Amplitude Modulation

Background: Two-channel auditory steady-state response (ASSR) recording at high and low MF (modulation frequency) most likely provides an insight about the response amplitude and latency from different directions at the brainstem level and at the thalamus or cortical level. Little is known about the combined relationship between MF (39 and 79 Hz) and electrode montages (ipsilateral and contralateral) to single AM (amplitude modulation) tones on the ASSR amplitude and latency. Purpose: To determine if ipsilateral versus contralateral response asymmetries are present at the brainstem level (79 Hz ASSR) and at the thalamus or cortical levels (39 Hz ASSR). Research Design: Descriptive and inferential statistics for interchannel ipsilateral and contralateral ASSR amplitude and latency to 79 and 39 Hz. Study Sample: Twenty-five normal-hearing, right-handed young female adults participated in the study. All participants were right-handed, and their age ranged between 18 to 28 years (mean 24.5 6 1.6 years). Data Collection and Analysis: Ipsilateral and contralateral ASSR to 39 and 79 Hz MF and 100% AM stimuli were recorded at 500, 2000, and 4000 Hz carrier frequencies at 65 dB SPL. The ASSR amplitudes and phases were determined for each MF across Fc (carrier frequency) for the two channels to the test (right) ear. ASSR amplitude and latency between recording montages for each MF and across carrier frequency were compared by computing two-way repeated measures ANOVA. The mean ipsilateral ASSR amplitudes to 39 Hz across frequency were slightly larger (228.6 6 61.6 mV) than the contralateral response amplitude (223.2 6 78 mV) while the mean ipsilateral 79 Hz amplitudes were smaller (127.3 6 114.8) compared to contralateral 79 Hz amplitude (154.6 6 112.7 mV). For latency response, the mean ipsilateral/contralateral latency difference, on average, was 1 msec or less for both MFs. Results, in normal female adults, indicated no significant interchannel ASSR asymmetries for amplitude and latency (p . 0.05) at the brainstem (79 Hz ASSR) and at the thalamus or cortical levels (39 Hz ASSR). Conclusions: Interchannel ipsilateral and contralateral ASSR amplitude and latency to 79 and 39 Hz are not significantly different in normal, young female adults. Two-channel recording of ASSR to different MFs may be of clinical value in otoneurologic assessment.

By recording the phase angle difference between the excitation force and the tip response in amplitude modulation AFM it is possible to image compositional variations in heterogeneous samples. In this contribution we address some of the experimental issues relevant to perform phase contrast imaging measurements. Specifically, we study the dependence of the phase shift on the tip-surface separation, interaction regime, cantilever parameters, free amplitude and tip-surface dissipative processes. We show that phase shift measurements can be converted into energy dissipation values. Energy dissipation curves show a maximum (∼10 eV/cycle) with the amplitude ratio. Furthermore, energy dissipation maps provide a robust method to image material properties because they do not depend directly on the tip-surface interaction regime. Compositional contrast images are illustrated by imaging conjugated molecular islands deposited on silicon surfaces.

Standard electromagnetic interference (EMI) shielding relieses on doping the insulating polymer matrix with conductive materials (e.g., multi-walled carbon nanotubes (MWCNT), copper, or graphene) to physically absorb or reflect the waves. In contrast, AI models for MRET materials focus on biophysical neutralization and harmonic manipulation rather than physically blocking the signal. This allows the nylon to mitigate the biological risks of radiation exposure while permitting the cellular or wireless signals to pass through unimpeded. MRET nylon is a specialized polymer material that is structured at the nanoscale into fractal geometries. When subjected to external EMR (such as microwave or radio frequency signals from cellular phones), the piezoelectric properties of the polymer cause it to generate subtle, random, low-frequency oscillations.

Standard electromagnetic interference (EMI) shielding relieses on doping the insulating polymer matrix with conductive materials (e.g., multi-walled carbon nanotubes (MWCNT), copper, or graphene) to physically absorb or reflect the waves. In contrast, AI models for MRET materials focus on biophysical neutralization and harmonic manipulation rather than physically blocking the signal. This allows the nylon to mitigate the biological risks of radiation exposure while permitting the cellular or wireless signals to pass through unimpeded. MRET nylon is a specialized polymer material that is structured at the nanoscale into fractal geometries. When subjected to external EMR (such as microwave or radio frequency signals from cellular phones), the piezoelectric properties of the polymer cause it to generate subtle, random, low-frequency oscillations.

