Carrier Frequency Modulation Research Articles

Single‐shot, simultaneous incoherent and holographic microscopy

In this work, we demonstrate single-shot, simultaneous recording and subsequent retrieval of one incoherent and two holographic (intensity and phase) images from the same camera frame. Demultiplexing of incoherent and holographic signals in the spatial frequency domain is made possible by carrier frequency modulation and spatial oversampling intrinsic to the off-axis digital holographic configuration. In particular, we show applications to combined fluorescence and digital holographic microscopy, as well as combined bright field and holographic second harmonic generation microscopy.

STATOR WINDINGS CURRENTS HARMONICS OF INDUCTION MOTOR, WHICH CONTROL FREQUANCY CONVERTER / DAŽNIO KEITIKLIU VALDOMO TRIFAZIO ASINCHRONINIO VARIKLIO STATORIAUS APVIJŲ SROVIŲ HARMONINĖS SUDĖTIES TYRIMAS

Paper presents examination of induction motor stator windings currents harmonics, when modulation index and carrier frequency are changed. Mathematical model of symmetrical induction motor connected as star without zero wire is developed. Matlab Simulink models are created and tested.

A Design of Wireless Transmission System

To design a wireless transmission system for water temperature data detection .This system uses FM as modulation scheme. The launching part adopts MC12017 and MC145152 as PLL, enabling to decrease the carrier frequency error to 1.8×10-4. The carrier frequency modulation is achieved by transfiguration diode HS113 and integrated VCO MC1648. The final stage amplifier adopts triode 2SC2053 with transmission power amounting to 0.245 mw. The receiving part adopts FM receiver chip MC3362 with low consumption and narrowband as main body, analog signals being amplified by LM386. C8051F410 is used as the control chip in the whole system to decode, frequency measure, and display. Experimental tests show that this system consumes lower power, reliable and steady, and is able to correctly transmit and receive data.

Reconfigurable FM-UWB transmitter

A 100 kbit/s frequency modulated ultra-wideband (FM-UWB) transmitter with digitally reconfigurable subcarrier modulation index (βsub), radio-frequency bandwidth (BRF) and carrier frequency band is presented and fabricated in 0.18 µm CMOS. A delta-sigma (ΔΣ) fractional-N phase-locked loop with an amplitude-controlled relaxation voltage-controlled oscillator (VCO) and digitally configurable 2-FSK modulation is designed for subcarrier generation, followed by a dual-path LC VCO, the centre frequency of which is set by a digitally configurable duty-cycled frequency-locked loop for nearly 600 MHz UWB signal generation.

An advanced monolithic digitalized random carrier frequency spread-spectrum clock generator for EMI suppression

A novel monolithic digitalized random carrier frequency modulation spread-spectrum clock generator (RCF-SSCG) is proposed. In this design, the output frequency of the proposed RCF-SSCG changes with the intensity of the capacitive charge and discharge current. Its analytical model is induced and the effect of the modulation parameters on the spread spectrum is numerically simulated and discussed. Compared with other works, this design has the advantages of small size, low power consumption and good robustness. The circuit has been fabricated in a 0.5 μm CMOS process and applied to a class D amplifier in which the proposed RCF-SSCG occupies an area of 0.112 mm2 and consumes 9 mW. The experimental results confirm the theoretical analyses.

Characteristic analysis of switching voltage power spectra under the mode of random carrier‐frequency modulation

PurposeThe purpose of this paper is to provide a theoretical platform for studying the characteristic of random carrier frequency (RCF) modulation and analyze the related parameters in terms of electromagnetic interference (EMI) suppressing.Design/methodology/approachIn this paper, the expression of the amplitude of switching voltage power spectra under the RCF mode is presented. According to the expression, the effectiveness of related parameters on EMI mitigation is discussed. Theoretical predictions are confirmed with a closed‐loop boost converter which power is 7.5 W and nominal switching frequency is 200 KHz. Finally, special attention has been paid to output voltage ripple.FindingsUnder RCF scheme, with increasing of random degree, the spectrum of switching voltage is dispersed, so the power spectrum density amplitude of switching voltage falls, and then the level of EMI is lowered. This theory shows that the voltage power spectrum density attains maximum when d=0.5, so in the spread spectrum modulation, the duty cycle of 0.5 should be avoided in terms of conducted EMI mitigation.Originality/valueThe analytical expression of switching voltage power spectra under the RCF mode is presented, providing a theoretical platform for the related research. The selection of duty cycle has effect on EMI level is put forward for the first time. Voltage ripple is discussed in close‐loop circuit.

