Abstract: A realtime spectrum trigger system on a realtime oscilloscope considers both the magnitude and phase of an input signal having a periodic component so that successive acquisitions of the input signal are time aligned. A user inputs a frequency, threshold and phase for triggering on the periodic component. Input signal samples are filtered by quadrature filters according to the frequency input to produce quadrature signal components. The square of the magnitude of the input signal is computed from the quadrature signal components, as well as the phase ratio and sign, for comparison with calculated values. When enabled by the magnitude of the input signal, a phase crossing determinator compares the phase ratio and sign with calculated values to determine the phase crossing to generate a trigger, resulting in successive acquisitions of the input signal being in time alignment.

Abstract: A flexible timebase for eye diagrams uses a stable free running oscillator as a sample clock for equivalent time sampling of an input serial digital signal and of a reference signal derived from a subdivided recovered clock of the input serial digital signal. The reference signal samples are provided to a digital phase-locked loop that provides the flexible timebase to an eye pattern generator. The eye pattern generator accumulates the input serial digital signal samples at times corresponding to the reference signal samples to produce the eye diagram. A linear phase detector in the digital phase locked loop converts the reference signal samples to a complex signal using a Hilbert transform and then to a linear ramp of phase values using a CORDIC algorithm with arctangent lookup table. The digital phase-locked loop feedback is subtracted from the linear ramp to provide the input to the loop filter.

Abstract: An improved hold-off algorithm that assures that all data associated with all trigger events in a data signal are displayed uses a designated interval starting with a first trigger event to determine whether any subsequent trigger events occurred within the designated interval. A first display frame is drawn based upon the first trigger event. A next display frame is drawn based either on a next trigger event that occurs outside the designated interval, or based on the last trigger event that occurred within the designated interval. In the latter case the two display frames provide an overlap to assure that no data related to the trigger events is lost on the display.

Abstract: A data analysis technique for a long data record in a memory uses a reference, either user-provided or calculated from the data in the long data record, as a representative event. Each event in the long data record is compared with the reference to determine whether there are significant deviations from the reference. Those events having significant deviations are identified as events of particular interest for a user. The reference may be either a waveform shape or a mean time interval between events. A tolerance value may be added to the waveform reference and varied for dynamic limit testing. Events that are outside the waveform reference as modified by the tolerance value are identified as outliers and may be reduced to iconic images for display simultaneously with the long data record and a selected one of the outliers.

Abstract: A method of determining configuration parameters of a mobile network topology for testing and monitoring purposes at an interface (lub) located between a first node and a second node of the mobile network where between the first and the second node there exist several channels includes finding the channel having signaling information, analyzing signaling information to determine the configuration parameters, updating the configuration parameters dynamically, and performing a monitoring activity or test scenario based on the configuration parameters.

Abstract: A fast rasterizer uses a fast memory that has a bit-set port for receiving data and a totally independent readout and clear port for outputting a waveform image. The fast memory is organized into rows and columns corresponding to the rows and columns of a raster display device, with each memory location or cell holding a single bit. The fast memory is divided into parallel sections so that one column of each section may be written into each clock cycle, resulting in the possibility of writing a plurality of columns into the fast memory each clock cycle. Each memory cell is set when a row and column write signal for the cell are asserted, and is read out and cleared when a row and column read signal for the cell are asserted. Row logic using thermometer codes is used to set the row lines for the selected column in each section.

Abstract: A video test system is provided with a circular buffer to capture a video input sequence in response to a trigger, and a test generator output to generate a video test sequence based upon the captured video test sequence. The system may be implemented using a single instrument, or a combination of instruments, such as video waveform monitors and video signal generators. A method is also provided for generating video test sequences based upon captured video sequences.

Abstract: A method of correcting the frequency response of an RF receiver having a frequency translation device and a fixed IF frequency section uses calibration data representing frequency responses over a wide frequency range for multiple center frequencies. The calibration data are based upon a multi-dimensional model for the frequency translation device that includes at least center frequency and offset frequency. The calibration data are stored in the RF receiver during factory calibration. A run-time normalization of the RF receiver produces a normalization frequency response at a reference frequency, and a relative frequency response at a desired center frequency is derived from the calibration data. The normalized and relative frequency responses are combined to produce an overall frequency response that is used by the RF receiver to configure an inverse filter to correct channel linear distortion produced by the frequency response of the frequency translation device at the desired center frequency.

Abstract: A realtime display compression for a waveform image uses a priority basis for combining groups of pixels when producing a compressed waveform image in order to preserve intensity information. As an example successive lines of data for the waveform image are demultiplexed into line buffers in a circulating manner, the number of line buffers being a function of the maximum desired integer compression ratio. The outputs from the line buffers are aligned and the corresponding pixels are combined according to a desired compression ratio, one output line for each integer compression ratio. The appropriate compressed line is selected as the output line according to the desired compression ratio, with the totality of the output lines forming the compressed waveform image.

Abstract: Pre-trigger and post-trigger acquisition for a no dead time acquisition system, where the data being displayed does not include a related trigger event, has a variable record length buffer having a maximum record length equal to a maximum desired pre-trigger interval, and has a trigger FIFO and timer for delaying the related trigger event. The record length of the buffer is determined by the desired pre-trigger interval, and fast rasterizers access the oldest data that encompasses the desired pre-trigger data. A first trigger event in the trigger signal may be delayed by a desired post-trigger interval before the fast rasterizers begin drawing the waveform data that encompasses the desired post-trigger data.

