Automatic Gain Control Algorithm Research Articles

NextGen ADS-B Software-Defined Reception with Enhanced Techniques

This paper provides research on the enhanced NextGen ADS-B reception method and its performance in laboratory and flight tests. It sheds the light on end-to-end reception techniques to comply with key requirements. ADS-B has emerged as among the most intriguing avionics for both researchers and companies since the launch of NextGen in 2009. ADS-B provides authorities with a mechanism for use in continuously monitoring the position and track of an airplane using periodic and independent broadcast messages that transmit Global Navigation Satellite System (GNSS) position information. The enhanced pulse detection technique is used to detect and validated preamble pulses. Besides the utilization of multiple amplitude samples technique not only improve bit and confidence declaration accuracy but also make it capable of deploying error detection/correction algorithms which are two aspects of enhanced Extended Squitter reception. In addition, applying a slow attack automatic gain control (AGC) algorithm improves system sensitivity and performance. The implementation is done in MATLAB Simulink and C++. Software Defined Radio (SDR) module, BladeRF, is used programable platform for the communication system. Subsequently, the lab experimental and flight test results show that when applying these strategies in a real environment, significant performance is achievable.

Real-Time Implementation of a Novel Automatic Gain Control Algorithm for Infrared Image Processing Based on MPSoC

Real-Time Implementation of a Novel Automatic Gain Control Algorithm for Infrared Image Processing Based on MPSoC

Spiking Cochlea With System-Level Local Automatic Gain Control

Including local automatic gain control (AGC) circuitry into a silicon cochlea design has been challenging because of transistor mismatch and model complexity. To address this, we present an alternative system-level algorithm that implements channel-specific AGC in a silicon spiking cochlea by measuring the output spike activity of individual channels. The bandpass filter gain of a channel is adapted dynamically to the input amplitude so that the average output spike rate stays within a defined range. Because this AGC mechanism only needs counting and adding operations, it can be implemented at low hardware cost in a future design. We evaluate the impact of the local AGC algorithm on a classification task where the input signal varies over 32dB input range. Two classifier types receiving cochlea spike features were tested on a speech versus noise classification task. The logistic regression classifier achieves an average of 6% improvement and 40.8% relative improvement in accuracy when the AGC is enabled. The deep neural network classifier shows a similar improvement for the AGC case and achieves a higher mean accuracy of 96% compared to the best accuracy of 91% from the logistic regression classifier.

Fast-Settling Two-Stage Automatic Gain Control for Multi-Service Fibre-Wireless Fronthaul Systems

With the development of fast digitiser and digital signal processing techniques, wide-band digital radio-over-fiber (DRoF) based wireless fronthaul systems have been extensively studied as a way of offering multi-service wireless coverage. With data compression, the high digital data rate caused by digitisation can be reduced so as to minimise the infrastructure cost for last-mile cellular coverage. However, data compression always comes with the cost of a lower input power dynamic range. To overcome the issue, this paper proposes a novel fast-settling two-stage automatic gain control (FSS-AGC) algorithm, in which gain adjustment is carried out by a multi-threshold decision mechanism with a fast-settling time (within $2~\mu $ s), high stability and great accuracy. By introducing a novel gain control mechanism which simultaneously adjusts the gain in the digital and RF domains, the loss of dynamic range after compression is compensated. This algorithm is applied and demonstrated in a DRoF based digital distributed antenna system (DDAS) which supports all current cellular services from 3 Chinese mobile network operators (MNOs). The demonstration shows over 73dB dynamic range, with 40dB improvement compared with conventional links. Its promising properties and excellent performance enable its potential application in next-generation converged networks for Internet of things (IoT) and 5G services.

DIGITAL AUTOMATIC GAIN CONTROL SYSTEM MODELING

The goal of automatic gain control is to maintain a constant output power level. Automatic gain control systems are used in various communication systems, both analog and digital. However, for all the variety of digital automatic gain control algorithms, the adjustment of the control parameters during the simulation process in reality is often ignored. In practice, this can lead to long-term overloads with a large change of the input signal power. There is also the risk that the model used was designed to work in linear mode only. In nonlinear mode, its behavior may not always be predictable. Research subject. The purpose of this article is to analyze digital AGC system characteristics and to model its operation in Matlab. Method. As part of the study, a Matlab model of hybrid automatic gain control system was developed. Core results. It is shown that the control time of the digital automatic gain control system with a non-linear gain control characteristic does not depend on the amplitude of the input signal. The performance of the proposed digital model is limited by the dynamic range of the linear path and the analog-to-digital converter. The mathematical dependence of the response time of the model on the input signal level change is obtained, in which the time constant of the automatic gain control filter has been replaced by the time constant of the entire automatic gain control system. Practical relevance. A digital model of hybrid automatic gain control system is proposed, which will allow to simulate digital automatic gain control systems parameters for both small and large changes in the input signal level. The results of this work are relevant to the development of digital receivers for communication systems of various purposes.

