Discrimination of the phase of amplitude modulation applied to different carriers: Effects of modulation rate and modulation depth for young and older subjects

2019 ◽  
Vol 146 (3) ◽  
pp. 1696-1704 ◽  
Author(s):  
Brian C. J. Moore ◽  
Aleksander P. Sęk
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Modulation Rate ◽  
Older Subjects

Design and Simulation of a Polarization-Independent Active Metamaterial Terahertz Modulator

2013 ◽  
Vol 455 ◽  
pp. 167-172 ◽  
Author(s):  
Li Shuang Feng ◽  
Bo Hao Yin ◽  
Zhen Zhou ◽  
Jia Wei Sui ◽  
Chen Long Li
Keyword(s):  
Theoretical Model ◽  
Resonance Frequency ◽  
Amplitude Modulation ◽  
Modulation Depth ◽  
Maximum Amplitude ◽  
High Modulation ◽  
Terahertz Communication ◽  
Modulation Rate ◽  
Polarization Independent ◽  
Modulation Speed

The design and simulation of a polarization-independent active metamaterial terahertz modulator is presented in this work. The device incorporates an array of gold triple SRRs on an n-doped gallium arsenide layer to create an active metamaterial terahertz modulator with a high modulation depth, a high modulation speed and an especial polarization-independent performance for use in terahertz communication, imaging and sense.We established the theoretical model and simulatedthe key performances of the device with Ansoft HFSS.The results showed that the device exhibits a polarization-insensitivebehavior with a maximum amplitude modulation depth of 71% and a modulation rate of3.2Mbps at the resonance frequency of0.86 THz.

scholarly journals Contribution of onset/offset information of modulation to amplitude modulation depth discrimination

2008 ◽  
Vol 123 (5) ◽  
pp. EL111-EL115 ◽  
Author(s):  
Derek R. Edwards ◽  
Jungmee Lee ◽  
Jennifer Andrews ◽  
Aileen Wong
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Depth Discrimination

scholarly journals Suppression of amplitude modulation induced by polarization mode dispersion using a multi-degree-of-freedom fiber filter

2018 ◽  
Vol 6 ◽  
Author(s):  
Rao Li ◽  
Youen Jiang ◽  
Zhi Qiao ◽  
Canhong Huang ◽  
Wei Fan ◽  
...  
Keyword(s):  
High Power ◽  
Amplitude Modulation ◽  
Transmission Spectrum ◽  
High Speed ◽  
Large Scale ◽  
Modulation Depth ◽  
Free Spectral Range ◽  
Polarization Mode Dispersion ◽  
Polarization Mode ◽  
Mode Dispersion

Polarization mode dispersion (PMD) in fibers for high-power lasers can induce significant frequency modulation to amplitude modulation (FM-to-AM) conversion. However, existing techniques are not sufficiently flexible to achieve efficient compensation for such FM-to-AM conversion. By analyzing the nonuniform transmission spectrum caused by PMD, we found that the large-scale envelope of the transmission spectrum has more serious impacts on the amount of AM. In order to suppress the PMD-induced FM-to-AM conversion, we propose a novel tunable spectral filter with multiple degrees of freedom based on a half-wave plate, a nematic liquid crystal, and an axis-rotated polarization-maintaining fiber. Peak wavelength, free spectral range (FSR), and modulation depth of the filter are decoupled and can be controlled independently, which is verified through both simulations and experiments. The filter is utilized to compensate for the PMD-induced FM-to-AM conversion in the front end of a high-power laser facility. The results indicate that, for a pulse with phase-modulation frequency of 22.82 GHz, the FM-to-AM conversion could be reduced from 18% to 3.2% within a short time and maintained below 6.5% for 3 h. The proposed filter is also promising for other applications that require flexible spectral control such as high-speed channel selection in optical communication networks.

scholarly journals Binaural summation of amplitude modulation involves weak interaural suppression

2018 ◽  
Author(s):  
D.H. Baker ◽  
G. Vilidaite ◽  
E. McClarnon ◽  
E. Valkova ◽  
A. Bruno ◽  
...  
Keyword(s):  
Amplitude Modulation ◽  
Modulation Depth ◽  
Visual Signal ◽  
Data Sets ◽  
Single Object ◽  
Ecological Constraints ◽  
Binaural Summation ◽  
Eeg Data ◽  
Signal Combination ◽  
The Brain

