Abstract: A system and method for in-service transmitter phase noise measurements determines phase nonlinearity by way of comparing unfiltered signal samples and regenerated reference signal samples to calculate phase nonlinearity error. Linear distortion is removed from the received signal samples in order to truly characterize nonlinear behavior of the transmitter. The unfiltered signal samples are generated without applying the receiver shaping filtering. Reference signal samples are regenerated from estimated transmitted symbols derived from the unfiltered signal samples. The transmitted symbols are estimated using a segmented slicer which dynamically estimates constellation decision levels from the unfiltered signal samples. A weighted, least-square based polynomial regression is performed on phase error samples of the unfiltered signal samples to estimate a phase nonlinear error function while suppressing the impact of other non-systematic distortions.

Abstract: A PIN diode switch reduces energy loss and stray capacitance by providing first and second series connected PIN diodes between first and second biasing sources. A third biasing source is coupled to the common node between the two PIN diodes via a first resistive element. A second resistive element is coupled between the PIN diodes and the second biasing source. An electronic switch couples a negative voltage source via a current generating means to bias the PIN diodes to a conductive ON state. AC current is coupled to ground in the ON state via a dual path circuit that includes one of the PIN diodes and a low loss capacitive element connected to the PIN diode and second resistive element node in one path and the other PIN diode and the biasing source to ground in the other path. In the OFF state the biasing sources provide reverse bias voltages for minimizing the reverse capacitance of the PIN diodes and are connected in a way that minimizes stray capacitance that is connected to the switched element.

Abstract: A probing adapter for Ball-Grid-Array packages has an elongate body with a centrally disposed slotted region formed therein containing a slider that is movable within the slotted region. An electrically conductive plunger is attached to the slider and electrically coupled to an electrical contact exposed outside of the probe body. An electrode extends from the plunger and through an aperture formed in one end of the probe body to expose a hooked-shaped contact for making electrical contact with a solder ball contact of the ball grid assay package.

Abstract: A measurement probe includes a sacrificial assembly fixture as part of the probe head. The probe head has probing contact at one end thereof and a transmission cable extending from the other end thereof and includes a housing having interior surfaces with the probing contact disposed in one end of the housing and the transmission cable extending from the other end. A substrate is disposed within the housing and is electrically connected to the probing contact and the transmission cable. An alignment fixture has a base with deformable ribs formed on one surface thereof and opposing sidewalls extending from the base opposite the surface with the deformable ribs. Each sidewall has an interior surface with a channel formed therein at the exposed ends of the sidewalls for engaging the substrate.

Abstract: A method for characterizing events in acquired time domain reflectometry data from a metallic cable under test uses an edge or event detector for generating an array where positive array elements represent a positive leading edge of an event and negative array elements represent a negative leading edge of an event. Predominantly contiguous groups of positive and negative array elements are identified for defining regions, and elbow points and peak-valley points are determined for the regions having location and amplitude values corresponding to one of the waveform data points. The height for the event is determined as a function of the elbow point and the peak-valley point, and elbow point representing the location of the event and the event height are stored.

Abstract: A probe adapter for coupling probe tip contacts of a electrical measurement probe to leads of a surface mounted integrated circuit IC device has an insulating housing from which extend first and second flexible electrically conductive leads having a pitch geometry compatible with the leads of the IC device. First and second electrical contacts, respectively coupled to the first and second flexible electrically conductive leads, are disposed in the housing and have a pitch geometry compatible with the probe tip contacts of the electrical measurement probe.

Abstract: A retractable connector mechanism for a signal connector has a recessed tub housing with a signal connector carrier rotatably fixed within the housing. The retractable connector mechanism rotates from the stored position in the housing to an angled positioned extending out of the housing. A biased carrier latch is attached to the signal connector carrier and is biased by a spring to rotate to a locked position. The biased carrier latch has a cam surface that travels on first and second guide surfaces within the housing such that rotating the signal connector carrier from the stored position to the angled position causes the cam surface to travel on the first guide surface and the biased carrier latch to rotate to a locked position on the second guide surface to latch the signal connector carrier in the angled position.

Abstract: A strain relief and pull-strength termination with controlled impedance for a transmission cable has a carrier with a flat portion for accepting one end of the cable and tabs extending from the flat portion. The cable is secured to the flat portion via soldering of the shielding conductor to the flat portion or by glueing. A housing having tabs formed therein receives the carrier. The tabs in the housing are bent down to engage the carrier tabs to provide strain relief and cable-pull strength.