인접 채널 간섭이 큰 환경에서 단일 반송파 무선 통신 시스템을 위한 새로운 자동 이득 제어 기법

무선 통신 시스템에서 기지국과 단말기 사이의 거리의 변화, 수신기의 움직임 등에 의해 수신된 신호의 크기 가 크게 변화한다. 특히 단일 반송파 시스템(single carrier systems)의 경우, 시간 영역에서 수신 신호의 복조가 수행되기 때문에 복조단에 입력되는 신호의 크기가 일정하도록 자동 이득 제어(automatic gain control, AGC)가 수행되어야 한다. 그러나 인접 채널 간섭(adjacent channel interference, ACI)이 큰 환경에서는 기존 기법들만을 고려할 경우, 복조단으로 입력되는 신호의 크기가 일정하게 유지되는 것을 보장할 수 없게 되거나 아날로그 디지털변환기(analog-to-digital converter, ADC) 입력 신호의 포화 현상을 방지하지 못하여 복조 성능이 크게 열화될 수 있다. 본 논문에서는 인접 채널 간섭이 큰 환경에서 간섭의 크기를 이용하여 자동 이득 제어를 조정하는 기법을 적용하여 기존 방식들에 비해 비트 오류율(bit error rate, BER) 성능을 향상 시킬 수 있는 방안을 제시한다.

A switched-capacitor-based low-power receiver for electrocardiogram and respiration rate detection

This paper presents an integrated switched-capacitor-based low-power fully-differential analog front-end (AFE) for simultaneously detecting electrocardiogram (ECG) and respiration rate (RR). A current-driven passive mixer is used to up-convert the RR signal, and a preamplifier including a driven-ground common-mode feedback (CMFB) loop amplifies both the ECG and modulated RR signals. The modulated RR signal is then down-converted to baseband to be further amplified and detected. Switched capacitors (SCs) are widely used in the proposed AFE to provide large time constants that are also easily adjustable via the clock frequency. The chip is highly programmable, which enables complex automatic gain control (AGC) algorithms based on using a microcontroller within the loop. The AFE was fabricated in the OnSemi $$0.5\,\upmu \hbox {m}$$ CMOS process. Both simulation and measurement results verify the functionality of the chip for measuring multiple biosignals, including ECG, RR, electromyography (EMG), and galvanic skin response (GSR). Performance metrics are competitive compared to the state of the art.

Application of AGC Technology in Software Radio

Abstract The characteristics of software radio are flexibility, openness, scalability. The hardware platform of software radio should be a general platform. This paper discusses automatic gain control(AGC) technology in software radio receiver and introduces an AGC algorithm applicable for DSP implement. This algorithm is tested in matlab and simulation results are provided.

A novel feed‐forward segmented digital automatic gain control algorithm for long‐term evolution digital radio‐over‐fibre systems

© 2017, The Institution of Engineering and Technology. This study describes a novel feed-forward segmented digital automatic gain control (FSD-AGC) algorithm for long term evolution (LTE) digital radio-over-fibre (DRoF) systems. It experimentally demonstrates the algorithm using a DRoF platform based on real-time field programmable gate arrays. The FSD-AGC algorithm is able to update power status accurately with a short delay (about 100 samples) and adjust the gain precisely by only one step. It can make full use of analogue-to-digital converter quantisation bits width without oversaturation and maintain a stable peak-to-average ratio to reduce the overall cost and energy consumption of digital links and to minimise the deterioration of error vector magnitude (EVM) in LTE systems. Compared with conventional solutions, the proposed algorithm shows significant improvement in the dynamic range (a 20 dB improvement is demonstrated experimentally) of 4G-LTE radio frequency signals in a DRoF system. This is a major step forward for the future commercialisation of DRoF systems for 4G and 5G network deployments. Meanwhile, FSD-AGC can be applied in both LTE time division duplexing and frequency division duplexing signals. Experimental results have shown a mean EVM of the DRoF system below 4.5%, which is well below the 8% required by 3rd generation partnership project.

