FM Modulation Research Articles

Performance Realization of CORDIC based GMSK System with FPGA Prototyping

The Gaussian Minimum Shift Keying (GMSK) modulation is a digital modulation scheme using frequency shift keying with no phase discontinuities, and it provides higher spectral efficiency in radio communication systems. In this article, the cost-effective hardware architecture of the GMSK system is designed using pipelined CORDIC and optimized CORDIC models. The GMSK systems mainly consist of the NRZ encoder, Integrator, Gaussian filter followed by FM Modulator using CORDIC models and Digital Frequency Synthesizer (DFS) for IQ Modulation in transmitter section along with channel, the receiver section has FM demodulator, followed by Differentiator and NRZ decoder. TheCORDIC algorithms play a crucial role in GMSK systems for IQ generation and improve the system performance on a single chip. Both the pipelined CORDIC and optimized CORDIC models are designed for 6-stages. The optimized CORDIC model is designed using quadrature mapping method along with pipeline structure. The GMSK systems are implemented on Artix-7 FPGA with FPGA prototyping. The Performance analysis is represented in terms of hardware constraints like area, time and power. These results show that the optimized CORDIC based GMSK system is a better option than the pipelined CORDIC based GMSK systems for real-time scenarios.

A Self-Calibrated 16-GHz Subsampling-PLL-Based Fast-Chirp FMCW Modulator With 1.5-GHz Bandwidth

This article presents a 16-GHz frequency-modulated continuous-waveform (FMCW) modulator for radar applications in 28-nm CMOS. A two-point modulation technique is applied to reach a fast-chirp operation. A digital-to-time converter (DTC)-based subsampling phase-locked loop (PLL) is implemented to eliminate the power and noise from the frequency divider. Compared with the conventional delta-sigma division ratio-modulated PLL, this article presents an FM modulator with a finer loop-time resolution that lowers the quantization noise and improves the chirp FM accuracy. A voltage-driven analog varactor enables a programmable chirp bandwidth up to 1.5 GHz. The frequency-digital to analog converter (FDAC) nonlinearity is pre-distorted by an on-chip calibration engine. This FMCW modulator chirps 1.5-GHz bandwidth within 10 μs. The corresponding root-mean-square (rms) frequency error is 230 kHz, which is less than 0.015% of the chirp bandwidth.

High-sensitivity vibrometer based on FM self-mixing interferometry

We present a new optical instrument for vibrations measurement, based on a method to read the frequency modulation of a laser diode self-mixing interferometer. The laser source, when exposed to back-injection of its emitted power, is perturbed in frequency and amplitude (self-mixing effect). When the optical back-injection level is low, the self-mixing effect introduces a frequency and amplitude modulation (FM and AM) of the emitted optical field. We demonstrated with a prototype instrument that the performances of FM modulation, in terms of resolution, sensitivity and bandwidth, show an improvement of two order of magnitude with respect to well-known AM self-mixing interferometer.

Analysis of the Acoustic Propagation Parameters of the Natural Sounds of Delphinapterus leucas and Odorrana tormota Fundamental in the Startle of the Female Anopheles Gambiae

The female Anopheles gambiae, a malaria vector detects ultrasound by the antennae causing startle responses attributed to neural stress. Resistance to the control and treatment measures by malaria vectors and pathogens has resulted to a low decline rate in malaria cases and deaths. Studies have shown a 46% evasive response in the A. gambiae by the 35-60 kHz sounds of Odorrana tormota. This study determined, analysed and compared acoustic propagation parameters of the sounds of Delphinapterus leucas and Odorrana tormota fundamental in the startle of the mosquito. The sound of D. leucas and O. tormota were acquired. The Avisoft-SASLab 5.2 and Raven Pro 1.5 software were used in the study. Spectral analysis of sounds of D. leucas and O. tormota showed composition of pulsate audible and utrasonic harmonics, FM and CF modulation. The mean of the fundamental frequency (mean entire) of D. leucas was 1.684kHz, less by 3.712kHz from that of the sound of O. tormota differing insignificantly. The sound of D. leucas recorded a maximum value of 64.8kHz in maximum frequency (mean) which was 25.5kHz above that of O. tormota with a highly significant difference. Also, the sound of D. leucas had a 64.10kHz bandwidth (mean entire) wider than that of O. tormota by 53.64kHz, a highly significant difference. The peak amplitude (mean entire) of the sound of D. leucas was 89.05Pa less by 39.837kHz from that of the sound of O. tormota differing significantly. The mean acoustic energy of D. leucas was 0.07Pa2s whereas the O. tormota possessed 2,496.63Pa2s differ insignificantly. These parameters are essential in the study of mosquito repellence and design of a repellent device.

