Gaussian Frequency Research Articles

Development of a Wireless Health Monitoring System for Measuring Core Body Temperature from the Back of the Body.

In this paper, a user-friendly and low-cost wireless health monitoring system that measures skin temperature from the back of the body for monitoring the core body temperature is proposed. To measure skin temperature accurately, a semiconductor-based microtemperature sensor with a maximum accuracy of ±0.3°C was chosen and controlled by a high-performance/low-power consumption Acorn-Reduced Instruction Set Computing Machine (ARM) architecture microcontroller to build the temperature measuring device. Relying on a 2.4 GHz multichannel Gaussian frequency shift keying (GFSK) RF communication technology, up to 100 proposed temperature measuring devices can transmit the data to one receiver at the same time. The shell of the proposed wireless temperature-measuring device was manufactured via a 3D printer, and the device was assembled to conduct the performance tests and in vivo experiments. The performance test was conducted with a K-type temperature sensor in a temperature chamber to observe temperature measurement performance. The results showed an error value between two devices was less than 0.1°C from 25 to 40°C. For the in vivo experiments, the device was attached on the back of 10 younger male subjects to measure skin temperature to investigate the relationship with ear temperature. According to the experimental results, an algorithm based on the curve-fitting method was implemented in the proposed device to estimate the core body temperature by the measured skin temperature value. The algorithm was established as a linear model and set as a quadratic formula with an interpolant and with each coefficient for the equation set with 95% confidence bounds. For evaluating the goodness of fit, the sum of squares due to error (SSE), R-square, adjusted R-square, and root mean square error (RMSE) values were 33.0874, 0.0212, 0.0117, and 0.3998, respectively. As the experimental results have shown, the mean value for an error between ear temperature and estimated core body temperature is about ±0.19°C, and the mean bias is 0.05 ± 0.14°C when the subjects are in steady status.

A 3.7-mW 2.4-GHz Phase-Tracking GFSK Receiver With BBPLL-Based Demodulation

This paper describes a low-power phase-domain receiver with single-bit phase-to-digital conversion by utilizing a divider-less bang-bang phase-locked loop (BBPLL). The BBPLL performs 1-bit oversampled noise-shaping demodulation as a secondary loop in the receiver, offering a flexible gain control as well as a simple baseband interface. A prototype 2.4-GHz receiver with an auxiliary 50-MHz BBPLL is implemented in 65-nm CMOS. In the RF loop, a dual-path LC voltage-controlled oscillator (VCO) with partitioned coarse tuning is designed to have a low gain constant over temperature variation. In the BBPLL, a dual-input ring VCO provides separate gain control and low-pass filtering for the demodulation path. The receiver performs 100-kb/s Gaussian Frequency Shift Keying (GFSK) demodulation with the sensitivity of -89 dBm and the power consumption of 3.7 mW from a 0.8-V supply in which 0.15 mW is consumed by the BBPLL.

Cross-Technology Communications for Heterogeneous IoT Devices Through Artificial Doppler Shifts

Recent years have seen major innovations in developing energy-efficient wireless technologies such as Bluetooth Low Energy (BLE) for Internet of Things (IoT). Despite demonstrating significant benefits in providing low power transmission and massive connectivity, hardly any of these technologies have made it to directly connect to the Internet. Recent advances demonstrate the viability of direct communication among heterogeneous IoT devices with incompatible physical (PHY) layers. These techniques, however, require modifications in transmission power or time, which may affect the media access control (MAC) layer behaviors in legacy networks. In this paper, we argue that the frequency domain can serve as a free side channel with minimal interruptions to legacy networks. To this end, we propose DopplerFi, a communication framework that enables a two-way communication channel between BLE and Wi-Fi by injecting artificial Doppler shifts, which can be decoded by sensing the patterns in the Gaussian frequency shift keying (GFSK) demodulator and Channel State Information (CSI). The artificial Doppler shifts can be compensated by the inherent frequency synchronization module and thus have a negligible impact on legacy communications. Our evaluation using commercial off-the-shelf (COTS) BLE chips and 802.11-compliant testbeds have demonstrated that DopplerFi can achieve throughput up to 6.5~Kbps at the cost of merely less than 0.8% throughput loss.

