Abstract: In addition to other aspects disclosed, a method comprises providing a signal to a transformer for supplying power during a reduced activity state. The signal comprises a series of pulses that comprises a positive pulse and a negative pulse. The signal is a segmented version of another signal provided to the transformer during the active state.

Abstract: In addition to other aspects disclosed, a method comprises providing a signal to a transformer for supplying power during a reduced activity state. The signal comprises a series of pulses that comprises a positive pulse and a negative pulse. The signal is a segmented version of another signal provided to the transformer during the active state.

Abstract: A test unit for measuring crosstalk in twisted pair cable. The test unit has an output signal balance (OSB) circuit that compensates for parasitic capacitance at its output terminals. The OSB circuit has a voltage controlled capacitance connected in circuit with each output terminal to control the effective capacitance between the output terminals and ground. The bias voltage for the variable capacitances is calibrated by a method in which the voltage for one of the variable capacitors is held constant while the voltage for the other capacitor is varied in voltage levels. A test signal frequency sweep is applied to the test unit output terminals. First and second voltage values are obtained and a final bias voltage value is calculated from using these two values.

Abstract: A test system method for measurement of crosstalk in a multi-pair cable of the type used in local area networks. The system uses a far end signal generator at one end of the cable and a near end signal generator at the near end of the cable. For a far end crosstalk measurement, the far end test unit transmits a high frequency far end test signal and a lower frequency reference signal on one of the wire pairs of the cable. The near end test unit responds to the received reference signal to generate a near end test signal in phase coherency with the far end test signal. A far and crosstalk measurement analysis is then conducted using the received far end test signal, the near end test signal and a crosstalk signal induced by the far end test signal in one of the other wire pairs of the cable.

Abstract: A test unit for measuring crosstalk in twisted pair cable. The test unit has an output signal balance (OSB) circuit that compensates for parasitic capacitance at its output terminals. The OSB circuit has a voltage controlled capacitance connected in circuit with each output terminal to control the effective capacitance between the output terminals and ground. The bias voltage for the variable capacitances is calibrated by a method in which the voltage for one of the variable capacitors is held constant while the voltage for the other capacitor is varied in voltage levels. A test signal frequency sweep is applied to the test unit output terminals. First and second voltage values are obtained and a final bias voltage value is calculated from using these two values.

Abstract: A test unit for measuring crosstalk in twisted pair cable. The test unit has an output signal balance (OSB) circuit that compensates for parasitic capacitance at its output terminals. The OSB circuit has a voltage controlled capacitance connected in circuit with each output terminal to control the effective capacitance between the output terminals and ground. The bias voltage for the variable capacitances is calibrated by a method in which the voltage for one of the variable capacitors is held constant while the voltage for the other capacitor is varied in voltage levels. A test signal frequency sweep is applied to the test unit output terminals. First and second voltage values are obtained and a final bias voltage value is calculated from using these two values.

Abstract: The magnitude of successive peaks in a time varying electrical signal are measured by applying the signal to magnitude circuitry capable of providing an output related to signal magnitude. The circuitry has a first state during which the output is dependent of changes in signal magnitude and a second state during which the output is substantially independent of such changes. The circuitry enters the first state during a first time interval within which a first peak is applied to the magnitude circuitry, and during a second time interval within which a second peak is applied to the magnitude circuitry. During a third time interval intermediate the first and second time intervals, the circuitry enters the second state. The magnitude circuitry's output during the second time interval is independent of its output during the third time interval so that successive outputs of the circuitry are related to the respective magnitudes of said successive peaks.

Abstract: A magnetic head tester has a popcorn noise detector for discriminating internally generated popcorn noise events from externally generated noise events. The popcorn noise detector includes a discriminator which receives the magnetic head output signal from the head and generates a comparator pulse for each popcorn noise event detected. A counter counts the number of pulses output from the detector. The discriminator includes a retriggerable noise detection gate circuit for producing a noise detection gate signal when triggered by a comparator pulse. The discriminator responds to a single comparator pulse during the gate period by indicating a popcorn noise event at the output of the discriminator. The discriminator responds to a plurality of comparator pulses during the gate period by indicating that no popcorn noise event has occurred.