A vibration control for disassembly of turbine blades

Typically, disassembly forces are unknown due to high forces or high temperatures during product operation, where assembly connections solidify. For the regulation of disassembly forces a controller is developed. The controller is formed for two steps: The first step is a PID controller that produces a force, which overcomes a solidifying force slightly. The second step is a vibration controller with a FM modulation to regulate the frequency of impacts. Vibrations are useful for decreasing the force amplitude for caring the joined components. Finally, the control is validated with disturbances in a simulation.

Modulation spectroscopy of coherent population trapping resonance and light shifts

We develop a theory of modulation response of the coherent population trapping (CPT) resonance. We consider the simplest three-level atom, but take into account the polychromatic spectrum of the pumping and probing light produced by pure FM modulation of single frequency field. The analysis based on the density matrix equations rigorously includes the most important for applications range of modulation parameters where modulation frequency and deviation are comparable with or greater than the CPT linewidth, so the response of the atomic medium is not adiabatic. Some theoretical results, in particular the possibility of using a quadrature response to modulation to suppress light shift, are compared with the experiment carried out with a diode laser (VCSEL) and 87Rb atoms.

高精度デジタル型FM変調器の開発とFM同期放送の実現

高精度デジタル型FM変調器の開発とFM同期放送の実現

High-Accuracy AM-FM Radar with an Active Reflector

An amplitude-modulated and frequency-modulated (AM-FM) radar with an active reflector to produce high-accuracy distance measurements is proposed and demonstrated in this paper. The proposed radar consists of an AM-FM base module and an active reflector. The combination of AM and FM modulations resolves ambiguity of the absolute distance in typical AM radars, while improving range accuracy in typical FM radars with narrow bandwidth. Also, the active reflector, which translates the frequency of the received signal, resolves the problem of phase detection interference due to the direct Tx-to-Rx leakage in AM radars. In this paper, the operating principle, experimental tests, and analysis are presented. The implemented AM-FM radar operates in X-band (Tx: 10.5 GHz, Rx: 8.5 GHz) with the 620 MHz bandwidth. The measured range accuracy of less than ±10 mm at a distance of 70 m is obtained.

Teaching Frequency Modulation to Undergraduate Electrical and Electronics Engineering Students Using MATLAB/SIMULINK

Teaching scientific concepts to undergraduate students is quite difficult sometimes especially when lots of mathematical terms are involved in the teaching process. Frequency modulation is one of these concepts. With the aid of MATLAB/SIMULINK toolbox it becomes much easier to realize this concept (FM Modulation) whether in time domain or in frequency domain. In doing so, the students will grasp the concept of Frequency Modulation faster and easier. The present paper tackles the task of explaining the FM modulation concept in a simple and straightforward way. That is done by using MATLAB/SIMULINK tool box in both possible domains: time domain and frequency domain. The simulation results obtained by such simple system is validated by a counterpart experimental investigation. Quite satisfactory agreements are reached when comparing the simulation results with that of practical counterpart.