SFD-AGC algorithm with ADC digitalizing bit fully utilized and stable PAR

Aiming at making full use of analog to digital converter (ADC) digitalizing bit without oversaturation while keeping peak to average ratio (PAR) stable, this paper puts forward a new segmented full-digital (SFD)-automatic gain control (AGC) algorithm for a new long term evolution (LTE) communication system. Segmented digital gain control strategy is adopted to adjust the gain by only one step based on detected power status. Whether the gain needs to be adjusted is determined by current signal state derived from the change ranges of adjacent root mean square (RMS) of input signal, but not the difference between the power level of current signal and target signal. Software simulation and hardware implementing had been conducted with LTE frequency division dual (FDD) uplink signal and the results indicated that the proposed AGC algorithm can judge power status accurately and hence adjust the gain precisely in one step with a short delay, further, it can make full use of ADC digitalizing bit without oversaturation as well as keeping stable PAR. In addition, the mean error vector magnitude (EVM) was confined less than 1.6% to meet the 3rd generation partnership project (3GPP) standard well.

An Automatic Loop Gain Control Algorithm for Bang-Bang CDRs

An automatic loop gain control algorithm (ALGC) for a bang-bang (BB) clock and data recovery (CDR) is proposed. The proposed algorithm finds the optimum loop gain using the autocorrelation of a BBPD output signal for minimum MSE performance. Mathematical proof of the algorithm is presented for both rotator-based and VCO-based CDRs with finite loop delay. A 25 Gb/s transceiver IC is fabricated using a 40 nm CMOS process to validate the performance of the algorithm. The power consumptions of TX and RX are 37.8 mW and 46.8 mW, respectively and the synthesized area implementing a digital loop filter together with the proposed ALGC occupies 140 $\mu$ m $\times$ 170 $\mu$ m.

Digital AGC based on coherent adjustment cycle for DSSS receiver

In order to meet the requirements for zero value stability of direct sequence spread spectrum (DSSS) signal processing in high dynamic scenario, digital automatic gain control (AGC) is employed to regulate power. However, conventional AGC causes degradation in the synchronization performance of DSSS receiver. Based on the theoretical analysis of the influence of digital AGC on DSSS signal synchronization, this paper proposes a new AGC algorithm, which is applicable to multi-channel digital DSSS signal receiver. By making power adjustment cycle and synchronization cycle coherent with each other adaptively, the influence of digital AGC on subsequent synchronization processing has been eliminated. Theoretical analysis, simulation results and experimental data verify the validity of the proposed algorithm. By virtue of the proposed algorithm, the influence of digital AGC on DSSS signal synchronization is eliminated. This algorithm applies to an aerospace engineering project successfully.

Thermal Conductivity Detector for Gas Chromatography: Very Wide Gain Range Acquisition System and Experimental Measurements

The aim of this paper is to present an acquisition system featuring a very wide gain range and experimental measurements of a new micromachined thermal conductivity detector ( $\mu$ TCD), applied downstream of a gas-chromatography (GC) system. We describe a simple and innovative electronics for $\mu$ TCD control and data acquisition, outlining its resistance control, native imbalance compensation, and automatic gain control (AGC) algorithm. The acquisition electronics features two parallel amplification stages with programmable gain: a high-gain stage (gain: 70–1280) and a low-gain or attenuating stage (gain: 0.6–30). The resulting detection range turns out to be very wide, with full scales ranging between 3.9 mV and 6.5 V while voltage is acquired with a 10-b-resolution analog-to-digital converter. Measurements and sensitivity tests have been carried out by connecting our $\mu$ TCD and acquisition system downstream of the microfluidic section and GC column of a commercial GC system. Sensitivity measurements on several toluene masses gave very good results, having observed a system sensitivity of $15.2 \pm 0.6 \mu\hbox{Vs/ng}$ . This high sensitivity will enable the $\mu$ TCD to be used in many portable applications like in-line quality control, and industrial security and safety. We also show the good operation of the AGC algorithm.

SDR 통신장비를 위한 2단계 적응형 Digital AGC 기법

In this paper, an adaptive digital automatic gain control(AGC) algorithm with two stages is proposed. AGC technique is crucial for mobile communication equipment because path loss in wireless channel and gain fluctuation in receiver front-end continuously change the received signal strength. Furthermore, adaptive criteria should be applied to the design of AGC algorithm in order to support many waveforms with one SDR communication device. With these reasons, a two-stage structure is proposed to satisfy both flexibility and adaptiveness. Compared with conventional method, it also requires shorter convergence time. Numerical results show that the gain value of variable gain amplifier(VGA) is converged within proper time and proposed scheme controls the input level of analog to digital converter(ADC) to be stable during long range of time.

