Amplitude Shift Keying Research Articles

Photonic Microwave Signal Mixing Using Sagnac-Loop-Based Modulator and Polarization-Dependent Modulation

A photonic-assisted microwave mixer using a Sagnac-loop-based modulator and polarization-dependent modulation is proposed and experimentally demonstrated. In this scheme, a dual-parallel Mach–Zehnder modulator (DPMZM) is incorporated in a Sagnac loop, where light is single-sideband (SSB) modulated along one direction with no modulation along the opposite direction due to the traveling-wave velocity mismatch in DPMZM. The SSB-modulated light and unmodulated optical carrier (OC) with opposite propagation directions and orthogonal polarizations are combined via a polarization beam combiner, and thus, a partial orthogonal SSB-modulated signal is obtained, which is then injected into a Mach–Zehnder modulator (MZM) via a polarization controller to ensure the polarization of the unmodulated OC paralleling with the transverse electric (TE) principal axis of MZM. Thus, only the OC is modulated by the data, and the first-order sidebands pass through the MZM directly without modulation based on the polarization dependence of MZM. After a polarizer for polarization interference and a photodetector for optical-to-electrical conversion, a phase-stable microwave signal is obtained. By adjusting the bias point of MZM, clear eye diagrams, and waveforms of 1 Gb/s on-off keying (OOK), amplitude-shift keying (ASK), and binary-phase-shift keying (BPSK) signals at 8 GHz are experimentally achieved.

Improvement of Measurement Range via Chaotic Binary Frequency Shift Keying Excitation Sequences for Multichannel Ultrasonic Ranging System

The important indicators of multichannel ultrasonic ranging system are correlation characteristics and energy efficiency. The excitation sequences with good correlation characteristics can help avoid crosstalk among multichannel ultrasonic sensors. High energy efficiency can enhance measurement range. This paper proposes a crosstalk elimination method by using the optimal binary excitation sequences modulated with chaotic codes, which include chaotic binary amplitude shift keying (c-BASK), chaotic binary phase shift keying (c-BPSK) and chaotic binary frequency shift keying (c-BFSK). To obtain the both best correlation characteristics and energy efficiency, the Nondominated Sorting Genetic Algorithm-II (NSGA-II) is applied to optimize the chaotic binary excitation sequences. Real experiments have been conducted using an ultrasonic ranging system that consists of eight-channel SensComp 600 series instrument-grade electrostatic sensors excited with chaotic binary modulation sequences. The experimental results show that the c-BFSK outperforms the c-BASK and c-BPSK in terms of the correlation characteristics and energy efficiency. With 2 ms c-BFSK excitation sequences, the longest measurable distance was 720 cm (i.e., increased 11% and 27% with c-BPSK and c-BASK, respectively) with maximal relative error 2.4%.

Wireless multi-level terahertz amplitude modulator using active metamaterial-based spatial light modulation.

The ever increasing demand for bandwidth in wireless communication systems will inevitably lead to the extension of operating frequencies toward the terahertz (THz) band known as the 'THz gap'. Towards closing this gap, we present a multi-level amplitude shift keying (ASK) terahertz wireless communication system using terahertz spatial light modulators (SLM) instead of traditional voltage mode modulation, achieving higher spectral efficiency for high speed communication. The fundamental principle behind this higher efficiency is the conversion of a noisy voltage domain signal to a noise-free binary spatial pattern for effective amplitude modulation of a free-space THz carrier wave. Spatial modulation is achieved using an an active metamaterial array embedded with pseudomorphic high-electron mobility (pHEMT) designed in a consumer-grade galium-arsenide (GaAs) integrated circuit process which enables electronic control of its THz transmissivity. Each array is assembled as individually controllable tiles for transmissive terahertz spatial modulation. Using the experimental data from our metamaterial based modulator, we show that a four-level ASK digital communication system has two orders of magnitude improvement in symbol error rate (SER) for a degradation of 20 dB in transmit signal-to-noise ratio (SNR) using spatial light modulation compared to voltage controlled modulation.

Design and Simulation of a Multi-channel Neural Recording Microsystem with Inductive Power Telemetry Link

Neural micro-probing not only allows us to access the brain signals, it is also one of the key tools to achieve a better understanding of the fundamental mechanisms of the brain and nervous system. This knowledge is extremely essential to implement complex neural prosthetics. Considering the importance of the size, power consumption, and accuracy, in this Paper, a compact, low-power eight-channel implantable neural recording microsystem is presented. To this end, Time Division Multiplexing (TDM) method is used for multiplexing 8 input channels. Thus, only one Analog to Digital Converter (ADC) block is used, resulting in a small circuit size and low power consumption. Also, a new structure of Amplitude-Shift Keying (ASK) modulation technique with simple configuration and low power consumption is proposed and applied. This system is designed in TSMC 0.18 μm CMOS technology with 1.8 V power supply and simulated with HSPICE. The total power consumption of the system is measured to 2 mW. Neural signals recorded from auditory cortex of a guinea pig are used as the inputs of the eight channels of the system. Total RMS error between inputs and outputs caused by the system is 2.8%.