Study and Optimization of CPT Resonance Parameters in 87 Rb/Ar/Ne Microcells Aimed for Application in Metrology

The paper shows the presents results of studies of small-size rubidium cells with argon and neon buffer gases, produced by a patent pended technique of laser welding [Fishman et al. (2014)]. Cells were designed for miniature frequency standard. Temperature dependence of the frequency of the coherent population trapping (CPT) resonance was measured and used to optimize the ratio of partial pressures of buffer gases. The influence of duration and regime of annealing on the CPT-resonance frequency drift was investigated. The parameters of the FM modulation of laser current for two cases which correspond to the highest amplitude of CPT resonance and to the smallest light shifts of the resonance frequency were determined. The temperature dependences of the CPT resonance frequency were found to be surprisingly different in the two cases. A non-linear dependence of CPT resonance frequency on the temperature of the cell with the two extremes was revealed for one of these cases.

Effect of Short-term 900 MHz low level electromagnetic radiation exposure on blood serotonin and glutamate levels.

Long term exposure to low level electromagnetic radiation (LLER) by using cellular phones causes serious health problems. Ten male Wistar Albino rats were anesthetized 30 min before the LLER exposure, 0.5 ml blood was taken from the tail vein of rats in order to determine control values. Rats were grouped by three and placed on a plexi-glass flat. A fixed equivalent frequency emitter device was used. A sign to be an electromagnetic field 15.14 V/m (608 mW/m(2)) in strength in the head region with 100 kHz FM modulation at 900 MHz was applied to the animals. After calculating the ideal position for the device, electromagnetic LLER energy was applied for 45 minutes from a distance to be equal with energy transmitted by a mobile phone from a 0.5-1 cm distance to their head regions. After 1.5 hours and before the rats awoke, 0.5 ml of blood was taken from the tail veins in order to determine the treatment values. Plasma 5-HT and glutamate levels were measured by enzyme immunoassay (EIA) using commercial kits. It was found that a single 45 min of LLER exposure increased the blood 5-HT level significantly, but did not change the glutamate level of rats. It was concluded that even a single 45 min of LLER exposure may produce an increase in 5-HT level without changing the blood glutamate level. Increased 5-HT level may lead to a retarded learning and a deficit in spatial memory (Tab. 2, Fig. 2, Ref. 24).

Stimulus-specific adaptation in field potentials and neuronal responses to frequency-modulated tones in the primary auditory cortex.

In order to structure the sensory environment our brain needs to detect changes in the surrounding that might indicate events of presumed behavioral relevance. A characteristic brain response presumably related to the detection of such novel stimuli is termed mismatch negativity (MMN) observable in human scalp recordings. A candidate mechanism underlying MMN at the neuronal level is stimulus-specific adaptation (SSA) which has several characteristics in common. SSA is the specific decrease in the response to a frequent stimulus, which does not generalize to an interleaved rare stimulus in a sequence of events. SSA was so far mainly described for changes in the response to simple pure tone stimuli differing in tone frequency. In this study we provide data from the awake rat auditory cortex on adaptation in the responses to frequency-modulated tones (FM) with the deviating feature being the direction of FM modulation. Adaptation of cortical neurons to the direction of FM modulation was stronger for slow modulation than for faster modulation. In contrast to pure tone SSA which showed no stimulus preference, FM adaptation in neuronal data differed sometimes between upward and downward FM. This, however, was not the case in the local field potential data recorded simultaneously. Our findings support the role of the auditory cortex as the source for change-related activity induced by FM stimuli by showing that dynamic stimulus features such as FM modulation can evoke SSA in the rat in a way very similar to FM-induced MMN in the human auditory cortex.

Manatee hearing and sound localization can help navigate noisy shallow waters and cocktail events, no Lombard's needed

Simultaneous masking procedures were used to measure the hearing and underwater sound localization abilities of West Indian manatees. Auditory detection thresholds of pulsed, no-pulsed pure tones, and complex sounds were measured against white noise using forced-choice paradigms. Auditory thresholds as a function of intensity, center frequency, bandwidth, pulse rate, and spectral characteristics were measured. Resulting critical ratios for pure tone measurements demonstrated manatees have acute frequency filtering abilities compared with humans and other marine mammals. Signal repetition rate along with amplitude and frequency modulation providing temporal contrasts against aperiodic background noise and lowered detection thresholds. FM signal detection thresholds were measured at or below ambient background levels. Results with species specific calls and boat noise suggested loudness summation across distant critical bands, as well as FM and amplitude modulation reduced the masking effects observed with pure tones. Manatees are well adapted for hearing and locating high frequency sounds in noisy shallow water habitats where physical boundary and near surface phenomena impede the propagation of low frequencies. Narrow critical bands and selective perception of pulsed signals may be adaptations for detecting and locating species-specific vocalizations. High frequency harmonics in manatee calls provide essential directional cues between mothers and calves.

