Abstract: A time qualified frequency mask trigger triggers on signals that violate a frequency mask for at least a specified time duration. A frame of digital data representing an input signal is transformed into a frequency spectrum having at least one frequency bin, with each frequency bin having a power amplitude value. A trigger signal is generated when any of the power amplitude values violates an associated reference power level for at least a specified time duration.

Abstract: A power trigger is provided having time qualified and sequential event capability. Digital data representing an input signal is converted into a power signal. The power signal is compared to a trigger level. A trigger signal is generated when the power signal violates the trigger level for either at least or less than a specified time duration. Alternatively, the trigger signal may be generated on the occurrence of a sequence of such violations.

Abstract: Embodiments of the present invention comprise methods, systems, and apparatus for multi-domain markers.

Abstract: An enhanced impulse response measurement for a pulsed frequency modulation (FM) radar signal provides a more accurate measurement of the amplitude of a secondary response relative to the amplitude of a main response. The pulsed FM radar signal is sampled to produce a time-domain sample record. The sample record is windowed to produce a windowed sample record. The windowed sample record is transformed into a frequency-domain spectrum. The spectrum is multiplied with the complex conjugate of a frequency-domain estimate of a transmitted pulsed FM radar signal to produce a de-spreaded pulse. The de-spreaded pulse is transformed into the time domain to produce a measurement of the impulse response having a main response and a secondary response. The amplitude of the secondary response is corrected to eliminate errors caused by the windowing.

Abstract: A frequency mask trigger having frequency selective amplitude discrimination capability is provided for triggering when selected frequency components of an input signal fail to reach a desired power level. A frame of digital data representing an input signal is transformed into a frequency spectrum having at least one frequency bin, each frequency bin having a power amplitude value. Each power amplitude value is compared to an upper lower reference power levels and a lower reference power level. A trigger signal is generated when the power amplitude value in any frequency bin is above the lower reference power level and below the upper reference power level for a specified time duration.

Abstract: A waveform display apparatus that can display a waveform in a desired position even when an internal reference mode is switched to an external reference mode. The internal and external reference modes are switched with a reference select button 60. A user operates a phase adjustment knob 64 while watching a display 54 to adjust a phase relationship between an external reference video signal and a video signal under test. When the phase relationship becomes proper an offset save button 66 is pressed to store the phase offset at the situation in a memory 56. A CPU 30 reads out the phase offset according to needs such as the waveform display apparatus is turned on, etc. to control a phase adjustment circuit 44 for adjusting the phase relationship between the external reference video signal and the video signal under test.

Abstract: A data converter system provides an output signal having reduced spurious tones by confining an input signal to a specified frequency band and over-sampling so that the converted input signal “straddles” or “avoids” spurious tones. The spurious tones may then be filtered away, providing an output signal having a much cleaner spurious free dynamic range than a conventional data converter. For example, in one embodiment, an interleaved data converter system converts an input signal that is confined to the second Nyquist zone of one of the interleaved data converters into an interleaved signal, and then filters the interleaved signal with a filter having a pass-band that transmits the converted input frequencies and a stop-band that attenuates the spurious tones. The resulting output signal has a bandwidth that is the same as could be achieved using a single data converter, but is not impaired by interleave images or certain distortion products.

Abstract: A measurement indicator, “transfer efficiency,” is provided for evaluating conditions of propagation paths of wireless communication systems having a plurality of transmitting and receiving antennas. Transfer functions of signal paths are calculated from data of received signals that are obtained with receiving antennas by receiving OFDM signals transmitted by transmitting antennas. A demodulation matrix is calculated for demodulating a transmitting vector from a receiving vector concerning a desired subcarrier of the received signals. A noise amplification factor is calculated as a square root of a sum of second powers of components of the demodulation matrix of the receiving antennas concerning the desired transmitting antenna. The noise amplification factor or the inverse is displayed as a value or as a graph that has an axis concerning the subcarrier and an axis concerning the noise amplification factor or the inverse.

Abstract: Sets of time domain data of respective frequency bands from Fd-1 to Fd-n of a periodic input signal Fs are acquired. Sets of the time domain data of the common frequency band are extracted from the sets of the time domain data of the frequency bands Fd-1 and Fd-2 in the acquired frequency bands. Correlativity between the sets of the time domain data of the common frequency band is determined while shifting time relationship between the sets each other to identify the sets of time domain data having correspondence relationship. The sets of the time domain data having the correspondence relationship in the time domain data of the adjacent frequency band Fd-1 and Fd-2 are converted to the sets of the frequency domain data respectively, and the sets of the frequency domain data are combined to produce one set of combined frequency domain data.

Abstract: A trigger circuit generates a trigger signal when a differential input signal crosses a differential threshold voltage level. A first side of the differential input signal is applied to a first terminal of a first load termination resistor. A second side of the differential signal is applied to a first terminal of a second load termination resistor. A first side of the differential threshold voltage level is applied to a second terminal of the first load termination resistor. A second side of the differential threshold voltage level is applied to a second terminal of the second load termination resistor. A comparator generates the trigger signal when a voltage level at the first terminal of the first resistor exceeds a voltage level at the first terminal of the second resistor.

Abstract: While combining AD converters that one is wide band but narrow dynamic range and the other is narrow band but wide dynamic range, it allows settings to provide a common intermediate frequency signal to the AD converters. A first BPF 50 provides a first AD converter 54 with the output signal obtained by getting an intermediate frequency signal Sif through a first band in the second Nyquist zone of the first AD converter 54. A second BPF 52 provides a second AD converter 56 with the output signal obtained by getting the intermediate frequency signal Sif through a second band in the third Nyquist zone of the second AD converter 56. At this time, the second band is set in the center portion of the second Nyquist zone band, and the first band is set in the center portion of the band of the intermediate frequency signal.

Abstract: An improved interpolation technique for reconstructing a complex signal from sampled data estimates a carrier phase for each sampled data time. The carrier phase is then used to compensate for frequency variation in the complex signal. The complex components of the sampled data are then interpolated separately with the interpolated results being used to produce an interpolated magnitude that is the reconstructed complex signal.

Abstract: A realtime power mask trigger generator for an instrument that acquires data in response to a trigger signal integrates power amplitudes over a defined bandwidth within a frequency spectrum for an input signal to produce an average signal power, and compares the average signal power with a specified reference power level for the defined bandwidth. Violation of the reference power level by the average signal power generates the trigger signal for acquiring data from the input signal about the trigger event by the instrument. The frequency spectrum may be divided into more than one defined frequency bandwidth, and each defined frequency bandwidth may have its own specified reference power level. The defined frequency bandwidths and associated reference power levels define a realtime power mask trigger.

Abstract: A test and measurement Instrument samples an input digital logic signal to produce logic samples, compresses the logic samples into compression codes, and stores the compression codes into acquisition memory. Compression includes parsing the logic samples into groups and assigning compression codes to those groups, and is performed so as not to lose information about the input digital logic signal's activity. The instrument converts the stored compression codes into a waveform image in display memory and displays the stored waveform image on a display device.