Signal Pre-emphasis Research Articles

Signal Pre-emphasis Technique for 10-60-MHz High-speed Implant Communication System with Bandwidth-limited Small Antennas

Signal Pre-emphasis Technique for 10-60-MHz High-speed Implant Communication System with Bandwidth-limited Small Antennas

A Study of Artificial Intelligence-Assisted Listening Training in College English Teaching

Abstract The rapid development of intelligent technology and its wide application in various industrial fields have caused a big change in the teaching mode of university English listening training. Based on the C/S architecture, this paper establishes an intelligent English teaching listening training system by combining artificial intelligence technology, analyzes the auxiliary role of artificial intelligence technology for listening training, and designs an intelligent English listening training teaching mode based on this system. In order to obtain a diversity of English listening training materials, this paper first utilizes speech signal pre-emphasis, frame-splitting, windowing, and other methods to carry out signal preprocessing and then realizes end-point detection of speech signals through the improved double-threshold algorithm. Based on the characteristics of English speech signals, the Seq2Seq model is optimized by the attention mechanism, and the WaveNet model is introduced to establish a speech synthesis model for listening training. Pre-emphasis can improve the clarity of the speech signal by 50%, and the improved double threshold algorithm improves the recognition effect of speech segment clear tone, and the mean value of speech synthesis MOS score is 4.39. After adopting the intelligent English listening training teaching model, the English listening scores of the students in the observation group increased by 8.21 points compared with those of the control group, and the students who were very uninterested in English listening learning decreased by 20 percentage points. The introduction of artificial intelligence technology can provide students with more diverse English listening training materials, which can help them improve their listening level and learnability.

Using Voice Biomarkers to Classify Suicide Risk in Adult Telehealth Callers: Retrospective Observational Study.

BackgroundArtificial intelligence has the potential to innovate current practices used to detect the imminent risk of suicide and to address shortcomings in traditional assessment methods.ObjectiveIn this paper, we sought to automatically classify short segments (40 milliseconds) of speech according to low versus imminent risk of suicide in a large number (n=281) of telephone calls made to 2 telehealth counselling services in Australia.MethodsA total of 281 help line telephone call recordings sourced from On The Line, Australia (n=266, 94.7%) and 000 Emergency services, Canberra (n=15, 5.3%) were included in this study. Imminent risk of suicide was coded for when callers affirmed intent, plan, and the availability of means; level of risk was assessed by the responding counsellor and reassessed by a team of clinical researchers using the Columbia Suicide Severity Rating Scale (=5/6). Low risk of suicide was coded for in an absence of intent, plan, and means and via Columbia suicide Severity Scale Ratings (=1/2). Preprocessing involved normalization and pre-emphasis of voice signals, while voice biometrics were extracted using the statistical language r. Candidate predictors were identified using Lasso regression. Each voice biomarker was assessed as a predictor of suicide risk using a generalized additive mixed effects model with splines to account for nonlinearity. Finally, a component-wise gradient boosting model was used to classify each call recording based on precoded suicide risk ratings.ResultsA total of 77 imminent-risk calls were compared with 204 low-risk calls. Moreover, 36 voice biomarkers were extracted from each speech frame. Caller sex was a significant moderating factor (β=–.84, 95% CI –0.85, –0.84; t=6.59, P<.001). Candidate biomarkers were reduced to 11 primary markers, with distinct models developed for men and women. Using leave-one-out cross-validation, ensuring that the speech frames of no single caller featured in both training and test data sets simultaneously, an area under the precision or recall curve of 0.985 was achieved (95% CI 0.97, 1.0). The gamboost classification model correctly classified 469,332/470,032 (99.85%) speech frames.ConclusionsThis study demonstrates an objective, efficient, and economical assessment of imminent suicide risk in an ecologically valid setting with potential applications to real-time assessment and response.Trial RegistrationAustralian New Zealand Clinical Trials Registry ACTRN12622000486729; https://www.anzctr.org.au/ACTRN12622000486729.aspx

Efficient Built-In Test and Calibration of High Speed Serial I/O Systems Using Monobit Signal Acquisition

