Frequency Shift Keying Demodulator Research Articles

A Cycle by Cycle FSK Demodulator With High Sensitivity of 1% Frequency Modulation Index for Implantable Medical Devices

This paper presents a cycle by cycle Frequency Shift Keying (FSK) demodulator, able to demodulate a FSK signal with 1% frequency modulation index (MI), in a single cycle. Based on the proposed demodulation scheme, a high rate data transmission link can be established through a high-Q inductive coupling link, breaking the basic tradeoff between the power transfer efficiency (PTE) and data rate in single carrier wireless power and data transfer systems. Designed and simulated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18\mu m$ </tex-math></inline-formula> CMOS process, the proposed FSK demodulator, detects successfully a 5Mbps data with a carrier frequency of 5MHz. A test chip is fabricated in 180nm CMOS technology. Measurement results shows that the demodulator is able to demodulate the cycle-by-cycle modulated FSK signals with low modulation index of 2.5%, with a BER of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.24\times 10^{-5}$ </tex-math></inline-formula> .

Design and implementation of reconfigurable ASK and FSK modulation and demodulation algorithm on FPGA (Field Programmable Gate Array)

Our modern world is completely driven by our ability to communicate all over the world with great precision, accuracy, and the least amount of time possible. Communication systems are used vastly in our worlds such as radar, aerospace, naval/maritime communication, underwater communication, mobile communication, or even in outer space such as satellite communication or space missions. Different communication system needs different types of modulation techniques. Design and implementation of reconfigurable modulators on cyclone-II FPGA (Field-programmable gate array) are proposed in this paper, wherein the type of modulations and demodulation can be dynamically reconfigured on the fly based on the requirement at any particular instance. The demodulator is intelligent enough to demodulate any modulated signal. FPGA or Field Programmable Gate Array is a computing device that can be programmed like CPU (Central Processing Unit) but fasted than CPU in parallel processing and DSP (Digital Signal Processing) related tasks. Consisting method of FPGA-based modulation does not support multiple modulation techniques at the same time and is not fast as they used Simulink-based simulation. This study has proposed FPGA based alternative to that, which can embody all the modulation techniques at once, making it way more versatile, cost-effective, and easy to use and test. The process begins with designing an algorithm. Then this algorithm has to be simulated. The algorithm is designed for both modulation and demodulation. In the modulation part, it is just simple logic to create different phrases and different frequencies of sinusoidal waves. But in demodulation, based on the frequency it can detect ASK (Amplitude Shift Keying) or FSK (Frequency Shift Keying) signal all by itself. Depending on the period of the signal, the algorithm can decide whether it is an ASK or FSK signal. After deciding it is an ASK of FSK signal, it starts to demodulate the signal. The outcome is, this FPGA-based modulator and demodulator are cheap, easy to configure, and can demodulate any type of demodulated signal. As it is reconfigurable, it's easy to deploy in any situation.

Robust Intra-Body Communication Using SHA1-CRC Inversion-Based Protection and Error Correction for Securing Electronic Authentication.

The explosive increase in the number of IoT devices requires various types of communication methods. This paper presents secure personal authentication using electrostatic coupling Intra-body communication (IBC) based on frequency shift keying (FSK) and error correction. The proposed architecture uses GPIO for a transmitter and analog-to-digital conversion (ADC) for a receiver. We mplemented FSK modulation, demodulation, data protection, and error correction techniques in the MCU software without applying hardware devices. We used the characteristic that the carrier signal is 50% duty square wave for 1-bit error correction and applied a method of randomly inverting SHA1 hash data to protect user authentication data during transmission. The transmitter modulates binary data using a square wave as a carrier signal and transmits data through the human body. The receiver demodulates the signal using ADC and decrypts the demodulated binary data. To determine the carrier frequency from ADC results, we applied a zero-crossing algorithm which is used to detect edge characteristics in image processing. When calculating the threshold value within the zero-crossing algorithm, we implemented an adaptive threshold setting technique utilizing Otsu’s binarization technique. We found that the size of the electrode pad does not affect the signal strength, but the distance between the electrode pad and the skin has a significant effect on the signal strength. Our results show that binary data modulated with a square wave can be successfully transmitted through the human body, and, when 1-bit error correction is applied, the byte error rate on the receiver side is improved around 3.5% compared to not applying it.

Novel low complexity decoding method for the binary coded frequency shift keying modulation

SummaryThis paper proposes a coded modulation scheme based on frequency shift keying (FSK) modulation and a simple binary permutation code. FSK detection is based on the knowledge of the probability density function (PDF) of the noise and the attenuation of the channel, called FSK “Soft‐Decision” (FSK/SD) detection. We introduce an approximation of the FSK/SD, called FSK “Select Largest” (FSK/SL). We compare the FSK/SL detection with the classical PDF‐based detection techniques, such as FSK/SD and spread‐FSK (SFSK), for both coded and uncoded transmission. As a practical application, we use the power line communication (PLC) channel. We analyze and compare the performances for a narrowband PLC channel with attenuation and impulse noise.