AbstractThe brain combines sounds from the two ears, but what is the algorithm used to achieve this summation of signals? Here we combine psychophysical amplitude modulation discrimination and steady-state electroencephalography (EEG) data to investigate the architecture of binaural combination for amplitude-modulated tones. Discrimination thresholds followed a ‘dipper’ shaped function of pedestal modulation depth, and were consistently lower for binaural than monaural presentation of modulated tones. The EEG responses were greater for binaural than monaural presentation of modulated tones, and when a masker was presented to one ear, it produced only weak suppression of the response to a signal presented to the other ear. Both data sets were well-fit by a computational model originally derived for visual signal combination, but with suppression between the two channels (ears) being much weaker than in binocular vision. We suggest that the distinct ecological constraints on vision and hearing can explain this difference, if it is assumed that the brain avoids over-representing sensory signals originating from a single object. These findings position our understanding of binaural summation in a broader context of work on sensory signal combination in the brain, and delineate the similarities and differences between vision and hearing.

scholarly journals Aging Does Not Affect Beta Modulation during Reaching Movements

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Serena Ricci ◽  
Ramtin Mehraram ◽  
Elisa Tatti ◽  
Aaron B. Nelson ◽  
Martina Bossini-Baroggi ◽  
...  
Keyword(s):  
Modulation Depth ◽  
Movement Time ◽  
Peak Latency ◽  
Reaching Movements ◽  
Performance Indices ◽  
Reaching Task ◽  
Beta Power ◽  
Total Movement ◽  
Older Subjects ◽  
Highly Correlated

During movement, modulation of beta power occurs over the sensorimotor areas, with a decrease just before its start (event-related desynchronization, ERD) and a rebound after its end (event-related synchronization, ERS). We have recently found that the depth of ERD-to-ERS modulation increases during practice in a reaching task and the following day decreases to baseline levels. Importantly, the magnitude of the beta modulation increase during practice is highly correlated with the retention of motor skill tested the following day. Together with other evidence, this suggests that the increase of practice-related modulation depth may be the expression of sensorimotor cortex’s plasticity. Here, we determine whether the practice-related increase of beta modulation depth is equally present in a group of younger and a group of older subjects during the performance of a 30-minute block of reaching movements. We focused our analyses on two regions of interest (ROIs): the left sensorimotor and the frontal region. Performance indices were significantly different in the two groups, with the movements of older subjects being slower and less accurate. Importantly, both groups presented a similar increase of the practice-related beta modulation depth in both ROIs in the course of the task. Peak latency analysis revealed a progressive delay of the ERS peak that correlated with the total movement time. Altogether, these findings support the notion that the depth of beta modulation in a reaching movement task does not depend on age and confirm previous findings that only ERS peak latency but not ERS magnitude is related to performance indices.

Amplitude-modulation following response (AMFR): Effects of modulation rate, carrier frequency, age, and state

1993 ◽  
Vol 68 (1) ◽  
pp. 42-52 ◽  
Author(s):  
Ellen C. Levi ◽  
Richard C. Folsom ◽  
Robert A. Dobie
Keyword(s):  
Amplitude Modulation ◽  
Carrier Frequency ◽  
Modulation Rate

scholarly journals Association of Auditory Steady State Responses with Perception of Temporal Modulations and Speech in Noise

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Venugopal Manju ◽  
Kizhakke Kodiyath Gopika ◽  
Pitchai Muthu Arivudai Nambi
Keyword(s):  
Steady State ◽  
Speech Perception ◽  
Amplitude Modulation ◽  
Modulation Depth ◽  
Normal Hearing ◽  
Positive Correlation ◽  
Behavioral Method ◽  
Modulation Detection ◽  
Auditory Steady State Responses ◽  
40 Hz

Amplitude modulations in the speech convey important acoustic information for speech perception. Auditory steady state response (ASSR) is thought to be physiological correlate of amplitude modulation perception. Limited research is available exploring association between ASSR and modulation detection ability as well as speech perception. Correlation of modulation detection thresholds (MDT) and speech perception in noise with ASSR was investigated in twofold experiments. 30 normal hearing individuals and 11 normal hearing individuals within age range of 18–24 years participated in experiments 1 and 2, respectively. MDTs were measured using ASSR and behavioral method at 60 Hz, 80 Hz, and 120 Hz modulation frequencies in the first experiment. ASSR threshold was obtained by estimating the minimum modulation depth required to elicit ASSR (ASSR-MDT). There was a positive correlation between behavioral MDT and ASSR-MDT at all modulation frequencies. In the second experiment, ASSR for amplitude modulation (AM) sweeps at four different frequency ranges (30–40 Hz, 40–50 Hz, 50–60 Hz, and 60–70 Hz) was recorded. Speech recognition threshold in noise (SRTn) was estimated using staircase procedure. There was a positive correlation between amplitude of ASSR for AM sweep with frequency range of 30–40 Hz and SRTn. Results of the current study suggest that ASSR provides substantial information about temporal modulation and speech perception.

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