Evaluation of Data Telemetry for Future Leadless Cardiac Pacemaker

Multi-node leadless pacemaker system overcomes the main limitations related to lead complications of the conventional cardiac pacemaker and will thus replace them in the near future. The multiple nodes of the technology require the development of low-power, low data-rate and energy-efficient communication framework for device synchronization and bi-directional communication between them. Moreover, the nodes need to communicate with the outer peripheral devices for data telemetry, control and remote monitoring. This paper focuses on evaluation of different energy-efficient modulation schemes at 433 MHz for bi-directional communication between the nodes using homogeneous liquid phantom model of human heart and living animal experiments. In this paper, we have analyzed three simple, low-budget modulation schemes - On Off-Keying (OOK), Frequency Shift-Keying (FSK), and Gaussian Frequency Shift-Keying (GFSK). The analysis is done based on the total transmitter power required to achieve a reliable communication indicated by the minimum threshold values of bit-error rate and packet-error rate. The experiments have been conducted for three common implant communication scenarios - in-body to in-body, in-body to on-body and in-body to off-body links. For conducting the experiments, we have designed the experimental setup with electronic components and fabricated antennas. The results have shown that GFSK has the best performance among the other modulation techniques based on the total transmitter power. We also investigated higher order of the same modulation schemes – 4-FSK and 4-GFSK. The results showed that GFSK performed much better than 4-FSK and 4-GFSK. This research will be carried forward to build the entire radio frequency communication framework for the multi-node pacemaker technology.

All-Digital PLL for Bluetooth Low Energy Using 32.768-kHz Reference Clock and ≤0.45-V Supply

In this paper, we introduce an all-digital phase-locked loop (ADPLL) for Bluetooth low energy (BLE) that eliminates the need for a crystal oscillator (XO) other than a 32.768-kHz real-time clock (RTC) already present in wireless systems. Specifically, we propose to replace the conventional channel settling with a band settling that would be carried out only once per global device power up. The ADPLL locks to the center of the Bluetooth band (2440 MHz) upon system power-up and jointly performs an instantaneous channel hopping and Gaussian frequency shift keying (GFSK) modulation in a two-point manner to overcome the narrow PLL bandwidth (BW) due to the 32.768-kHz reference. Extensive calibrations linearize the effective cubic digitally controlled oscillator (DCO) transfer function to achieve a precise frequency range of hopping and modulation. Realized in 16-nm FinFET, it consumes <1 mW at ≤0.45 V, while achieving best-in-class performance and <100-ns hopping time.

Digital linear GFSK demodulator for IoT devices

Companies and developers of emerging Internet-of-Things (IoT) technologies consider Bluetooth low-energy (BLE) standard as a strong candidate to be the backbone of wireless IoT devices and support their low-power requirements. Likewise, the BLE has adopted Gaussian frequency shift-keying (GFSK) signalling due to its power and spectral efficiencies, which are the most fundamental performance criteria for modulation schemes. For this reason, it is worthwhile to research and develop transceivers that maintain these advantages and achieve a low-complexity implementation for the digital modulator and demodulator. Different techniques have been proposed for this purpose, such as hardware usage optimisation, efficient pulse shaping and decomposition of the signal. This study presents a novel linear GFSK demodulator which has the following attractive advantages: low complexity, near-optimal performance in the additive white Gaussian noise channel and the possibility of operating with different GFSK modulators (with a nominal modulation index of 0.5) so it could be applied in BLE devices. In addition, the theoretical error probability is obtained and compared with simulation results.

A Novel Delay-Based GFSK Demodulator in 65 nm CMOS for Low Power Biomedical Applications

This article describes how, in recent years, with the development of microelectronics, implantable electronic devices have been playing a significant role in modem medicine. Examples of such electronic implant devices are, for instance, retinal prosthesis and brain implants. It brings great challenges in low power radio frequency (RF) and analog designs. This article presents a low power Gaussian frequency shift keying (GFSK) demodulator designed for Medical Implant Communications Service (MICS) band Receiver. This demodulator utilizes a novel structure that a wide IF range can be handled and presents the smallest Δf/f ratio in any published GFSK demodulators. In theory the demodulation method can be applied to any RF frequency. The demodulator draws 550uA from a 1 V power supply. A maximum data rate of 400 Kbits/s can be achieved within the 300 KHz channel bandwidth defined by MICS. A simulated signal-to-noise ratio (SNR) of 15.2dB at AWGN channel is obtained to achieve 10-3 bit error rate (BER). This demodulator is fabricated on 65-nm CMOS and occupies 0.12mm2 silicon area.