Specific and rapid effects of acoustic stimulation on the tonotopic distribution of Kv3.1b potassium channels in the adult rat

Recent studies have demonstrated that total cellular levels of voltage-gated potassium channel subunits can change on a time scale of minutes in acute slices and cultured neurons, raising the possibility that rapid changes in the abundance of channel proteins contribute to experience-dependent plasticity in vivo. In order to investigate this possibility, we took advantage of the medial nucleus of the trapezoid body (MNTB) sound localization circuit, which contains neurons that precisely phase-lock their action potentials to rapid temporal fluctuations in the acoustic waveform. Previous work has demonstrated that the ability of these neurons to follow high-frequency stimuli depends critically upon whether they express adequate amounts of the potassium channel subunit Kv3.1. To test the hypothesis that net amounts of Kv3.1 protein would be rapidly upregulated when animals are exposed to sounds that require high frequency firing for accurate encoding, we briefly exposed adult rats to acoustic environments that varied according to carrier frequency and amplitude modulation (AM) rate. Using an antibody directed at the cytoplasmic C-terminus of Kv3.1b (the adult splice isoform of Kv3.1), we found that total cellular levels of Kv3.1b protein—as well as the tonotopic distribution of Kv3.1b-labeled cells—was significantly altered following 30 min of exposure to rapidly modulated (400 Hz) sounds relative to slowly modulated (0–40 Hz, 60 Hz) sounds. These results provide direct evidence that net amounts of Kv3.1b protein can change on a time scale of minutes in response to stimulus-driven synaptic activity, permitting auditory neurons to actively adapt their complement of ion channels to changes in the acoustic environment.

Age Effects in Temporal Envelope Processing: Speech Unmasking and Auditory Steady State Responses

The purpose of this study was to determine whether temporal envelope processing is reduced in older listeners. Experiment 1 tested the hypothesis that older listeners exhibit reduced speech unmasking at higher modulation rates. Experiment 2 tested the hypothesis that auditory steady state response (ASSR) amplitudes are reduced in older listeners at high modulation rates. Two groups of observers with relatively normal hearing (younger, mean age = 25.0 years and older, mean age = 68.7 years) participated in two experiments. Experiment 1 examined speech unmasking in modulated noise as a function of masker modulation rate (16 and 32 Hz) and target speech rate (normal and 33% time compressed). Experiment 2 measured ASSR amplitudes as a function of modulation rate (32 and 128 Hz) and carrier frequency (500 and 2000 Hz). Experiment 1 indicated that older listeners show reduced speech unmasking for normal-rate speech and reduced recognition of rapid speech in steady noise. However, for rapid speech, there is no age effect for speech unmasking and no difference in the magnitude of masking release as a function of modulation rate. In general, effects of listener age and masker modulation rate on the magnitude of masking release are observed only for normal-rate speech. Experiment 2 showed that the ASSR amplitudes of older listeners are reduced for a 128-Hz modulation rate but not for a 32-Hz modulation rate, irrespective of carrier frequency. These results suggest that the reduced speech unmasking seen in older listeners for relatively slow modulation rates is not caused by deficits in envelope processing but rather is associated with the more constrained redundancy of the speech material available during the masker minima. Deficits in temporal envelope processing are evident in advanced age but only for relatively high envelope frequencies.