Abstract: The present invention relates to a protocol tester and method for performing a test task relating to a specific protocol layer (E2) of a protocol stack in an apparatus to be tested where the specific protocol layer (E2) is superordinated to a higher-level protocol layer (E3) as a next higher protocol layer and is subordinated to a lower-level layer (E1) as a next lower layer. In the protocol tester there is inserted between the higher-level protocol layer (E3) and the lower-level layer (E1) a test layer into the protocol stack, the test layer in the protocol tester having the specific protocol layer (E2) and a complementary layer (ES).

Abstract: Subjectively weighting noise measurements for multiple video formats based upon a defined standard for a standard definition video format uses a ratio between the active line time for the standard definition video format and the active line time for another video format to be measured in order to rescale a unified weighting filter for the standard definition video format for the another video format.

Abstract: An eye violation and excess jitter trigger for a digital signal uses a mask within a unit interval of the digital signal, such as a rectangular mask having corners defined by a high threshold, a low threshold, an early clock and a late clock, the early and late clocks being derived from a reference clock. The reference clock may be a recovered clock derived from the digital signal or from high and low threshold comparator outputs, or may be an external clock. For the excess jitter trigger, which is a special case of the eye violation trigger, the high and low thresholds are essentially equal. A status of the digital signal with respect to the mask is determined using the high and low thresholds and the early and late clocks, and a violation signal is output when the status indicates that a portion of the digital signal crossed into the mask. The violation signal may then be used to trigger data acquisition or for other purposes.

Abstract: A robust video temporal method for registration between test and reference video sequences without a priori knowledge of the respective signal parameters initially produces frame and subimage distillation measurements from the test and reference video sequences. The frame distillation measurements are linearly aligned using a local Pearson's cross-correlation coefficient (LPCCC) image to obtain a best alignment line, each pixel of which represents an LPCCC cross-correlation coefficient between frames of the test and reference video sequences. For each pixel of the best alignment line that is below a threshold, a vertical search is performed in the LPCCC image for a higher cross-correlation coefficient as the best cross-correlation coefficient to achieve temporal mapping between frames of the test and reference video sequences.

Abstract: An apparatus and method for demultiplexing sampled data at a first data rate on a data line using a non-standard demultiplex mode is achieved by first demultiplexing the sampled data using a standard, factor of two, demultiplex mode, to produce n data lines at 1/n time the first data rate, and then down-converting n data lines to m data lines at 1/m times the first data rate to produce the non-standard demultiplex mode. As a specific example sampled data is demultiplexed using a standard 4× mode and then converted to a non-standard 3× mode.

Abstract: A method of displaying a time sequence of 2-dimensional data represents each data set in the time sequence as a normalized figure based upon a reference set of data. The perimeter of the normalized figure is color coded to represent deviations from a data standard that corresponds to the 2-dimensional data. For subsequent data sets in the time sequence each normalized figure is sized to form a series of concentric figures for display representing all the data sets in the time sequence so that patterns of both rotational and magnitude changes are visually apparent.

Abstract: A method of measuring transport delay and jitter with a realtime oscilloscope using cross-correlation acquires waveforms from two test points in a system under test. Clock recovery is run on both waveforms to obtain respective rates and offsets. A time offset between the two waveforms is computed. The jitter from the two test points is filtered and a mean-removed cross-correlation coefficient is computed from the filtered jitters. A fractional delay is computed using interpolation based on LMS error, and the respective computational components are summed to compute a transport delay between the two test points. The transport delay may be used to adjust clock edges from one waveform for comparison with data transition edges of the other waveform to measure jitter.

Abstract: A method for determining a transmission parameter at an interface between nodes of a transmission system for a specific channel, where there exist a plurality of channels between the nodes serving either for communication between the nodes or for communication with a subscriber, first determines whether the transmission parameter relates to a protocol for communication between nodes or a protocol for communication with the subscriber. If the protocol is for communication between nodes, then the particular protocol is determined by analyzing octets of data and awarding points to one or the other of such protocols, the protocol with the most points corresponding to the transmission parameter. If the protocol is for communication with the subscriber, then the particular protocol corresponding to the transmission parameter is determined by analyzing length of header information data, direction of data flow and number of bits in a specified location.

Abstract: A transport stream of a compressed video signal is monitored. Information elements extracted from the transport stream prompt the generation of messages which are assigned a predetermined priority dependent upon their pre-determined criticality to integrity of the video signal. The generated messages are queued for analysis by analyzer modules only if their priority exceeds a current value of a variable threshold priority level for the queue. The variable threshold priority level is varied dependent on the current length of the queue. When the threshold level is raised, messages already in the queue having a lower priority than the new threshold priority are discarded from the queue without analysis.

Abstract: An activity display for multiple data channels over a period of time for a communication link provides a quasi-three-dimensional presentation having time periods and data channels as orthogonal axes and shading within each time period/data channel rectangle representing ones density for the channel during that time period. One or more frames of the communication link corresponding to one time period are captured, and then each frame is processed in sequence one data channel at a time to build up a line of the display for the time period. Over multiple time periods the display is built up line by line, with the oldest line being dropped as a new line is added when the maximum number of lines for the display is achieved. In this way an operator has a high level all-in-one glance at the operation of the communication link.