400-MHz/2.4-GHz Combo WPAN Transceiver IC for Simultaneous Dual-Band Communication With One Single Antenna

A 400-MHz/2.4-GHz combo transceiver (TRX) integrated chip (IC) Supporting simultaneous dual-band communication is designed and fabricated in a 65-nm CMOS technology for compact wireless personal area network applications. The IC is composed of a 3–10 Mb/s quadrature phase shift keying (QPSK)/offset QPSK (OQPSK) TRX working at the 400–500 MHz band, and a 1–3 Mb/s Gaussian frequency shift keying (GFSK)/half sine OQPSK (HS-OQPSK) TRX at the 2.4–2.4835 GHz band for the Bluetooth low energy/IEEE 802.15.4 protocols. The presented combo TRX IC requires one single antenna without any bidirectional RF coupler, to support simultaneous dual-band communication. Two key circuit techniques, namely, the combination biasing technique to suppress the high-order harmonics and the active in-band interference cancellation, are adopted to tackle the crosstalk interference between the two bands during simultaneous dual-band operation. Measurement results show that the in-band interference presented to the 2.4-GHz receiver due to the 400-MHz transmitter is suppressed by 19 dB with the presented design techniques.

ForceGen: atomic covalent bond value derivation for Gromacs

A large number of crystallographic protein structures include ligands, small molecules and post-translational modifications. Atomic bond force values for computational atomistic models of post-translational or non-standard amino acids, metal binding active sites, small molecules and drug molecules are not readily available in most simulation software packages. We present ForceGen, a Java tool that extracts the bond stretch and bond angle force values and equilibrium values from the Hessian of a Gaussian vibrational frequency analysis. The parameters are compatible with force fields derived using the second order tensor of the Hessian. The output is formatted with the Gromacs topology in mind. This study further demonstrates the use of ForceGen over the quantum mechanically derived structures of a small organic solvent, a naturally occurring protein crosslink derived from two amino acids following post-translational modification and the amino acid ligands of a zinc ion. We then derive Laplacian bond orders to understand how the resulting force values relate back to the quantum mechanical model. The parameterisation of the organic solvent, toluene, was verified using Molecular Mechanics simulations. The structural data from the simulation compared well with the quantum mechanical structure and the system density compared well with experimental values.

Design and Analysis of a 1.8-GHz Open-Loop Modulator for Phase Modulation and Frequency Synthesis Using TDC-Based Calibration

A nonlinearity calibration technique is proposed for an open-loop phase modulator (PM), for wideband phase modulation, and for multiple-output, low-jitter clock generation. The design considerations and key performance aspects of the calibration technique are discussed. The PM integrates a digital phase-locked loop, local oscillator distribution network, and digital calibration. A prototype was implemented in 0.13- $\mu \text{m}$ CMOS 1.8-GHz Gaussian frequency shift keying (GFSK) transmitter integrated circuit. Measurements on the prototype show that out-of-band quantization noise is 56 dB lower than that of the signal when transmitting 20-Mb/s GFSK signal and the rms error is only 3.2%. The power consumption of the PM is 18 mW. The measured spurious tones of the clock generation unit are below −46 dBc.

All-Digital Galvanically-Coupled BCC Receiver Resilient to Frequency Misalignment.

It is promising for wearable devices to go to a miniature size to alleviate the load of human body. One way to miniaturize the communication nodes on human body is to remove the bulky components such as antenna and crystal. Galvanically-coupled body channel communication (GC-BCC) has a great advantage over conventional wireless communications in reducing the size of wearable devices because it reuses the monitoring electrodes for signal transmission in place of antennas. To remove the crystal as well, the receiver must be immune to different types of frequency misalignments. This paper presents a GC-BCC receiver based on low power all-digital Gaussian frequency shift keying (GFSK) demodulation and clock-data recovery (CDR). A carrier tracking technique is proposed to detect and automatically adapt to the misalignment of carrier frequency. In addition, we also propose a circle-index CDR circuit to deal with the inaccuracy or drift of the clock frequency. The proposed circuit is implemented with 0.18 μm CMOS technology, and it operates at 200 kHz with a BFSK/GFSK modulation index of 1.0. Measured results show that the chip consumes 0.53 mA at a data rate of 100 kb/s. At a 10 cm body channel length, the GC-BCC receiver can tolerate a carrier misalignment up to [Formula: see text] and a clock error up to [Formula: see text], while keeping the bit error rate (BER) below 0.1%.