RF low power subsampling architecture for wireless communication applications

With the increasing demands of wireless communication, flexible, complex, and diversified wireless communication applications are required. However, the difficulty of enabling new wireless communication applications is the lack of low power radio frequency (RF) transmission devices, especially the RF receiver. In order to alleviate this problem, an RF low power subsampling architecture for wireless communication applications is proposed in this paper. This subsampling architecture adopts a single-ended to differential configured balun low noise amplifier (balun-LNA), a subsampling mixer with high sampling ratio and a finite input response (FIR) filter and infinite impulse response (IIR) filter achieving frequency down-conversion, avoiding using high power-hungry blocks. Based on a subsampling theory, an optimum sampling frequency for the subsampling architecture is necessary to relax the complexity of the system. For the application of internet of things (IoT) wireless communication, the paper provides the implementation of the subsampling receiver solutions to get a tradeoff between power consumption, gain, noise, and sensitivity. It can achieve −85 dBm sensitivity for an amplitude shift keying (ASK) modulation at the data rate of 1 Mbps with the clock sampling frequency of 40 MHz. Finally, the theoretical analysis and simulation results show that the performance of the subsampling architecture has several advantages over others.

Optimal Multilevel ASK With Noncoherent Diversity Reception in Uncorrelated Nonidentical and Correlated Rayleigh Fading

A noncoherent quadratic diversity reception system for multilevel amplitude-shift keying (ASK) signals in Rayleigh fading with different cases of the channel covariance matrix is considered. These include the important case of distributed antennas, which exhibit uncorrelated fading with distinct mean-squared channel gains (uncorrelated nonidentical fading) and weighted energy detectors, and the cases of exponentially correlated and uniformly correlated channels with equal mean-squared channel gains. For these cases, closed-form expressions for the symbol error probability (SEP) of the system are derived using the decision statistics obtained from the maximum likelihood receiver. The problem of determining the optimal amplitude levels that minimize the SEP under a total signal energy constraint is formulated and solved analytically for the high signal-to-noise ratio (SNR) configuration and numerically for the general configuration. For the high SNR configuration, it is shown that the optimal ASK levels should follow an approximately geometric progression. It is also observed that an equally spaced ASK constellation is not optimal in terms of achieving the minimum SEP. Numerical results are presented to highlight performance trends for channel gain imbalance and correlation.

Low-Power ASK Detector for Low Modulation Indexes and Rail-to-Rail Input Range

A high-performance ultrahigh-frequency amplitude shift keying (ASK) detector for low-power radio-frequency (RF) receivers is proposed. The circuit is based on a high-gain common-source topology with a feedback loop that provides adaptive biasing. Hence, high sensitivity and rail-to-rail input operation are achieved along with low power consumption. The detector was implemented in a standard 130-nm complementary metal–oxide–semiconductor technology. Sensitivity measurements demonstrate correct detection of a 2-Mb/s ASK-modulated 915-MHz signal with a peak level and a modulation index of around 200 mV and 5%, respectively, which means an envelope signal amplitude of as low as 5 mV. The circuit draws less than $3.4 \mu\mbox{A}$ from a 1.2-V power supply while operating with rail-to-rail RF variations and modulation indexes from 5% to 100%. This performance makes the detector suitable for batteryless systems with RF energy harvesting.

Generation of 64 GBd 4ASK signals using a silicon-organic hybrid modulator at 80°C.

We demonstrate a silicon-organic hybrid (SOH) Mach-Zehnder modulator (MZM) generating four-level amplitude shift keying (4ASK) signals at symbol rates of up to 64 GBd both at room temperature and at an elevated temperature of 80°C. The measured line rate of 128 Gbit/s corresponds to the highest value demonstrated for silicon-based MZM so far. We report bit error ratios of 10-10 (64 GBd BPSK), 10-5 (36 GBd 4ASK), and 4 × 10-3 (64 GBd 4ASK) at room temperature. At 80 °C, the respective bit error ratios are 10-10, 10-4, and 1.3 × 10-2. The high-temperature experiments were performed in regular oxygen-rich ambient atmosphere.

Triboelectric Nanogenerator as a Self-Powered Communication Unit for Processing and Transmitting Information.