Analysis and Design of a Foam-Cladded PMF Link With Phase Tuning in 28-nm CMOS

This paper presents a fully packaged 140-GHz dielectric waveguide (DWG) communication link using a foam-cladded fiber. A novel frequency shift keying (FSK) demodulator topology is proposed with a low-frequency feedback loop for optimal FSK demodulation under process, voltage, and temperature variation. The introduction of phase shifters and an on-chip local oscillator relaxes the design requirements and the IF-stage benefits from larger gain. The transmitter is based on a fundamental oscillator at 140 GHz with a transformer-coupled buffer to decrease capacitive loading. Both chips are implemented in a 28-nm bulk CMOS design with a nominal supply of 0.9 V and a combined power consumption of 230 mW. An analysis of the DWG data capacity limitations is presented and compared with measurement results. Data rates of 12 Gb/s/10 Gb/s/7 Gb/s over 1 m/2 m/4 m of touchable polytetrafluoroethylene (PTFE) fiber are achieved.

An RF-Powered Transceiver Exploiting Sample and Hold Operation on the Received Carrier

This paper presents an RF-powered transceiver for wireless sensor network applications. The circuit is composed of an RF energy harvesting system, implemented by means of a threshold-compensated multistage rectifier, power management unit, and phase-locked loop (PLL)-based RF front end. Initially, the PLL in closed-loop condition locks the voltage-controlled oscillator (VCO) to a multiple of the RF input frequency and allows frequency-shift keying (FSK) data recovery. Then, the PLL feedback loop is opened and the VCO signal is used to generate the uplink carrier, thus enabling active transmission without requiring external quartz for frequency reference. This approach overcomes the reader self-jamming drawback that greatly limits the operating range of backscattering-based RF-powered devices. Moreover, uplink and downlink operations are performed by exploiting a single carrier frequency according to a half-duplex communication scheme, which results in a low-complexity and low-cost wireless solution. The circuit was fabricated in a 130-nm CMOS technology and operates with a minimum input power as low as −18.8 dBm. It supports the FSK and ASK demodulation and OOK data transmission in the industrial scientific and medical band at 915 MHz.

A 1.1-mW Ground Effect-Resilient Body-Coupled Communication Transceiver With Pseudo OFDM for Head and Body Area Network

This paper presents a body-coupled communication (BCC) transceiver (TRX) that mitigates all the practical impairments of the body channel at once. The proposed pseudo orthogonal frequency-division multiplexing (P-OFDM) TRX combines baseband BPSK-OFDM with frequency-shift keying (FSK) to alleviate the impacts of variable ground effect and variable skin-electrode contact impedance, which have been the two major issues on the BCC. It can tolerate up to 20 dB of channel gain variation with measured bit error rate improvement of >70% compared to FSK modulation alone. The RC relaxed contact impedance monitor continuously monitors and compensates the variable skin-electrode contact impedance at both transmitter (TX) and receiver (RX). The proposed power-gated 8-point inverse fast Fourier transform/fast Fourier transform with no floating-point multipliers (FPMs) reduces the gate count and power by 54% and 30% compared to conventional FPMs, respectively. Additionally, the simple floating-point adder (FPA) reduces the gate count and energy consumption by 34% and 20% compared to conventional FPAs, respectively. A high input impedance glitch-free FSK demodulation RX with variable threshold limiter and all digital cycle correction is also proposed to support a scalable data rate (200 Kbps-2 Mbps). The 0.54 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> TRX in 65-nm CMOS consumes 1.1 mW.

Ultra‐low power frequency‐shift keying demodulator based on injection‐locking ring oscillator without using phase locked loop for wireless body area networks

An ultra-low power frequency-shift keying (FSK) demodulator based on injection-locking ring oscillator for wireless body area networks is presented. The proposed system uses the power-efficient injection-locking ring oscillator (ILRO) to replace the LC oscillator which occupies much more area on chip with higher power consumption. In addition, through the ILRO, the frequency modulated input signal is converted to a full swing rectangular signal, which can be directly demodulated by a chain of down-conversion passive mixers, lowpass filters and a comparator. Power efficiency and simplicity of the proposed structure eliminate conventional FSK demodulator based on power-hungry phase locked loops, which needs to be calibrated by auto-frequency calibrator to periodically compensate the free running frequency deviations due to temperature variations and charge pump leakage current. The proposed FSK demodulator is designed and simulated in 180 nm CMOS technology while consuming only 23.37 µW from a 0.7 V supply.