새로운 소용량 승압형 PWM 초퍼 회로의 특성

Actually, The hard switching high frequency PWM DC-DC converters are existing accompany, the high frequency of pulse modulation carrier frequency increase of switching loss of power semiconductor switching elements, there are have some problem points of EMI etc. This compliance with a voltage surge or the electric current surge are where the switching transient phenomenon accompanies. In order to solve like this problem effectively it described the principle of operation of New Small Scale Boost PWM Chopper circuits from the present paper, draw Characteristics from simulation and experiment.

Multiple Auditory Steady State Responses (80-101 Hz): Effects of Ear, Gender, Handedness, Intensity and Modulation Rate

To evaluate how the amplitudes and latencies of auditory steady state responses (ASSRs) to multiple stimuli presented at rates between 80 and 101 Hz vary with the ear of stimulation, the handedness or gender of a subject, and the rate and intensity of the stimuli. ASSRs were recorded in a group of 56 young adults (27 females, 13 left handed) using several stimulus conditions. In the two main conditions, four sinusoidally amplitude-modulated tones (each uniquely modulated using rates between 80 and 105 Hz) with carrier frequencies of 500, 1000, 2000, and 4000 Hz, were presented concurrently to each ear (eight total). In the first condition the modulation rates for the left ear were slower than those for the right and in the second condition this relationship was reversed. Other conditions evaluated the responses to single stimuli, to multiple stimuli presented in one ear only and to multiple stimuli presented dichotically (four in each ear) with rates that decreased rather than increased with increasing carrier frequency. Stimuli were presented at an intensity of 73 dB SPL except in two conditions wherein the intensity was 53 dB SPL. At 73 dB SPL, multiple-stimulus ASSRs were significantly reduced (monotic or dichotic) compared with single-stimulus ASSRs, especially at 1000 and 2000 Hz. There were significant differences between monotic and dichotic stimulation. When the stimuli were presented dichotically, the amplitude of the response varied with the relative rates of modulation for the stimuli presented in each ear. ASSRs were larger in the ear with the higher rate when the carrier frequencies were 500 and 1000 Hz and when the modulation rates were <90 Hz. There were no consistent effects of gender or ear of stimulation. There were also no significant effects of handedness. Presenting multiple stimuli at 73 dB SPL in the same ear decreases the amplitude of the ASSR compared with when the stimuli are presented singly. This is caused by the masking effect of low on higher carrier frequencies and some other inhibitory effect of high on lower frequencies. Dichotic stimulation can increase the amplitude of the response to stimuli modulated more rapidly (and concomitantly decrease the responses to the stimuli modulated more slowly). This effect occurs only for carrier frequencies <2000 Hz and for modulation frequencies <90 Hz. Dichotic stimulation also causes a small but highly significant decrease in the latency of the response compared with monotic stimulation.

Frequency Modulation and First-Order Delta Sigma Modulation: Signal Representation With Unity Weight Dirac Impulses

Signal representation by means of unity weight and continuous-time aperiodic Dirac impulses is discussed, where the Dirac impulses are triggered at the zero crossings of frequency-modulated (FM) sinusoids. Analysis is based on generalized FM. The Fourier spectrum Psi(f) of such a Dirac impulse sequence psi(t) is composed of the signal spectrum plus a superposition of weighted FM spectra around integer multiples of the carrier frequency. It is demonstrated that FM-related sequences Psi(t) are generated by asynchronous DeltaSigmamodulators of first order. Practically relevant clock-synchronous versions psid(t) of Psid(t) are obtained, when the clock rate is twice the FM carrier frequency. A DeltaSigma-spectrum psid(f) can be regarded as a superposition of weighted and shifted versions of psi(f), whereby the first partial FM spectrum in psi(f) around the FM carrier frequency plays a dominant role.