Grid fundamental harmonic measurement in presence of Gaussian frequency deviation using 2-bit flash A/D converter

Grid fundamental harmonic measurement in presence of Gaussian frequency deviation using 2-bit flash A/D converter

Reduced-complexity MPA decoder based on multi-level dynamic input thresholds

As a key technology of the fifth generation (5G) wireless communications, sparse code multiple access (SCMA) system has quite high frequency utilization, but its message passing algorithm (MPA) decoder still has high time complexity. By the aid of the proposed multi-level dynamic threshold, the complexity of the MPA decoding can be greatly reduced with little error performance loss. In order to reduce a great deal of insignificant computational amounts of message update, we compare the multi-level symbols probability products with optimized multi-level thresholds step by step before they are used for message update calculation. The dynamic threshold configuration refers to the three factors: the level of input symbol probabilities, signal noise ratio (SNR) and the number of iterations. Especially, in the joint iterative MPA-Turbo decoding procedure, since most encoded bits have good convergence, the input thresholds can avoid more unnecessary computational overhead of message update and reduce the decoding time more significantly. The simulation results show that the proposed multi-level dynamic thresholds considerably reduce the decoding delay in both additive white Gaussian noise (AWGN) channel and frequency selective fading channel.

The persistence of tuberculosis in the United States: Spatial analysis and predictive modeling in the move toward elimination of tuberculosis (TB)

Though tuberculosis (TB) prevalence has decreased dramatically in the United States, its continual presence remains a threat to those whose needs are often overlooked. Those already impacted by poverty are the most vulnerable to TB, and stand to bear the worst health impacts, should they contract this disease. Mathematical modeling and spatial analysis have become invaluable tools in TB surveillance monitoring and elimination efforts. In this contribution, we demonstrate the capability of employing a time series, interpolative, vulnerability model to forecasted, state-level TB prevalence in the United States by determining areas influenced by poverty, as well as existing TB data acquired from the Center of Disease Control (CDC). The random effects term in this orthogonal eigenvector spatial filter model was comprised of spatially structured and stochastic effects (that is, spatially unstructured) terms, which were substituted for diagnostic, remote, and clinical covariates in our model. It was assumed that random effects terms in the TB risk model had followed a Gaussian frequency distribution with a mean of zero. The estimate equations were as follows: and . The resulting estimated number of cases for a given state and year was . The Moran coefficient (MC) was 0.66, and its Geary Ratio (GR) was 0.35. The spatially unstructured random effects terms have only trace levels of spatial autocorrelation, with MC = 0.02, and Gr = 0.89. Thus, the assumption of non-zero spatial autocorrelation was violated. The forecast revealed possible hyperendemic transmission of TB in non-coastal, Northwestern states, as well as in some Northeastern states. As such, more intervention efforts should be directed towards these areas. Key words: Tuberculosis (TB), poverty, center of disease control (CDC).

Effect of various chirped frequency functions on Gaussian laser beam characteristics

In this paper, a chirped Gaussian laser beam with a general chirped frequency function has been considered. In order to find how the chirping frequency can affect Gaussian laser parameters, the wave equation governing the electric field of the laser beam was solved in paraxial approximation, self-consistently. The parameters of the chirped laser beam, such as the Rayleigh length, beam waist radius, spot size, as a function of the chirped frequency, have hereby been presented. Several different chirping functions, including linear, quadratic, Gaussian, exponential and sinusoidal ones, were employed to compare the effect of frequency chirping type. It was shown that the chirping, as well as the kind of chirping of laser frequency, plays an important role in the evolution of the laser parameters along the pulse length. It has also been shown that a Gaussian chirped frequency function can provide a more effective laser intensity distribution, which can be useful in laser-driven charged particle acceleration. Yet another notable result is the reshaping of the laser pulse due to its chirping frequency which can be considered important for numerous applications of the laser pulse.