A Pseudo OFDM With Miniaturized FSK Demodulation Body-Coupled Communication Transceiver for Binaural Hearing Aids in 65 nm CMOS

A power-efficient body-coupled communication pseudo orthogonal frequency-division multiplexing (P-OFDM) transceiver (TRX) is presented for binaural hearing aids (BHAs). Channel measurements are performed for different body postures between human head-to-hand and ear-to-ear to characterize the body channel path loss. The TRX exploits baseband 16-quadrature amplitude modulation OFDM symbols transmitted through a binary frequency-shift keying (FSK) modulation to mitigate the multipath and interference problems, which are the most serious issues in BHA, with bit error rate improvement of 74% compared to FSK. It is also free from the peak-to-average power ratio problem. A power-of-two decomposition constant multiplier is implemented to achieve area-efficient constant multiplications in 64-FFT. The proposed energyand area-efficient miniaturized direct conversion FSK demodulation receiver is capable of demodulating up to 20 Mbps signals while reducing the area by >50% compared to conventional implementations. The 1 Mbps TRX is implemented in a 65 nm CMOS process with an active area of 2.13 mm 2 while consuming 1.4 mW.

인체 임피던스를 이용한 양방향 통신 시스템의 설계

Article history: In this study, a half-duplex mutual communication device via human skin was developed. Frequency-shift keying (FSK) digital modulation and demodulation control were used to transmit and receive data. Data communication through the human body is an effective communication technique and has high-grade security characteristics. In addition, making contact is a natural instinct of humans. Transmitting data through the human body is currently a highly conspicuous technology, because recently a lot of commercial sensors for humans have been developed. A body area network (BAN) can be easily constructed by this communication method on human skin. In this study, a half-duplex FSK mutual communication device was developed using a commercial FSK modulator and demodulator. A special control switching circuit and communication sequence were developed for mutual communication through human skin.

A Joint Power Harvesting and Communication Technology for Smartphone Centric Ubiquitous Sensing Applications

Smartphone centric ubiquitous sensing applications use a smartphone with external sensors. The 3.5mm audio interface provide a common data interface for communication in different smartphones. The 3.5mm audio interface cannot provide DC power to external sensors. Thus, power needs to be harvested from an earphone channel. The existing technology uses one earphone channel to harvest power. Consequently, for many smartphones the technology cannot harvest enough power to support external sensors. In this paper, based on frequency shift keying (FSK) modulation scheme, the authors have proposed a joint power harvesting and communication technology that can simultaneously harvest power and transfer data with the same earphone channels. Circuit measurements show that, the proposed technology can extract more than two times of power as from one earphone channel. Meanwhile, demodulation tests show that our newly-developed timer-based FSK demodulator can reliably recover the data transferred from a smartphone to external sensors without any error.

An Ultralow Power Multirate FSK Demodulator With Digital-Assisted Calibrated Delay-Line Based Phase Shifter for High-Speed Biomedical Zero-IF Receivers

An ultralow power (ULP), multirate frequency shift keying (FSK) demodulator applied for high-speed biomedical zero-IF receivers is presented. A digital-assisted calibrated delay-line (DL) based phase shifter is used for realizing multirate and low jitter demodulation under reported highest data rate. All circuits are operated in subthreshold region for achieving ULP consumption. Moreover, the power consumption of the demodulator is relative to the data rate. Therefore, energy consumption per received bit can be optimized according to the applications. Implemented in 0.18 $\mu{\rm m}$ CMOS process, a minimum energy consumption of 11 pJ per received bit and demodulated peak-to-peak jitter of 1.89 ns are achieved under the maximum data rate of 40 Mb/s.

Design of Digital Communication System of XCTD Based on FSK

According to the problem of expendable conductivity temperature depth profile (XCTD) of transmission signal waveform distortion and undistinguishable information caused by cable time-varying parameters and influence of seawater. This paper designed a based on FSK (Frequency shift keying) of digital communication system. It used single-chip modem chip FX604 used in FSK modulation and demodulation of the signal. And it implements the digital signal transmission on thin wire communication on the water. The system overcomes unfavorable conditions about transmission channel and marine environment. The circuit is easy and practical.

THE DESIGN AND IMPLEMENTATION OF A WIRELESS DATA ACQUISITION/TRANSMITTING SYSTEM FOR EURO-BALISE

This paper presents a design and implementation of a wireless data acquisition/transmitting system for Euro-balise. The presented system contains three parts: a power signal generator, a receiver and a transmitter. We also propose an all-digital coherent-like frequency shift keying (FSK) demodulator for the receiver of the system. The proposed demodulator based on the use of multi-bit XOR gates and a mean value filter can improve bit error ratio (BER) performance without increasing obvious complexity. Differential bi-phase level (DBPL) coding is adopted to ensure the reliability of the transmitter. The FSK demodulator and DBPL coder was implemented on field programmable gate array (FPGA). Hardware test results show that the equipment based on the presented system has good application in reading and writing data of the Euro-balise.

