Acoustic OFDM Technology and System

2013 ◽  
pp. 90-103 ◽  
Author(s):  
Hosei Matsuoka
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Audio Signal ◽  
Subjective Assessment ◽  
Text Messages ◽  
Handheld Devices ◽  
Frequency Division Multiplexing ◽  
Short Text ◽  
Audio Data ◽  
Ofdm Signals

This chapter presents a method of aerial acoustic communication in which data is modulated using OFDM (Orthogonal Frequency Division Multiplexing) and embedded in regular audio material without significantly degrading the quality of the original sound. It can provide data transmission of several hundred bps, which is much higher than is possible with other audio data hiding techniques. The proposed method replaces the high frequency band of the audio signal with OFDM carriers, each of which is power-controlled according to the spectrum envelope of the original audio signal. The implemented system enables the transmission of short text messages from loudspeakers to mobile handheld devices at a distance of around 3m. This chapter also provides the subjective assessment results of audio clips embedded with OFDM signals.

Some OFDM waveforms for a fully polarimetric weather radar

2012 ◽  
Vol 4 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Piet van Genderen ◽  
Oleg A. Krasnov ◽  
Zongbo Wang ◽  
Recep Firat Tigrek
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Weather Radar ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Cloud Parameters ◽  
Polarimetric Weather Radar ◽  
Ofdm Signals ◽  
Simultaneous Transmission

Retrieval of cloud parameters in weather radar benefits from polarimetric measurements. Most polarimetric radars measure the full backscatter matrix (BSM) using a few alternating polarized sounding signals. Using specially encoded orthogonal frequency division multiplexing (OFDM) signals however, the BSM can be measured in a single simultaneous transmission of two orthogonally polarized signals. Based on a set of parameters for weather radar, the properties of such a signal are explored and its merit as a useful capability is shown.

Evaluating and Reducing the Envelope Fluctuations of OFDM Signals Based on Distortion Prediction

Frequenz ◽  
2017 ◽  
Vol 71 (1-2) ◽  
pp. 73-81
Author(s):  
Xiangyin Zhang ◽  
Xiaodong Zhu ◽  
Youxi Tang
Keyword(s):  
System Performance ◽  
Orthogonal Frequency Division Multiplexing ◽  
Nonlinear Distortion ◽  
Average Power ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Selective Mapping ◽  
Mapping Scheme ◽  
Ofdm Signals

Abstract Orthogonal frequency division multiplexing (OFDM) signals with large envelope fluctuations are prone to be affected by power amplifier (PA), resulting in degradation of system performance. Peak-to-average power ratio (PAPR) and cubic metric (CM) are commonly used as the reduction criteria of envelope fluctuations of OFDM signals. However, our analysis shows that minimizing the PAPR or CM does not necessarily mean the optimization of system performance, since both metrics are inadequate to quantify the distortion in nonlinear OFDM transmission. In this paper, we fully discuss the effects of PA nonlinearity on OFDM signals and propose a new metric called distortion component metric (DCM), which is closely related to the nonlinear distortion caused by the PA. We compare the system performance when several metrics are respectively used as the reduction criterion for the selective mapping scheme. It is shown that in the presence of memoryless or memory PA, the usage of DCM can provide better inband and out-of-band performance than PAPR and CM.

Radar Orthogonal Frequency Division Multiplexing Waveforms Agility Processing with Compressive Sensing

2013 ◽  
Vol 416-417 ◽  
pp. 1181-1186
Author(s):  
Feng Xie ◽  
Feng Liu ◽  
Xiao Hui Ye
Keyword(s):  
Compressive Sensing ◽  
Orthogonal Frequency Division Multiplexing ◽  
Matched Filter ◽  
New Method ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Measurement Matrix ◽  
Range Profile ◽  
Ofdm Signals

CS is a very new method that is being evaluated for many applications, in which signals are sparse in some basis/dictionary, e.g. the radar range profile. In this article, we have formulated the range processing with CS and introduced fair comparisons between matched filter and CS with chirps and OFDM signals. Two relevant features have been inspected: waveform bandwidth and measurement matrix.

Investigations of wavelength division multiplexing-orthogonal frequency division multiplexing (WDM-OFDM) system with 50 Gb/s optical access

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gagandeep Kumar ◽  
Kulwinder Singh
Keyword(s):  
Optical Networks ◽  
Wavelength Division Multiplexing ◽  
Laser Power ◽  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Wavelength Division ◽  
Ofdm Signal ◽  
Power Mapping ◽  
Ofdm Signals

Abstract In the present work, orthogonal frequency division multiplexing (OFDM) is combined with wavelength division multiplexing-passive optical networks (WDMPONs) to obtain the combined benefits of both technologies for overall system improvement. performance of five OFDM signals using WDM is analyzed. An optical system is designed using the OFDM signal, and its performance is analyzed using various matrices like bit error rate (BER) and Q-factor under the effect of varying laser power. Mapping of OFDM signals is done using 16-QAM modulation. The system shows an enhancement in the performance by increasing the laser power but up to some limit, and efficient results are obtained in the 70–130 mW laser power range.

Feasibility and Clinical Implications of Remotely Guided Ultrasound Examinations

2020 ◽  
Vol 91 (7) ◽  
pp. 592-596
Author(s):  
Quinn Dufurrena ◽  
Kazi Imran Ullah ◽  
Erin Taub ◽  
Connor Leszczuk ◽  
Sahar Ahmad
Keyword(s):  
Clinical Utility ◽  
Regional Wall Motion ◽  
Subjective Assessment ◽  
Clinical Implications ◽  
Pilot Studies ◽  
Objective Quality ◽  
The Us ◽  
Regional Wall Motion Abnormalities ◽  
Wall Motion Abnormalities

BACKGROUND: Remotely guided ultrasound (US) examinations carried out by nonmedical personnel (novices) have been shown to produce clinically useful examinations, at least in small pilot studies. Comparison of the quality of such exams to those carried out by trained medical professionals is lacking in the literature. This study compared the objective quality and clinical utility of cardiac and pulmonary US examinations carried out by novices and trained physicians.METHODS: Cardiac and pulmonary US examinations were carried out by novices under remote guidance by an US expert and independently by US trained physicians. Exams were blindly evaluated by US experts for both a task-based objective score as well as a subjective assessment of clinical utility.RESULTS: Participating in the study were 16 novices and 9 physicians. Novices took longer to complete the US exams (median 641.5 s vs. 256 s). For the objective component, novices scored higher in exams evaluating for pneumothorax (100% vs. 87.5%). For the subjective component, novices more often obtained clinically useful exams in the assessment of cardiac regional wall motion abnormalities (56.3% vs. 11.1%). No other comparisons yielded statistically significant differences between the two groups. Both groups had generally higher scores for pulmonary examinations compared to cardiac. There was variability in the quality of exams carried out by novices depending on their expert guide.CONCLUSION: Remotely guided novices are able to carry out cardiac and pulmonary US examinations with similar, if not better, technical proficiency and clinical utility as US trained physicians, though they take longer to do so.Dufurrena Q, Ullah KI, Taub E, Leszczuk C, Ahmad S. Feasibility and clinical implications of remotely guided ultrasound examinations. Aerosp Med Hum Perform. 2020; 91(7):592–596.

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