Abstract: A test and measurement system includes a test and measurement device having input channels, a reference array of antennas connected to the input channels, one or more processors in the test and measurement device configured to execute code to cause the one or more processors to receive a first signal from a phased array of antennas connected to a device under test directed at a first side of the reference array, receive a second signal from the phased array of antennas connected to the device under test directed at a second side of the reference array, without moving the device under test, the phased array, or the reference array.

Abstract: A test and measurement instrument has an arbitrary waveform generator having at least two waveform generators. Each waveform generator includes a signal generator to generate in-phase (I) and quadrature (Q) digital signals according to a selected signal type for a digital constituent output signal, a pulse envelope sequencer to modulate amplitude of the I and Q digital signals, and one or more multipliers to combine the I and Q digital signals with a carrier signal to produce the digital constituent output signal. The arbitrary waveform generator includes a stream manager to produce modulation descriptor words for the waveform generators, a summing block to selectively combine digital constituent output signals to produce a digital multi-constituent output signal, a digital-to-analog converter to convert the digital multi-constituent output signal to an analog output signal, and an internal signal analyzer to receive an analyzer input of one of more of the digital output signals.

Abstract: An accessory device has a test port, an instrument port to connect to an instrument having an operating bandwidth, and one or more configurable signal paths connectable between the test port and the instrument port to convert a signal from the test port having a first frequency range to a signal having a second frequency range different than the first frequency range. A test and measurement system has a test and measurement instrument having an operating bandwidth, and an accessory device. The accessory device has a first instrument port to connect the accessory device to the test and measurement instrument, a test port to connect the accessory device to a device under test, and one or more configurable signal paths connectable between the test port and the instrument port to down-convert a signal from the test port having a first frequency range to a signal having a second frequency range lower than the first frequency range.

Abstract: A test and measurement system includes a test and measurement device having input channels, a reference array of antennas connected to the input channels, one or more processors in the test and measurement device configured to execute code to cause the one or more processors to receive a first signal from a phased array of antennas connected to a device under test directed at a first side of the reference array, receive a second signal from the phased array of antennas connected to the device under test directed at a second side of the reference array, without moving the device under test, the phased array, or the reference array.

Abstract: An accessory device has a test port, an instrument port to connect to an instrument having an operating bandwidth, and one or more configurable signal paths connectable between the test port and the instrument port to convert a signal from the test port having a first frequency range to a signal having a second frequency range different than the first frequency range. A test and measurement system has a test and measurement instrument having an operating bandwidth, and an accessory device. The accessory device has a first instrument port to connect the accessory device to the test and measurement instrument, a test port to connect the accessory device to a device under test, and one or more configurable signal paths connectable between the test port and the instrument port to down-convert a signal from the test port having a first frequency range to a signal having a second frequency range lower than the first frequency range.

Abstract: A mixed-domain oscilloscope (MDO) includes a signal generator configured to generate a test signal having a span ranging from a user-configurable start frequency to a user configurable stop frequency, an output channel coupled to the signal generator and configured to transmit the test signal, an RF input channel configured to receive a return signal based on the test signal, an acquisition section configured to acquire and digitize the return signal as an acquisition record, and a ramp busy signal generator configured to substantially time-align the acquisition record with the test signal. The test signal includes a chirp signal that is a linearly swept sine wave that spans between the user-configurable start frequency and the user-configurable stop frequency. Methods include calibrating the chirp signal, connecting the MDO in various test configurations relative to external return loss bridge and DUT equipment, and performing measurements such as S21 (db), S11 (db), and distance-to-fault type measurements.

Abstract: A mixed-domain oscilloscope (MDO) includes a signal generator configured to generate a test signal having a span ranging from a user-configurable start frequency to a user configurable stop frequency, an output channel coupled to the signal generator and configured to transmit the test signal, an RF input channel configured to receive a return signal based on the test signal, an acquisition section configured to acquire and digitize the return signal as an acquisition record, and a ramp busy signal generator configured to substantially time-align the acquisition record with the test signal. The test signal includes a chirp signal that is a linearly swept sine wave that spans between the user-configurable start frequency and the user-configurable stop frequency. Methods include calibrating the chirp signal, connecting the MDO in various test configurations relative to external return loss bridge and DUT equipment, and performing measurements such as S21 (db), S11 (db), and distance-to-fault type measurements.

Abstract: A mixed-domain oscilloscope (MDO) includes a signal generator configured to generate a test signal having a span ranging from a user-configurable start frequency to a user configurable stop frequency, an output channel coupled to the signal generator and configured to transmit the test signal, an RF input channel configured to receive a return signal based on the test signal, an acquisition section configured to acquire and digitize the return signal as an acquisition record, and a ramp busy signal generator configured to substantially time-align the acquisition record with the test signal. The test signal includes a chirp signal that is a linearly swept sine wave that spans between the user-configurable start frequency and the user-configurable stop frequency. Methods include calibrating the chirp signal, connecting the MDO in various test configurations relative to external return loss bridge and DUT equipment, and performing measurements such as S21 (db), S11 (db), and distance-to-fault type measurements.