Self-Coherent OFDM With Undersampling Downconversion for Wireless Communications

In this paper, we introduce self-coherent orthogonal frequency-division multiplexing (OFDM), a well-known non-coherent technique in optical communications, for wireless radio frequency communications. Self-coherent OFDM provides complete immunity against phase noise (PN) using a non-coherent receiver and a significantly higher spectral efficiency than self-heterodyne (self-het) OFDM, which utilizes at most 50% of the available spectrum for communications. We present the performance analysis of self-coherent OFDM over additive white Gaussian noise and frequency selective fading channels, and show by simulations that self-coherent OFDM provides both higher spectral efficiency and better bit error rate performance than self-het OFDM. Considering that filter realization in high-frequency bands is challenging, we adopt the undersampling downconversion technique in conjunction with self-coherent OFDM. We show that with the self-coherent demodulation, the additional PN introduced by undersampling downconversion can be significantly reduced. We compare analytically the system performance of self-coherent OFDM using undersampling downconversion with two other conventional OFDM systems: one with super-heterodyne receiver and the other with undersampling downconversion. We show theoretically and by simulations that both in AWGN and frequency selective fading channels, self-coherent OFDM with undersampling downconversion outperforms the two conventional OFDM systems even when intercarrier interference compensation schemes are applied.

A constant false alarm rate frame detector for satellite‐based automatic identification system

SummaryFrame detection is an important step in satellite‐based automatic identification system for its contributions in verifying the presence of automatic identification system signal before frame synchronization. In this paper, a constant false alarm rate frame detector is proposed, which exploits the feature implied in the training sequence, to realize frame detection in the presence of additive white Gaussian noise and frequency offset. False alarm probability is related with a threshold, which is independent of the signal and noise. For fixed false alarm probability, the relationship between detection performance and Eb/N0 is analyzed. Simulations prove that the proposed detector outperforms the detector based on cyclic autocorrelation when message collisions exist. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Corrections to “A Multi-Frequency Multi-Standard Wideband Fractional-&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$N$ &lt;/tex-math&gt; &lt;/inline-formula&gt; PLL With Adaptive Phase-Noise Cancellation for Low-Power Short-Range Standards”

In the above paper [1] the version of Fig. 12 that appears is incorrect. The correct version of the figure appears here, showing the phase-locked loop (PLL) output spectral of 1-Mb/s data rate, 250-kHz frequency-deviation Gaussian frequency shift keying (GFSK) modulated Bluetooth LE baseband signal.

Performances of Orthogonal Wavelet Division Multiplex (OWDM) System Under AWGN, Rayleigh and Ricean Channel Conditions

Orthogonal Wavelet Division Multiplexing (OWDM) has been considered as an alternative of Orthogonal Frequency Division Multiplexing (OFDM) in the recent years. OWDM has lower computational complexity and higher flexibility compared to its OFDM counterpart. The core component of OWDM is wavelet. Wavelet has been a much investigated and applied topic in digital image processing for a long time. Recently, it has drawn considerable attention of the researchers working in communication field. In this work we investigate the performances of OWDM under different channel conditions. We consider three channel conditions namely Additive White Gaussian Noise (AWGN), Rayleigh, Ricean, and frequency selective. We consider a number of wavelets namely Haar, Daubechies, Biorthogonal, Reverse Biorthogonal, Coiflets, and Symlets in OWDM design. For system model we choose Digital Video Broadcasting-Terrestrial (DVB-T). Originally DVB-T system was designed based on OFDM. In this work we use OWDM instead. The simulation results show OWDM outperforms OFDM in terms of bit error rate (BER), noise resiliency, and peak-to-average ration. The results also show that the Haar wavelet based OWDM outperforms other wavelets based OWDM system under all three considered three channel conditions.

Estimating spacetime parameters with a quantum probe in a lossy environment

We study the problem of estimating the Schwarzschild radius of a massive body using Gaussian quantum probe states. Previous calculations assumed that the probe state remained pure after propagating a large distance. In a realistic scenario, there would be inevitable losses. Here we introduce a practical approach to calculate the Quantum Fisher Informations (QFIs) for a quantum probe that has passed through a lossy channel. Whilst for many situations loss means coherent states are optimal, we identify certain situations for which squeezed states have an advantage. We also study the effect of the frequency profile of the wavepacket propagating from Alice to Bob. There exists an optimal operating point for a chosen mode profile. In particular, employing a smooth rectangular frequency profile significantly improves the error bound on the Schwarzschild radius compared to a Gaussian frequency profile.