Frequency Shift Keying Modulation Technique Research Articles

Binary frequency shift keying modulation in spin torque oscillators with synthetic antiferromagnetic layer

Antiferromagnets exhibit ultrafast magnetization precession, which has the potential to enable the development of terahertz spin torque nano-oscillators. By utilizing perpendicularly magnetized magnetic nanopillars with a synthetic antiferromagnetic (SAF) free layer, we have demonstrated through theoretical and numerical analysis that stable out-of-plane precession states can be achieved by applying current and an electric field. In the case of small current, the two magnetic layers of the SAF are in antiparallel alignment and rotate around the z-axis with the precession frequency decreasing as the current strength increases. When the current-induced spin torque is strong enough to fully overcome the antiferromagnetic coupling, the SAF free layer is driven into a scissor-like precession state around the z-axis with the frequency increasing with current. By selecting the appropriate combination of the current and electric field, the magnetization precession orbits and precession frequencies can be adjusted. These controllable procession orbits with tunable frequencies and fixed magnetization precession amplitude may be a promising candidate for implementing binary frequency shift keying modulation techniques.

Capacitive Power Transfer System With Integrated Wide Bandwidth Communication

This letter proposed a novel method for compensation network design used in capacitive power transfer (CPT) systems to achieve simultaneous power and data delivery. The proposed method combines both ladder filter and resonant circuit designs, allowing the existing double-sided CL compensation topology to exhibit different characteristics under the power channel and the communication channel. The proposed system significantly reduces the design complexity and increases the bandwidth for data transfer while maintaining the circuit resonance at the wireless power transfer frequency. The system is compatible with both amplitude shift keying (ASK) and frequency shift keying (FSK) modulation methods, passing the high-frequency data carrier with an approximately unity gain. Detailed circuit parameter design and system performance analysis are presented, and a new metric power to signal is introduced to analyze the effect of the data communication on the power transfer. A prototype CPT system rated at 10 W is built, which demonstrates a 81.2% dc–ac efficiency and a data transfer rate of 10 kbps by using either ASK or FSK modulation techniques.

RSA encrypted FSK RF transmission powered by an innovative microwave technique for invulnerable security

Ensuring the secure communication is the prime concern for all kinds of data communication infrastructure. Several data encryption techniques are in use for secure communication. There is a scope for further improvement in the security level, as well as for the received signal quality. The selection of a proper combination of encryption and modulation techniques can improve the overall effectiveness of both the security level and the received signal quality. The combination of asymmetric cryptography (here use RSA (Rivest–Shamir–Adleman) algorithm) algorithm with the proposed reflex klystron-based frequency shift keying (FSK) modulation technique provides a high level of secure communication system. The performance of the proposed technique is experimentally verified. The conventional FSK modulation technique operates in the low-frequency band, but the proposed FSK modulation technique is powered by high-power microwave devices, which operate in the X band. The experimental result has been demonstrated and successfully verified for secured communication using the X band.

Radio Frequency Energy Harvesting with Phase Shift Keying Modulation Technique

Radio Frequency (RF) energy harvesting is a promising alternative energy source to provide power for low power electronic devices through the air. RF energy harvesting technologies are used in many application fields such as building automation, industrial monitoring, data center, security and defense. In this study, effects of frequency shift keying modulation technique on charging times of RF energy harvesting were measured and investigated in detail. An advanced measurement system was established and this measurement system was performed using an RF energy harvesting circuit, a signal generator, patch antennas and other equipment. The modulated signal at 14 dBm output power was generated by signal generator. Then, the energy produced by the signal generator was obtained from 20 cm to 60 cm at the interval of 5 cm distance by the RF energy harvesting circuit with 6 dBi patch antenna. According to measurement results, the shortest charging time was calculated as 1 s at a distance of 20 cm. In addition to that, the longest charging time was calculated as 7 s at a distance of 60 cm. It was determined that the charging time of the RF energy harvesting decreased as the distance between signal generator and RF energy harvesting circuit reduced.

Effects of Different Modulation Techniques on Charging Time in RF Energy-Harvesting System

Radio-frequency (RF) energy harvesting is a promising technology that obtains energy from electromagnetic waves. As an alternative energy source, this modern technology can provide power wirelessly enabling the practical use of battery-free devices and it is also expected to be widely used in future applications. Many studies have examined the effects of different modulation techniques on power or efficiency in RF energy-harvesting systems. In this article, the effects of different modulation techniques, such as amplitude shift keying (ASK), quadrature amplitude modulation (QAM), phase-shift keying (PSK), and frequency shift keying (FSK) on charging time, were measured and theoretically analyzed in detail. The measurement system was designed using a signal generator, an RF energy-harvesting circuit, and other auxiliary devices. The signal generator produced four different modulated signals as transmit power signals from 1 to 10 dBm at the interval of 1 dBm, and then, the RF energy-harvesting circuit was fed with these power signals. According to the measurement results, four different modulation techniques charged the RF energy-harvesting circuit at different times. It was observed that the 4-ASK modulation technique had the shortest charging time in the range of 1-10 dBm when comparing to QAM, PSK, and FSK modulation techniques, and thus, it was evaluated to be the most suitable modulation technique for the RF energy-harvesting system among these modulation techniques in terms of charging time.