In this paper, we demonstrate an application of a triboelectric nanogenerator (TENG) as a self-powered communication unit. An elaborately designed TENG is used to translate a series of environmental triggering signals into binary digital signals and drives an electronic-optical device to transmit binary digital data in real-time without an external power supply. The elaborately designed TENG is built in a membrane structure that can effectively drive the electronic-optical device in a bandwidth from 1.30 to 1.65 kHz. Two typical communication modes (amplitude-shift keying and frequency-shift keying) are realized through the resonant response of TENG to different frequencies, and two digital signals, i.e., "1001" and "0110", are successfully transmitted and received through this system, respectively. Hence, in this study, a simple but efficient method for directly transmitting ambient vibration to the receiver as a digital signal is established using an elaborately designed TENG and an optical communication technique. This type of the communication system, as well as the implementation method presented, exhibits great potential for applications in the smart city, smart home, password authentication, and so on.

Ultra‐low power current mode all‐ MOS ASK demodulator for radio frequency identification applications

An ultra-low power amplitude shift keying (ASK) demodulator for radio frequency identification (RFID) tags is presented. On the basis of a fast averaging stage, the proposed ASK-demodulator uses a current domain switching envelope amplifier which yields low-power operation. More importantly, it removes the need for a conventional voltage comparator. Designed and fabricated in a 0.18 µm complementary metal–oxide–semiconductor process on about 3000 µm2 silicon area, the proposed demodulator consumes only 7.5 µA from a magnetically coupled induced power. Operating with a 13.56 MHz carrier frequency, the circuit supports modulation indices from 7 up to 100%. The demodulator may as well be used in passive biomedical devices where power efficiency is crucial.

Correction of amplitude distortions for truncated Bessel beam and SER estimation for 4ASK

We apply amplitude corrections to a truncated Bessel beam that has propagated through turbulent atmosphere modelled by random phase screens. These corrections are realized via transmitting an unmodulated beam in parallel to the one carrying the 4 amplitude shift keying (ASK) modulated message signal. On the receiver side, the amplitude corrections are obtained by dividing the intensity of the unmodulated beam by its free space equivalence. The corrections are then used to restore the amplitude distortions of the beam carrying the 4ASK modulated message signal and in the determination of decision boundaries for the received 4ASK symbols. The success of the system is visually inspected by comparing the received intensity profiles before and after the application of corrections. Furthermore, simulation analysis of symbol error rate (SER) is made, where the proposed set-up is found to be quite insensitive to wavelength difference between the unmodulated and modulated beams. On the other hand, the difference in the structure constant values of these two beams seems to have profound effect on system performance.

Photonic-assisted microwave signal multiplication and modulation using a silicon Mach-Zehnder modulator.

Photonic generation of microwave signal is obviously attractive for many prominent advantages, such as large bandwidth, low loss, and immunity to electromagnetic interference. Based on a single integrated silicon Mach–Zehnder modulator (MZM), we propose and experimentally demonstrate a simple and compact photonic scheme to enable frequency-multiplicated microwave signal. Using the fabricated integrated MZM, we also demonstrate the feasibility of microwave amplitude-shift keying (ASK) modulation based on integrated photonic approach. In proof-of-concept experiments, 2-GHz frequency-doubled microwave signal is generated using a 1-GHz driving signal. 750-MHz/1-GHz frequency-tripled/quadrupled microwave signals are obtained with a driving signal of 250 MHz. In addition, a 50-Mb/s binary amplitude coded 1-GHz microwave signal is also successfully generated.

Performance Comparison among ASK, FSK and DPSK in Visible Light Communication

We consider the detection of Amplitude-Shift Keying (ASK), Frequency-Shift Keying (FSK) and Differential Phase-Shift Keying (DPSK) in Visible Light Communication (VLC). And their performance is compared according to data rate, transmission distance and incident angle respectively.

Comparison on Powering Passive Sensor RFID via Variation of Modulation Indexes

In this paper we present data on how powering passive sensor radio frequency identification (RFID) transponder can be performed more efficiently. We focused on the industrial, scientific and medical (ISM) band around 5.8 GHz. We investigated how different modulation indexes for amplitude shift keying (ASK) affect the rectification process. The rectifier configuration is Greinacher one with two HSMS2862 and the other with two PCC110 diodes from Avago and Powercast, respectively. The highest achieved power gain was 6.4 dB at a modulation index m of 100% compared to a continuous wave signal at an input power of –12.7dBm for the HSMS2862 rectifier.