The separation of out-of-plane displacement from in-plane components by fringe carrier method based on large image-shearing ESPI

A fringe carrier method for separating out-of-plane displacement from in-plane components based on large image-shearing electronic speckle pattern interferometry (ESPI) is presented. If the test object is respectively illuminated by two expanded symmetric illuminations in large image-shearing ESPI, two interferometers are formed. Carrier fringe patterns can be introduced by tilting reference surface a small angle. The carrier fringe patterns are demodulated after deformation of the object. Two phase maps, which include out-of-plane and in-plane displacement, can be obtained by using Fourier transform. Then out-of-plane displacement can be easily separated from in-plane displacement by simple operation between two unwrapped phase distributions. The principle of spatial carrier frequency modulation in large image-shearing ESPI is discussed. A typical three-point-bending experiment is completed. Experimental results are offered. The results show that the method offers high visibility of carrier fringes. And the system presented does not need a special beam as a reference light and has simple optical setup.

Spatial phase-shifting technique in large image-shearing electronic speckle pattern interferometry

A technique for deformation measurement by carrier is pre- sented, which is based on large image-shearing shearography. A refer- ence object is fixed on the side of a test object. They are all illuminated by one expanded laser beam. When a large image-shearing Wollaston crystal is used in front of a charge-coupled device CCD camera, one image of the object is superposed by one image of the reference surface. The carrier can be introduced by tilting the reference surface at a small angle. When Fourier transform is used to demodulate the modulated fringe pattern, the phase of deformation can be calculated and the de- formation can be measured accurately. The principle of spatial carrier frequency modulation in large-shearing electronic speckle pattern inter- ferometry ESPI is discussed. A typical experiment using a centrally loaded clamped circular plate is completed. Some experimental results are presented. The experimental results prove that the method can modulate a speckle pattern very well and the displacement fields can be measured effectively. © 2007 Society of Photo-Optical Instrumentation

Developmental Learning With Behavioral Mode Tuning by Carrier-Frequency Modulation in Coherent Neural Networks

We propose a developmental learning architecture with which a motion-control system learns multiple tasks similar to each other or advanced ones incrementally and efficiently by tuning its behavioral mode. The system is based on a coherent neural network whose carrier frequency works as a mode-tuning parameter. In our experiments, we consider two tasks related to bicycle riding. The first is to ride as temporally long as the system can before it falls down (task 1). The second is an advanced one, i.e., to ride as far as possible in a certain direction (task 2). We compare developmental learning to learn task 2 after task 1 with the direct learning of task 2. We also examine the effect of the mode tuning by comparing variable-mode learning (VML), where the carrier frequency is set free to move, with fixed-mode learning (FML), where the frequency is unchanged. We find that VML developmental learning results in the most efficient learning among the possible combinations. We discuss the effects of the incremental task assignment as well as the behavioral mode tuning in developmental learning.

Amplitude-Modulated Auditory Steady-State Responses in Younger and Older Listeners

The primary purpose of this investigation was to determine whether temporal coding in the auditory system was the same for younger and older listeners. Temporal coding was assessed by amplitude-modulated auditory steady-state responses (AM ASSRs) as a physiologic measure of phase-locking capability. The secondary purpose of this study was to determine whether AM ASSRs were related to behavioral speech understanding ability. AM ASSRs showed that the ability of the auditory system to phase lock to a temporally altered signal is dependent on modulation rate, carrier frequency, and age of the listener. Specifically, the interaction of frequency and age showed that younger listeners had more phase locking than old listeners at 500 Hz. The number of phase-locked responses for the 500 Hz carrier frequency was significantly correlated to word-recognition performance. In conclusion, the effect of aging on temporal processing, as measured by phase locking with AM ASSRs, was found for low-frequency stimuli where phase locking in the auditory system should be optimal. The exploration, and use, of electrophysiologic responses to measure auditory timing analysis in humans has the potential to facilitate the understanding of speech perception difficulties in older listeners.