This paper proposes a new high-speed self-calibrating digital transmitter with the ability to deliver high quality signals at low hardware cost. The proposed self-calibrating system performs on-line monitoring of the channel by performing measurements on the time-domain reflected (TDR) waveform. Unlike complex TDR instrumentation, the proposed system has the capability to reconstruct the reflected waveform using a single bit (monobit) sampler. Using very little hardware, a specific feature of the reflected waveform (area over time or integral) is extracted and used to drive a signal pre-emphasis scheme that maximizes the opening of the signal eye diagram without any communication with the receiver. The absence of such physical loopback significantly reduces the time and complexity of feedback based transmitter calibration techniques, especially where multiple transmission channels are concerned. Further, the proposed scheme is useful in the presence of single or multiple transmission line imperfections or defects. The proposed technique is implemented via a printed circuit board (PCB) prototype and measurement results demonstrate that it is capable of detecting defects in the digital I/O channel and adapting the channel to improve the received signal eye-diagram without direct feedback from the receiver.

A 65-nm 10-Gb/s 10-mm On-Chip Serial Link Featuring a Digital-Intensive Time-Based Decision Feedback Equalizer

A digital-intensive on-chip serial link achieving a 10 Gb/s data rate over a 10-mm interconnect was demonstrated in a 65-nm GP process. A three-tap half-rate feed-forward equalizer was implemented for signal pre-emphasis in the transmitted block. On the receiver (RX) side, a two-tap half-rate time-based decision feedback equalizer was employed to cancel out inter-symbol interference noise. A 215 – 1 pseudorandom binary sequence generator and an in situ bit error rate (BER) monitor were designed for bit stream generation and convenient eye-diagram measurements. The measured energy efficiency of the transmitter and RX was 31.9 and 45.3 fJ/b/mm, respectively, for a data rate of 10 Gb/s. A BER less than 10−12 was verified for an eye width of 0.43 unit interval.

Heterogeneously integrated III–V/Si MOS capacitor Mach–Zehnder modulator

Hybrid silicon optical modulator brings efficiency benefits. Demand for more transmission capacity in data centres is increasing due to the continuous growth of Internet traffic. The introduction of external modulators into datacom networks is essential with advanced modulation formats. However, the large footprint of silicon photonics Mach–Zehnder (MZ) modulators will limit further increases in transmission capacity1,2,3,4. To overcome this, we introduce III–V compound semiconductors because the large electron-induced refractive-index change, high electron mobility and low carrier-plasma absorption are beneficial for overcoming the trade-offs among the voltage–length product (VπL), operation speed and insertion loss of Si MZ modulators. Here, we demonstrate an MZ modulator with a 250-µm-long InGaAsP/Si metal-oxide–semiconductor (MOS) capacitor phase-shifter and obtain a VπL of 0.09 Vcm in accumulation mode, an insertion loss of ∼1.0 dB, a cutoff frequency of ∼2.2 GHz in depletion mode and a 32-Gbit s–1 modulation with signal pre-emphasis. These results are promising for fabricating high-capacity large-scale photonic integrated circuits with low power consumption.

Vertical junction silicon microdisk modulators and switches

Vertical junction resonant microdisk modulators and switches have been demonstrated with exceptionally low power consumption, low-voltage operation, high-speed, and compact size. This paper reviews the progress of vertical junction microdisk modulators, provides detailed design data, and compares vertical junction performance to lateral junction performance. The use of a vertical junction maximizes the overlap of the depletion region with the optical mode thereby minimizing both the drive voltage and power consumption of a depletion-mode modulator. Further, the vertical junction enables contact to be made from the interior of the resonator and therein a hard outer wall to be formed that minimizes radiation in small diameter resonators, further reducing the capacitance and drive power of the modulator. Initial simple vertical junction modulators using depletion-mode operation demonstrated the first sub-100 fJ/bit silicon modulators. With more intricate doping schemes and through the use of AC-coupled drive signals, 3.5 μm diameter vertical junction microdisk modulators have recently achieved a communications efficiency of 3 fJ/bit, making these modulators the smallest and lowest power modulators demonstrated to date, in any material system. Additionally, the demonstration was performed at 12.5 Gb/s, required a peak-to-peak signal level of only 1 V, and achieved bit-error-rates below 10(-12) without requiring signal pre-emphasis. As an additional benefit to the use of interior contacts, higher-order active filters can be constructed from multiple vertical-junction modulators without interference of the electrodes. Doing so, we demonstrated second-order active high-speed bandpass switches with ~2.5 ns switching speeds, and power penalties of only 0.4 dB. Through the use of vertical junctions in resonant modulators, we have achieved the lowest power consumption, lowest voltage, and smallest silicon modulators demonstrated to date.