Combining pseudo random-modulation techniques with cavity enhanced spectroscopy allows the estimation of both optical path length and absorption while using a cw diode laser as the light source. Two pseudo-random modulation approaches are described, in each case combined with an off-axis cavity consisting of two cylindrical mirrors oriented to produce a dense pattern of cavity modes. In one approach, the amplitude of the laser is modulated; deconvolution results in an exponential ring-down decay curve. In the second approach, tone bursts that modulate the laser frequency are switched on and off with a pseudo-random code. Deconvolution yields the first derivative of an exponential whose amplitude is proportional to absorbance. With either approach the dynamic range of the transmitted intensity is much smaller than for a ring-down experiment, allowing high gain before the signal is digitized. Initial experimental results measuring carbon monoxide are presented, and the dependence of d...

At Aso volcano, Kyushu, Japan, several different types of volcanic tremor have been observed for many years. One of them is the continuous tremor, the ground vibration which has dominant frequency between 3 and 10 Hz and has approximately constant amplitudes without any clear beginning and ending. We observed the continuous tremor at Aso using short period seismometer arrays for 3 days in 1999. We locate the source of the continuous tremor by seismic array data processing. We use the semblance coefficients in order to estimate the arrival azimuth and apparent slowness by grid search. The epicenters of the continuous tremor are located around the currently active crater, and the source depths are likely to be shallower than 600 m. We find that the estimated epicenter clearly migrates synchronized with the change in the tremor amplitude. The migration often occurs periodically with a period of about 80 s, but aperiodic occurrence of the migration is also often seen. In both cases, the epicenter is located southeastward (northwestward) when the amplitude is larger (smaller). We propose that there are two or more independent tremor sources with fixed locations, and that their amplitudes modulate either aperiodically or periodically with periods nearly 80 s. The tremor signals from those sources are mixed at the arrays, and the estimated epicenter parameters vary according to which signal dominates the seismograms. The simplest model is that there are two point sources, one at west and the other at south of the crater (we call the two sources as "NW source" and "SE source", respectively), and the amplitude of the SE source changes with time. Consequently, the SE source dominates the seismogram when the observed amplitude is larger, whereas the NW source dominates when the amplitude is smaller. We generate synthetic seismograms, and apply the location technique to them to verify the validity of the two point source model and to search the locations of two sources which can explain the observed synchronization between the amplitude and the apparent epicenter location. We find that the distance between the two sources needs to be more than 400 m to agree with the observation. We also analyze the seismic array data observed in 2001, and infer that the NW source in 1999 may be identical to the tremor source of the 2001 data.

We have proposed a square wave quadrature amplitude modulation (SW-QAM) scheme for visible light communication (VLC) using an image sensor in our previous work. Here, we propose a robust and unified system by using a neural decoding method. This method offers essential SW-QAM decoding capabilities, such as LED localization, light interference elimination, and unknown parameter estimation, bundled into a single neural network model. This work makes use of a convolutional neural network (CNN) that has a capability in automatic learning of unknown parameters, especially when it deals with images as an input. The neural decoding method can provide good solutions for two difficult conditions that are not covered by our previous SW-QAM scheme: unfixed LED positions and multiple point spread functions (PSFs) of multiple LEDs. Responding to the above solutions, three recent CNN architectures- VGG, ResNet, and DenseNet-are modified to suit our scheme and other two small CNN architectures- VG...