Concurrent Encoding of Frequency and Amplitude Modulation in Human Auditory Cortex: MEG Evidence

A natural sound can be described by dynamic changes in envelope (amplitude) and carrier (frequency), corresponding to amplitude modulation (AM) and frequency modulation (FM), respectively. Although the neural responses to both AM and FM sounds are extensively studied in both animals and humans, it is uncertain how they are corepresented when changed simultaneously but independently, as is typical for ecologically natural signals. This study elucidates the neural coding of such sounds in human auditory cortex using magnetoencephalography (MEG). Using stimuli with both sinusoidal modulated envelope (f(AM), 37 Hz) and carrier frequency (f(FM), 0.3-8 Hz), it is demonstrated that AM and FM stimulus dynamics are corepresented in the neural code of human auditory cortex. The stimulus AM dynamics are represented neurally with AM encoding, by the auditory steady-state response (aSSR) at f(AM). For sounds with slowly changing carrier frequency (f(FM) <5 Hz), it is shown that the stimulus FM dynamics are tracked by the phase of the aSSR, demonstrating neural phase modulation (PM) encoding of the stimulus carrier frequency. For sounds with faster carrier frequency change (f(FM) > or = 5 Hz), it is shown that modulation encoding of stimulus FM dynamics persists, but the neural encoding is no longer purely PM. This result is consistent with the recruitment of additional neural AM encoding over and above the original neural PM encoding, indicating that both the amplitude and phase of the aSSR at f(AM) track the stimulus FM dynamics. A neural model is suggested to account for these observations.

Transmission of Vibronic Signals in Molecular Circuits

It is proposed and demonstrated using molecular dynamics and digital signal processing techniques that molecular vibrations can be used to transport signals in molecular circuits, revealing that signals transmitted along polypeptide molecules by a frequency-modulated carrier in the terahertz domain consume only 0.2 eV to successfully transfer one information bit; this energy is several orders of magnitude smaller than the several thousands of electronvolts needed using electrons in present electronic devices.

Frequency-multiplexed logic circuit based on a coherent optical neural network

We propose an adaptive logic circuit whose function can be controlled by optical carrier frequency modulation. The circuit learns the desired functions by adjusting the delay time at a spatial light modulator with a complex-valued Hebbian learning rule. After the learning, the circuit can switch its function all at once. A high degree of mechanical stability is achieved by spatial phase-difference coding. Two orthogonal phase components are detected in parallel spatially. Experiments demonstrate that the system works as an AND circuit at a certain frequency and as an XOR at another. The proposal will enhance the design of optical plastic cell architectures.

An evaluation of the spectral characteristics of switching converters with chaotic carrier-frequency modulation

This paper presents an evaluation of the spectral characteristics of switching converters with a chaotic carrier-frequency modulation scheme (CCFMS). By incorporating a Chua's circuit (CC) into the pulsewidth modulator for driving the switches, three modulation schemes, including the standard pulsewidth modulation scheme, periodic carrier-frequency modulation scheme, and CCFMS, can be realized with the CC in equilibrium, limit cycle, and chaos, respectively. The property of frequency spreading in CCFMS is studied by using a statistical analysis method. The developed model is applied to formulate the power spectral densities of the input current and the output voltage of the three basic DC/DC converters under CCFMS. Theoretical predictions are verified with experimental measurements.

A comparative study of carrier-frequency modulation techniques for conducted EMI suppression in PWM converters

A rigorous mathematical analysis and a comparative study of carrier-frequency modulation (CFM) techniques for the conducted electromagnetic interference (EMI) suppression in pulsewidth-modulated converters is presented. CFM techniques dither the switching period with a small amplitude variation around the nominal value, so that the harmonic power is redistributed over the spectrum of concern. Two types of dithering signals, including the periodic and random signals, are investigated in this paper. The operational characteristics as well as the input and output power spectra of the converters with the two modulating signals are compared. In particular, their characteristics in the low- and high-frequency harmonic power redistribution will be depicted. It is shown that random CFM (RCFM) gives a more effective way to disperse the harmonics around the switching frequency than the periodic CFM (PCFM) with the same frequency deviation. However, RCFM introduces higher low-frequency harmonics than the PCFM at the converter output. Furthermore, effects of the resolution filter bandwidth in the electromagnetic compatibility analyzer on conducted EMI measurement is discussed. The validity of the analyses is confirmed experimentally by using a dc/dc buck converter operating in continuous conduction mode.