Real-time Digital Oscilloscope Research Articles

Cyclostationary Crosstalk Cancelation in High-Speed Transmission Lines

The theoretical and experimental evaluation of the cyclostationary random data transferring process corrupted by the individually and jointly cyclostationary crosstalk interference is presented. The interference and the message signals were measured by the real time digital oscilloscope. Autocorrelation functions were evaluated by synchronous cyclic averaging procedure. The analyzed periodic two-dimensional impulse response of the time-varying filter allows to obtain the output random process with the same cyclic frequency at the output of the filter by separation of orthogonal stationary waveforms constituting the input cyclostationary random process (CSRP). The filtering of the measured random process was implemented by the cyclic Wiener filter. The evaluation of the two-dimensional autocorrelation function and eye diagrams at the output of the cyclic Wiener filter showed significant reduction of the independent interference components in the estimated message signal.

Dual-Comb Spectrometer Based on Gain-Switched Semiconductor Lasers and a Low-Cost Software-Defined Radio

Dual-comb spectroscopy has become a topic of growing interest in recent years due to the advantages it offers in terms of frequency resolution, accuracy, acquisition speed, and signal-to-noise ratio, with respect to other existing spectroscopic techniques. In addition, its characteristic of mapping the optical frequencies into radio-frequency ranges opens up the possibility of using non-demanding digitizers. In this paper, we show that a low-cost software defined radio platform can be used as a receiver to obtain such signals accurately using a dual-comb spectrometer based on gain-switched semiconductor lasers. We compare its performance with that of a real-time digital oscilloscope, finding similar results for both digitizers. We measure an absorption line of a H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> C <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> N cell and obtain that for an integration time of 1 s, the deviation obtained between the experimental data and the Voigt profile fitted to these data is around 0.97% using the low-cost digitizer while it is around 0.84% when using the high-end digitizer. The use of both technologies, semiconductor lasers and low-cost software defined radio platforms, can pave the way towards the development of cost-efficient dual-comb spectrometers.

Combined Power Ratio Calculation, Hadamard Transform and Least Mean Squares Algorithm for Channel Mismatch Calibration in Time-Interleaved ADCs

This paper presents a method for all-digital background calibration of multiple channel mismatches including offset, gain and timing mismatches in time-interleaved analog-to-digital converters (TIADCs). The average technique is used to remove offset mismatch at each channel. The gain mismatch is calibrated by calculating the power ratio of the sub-ADC over the reference ADC. The timing skew mismatch is calibrated by using Hadamard transform for error correction and LMS for timing mismatch estimation. The performance improvement of TIADCs employing these techniques is demonstrated through numerical simulations. Besides, achievement results on the field-programmable gate array (FPGA) hardware have demonstrated the effectiveness of the proposed techniques.&#x0D; KeywordsTime-interleaved analog-to-digital converter (TIADC), channel mismatches, all-digital background calibration&#x0D; References[1] Melamed and S. 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Autocorrelation Analysis and Near-Field Localization of the Radiating Sources With Cyclostationary Properties

Stochastic electromagnetic fields caused by the data transferring signals along the printed circuit boards are potentially harmful interference sources for modern digital electronic devices. The characterization of the near-field electromagnetic emissions from the electronic device in time domain was implemented by real-time digital oscilloscope in conjunction with the sequential scanning system of the near-field probes. Excluding of the periodic sample mean function reveals the hidden cyclostationarity of the data transferring process measured by the near-field scanning system. In this article, the quantitative autocorrelation analysis of the hidden cyclostationary properties of the random nonperiodic data sequences is presented. The time-domain evolution of the autocovariance cross sections estimated at each scanning point were exploited for spatial-time localization of the transmission line.

Uncertainty Analysis for Characterization of a Commercial Real-Time Oscilloscope Using a Calibrated Pulse Standard

In this paper, we describe a traceable measurement method for the frequency response of commercial real-time digital oscilloscopes (RTDOs). Since the commercial RTDOs usually use multiple analog digital convertors (ADCs), it is very challenging to characterize each ADC without having access to the internal circuitry. In this study, we use an additional continuous wave (CW) source to match the sampling sequence in a time interleaved ADC (TIADC). We also use a calibrated pulse standard traceable to the National Institute of Standards and Technology (NIST). Since the sampling rate of a single ADC is greatly reduced, we slightly misalign the sampling rate of the pulse and the single ADC and then stack the multiple measured pulses as a single pulse. As a result, the sampling rate can be greatly increased by about 8000 times. The frequency response of the RTDO during testing shows a variation of ±1 dB in amplitude and ±7° in phase between ADCs at the maximum operating frequency. These differences need to be calibrated as they cause systematic errors in the measurement. The 95% confidence interval of the measured frequency response is about 0.2 dB in amplitude and 3° in phase. Finally, the measured amplitude is compared with the swept sine measurement method, which confirms that they agree well within its uncertainties.

Heavy Ion and Laser Microbeam Induced Current Transients in SiGe Heterojunction Bipolar Transistor**Supported by the National Natural Science Foundation of China under Grant Nos 61274106 and 61574171.

Silicon-germanium (SiGe) hetero-junction bipolar transistor current transients induced by pulse laser and heavy iron are measured using a real-time digital oscilloscope. These transients induced by pulse laser and heavy iron exhibit the same waveform and charge collection time except for the amplitude of peak current. Different laser energies and voltage biases under heavy ion irradiation also have impact on current transient, whereas the waveform remains unchanged. The position-correlated current transients suggest that the nature of the current transient is controlled by the behavior of the C/S junction.

Design and Implementation of a Preprocessing Circuit for Bandpass Signals Acquisition

The processing capabilities that are included into the acquisition block of the real-time digital oscilloscopes largely contribute to determine the overall performance of the instrument. Their remarkable improvement has made it possible to enhance the performance in terms of increased measurement rate, automation, and reduced measurement uncertainty related to quantization and noise. This paper presents the implementation of a preprocessing circuit for a novel acquisition mode of bandpass signals, which is characterized by an increased vertical resolution. Although the theoretical foundations were recently presented with simulative results, here, the circuital implementation of such an acquisition mode is presented. The focus is on mid or low cost digital oscilloscopes that can improve their vertical resolution at a negligible additional cost. First, a preliminary field programmable gate array implementation is considered to evaluate the achievable performance both from a theoretical point of view and throughout experimental tests. Then, a custom application specific integrated circuit implementation, in 28-nm complementary metal-oxide-semiconductor technology is analyzed. Along with the parameter optimization, the work experimentally tests the acquisition mode and evaluates the effects of nonideal characteristics such as finite word length and nonideal filtering. The increase in the effective number of bit (ENoB) is up to 2.5 bit, whereas the ENoB degradation because of word length and nonideal filtering is quantified as ~ 1.1 and 0.5 bit. The design highlights that there is substantial margin for parallel implementation that is the base to candidate the proposed solution as a remarkable option for the next generation oscilloscopes.

Traceable Measurement of Source and Receiver EVM Using a Real-Time Oscilloscope

A method to traceably calibrate wideband code-division multiple-access (WCDMA) error vector magnitude (EVM) contributions of a source or a receiver is described using a real-time digital oscilloscope as the reference receiver. The results and uncertainties are presented for a receiver calibrated using four WCDMA sources from different manufacturers. The weighted mean EVM of the receiver at 900 MHz is 0.35 ± 0.03% at 95% confidence. Measurement results at 1780 and 2510 MHz are also reported.