Radio over fiber (RoF) can be assessed as a system of most convenient combination of optical fiber and radio signals. The technique of orthogonal frequency division multiplexing (OFDM) considers as a data distribution over a huge number of carriers having spaced from each other with specific frequencies at overlap bands. Hence incorporates OFDM with the optical fiber, OFDM-RoF system can be increased the modulation RF access capacity besides high-speed data transmission, it considers a broadband communication trend of the current and future applications specifically for 5G mobile. The optical network scenarios of various RF can be model with optisystem software, and OFDM in addition to use a section of the orthogonal multiplex frequency of 16-quadrature amplitude modulation (QAM) RF modulating signal. In the optical domain, Mach-Zehnder modulator (MZM) optical modulators are used to carry out different results with different fiber lengths. An OFDM-RoF wireless communication system considers as advanced data rate transmission achievement by minimum delays. The essential goal of this paper is for identifying the minimum bit error rate (BER) for the 16-QAM modulation with varying fiber length. The OFDM-RoF system can be able for realizing a fiber length 100 km with a restricted decreasing in the received power so that the constellation noise is became greater despite of applying electrical amplification and optical amplification.

Squeezed state of light explores a new era in noiseless communication and data processing recently breaking the quantum limit of noise. We propose a new mechanism of modulating an amplitude-squeezed signal with the instantaneous intensity variation of a coherent signal. The modulating signal is a coherent light where the amplitude-squeezed light takes the role of a carrier signal.

The accuracy of target position detection in IR seeker depends on the accuracy of tracking error signal (TES) extraction from seeker Field of View (FOV). The type of reticle inside the seeker determines the output modulation signal that carries the TES. In this paper, the stationary wagon wheel reticle is used, which makes the type of the output signal as FM modulation in the linear region of FOV, but the signal will be distorted by changing the radius of target image spot (TIS) and in the nonlinear region of FOV. Firstly, we applied the Hilbert transform algorithm for the first time in this field and compared it with the conventional algorithm in the linear region of FOV to decrease the effect of changing the radius of TIS. Secondly, we presented a new method in the nonlinear region to extract the TES. The results show improvement in TES accuracy extraction in the linear and nonlinear region over the FOV for different radii of TIS.

The title of my address suggests that propose to discuss the problems connected with wireless telegraphy and telephony. It should be observed, however, that ordinary telegraphy and telephony and electrical transmission of large amounts of power is aerial transmission and faces some of the problems which confront us today in wireless transmission. But, of course, the problems of aerial transmission in their relation to wireless telegraphy and telephony present their most interesting aspect and I shall, therefore, devote most of my time this evening to this particular aspect, of the problem of aerial transmission.

Recently, several studies were conducted on the micro-Doppler(MD) phenomenon to identify a warhead from decoys. Both, the warhead and decoy, can be modeled as various shapes and maneuver with their own micro-motion. Their MD phenomenon can be demonstrated by amplitude modulation and phase modulation. Most studies have utilized approximate solutions to express the amplitude modulation regardless of various warhead and decoy shapes. However, the exact solution of the amplitude modulation is required for more effective warhead identification. In this study, we proposed a new modeling method of receiving radar signals from warheads and decoys based on physical optics. The proposed solution was evaluated using an electromagnetic prediction technique and computer-aided design models.

Barcode technology is slowly being replaced with transponder tags that have many benefits over barcodes. Four issues with transponder tags are battery life, power requirement, range of communication, and physical size. Microwave backscatter modulation (MBM) is used throughout industry to reduce the power requirement and size on the transponder tags while compromising range. Researchers and designers of current transponder tags typically utilize a passive carrier-present carrier-absent (CPCA) reflection of the reader's carrier wave, or their transponder design uses an active backscatter system with an amplifier and circular polarization modulation. This research project develops a communication system that mixes a reader's carrier wave with an intermediate frequency (IF) at the active Probe in order to improve isolation of the data signal in a high-clutter environment. The design and testing ofProbe and Reader concepts are discussed, and the advantages and weaknesses of each ...

All-optical gate control signal generation is demonstrated from flag pulses, using a Fabry-Pérot filter followed by a semiconductor optical amplifier. Ten control pulses are generated from a single flag pulse having less than 0.45-dB amplitude modulation. By doubling or tripling the number of flag pulses, the number of control pulses increases approximately by a factor of two or three. The circuit can control the switching state of all-optical switches, on a packet-by-packet basis, and can be used for nontrivial network functionalities such us self-routing.

We demonstrate an optical power limiter using a semiconductor optical amplifier (SOA)-based interferometric gate powered by a strong continuous-wave input signal. We present a detailed theoretical and experimental investigation of the power limiting characteristics of saturated SOA-based switches, showing good agreement between theory and experiment.