Abstract: An improved time domain reflectometer (TDR) includes a capacitor coupled in series between a transmission medium under test and the TDR receiver input. A switch, operating under microprocessor control, selectively couples and uncouples the capacitor to a voltage reference, such as ground. During the generation of interrogating pulses from the TDR and the acquisition of data from the transmission medium under test, the capacitor is uncoupled from the voltage reference and acts as a DC blocking capacitor. During periods of non-TDR activity, the capacitor is coupled to voltage reference and acts as a load for low frequency interference appearing on the transmission medium. The capacitor-switch operation blocks low frequency interference signals from the receiver input of the TDR.

Abstract: An interleaved digital peak detector has multiple acquisition pipes with each pipe receiving a common input signal. Each acquisition pipe receives a common sample clock signal that is delayed through an analog delay circuit for selectively delaying the sample time of each analog-to-digital converter in the pipe. Each pipe has peak detector that receives the digitalized output from the analog-to-digital converter and accumulates maximum and minimum peak values. A programmable decimator receives the sample clock signal and a decimation value for establishing an acquisition clock by decimating the sample clock signal as a function of the decimation value to trigger a latch circuit for storing the accumulated maximum and minimum values from the peak detector.

Abstract: An apparatus for acquiring waveform data from a metallic transmission cable under test includes a transmitter for generating interrogating pulses for examining a segment or segment lengths of the transmission cable under test. A variable gain receiver receives a return signal from the segment or segment lengths of the cable and generates at least two gain segment acquisitions of waveform data representative of the signal from each segment or segment lengths with each gain segment acquisition of waveform data being generated with a different receiver gain. A controller operating under program control initiates the generation of interrogating pulses, establishes the receiver gain for each gain segment acquisition of waveform data, and controls the gain segment acquisitions of waveform data over the segment or segment lengths. An event table is created containing event characterization data for each gain segment.

Abstract: An improved pulse generator circuit includes a pulse shaper circuit for generating interrogating bipolar pulse having reduced or no energy at zero frequency for use in a measurement test instrument for characterizing a transmission medium, such a twisted pair and coaxial transmission cables.

Abstract: An electrical receptacle mountable on and positionable within a substrate has an electrically conductive element that includes a conductive member with deformable electrical leads extending therefrom. The deformable electrical leads have first and second portions with the first portion extending outward from the conductive member and the second portion being adjacent to and approximately parallel with the conductive member. A body of electrically insulating material encapsulates the conductive member about the exterior surface of the conductor with the electrically insulating material having an exterior surface on which is formed support ribs and alignment ribs with the support ribs providing initial support for the electrical receptacle over an aperture formed in the substrate and the alignment ribs providing positioning alignment of the electrical receptacle within the aperture of the substrate.

Abstract: An optical time domain reflectometer (OTDR) is treated as a linear shift-invariant system modeled as a ideal resistive-capacitive network. A step pulse is applied to a fiber under test and the return optical energy from the fiber under test is converted to signal samples representative of the return optical energy. The signal samples are processed in a controller for producing step impulse stimulus signal samples corrected for the bandwidth limited system response of the optical time domain reflectometer by modeling the OTDR as an exponential linear shift-invariant system that includes the optical transmitter, optical receiver and the fiber under test. The controller takes the time derivative of the step impulse stimulus signal samples for generating signal samples representative of the impulse response for the fiber under test.

Abstract: A method for measuring interference in a cable transmission system includes the step of establishing a spectrum frequency measurement window having start and stop frequencies and an amplitude threshold. Data is acquired over the window representative of the spectral energy of the cable transmission system within the window and the data is compared against the threshold value. If the data falls below the threshold value, indicating the absence of a carrier signal within the window, a display is generated characterizing the interference over the window. Additional measurement windows may be established having different start and stop frequencies and thresholds for measuring different portions of the cable transmission system frequency spectrum.

Abstract: An instrument housing defines a chamber and has a metal shell with an aperture region defining an array of parallel elongated apertures. The shell has an elongated web between each pair of adjacent apertures, and a raised element protrudes from the web. The raised element is spaced apart from each aperture to reveal a portion of the web near each aperture. A resilient, electrically conductive spring element is electrically connected to the web and has a compressible portion extending away from the web, such that a metal plate pressed toward the revealed surface makes electrical contact with the spring and thereby to the shell, and is laterally constrained by the raised element. The raised element may be welded to the web with the spring captured between, or the raised element may be partially sheared to protrude from the web, with an aperture in the spring closely receiving the raised portion with an interference fit.

Abstract: An active avalanche photo-diode, APD, gain control circuit for use in an optical receiver includes a bias generator for varying the bias on a variable gain APD in response to bias control values generated by a controller. The controller receives the output of the optical receiver and determines the system noise of the receiver for the various bias control values. The system noise is compared to a threshold value for establishing the optimum bias for optimum gain of the APD. The gain control circuit is useable in an optical receiver in an optical time domain reflectometer, OTDR, for increasing the dynamic range of the OTDR.