Bit Error Rate Performance Comparison of Large Scale MIMO Receivers using Spatial Modulation

This paper proposes a novel approach of an Approximate Message Passing (AMP) detection method for Large Scale Multiple Input Multiple Output (LS-MIMO) receiver which uses MT transmit antennas and MR receive antennas to detect the information bits transmitted. An efficient transmission technique called Spatial Modulation (SM) in which the information bits are encoded and conveyed through the indexes of the transmit antennas using M-ary Amplitude and Phase Shift Keying (APSK) modulation to increase the efficiency of the receiver. Simulation results show that the Bit Error Rate (BER) performance of the proposed detection method performs near to the Maximum Likelihood (ML) detection and outperforms than the Modified Maximum Ratio Combiner (MMRC) detection.

A Near-Threshold Energy-Efficient ASK Transmitter for Biomedical Implants

A near-threshold amplitude shift keying (NT-ASK) transmitter for biomedical implants is presented in this paper. The ASK transmitter supports a 100-Mb/s baseband data rate with a carrier frequency of 2.4 GHz. The design incorporates an LC voltage-controlled oscillator (VCO), ASK modulator, and a class-E power amplifier. The carrier is generated by a low phase noise LC-VCO, and then directly modulated by an NT-ASK modulator. The modulated signal is amplified by a class-E power amplifier and transmitted through an inductive coil. The transmitter achieves a total power consumption of 1.65 mW at 0.5 V, an energy efficiency of 16.5 pJ/b, and a phase noise of −115.7 dBc/Hz at 1-MHz offset at a center frequency of 2.4 GHz. The output power level of the transmitter is −14 dBm. The ASK transmitter is implemented in a standard 0.13- $\mu \text{m}$ CMOS process with a core area of 0.63 mm2.

Bandwidth Efficient and Rate-Matched Low-Density Parity-Check Coded Modulation

A new coded modulation scheme is proposed. At the transmitter, the concatenation of a distribution matcher and a systematic binary encoder performs probabilistic signal shaping and channel coding. At the receiver, the output of a bitwise demapper is fed to a binary decoder. No iterative demapping is performed. Rate adaption is achieved by adjusting the input distribution and the transmission power. The scheme is applied to bipolar amplitude-shift keying (ASK) constellations with equidistant signal points and it is directly applicable to two-dimensional quadrature amplitude modulation (QAM). The scheme is implemented by using the DVB-S2 low-density parity-check (LDPC) codes. At a frame error rate of $10^{-3}$ , the new scheme operates within less than 1.1 dB of the AWGN capacity $\frac{1}{2}\log_2(1+{\mathsf{SNR}})$ at any spectral efficiency between 1 and 5 bits/s/Hz by using only 5 modes, i.e., 4-ASK with code rate 2/3, 8-ASK with 3/4, 16-ASK and 32-ASK with 5/6, and 64-ASK with 9/10.

Threshold voltage-level change in ASK demodulator related to RF input signal amplitude for the ultra-high frequency RFID passive tag

In this paper, an amplitude shift keying (ASK) demodulator with 100% modulation depth is proposed. In order to achieve the higher power and wider reading range the designed ASK demodulator works in the ultra-high frequency. In this design, the average detector and voltage divider are used in order to define the appropriate threshold voltage level for the radio frequency input signal which leads to the accurate data detecting even at long distances between the tag and reader. In addition, for diminishing the power dissipation of the proposed demodulator, an enable input is used in the buffer and comparator. This circuit is simulated in 0.18 μm complementary metal–oxide–semiconductor (CMOS) technology with Cadence software. Its power dissipation and chip area are 3.9 nW and 0.0025 mm2, respectively.

Dispersion insensitive demodulation using spectral symmetry of real‐valued signals

A chromatic dispersion insensitive demodulation for real-valued signals (e.g. binary shift keying and 4 amplitude shift keying) is proposed. This method utilises the symmetric spectrum of the signals and can be implemented simply in feed-forward manner. Its feasibility is confirmed by simulations and experiments.

Information Rates of ASK-Based Molecular Communication in Fluid Media

This paper studies the capacity of molecular communications in fluid media, where the information is encoded in the number of transmitted molecules in a time-slot (amplitude shift keying). The propagation of molecules is governed by random Brownian motion and the communication is in general subject to inter-symbol interference (ISI). We first consider the case where ISI is negligible and analyze the capacity and the capacity per unit cost of the resulting discrete memoryless molecular channel and the effect of possible practical constraints, such as limitations on peak and/or average number of transmitted molecules per transmission. In the case with a constrained peak molecular emission, we show that as the time-slot duration increases, the input distribution achieving the capacity per channel use transitions from binary inputs to a discrete uniform distribution. In this paper, we also analyze the impact of ISI. Crucially, we account for the correlation that ISI induces between channel output symbols. We derive an upper bound and two lower bounds on the capacity in this setting. Using the input distribution obtained by an extended Blahut-Arimoto algorithm, we maximize the lower bounds. Our results show that, over a wide range of parameter values, the bounds are close.