High‐data‐rate FSK demodulator for wireless communication

A low-power frequency-shift keying (FSK) demodulator capable of demodulating 5 Mbit/s data rate is presented. No high sampling clock is needed in this demodulator design, and thus the design not only greatly reduces the circuit complexity but also achieves a high data rate. It is suitable for a digital data transmission chain of wireless communication.

A 3.8-mW 3.5–4-GHz Regenerative FM-UWB Receiver With Enhanced Linearity by Utilizing a Wideband LNA and Dual Bandpass Filters

A low-power regenerative frequency-modulated ultra-wideband (FM-UWB) receiver with wideband signal reception and linear FM-AM conversion is implemented in 65-nm CMOS for short-range communication systems. Different from the conventional regenerative FM-UWB receiver having the narrowband low-noise amplifier (LNA), the proposed receiver employs a wideband LNA and dual bandpass filters (BPFs) to improve the robustness against narrowband interference and frequency shift-keying demodulation with a relaxed Q requirement of the BPF. A 3.5-4-GHz FM-UWB receiver consisting of a stacked LNA, dual BPFs, two envelop detectors, and a subtractor successfully performs FM demodulation through wireless transmission from a 100-kb/s FM-UWB transmitter, consuming the total power of 3.8 mW.

PLL-Based Contactless Energy Transfer Analog FSK Demodulator Using High-Efficiency Rectifier

This paper proposes a new phase-locked-loop (PLL)-based inductive coupled contactless energy transfer (CET) analog frequency-shift keying (FSK) demodulator using a high-efficiency RF-to-dc rectifier for biomedical implanted devices. The analog FSK demodulator is composed of a modified CMOS three-stage rectifier, a voltage regulator, an FSK signal generator, and a PLL. The proposed modified single-stage rectifier with both positive and negative output voltages using a PMOS and an NMOS pass transistor, an inverter, and two capacitors has a small active area and can enhance the power conversion efficiency. The proposed RF-to-dc rectifier achieves an efficiency of 64% at 8.4 dBm. The power consumption of the demodulator is as low as 0.76 mW, and the active area is 0.084 mm2. The analog FSK demodulator supports a data rate of 100 kb/s to 1 Mb/s. The chip was implemented in a Taiwan Semiconductor Manufacturing Company (TSMC) 0.35- μm double-poly quadruple-metal CMOS technology to verify the proposed CET circuit. Two figures of merit are provided to illustrate the advantages of the proposed architecture.

Digital System for Serial FSK Modulated Data Reception

This paper describes a complete software developed system, designed, implemented and tested, for the reception of serial, low rate, data transmitted employing binary FSK (Frequency Shift Keying) modulation. The FSK demodulation process is implemented using an algorithm for a digital version of a PLL (Phase Locked Loop) in software. The complete reception process is implemented using methodologies and techniques from the digital signal processing field and they are implemented using C language in a dsPIC microcontroller from Microchip.

The Design and Implement of a Receiver for FSK Signal

A novel frequency shift keying (FSK) receiver is presented, including receiving antennas, a low noise amplifier (LNA), band-pass filters (BPF) and a novel all-digital 2-level FSK demodulator. The Matlab simulation results of the all-digital FSK demodulator show that it can improve bit error ratio (BER) performance compared with pseudo-coherent FSK demodulation (PCFSK). The novel FSK demodulator defined using Verilog HDL is easy to be implemented on Field Programmable Gate Array (FPGA) and in CMOS integrated circuit. The whole FSK receiver designed and implemented on a PCB board can receive FSK signal and send the recovered data to computer through RS-232 interface.

A New CMOS Analog Front End for RFID Tags

This paper presents a new CMOS integrated analog front-end circuit for 13.56-MHz radio-frequency identification tags. The proposed analog front end consists of a novel CMOS rectified voltage multiplier, a voltage regulator, and a new frequency-shift keying (FSK) demodulator. The proposed single-stage rectifier employing only a PMOS/NMOS pass transistor, an inverter, and one capacitor gets minimal active area and enhances the power conversion efficiency. Moreover, a new technique is used in the proposed FSK demodulator, which includes the data recovery circuit, the multiplexer, the shift register, the phase frequency detector, and the charge-pump circuit. The analog front end has been fabricated in a CMOS 0.35-mum 2P4M technology. The demodulator circuit supports a data rate of 10 kb/s to 1 Mb/s. The power consumption is as low as 0.96 mW, and the chip area without pads is only 0.74 mm times 0.43 mm. Experimental results show that the proposed analog front end works well and confirms the theoretical analysis.