We present a new technique for extending the decay time of the impulse response function of a Fabry-Pérot filter while simultaneously maintaining a large bandwidth. It involves double passing through the filter and it can be used for the easy multiplication of the repetition rate of optical sources. We apply the concept to a 10-GHz pulse train to demonstrate experimentally the rate quadruplication to 40 GHz.

We present methods for obtaining high-repetition-rate full duty-cycle RZ optical pulse trains from lower rate laser sources. These methods exploit the memory properties of the Fabry-Perot filter for rate multiplication, while amplitude equalization in the output pulse train is achieved with a semiconductor optical amplifier or with a second transit through the Fabry-Perot filter. We apply these concepts to experimentally demonstrate rate quadruplication from 10 to 40 GHz and discuss the possibility of taking advantage of the proposed methods to achieve repetition rates up to 160 GHz.

Multi-band carrierless amplitude and phase modulation and subcarrier multiplexing (SCM) are combined to produce a novel multi-users access scheme for visible light communications (VLC). To demonstrate this scheme, an experimental and realistic scenario is set-up by using a low-cost commercial office white light-emitting diode (LED) downlight. Furthermore, subcarrier spacings are added to reduce the inter-channel interferences and the parameters of the pulse shaping filters are optimized. The distance between the transmitter and the receiver is fixed at 2.15 m. After the optimization, the experiment setup achieves a spectral efficiency of 5.08 b/s/Hz after subcarrier spacing and with very light post-processing. A total of 20 users can be provided with the multi-users access scheme with a sum data rate of 162.5 Mb/s. The receiving attocell is measured at 4.56 m 2 . To the best of our knowledge, the resulting work presents the highest range, and one of the highest spectral efficiencies for a phosphorous white LED (ph-LED)-based VLC system, thanks to subcarrier spacing. With SCM, it is also the first ph-LED-based VLC multi-users system. INDEX TERMS Multi-band CAP, subcarrier multiplexing, multi-user access, visible light communication, white LED, subcarrier spacing, attocell.

Wearable sensing has enabled physiological monitoring in everyday life. Clinically, cardiovascular and respiratory monitoring commonly requires separate devices. However, for feasibility in wearable systems, they are integrated into a single device. Since seismocardiography (SCG) records the motion of the chest wall, it has the potential to monitor both vital signs. The primary application of SCG is cardiovascular monitoring. As a result, its ability to detect respiration has been less defined. This study characterizes how SCG is affected by respiration and consequently, how respiratory metrics can be derived from these effects. The sternal motion of 40 subjects was recorded using an inertial measurement unit with a spirometer for reference. Three scenarios were examined with the subject at rest, holding their breath at peak inhalation, and holding their breath when exhaled. Three main aspects of respiratory modulation were explored: amplitude modulation, frequency modulation, and baseline wandering. The SCG amplitude was observed to be dependent on respiratory volume whereas baseline and frequency modulation were dependent on inhalation phase. All three effects were employed separately in the calculation of respiratory rate. Estimations from baseline wandering, amplitude modulation, and heart rate modulation produced r-squared values of 0.71, 0.44, and 0.66, respectively. The accuracy of tidal volume measurement was limited by a high inter-subject variability. Estimation of the respiratory waveform produced an average r-squared of 0.76 using multivariate linear regression. This demonstrates the potential of SCG as a tool for respiratory monitoring within an integrated, noninvasive cardiorespiratory monitoring system from a single point of contact.

In the research aims to analyzed feedback parameter on Self-Mixing Interferometry (SMI) signals. It is because the feedback parameter is one of the determined parameters in SMI vibration sensor research. The experimental apparatus consists of a laser diode as the light source, mirror as a target, collimator as light alignment, and PLX-DAQ as data acquisition executed by Arduino Uno. The principle of data retrieval with the manner of the light source is directed exactly perpendicular to the vibrating target, then reflected and arrested by the detector (photodiode) contained in the laser diode. Light arrested by the photodiode in the form of optical value then automatically converted into voltage value displayed on a personal computer (PC). This feedback on SMI is obtained by variation of the vibration frequency given to a target. The variation of vibration given is 10-100 Hz with 10 Hz increment and each frequency is taken 1000 data. Based on the research that has been done then resu...