Brillouin optical correlation analysis system using a simplified frequency-modulated time division method

A time-division Brillouin optical correlation domain analysis system was successfully achieved using simplified laser diode (LD) modulation and pump lightwave optimization. A complicated transfer function for a precise output waveform of a LD was required for the conventional system. However, a very simple modulation function gave a power output very close to a required ideal rectangle waveform without sacrificing optical output spectrum. An electrical input waveform applied into a gate in the pump lightwave path was also optimized for eliminating a probe lightwave included in a pump lightwave and for passing consecutive pump pulses alternatively. So the stimulated Brillouin scattering gain was attained without seriously distorting FM modulation, and the targeted spatial resolution was clearly accomplished. Additionally, using high speed response of a semiconductor optical amplifier (SOA), unlike an erbium-doped fiber amplifier (EDFA), the possibility was investigated that an SOA was going to replace an EDFA and a modulator used as a gate in the same time.

Power Line Carrier Communication

Communication is the backbone for all modes of development in this modern world. Without communication the whole world is virtually deaf and dumb. In order to minimise the cost spent on additional wires, we are using the same existing power lines as a medium of communication in this project. The data are mixed with radio frequency carrier (40-500 kHz) and then injected into high voltage power line using a suitable Coupling Capacitor.The power line has a rigid, long conductor parallel to the ground that guides the carrier waves to travel along the transmission line. This system which is economic and reliable for inter grid message transfer is mainly used for telecommunication, tele-protection and tele-monitoring between electrical substations through power lines at high voltages such as 110KV, 220KV, 440KV. I. INTRODUCTION The PLCC has a transmitter block and receiver block. In the transmitter block ,we use audio signal as an input which should be amplified with a pre amplifier before getting modulated. After pre amplification the audio signal is modulated with the carrier signal by FM modulator. Before transmitting the signal, it should be amplified once again using RF amplifier. Now the modulated and amplified signal is given to the transformer in which isolates RF signal with the 230V AC supply. Finally the signal is coupled to the AC line with the help of coupling capacitor, which allows high frequency modulated signal simultaneously providing high impedance to the power frequency (50 Hz). In receiver block the signal is received from the 230V power line through the coupling capacitor. Then the received signal is given to transformer which is used for isolation purpose and then the RF signal is amplified using RF amplifier. The amplified output is given to PLL FM demodulator for the extraction of audio signal from the modulated signal. Then demodulated output is power amplified and is given to the loud speaker. II. COMPONENTS A. I.Ne 555 Timer (Modulator) The NE555 is a highly stable controller capable of producing accurate timing pulses. It is an 8pin timer IC and has mainly two modes of operation: monostable and astable. With monostable operation, IC 555 is commonly used for generating time delays and pulses.In the time-delay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor.The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. This IC consists of 23 transistors, 2 diodes and 16 resistors. The explanation of terminals coming out of the 555 timer IC is as follows. The pin number used in the following discussion refers to the 8-pin DIP and 8-pin metal can packages.The NE555 is characterized for operation from 0°C to 70°C

Investigation of SNR Estimation Algorithms of FM Signal for the Underwater Acoustic Channel

SNR (Signal to Noise Ratio) estimation is a very important parameter for channel estimation of the communication system. In this paper, some SNR estimation methods of digital modulation system are applied and improved in FM modulation system. Then we summarize several SNR estimation methods (EHM (Envelope High order Moment method), SE (Spectrum Estimation method), FD (Frequency Domain method), EMV (Envelope Mean Variance method), M2M4 (Second order and Fourth order Moment method)) . Furthermore, according to the characteristics of FM modulation system, we put forward the improvement of M2M4 and also discuss the optimal algorithm for underwater acoustic Rayleigh channel, Rician channel and Bellhop channel by comparing these methods.

