for the interface of a transmission path with full-duplex transmission in the common carrier duplex process. A highly integrated interface unit is connected to the interface via a hybrid set and a transmitter on one side. A line termination or a network termination is connected as the test object on the other side. In order to perform measurements on the test object with such a measuring device relatively easily and accurately, a device simulating the arrangement of a hybrid set, a transmitter and a line or network termination is provided and with its connected to the highly integrated interface unit via a high-resistance differential amplifier, and its output connected to an input of a subtractor. Another input of the subtractor is connected to the interface via an additional differential amplifier. The output of the subtractor is connected to a measurement system.

Abstract: A phase-locked timebase for electrical and electro-optic sampling has an offset phase-locked loop for controlling the delay between a stimulus reference signal and a sample strobe signal. A reference signal source synchronizes a stimulus source for a device under test and also is input to the phase detector of a phase-locked loop. Also input to the phase-locked loop in the baseband section is a sample phase control signal. The output of the offset phase-locked loop is an integer multiple of the reference signal source that is delayed from the reference signal source by a controlled amount. The output of the offset phase-locked loop is input to a low noise synchronous detection circuit that mixes a response signal from the device with an impulse sample strobe generated from the output of the phase-locked loop. The mixed response signal is detected, integrated and output at a rate equal to or much lower than the sample rate, as determined by the integration time.