Noise reduction by dynamic signal preemphasis

In this work we propose an approach to reduce the digitization noise for a given dynamic range, i.e., the number of bits, of an analog to digital converter used in an NMR receiver. In this approach, the receiver gain is dynamically increased so that the free induction decay is recorded in such an emphasized way that the decaying signal is digitized using as many number of bits as possible, and at the stage of data processing, the original signal profile is restored by applying the apodization that compensates the effect of the preemphasis. This approach, which we call APodization after Receiver gain InCrement during Ongoing sequence with Time (APRICOT), is performed in a solid-state system containing a pair of 13C spins, one of which is fully isotopically labeled and the other is naturally abundant. It is demonstrated that the exceedingly smaller peak buried in the digitization noise in the conventional approach can be revealed by employing APRICOT.

Low-Voltage, Compact, Depletion-Mode, Silicon Mach&amp;#x2013;Zehnder Modulator

Through rigorous process, electrical, and optical simulations, we develop a new silicon depletion-mode vertical p-n junction phase-modulator implemented in Mach-Zehnder modulator configuration, enabling an ultralow measured <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">¿</sub> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> of only ~ 1 V·cm. Further, in a 500-¿m-long lumped element device, we demonstrate a 10-Gb/s nonreturn-to-zero data transmission with wide-open complementary output eye diagrams without the use of signal preemphasis.

High Speed and Low Energy Capacitively Driven On-Chip Wires

We present circuits for driving long on-chip wires through a series capacitor. The capacitor improves delay through signal pre-emphasis, offers a reduced voltage swing on the wire for low energy without a second power supply, and reduces the driven load, allowing for smaller drivers. Sidewall wire parasitics used as the series capacitor improve process tracking, and twisted and interleaved differential wires reduce both coupled noise as well as Miller-doubled cross-capacitance. Multiple drivers sharing a target wire allow simple FIR filters for driver-side pre-equalization. Receivers require DC bias circuits or DC-balanced data. A testchip in a 180 nm, 1.8 V process compared capacitively-coupled long wires with optimally-repeated full-swing wires. At a 200 mV swing, we measured energy savings of 3.8x over full-swing wires. At a 50 mV swing, we measured energy savings of 10.5x. Throughput on a 14 mm wire experiment due to capacitor pre-emphasis improved 1.7x using a 200 mV swing.

The design of L-band EDFA for multiwavelength applications

An accurate model for the erbium-doped fibre amplifier (EDFA) has been used to study the design criteria of single-stage (SS) and double-stage (DS) L-band EDFA for multiwavelength applications. The effects of erbium-doped fibre (EDF) length, pump configuration and pump wavelength have been studied. We show that a flat gain spectrum can be achieved in the range from 1550 to 1610 nm when the EDF length, pump power and pump configuration are appropriately chosen. Special care must be taken when selecting the EDF length. Noise figure improvement of the DS amplifier is demonstrated. The lowest noise figure was predicted for a DS amplifier with both stages co-directionally pumped at 980 nm. Transmission of 32 wavelength division multiplexed (WDM) channels with input power of -13 dB m/channel and interchannel spacing of 0.8 nm over a cascade of five L-band EDFAs has been investigated. If the WDM signal was appropriately placed, the signal level deviation between the best and the worst channel at the output of the cascade was 2.2 dB, without any gain equalizing filters or signal pre-emphasis.

Aurally sensitized flat frequency response noise reduction compansion system

A flat frequency response compansion noise reduction system employs both input signal and control signal preemphasis and deemphasis in its encoder and decoder networks respectively. The linear range of the frequency response curve of the input signal deemphasis is selected to approximate the frequency range within the audio spectrum at which the human ear is most sensitive, typically having a high frequency end of 3.617 kHz. The frequency response curve of the input signal preemphasis is a mirror image of the frequency response curve of the input signal deemphasis. The linear range of the frequency response curve of the control signal preemphasis is selected to provide an encoder output signal having a substantially flat response. The frequency response curve of the control signal deemphasis is a mirror image of the frequency response curve of the control signal preemphasis. The amount of preemphasis is maximized to the limits of the recording medium, typically ranging from 0 db to 20 db.