Facial Expression Recognition Based on Incremental Isomap with Expression Weighted Distance

The Isometric mapping algorithm is an unsupervised manifold learning algorithm, with no consideration of the class of training samples, while supervised isometric mapping treats the difference among classes equally. Considering the inner relationship between different expressions, we have proposed isometric mapping algorithm based on expression weighted distance, which assigns weighted values according to different sample distance in order to make full use of knowledge of expression classes when calculating the geodesic distance between training samples. We use incremental isometric mapping algorithm on new samples so as to simplify computation significantly when dealing with new samples. Then k-NN classifier is applied to classify different expression features. The facial expression recognition experiments are performed on the JAFFE database and the results show that this proposed algorithm performs better than ISOMAP algorithm and supervised ISOMAP algorithm, and it is more feasible and effective. /mtp_HPc (Envelope Mean Variance method), M2M4 (Second order and Fourth order Moment method)). Furthermore, according to the characteristics of FM modulation system, we put forward the improvement of M2M4 and also discuss the optimal algorithm for underwater acoustic Rayleigh channel, Rician channel and Bellhop channel by comparing these methods.

Frequency-modulated continuous-wave lidar using I/Q modulator for simplified heterodyne detection

A frequency-modulated continuous-wave (FMCW) lidar is demonstrated with heterodyne detection. The lidar transmitter utilizes an electro-optic I/Q modulator for the first time to generate carrier-suppressed and frequency-shifted FM modulation. This eliminates the need for an acousto-optic frequency shifter commonly used in heterodyne lidar transmitters. It also allows the use of a much wider modulation bandwidth to improve the range resolution. The capability of complex optical field modulation of the I/Q modulator provides an additional degree of freedom compared with an intensity modulator, which will benefit future lidar applications.

Basic Characteristics of IEC Flickermeter Processing

Flickermeter is a common name for a system that measures the obnoxiousness of flicker caused by voltage fluctuations. The output of flickermeter is a value of short-term flicker severity indicator, . This paper presents the results of the numerical simulations that reconstruct the processing of flickermeter in frequency domain. With the use of standard test signals, the characteristics of flickermeter were determined for the case of amplitude modulation of input signal, frequency modulation of input signal, and for input signal with interharmonic component. For the needs of simulative research, elements of standard IEC flickermeter signal chain as well as test signal source and tools for acquisition, archiving, and presentation of the obtained results were modeled. The results were presented with a set of charts, and the specific fragments of the charts were pointed out and commented on. Some examples of the influence of input signal’s bandwidth limitation on the flickermeter measurement result were presented for the case of AM and FM modulation. In addition, the diagrams that enable the evaluation of flickermeter’s linearity were also presented.

0.84 ps Resolution Clock Skew Measurement via Subsampling

An all-digital on-chip clock skew measurement system via subsampling is presented. The clock nodes are subsampled with a near-frequency asynchronous sampling clock to result in beat signals which are themselves skewed in the same proportion but on a larger time scale. The beat signals are then suitably masked to extract only the skews of the rising edges of the clock signals. We propose a histogram of the arithmetic difference of the beat signals which decouples the relationship of clock jitter to the minimum measurable skew, and allows skews arbitrarily close to zero to be measured with a precision limited largely by measurement time, unlike the conventional XOR based histogram approach. We also analytically show that the proposed approach leads to an unbiased estimate of skew. The measured results from a 65 nm delay measurement front-end indicate that for an input skew range of ±1 fan-out-of-4 (FO4) delay, ±3σ resolution of 0.84 ps can be obtained with an integral error of 0.65 ps. We also experimentally demonstrate that a frequency modulation on a sampling clock maintains precision, indicating the robustness of the technique to jitter. We also show how FM modulation helps in restoring precision in case of rationally related clocks.