Abstract: A mixed-domain oscilloscope (MDO) includes a signal generator configured to generate a test signal having a span ranging from a user-configurable start frequency to a user configurable stop frequency, an output channel coupled to the signal generator and configured to transmit the test signal, an RF input channel configured to receive a return signal based on the test signal, an acquisition section configured to acquire and digitize the return signal as an acquisition record, and a ramp busy signal generator configured to substantially time-align the acquisition record with the test signal. The test signal includes a chirp signal that is a linearly swept sine wave that spans between the user-configurable start frequency and the user-configurable stop frequency. Methods include calibrating the chirp signal, connecting the MDO in various test configurations relative to external return loss bridge and DUT equipment, and performing measurements such as S21(db), S11(db), and distance-to-fault type measurements.

Abstract: A method and apparatus for residual spur avoidance is disclosed. One embodiment comprises a method of generating a first local oscillator signal, mixing the first local oscillator signal with a radio frequency signal to generate an intermediate frequency signal, filtering the intermediate frequency signal at a band-pass frequency, mixing the filtered intermediate frequency signal with a second local oscillator signal having a first frequency offset from the band-pass frequency to generate an output intermediate frequency signal, and switching the second local oscillator signal to a second frequency offset to avoid a spur generated from the first frequency offset, wherein the second frequency offset is the opposite sign but same magnitude offset from the band-pass frequency.

Abstract: A tracking generator for an RF measurement instrument having a receiver and a controller includes a vector modulator internal to the tracking generator. The internal vector modulator modulates complex baseband signals based on data from the controller to produce a vector modulation signal. The vector modulation signal is used to modulate a local oscillator frequency from the receiver in an output mixing stage to produce a test signal having an output frequency that matches a measurement frequency to which the receiver is tuned. By controlling the complex baseband data from the controller, an adaptive filter at the output of a DAC that produces an analog signal from the digitally modulated complex baseband data, an internal independent oscillator for the vector modulator, or a large offset phase-locked loop, an offset from the measurement frequency may be generated for the output frequency.

Abstract: A frequency selective improved directivity of a return loss bridge is achieved by generating a counteractive reflected energy vector to cancel a reflected energy vector caused by imperfections, such as parasitic effects and an unbalanced balun, in the return loss bridge. The counteractive reflected energy vector of equal magnitude, but opposite in phase, to the undesired reflected energy vector may be induced into a transmission path between a test port and a coupled port. An open circuit stub in the transmission path between the test port and the coupled port may be used to provide the counteractive reflected energy vector. Alternatively a path across a coupling resistor in a return loss path coupled from the test port to the coupled port may be used to provide the counteractive reflected energy vector, with PIN diodes in the coupled path being used for tunability if desired.

Abstract: A method of broadband receiver amplitude/phase normalization uses internal normalization sources—a thermally compensated noise source and a pseudo random sequence generator. A calibrated signal is applied to the input of the broadband receiver and processed by a digital signal processor to generate a gain versus frequency table. Then the internal noise source is applied to the input of the broadband receiver and process by a digital signal processor to generate a noise level versus frequency table. Finally the internal pseudo random sequence generator applies a pseudo random sequence waveform to the input of the broadband receiver, the pseudo random sequence waveform being process by the digital signal processor to generate equalization filter coefficients for the IF stages.

Abstract: A frequency selective improved directivity of a return loss bridge is achieved by generating a counteractive reflected energy vector to cancel a reflected energy vector caused by imperfections, such as parasitic effects and an unbalanced balun, in the return loss bridge. The counteractive reflected energy vector of equal magnitude, but opposite in phase, to the undesired reflected energy vector may be induced into a transmission path between a test port and a coupled port. In one embodiment an open circuit stub in the transmission path between the test port and a coupling resistor coupled to the coupled port may be inserted to generate the counteractive reflected energy vector of the desired magnitude with a transmission line between the open circuit stub and the coupling resistor providing the desired phase.

Abstract: Overload distortion protection for a wideband receiver having a wideband variable gain input amplifier followed by a frequency conversion stage followed in turn by an intermediate frequency amplifier and detector to produce a measurement value in response to a signal input to the wideband variable gain input amplifier is achieved by detecting the peak power of the signal at the output of the wideband variable gain input amplifier and comparing it with the power output from the intermediate frequency amplifier and detector. If a threshold difference is exceeded, gain control signals for the wideband variable gain input and intermediate frequency amplifiers are adjusted for optimum dynamic range. If there is no range for adjusting the gain control signals, then a warning is provided to an operator to alert that the measurement value may contain distortion.

Abstract: An input protection circuit for an RF circuit has an input switch that decouples a RF input signal from the circuit path when the power level of the input signal is greater than a preselected threshold. An isolation device receives the input signal from the switch and couples a first portion of the signal to a switch control loop. The switch control loop includes a level detector that generates an output proportional to the average power of the input signal. The output of the detector is coupled to a comparator that also receives a reference signal for comparison with the detector output. The comparator generates an output signal that energizes the switch when the detector output exceeds the reference signal. The switch couples the input signal directly to ground or through a load to ground. A reset command resets the input switch to re-couple the input signal into the RF circuit.