Conventional approaches of digital modulation schemes make use of amplitude, frequency and/or phase as modulation characteristic to transmit data. In this paper, we exploit circular polarization (CP) of the propagating electromagnetic carrier as modulation attribute which is a novel concept in digital communications. The requirement of antenna alignment to maximize received power is eliminated for CP signals and these are not affected by linearly polarized jamming signals. The work presents the concept of Circular Polarization Modulation for 2, 4 and 8 states of carrier and refers them as binary circular polarization modulation (BCPM), quaternary circular polarization modulation (QCPM) and 8-state circular polarization modulation (8CPM) respectively. Issues of modulation, demodulation, 3D symbol constellations and 3D propagating waveforms for the proposed modulation schemes are presented and analyzed in the presence of channel effects, and they are shown to have the same bit error performance in the presence of AWGN compared with conventional schemes while provide 3dB gain in the flat Rayleigh fading channel.

The transmission performance of 112 Gb/s hybrid multiband (HMB) carrier-less amplitude and phase (CAP)/quadrature amplitude modulation (QAM) system over a single mode fiber (SMF) is investigated. Analog squared root-raised cosine (SRRC) orthogonal shaping filters are used to implement the CAP signal that is used to modulate  the 1550 nm (or 1310 nm) continuous wave (CW) laser using Mach-Zehnder modulator. Simulation of HMB CAP-M/QAM-M schemes with M=16, 32, and 64 is performed and the results are compared with that of the corresponding 112 Gb/s single-band of the same scheme. The results show that increasing the roll-off factor r will improve the bit error rate (BER) performance of the system. The optical power required to achieve a BER of for CAP-16/QAM-16 system reduces by 0.75 and 1.88dBm for four-subband and single-band schemes, respectively, when r increases from 0 to 0.4. While the improvement in the laser transmitted optical power for 4-subband and single-band CAP-32/QAM-32 s...

Ecological awareness increases energy production by wind turbines, but the considerable associated annoyance risk requires carefully designed noise control strategies when they are to be installed in densely populated regions. Well-chosen operational restrictions may reduce noise annoyance while preserving cost-effectiveness. This research project investigates the relationship between the inhabitants' wind turbine noise annoyance, exposure indicators, operational characteristics and environmental variables for a specific industrial site near a residential area. In contrast to most other research on wind turbine noise annoyance, in this study a six-month field experiment is conducted including regular on-line annoyance reports, continuous 1/3-octave band noise level registrations, periodic sound recordings, electricity production per minute and meteorological observations. Logistic regression reveals that the risk of high annoyance not only depends on the rotational speed, but also on the wind turbines' nacelle position relative to the location of the dwellings, i.e. the wind direction. This directivity effect can be captured when noise parameters such as the background noise level caused by other sources and a so-called fluctuation-indicator are introduced. Background noise measurements incorporate wind induced vegetation and road traffic noise; their LA95-level is inversely related to the risk of high annoyance. The fluctuation-indicator is calculated from the 1/3-octave band spectra to capture the periodic part of wind turbine noise; here the risk of high annoyance increases with increasing fluctuation strength. These detailed findings can be used for designing operational restrictions that limit noise annoyance while keeping production as high as possible.

In order to improve performance of analog signal transmission, we recently proposed a novel analog single-carrier transmission with frequency-domain equalization (analog SC-FDE). Analog SC-FDE adopts double sideband (DSB) technique (referred to as analog SC-DSB-FDE) to transmit signal. In this paper, in order to double the spectrum efficiency of analog SC-DSB-FDE, single sideband (SSB) technique is introduced. Analog SC-SSB-FDE applies discrete Fourier transform (DFT), frequency-domain spectrum shaping filter and mapping, inverse DFT (IDFT), and cyclic prefix (CP) insertion before transmission. At the receiver, one-tap FDE is applied to take advantage of frequency diversity and a spectrum copy for restoring spectrum is applied. By computer simulation, we show that analog SC-SSB-FDE achieves better normalized mean square error (NMSE) performance than conventional analog SSB transmission and keeps the performance quality similar to analog SC-DSB-FDE.