Performance Analysis of FSK-PPM Technique in Visible-Light Communication Systems

Abstract This paper presents a combination of the FSK (frequency shift keying) and the PPM (pulse position modulation) techniques for visible-light communication systems. We propose novel modulator architecture, which is referred as combined FSK-PPM (CFPPM), to observe the average power requirement of FSK technique. The proposed combined scheme is compared with the traditional FSK method in terms of average transmission power and BER (bit error rate) performance. The average transmission power of FSK modulation technique is independent on M that is expressed as modulation order. The results show that the requirement of average transmission power of proposed FSK can be gradually decreased dependent on M.

Optimization of the Ratio of Sampling Rate to Quantization Level for the Reconstruction of Audio Signal

Background and Objective: In this research work, the basic digital communication system with frequency shift keying modulation technique has been implemented in MATLAB. Methods: The same sinusoidal signal in audio frequency range has been transmitted and reconstructed with the different number of quantization level and sampling rate, where sampling frequency has been taken according to the Nyquist theorem. It has been seen that reconstructed signal at low data rate has appeared with better resolution compared with the reconstructed signal at the high data rate. Results and Conclusion: In this regard, it is evident that the resolution of a reconstructed signal not only depends on data rate but it also depends on the ratio of sampling rate to quantization level. So it is required to optimize the ratio of sampling rate to quantization level before transmitting audio signal.

Radio Frequency Energy Harvesting with Frequency Shift Keying Modulation Technique

Radio Frequency (RF) energy harvesting is a promising alternative energy source to provide power for low power electronic devices through the air. RF energy harvesting technologies are used in many application fields such as building automation, industrial monitoring, data center, security and defense. In this study, effects of frequency shift keying modulation technique on charging times of RF energy harvesting were measured and investigated in detail. An advanced measurement system was established and this measurement system was performed using an RF energy harvesting circuit, a signal generator, patch antennas and other equipment. The modulated signal at 14 dBm output power was generated by signal generator. Then, the energy produced by the signal generator was obtained from 20 cm to 60 cm at the interval of 5 cm distance by the RF energy harvesting circuit with 6 dBi patch antenna. According to measurement results, the shortest charging time was calculated as 1 s at a distance of 20 cm. In addition to that, the longest charging time was calculated as 7 s at a distance of 60 cm. It was determined that the charging time of the RF energy harvesting decreased as the distance between signal generator and RF energy harvesting circuit reduced.

Mitigating the interferences and intruders in cognitive radio networks using an authentication protocol over Reed-Solomon codes

Cognitive radio networks have emerged as a promising solution for spectrum scarcity problem. Secondary users (unlicensed users) accessing cognitive radio network suffer from continuous unintentional interference from primary users (licensed users). Also, the adversary present in the channel tries to thwart the secondary users' communication. To address these two problems, an inherent authentication protocol is defined over Reed-Solomon codes. Reed-Solomon codes with authentication protocol are used with M-ary frequency shift keying modulation technique, for transmissions over cognitive radio network. Similarly, the received message is demodulated and decoded to get the original information bits at the receiver. The performance of the proposed scheme is given in terms of bit error rate. The experimental results show that the proposed system performs better in terms of BER reduction. Also, it is shown that the proposed scheme is resistant to replay attack, man-in-the-middle and impersonation kind of attacks.

A Frequency-Shift Keying Modulation Technique Using a Fractal Ring-Oscillator

A novel way of achieving the well-known FSK(Frequency-Shift Keying) modulation was introduced and verified. A simple form of CMOS ring-oscillator, that is generating a GHz level of frequency, was used as a base frequency generator. With its fractal structure, a local change in the oscillator will yield a global frequency change, which is to serve for the FSK. A local change is done with different number of inverting amplifiers in the ring oscillator with a multiplexer. Depending on how many cell changes, the frequency shifts are controlled and can be selected. The measured frequency difference between the shifts was from 9.2% up to 22.5%, in GHz range in CMOS SPICE simulations. Layout for CMOS implementation is also included.

Ultra low-power transceiver with novel FSK modulation technique and efficient FSK-to-ASK demodulation.

Energy-efficient and high-data rate are desired in biomedical devices transceivers. A high-performance transmitter (Tx) and an ultra-low-power receiver (Rx) dedicated to medical implants communications operating at Industrial, Scientific and Medical (ISM) frequency band are presented. Tx benefits from a new efficient Frequency-Shift Keying (FSK) modulation technique which provides up to 20 Mb/s of data-rate and consumes only 0.084 nJ/b validated through fabrication. The receiver consists of an FSK-to-ASK conversion based receiver with OOK fully passive wake-up device (WuRx). This WuRx is battery less with energy harvesting technique which plays an important role in making the RF transceiver energy-efficient. The Rx is achieved with a reduced hardware architecture which does not use an accurate local oscillator, high-Q external inductor and I/Q signal path. The Rx shows -78 dBm sensitivity for 8 Mbps data rate while consuming 639 μW. The proposed circuits are implemented in IBM 0.13 μm CMOS technology with 1.2 V supply voltage.