Stochastic-Based Analyses of Noncoherent Code Tracking Loops Over Wireless Fading Circumstances

For band-limited pseudonoise signals, a noncoherent digital delay-lock loop (DDLL) equipped with a discrete automatic gain control algorithm under a RAKE scheme over frequency-selective fading channels is studied. Its associated statistical characteristics are analyzed based on the Nakagami- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> stochastic process. The transition timing error probability density function (pdf) of the Chapman-Kolmogorov equation is evaluated to drive an analytical expression for the steady-state timing error pdf. The mean time to lose lock and the mean square tracking error with its corresponding Cramér-Rao lower bound (CRLB) under frequency-selective Nakagami- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> fading environments are scrutinized, whereas their numerical results are confirmed by time-domain computer simulations. Moreover, the tracking performance of the DDLL in the presence of Doppler shifts is also examined.

Analysis and implementation of digital automatic gain control for DAB baseband decoder

Digital Audio Broadcasting (DAB) receiver requires fast Automatic Gain Control (AGC) to compensate the strength loss due to the multipath propagation in mobile receiving condition. But fast AGC could also incorrectly amplify DAB's null symbol and the following phase reference symbol to cause the synchronization problem. In this paper, we mathematically analyze the AGC circuit under a Rayleigh fading channel and give the basic rule to generate the AGC feedback voltage. Then a fast and high accuracy AGC algorithm with least affection on the DAB null symbol is proposed. The algorithm is simplified to have only add, shift and compare operations, making it easy for hardware and software implementation. Finally the algorithm is simulated and verified on Field Program Gate Array (FPGA) device. The test results show that the proposed AGC algorithm can be settled within 0.5 ms, and keep the received signal stable at a moving speed from stationary to over 120 km/h, both in city and suburban area. The algorithm and the analysis method can also be used for AGC design in other wireless systems.

An Enhanced Automatic Gain Control Algorithm for Initial Cell Search in 3GPP LTE TDD System

In this paper, we propose an AGC (Automatic Gain Control) algorithm for initial cell search in 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) TDD (Time Division Duplex) system. Since the received signal has a large signal power difference between uplink and downlink subframe in wireless communication systems using a TDD scheme, conventional AGC scheme cannot sufficiently adjust the AGC gain because the AGC gain cannot converge fast enough to properly respond. Therefore, conventional AGC scheme leads to increased AGC gain variation, and the received signal will be attenuated by large AGC gain variation. To overcome this limitation, we propose an AGC scheme based on the average amplitude ratio calculation which can not only effectively increase convergence speed of the AGC gain but also maintain the stability of AGC operation in LTE TDD system. Also, it is important for AGC to converge efficiently for the accurate radio frame timing detection during the subsequent initial cell search procedure. Therefore, we also consider the proposed AGC scheme in combination with PSS (Primary Synchronization Signal) detection interface for the first step of initial cell search process in LTE TDD system to obtain both a stable AGC operation and accurate PSS detection performance. By extensive computer simulation in the presence of frequency offset and various channel environments, we verified that the proposed method can obtain a good behavior in terms of demodulation and PSS detection performance in LTE TDD system.

Efficient automatic gain control algorithm and architecture for wireless LAN receivers

The performance of a receiver front-end limits the quality and range of the given communication link. An appropriate design based on well-defined system parameters and architecture can make a huge difference in the performance, cost and marketability of the entire system. In particular, there is a need for improved digital automatic gain control (AGC) for use in multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with application to wireless local area networks (WLANs), targeted for the upcoming 802.11n standard [Heejung Yu et al., IEEE 802.11 wireless LANs ETRI proposal specification for IEEE 802.11 TGn, IEEE 802.11 document, doc. No. 11-04-0923-00-000n, August, 2004; H. Yu, T. Jeon, S. Lee, Design of dual-band MIMO-OFDM system for next generation wireless LAN, in: IEEE International Conference on Communications (ICC), May, 2005]. In this paper, we propose an efficient algorithm and implementation of the digital AGC for next generation WLANs. The proposed AGC algorithm has two feedback loops for gain control to improve convergence speed, and at the same time maintains the stability of the AGC circuit. Also, a complete set of parameters for practical implementation is obtained by various experiments with fixed point constraints and accuracy requirements.

Analog AGC Circuitry for a CMOS WLAN Receiver

The IEEE 802.11a standard uses orthogonal frequency division multiplexing (OFDM) to allow high data rates in multipath WLAN environments. The high peak-to-average power ratio (PAPR) of OFDM signals, along with stringent settling-time constraints, make conventional closed-loop automatic gain control (AGC) schemes impractical for WLAN receivers. In a direct conversion receiver, AGC and channel-select filtering are performed by analog baseband circuitry. A baseband signal processor using a new open-loop analog gain-control algorithm for OFDM is described. The new AGC algorithm uses switched coarse gain-setting steps followed by an analog open-loop fine gain-setting step to set the final gain of variable gain amplifiers (VGAs). The AGC was implemented in a 0.18-mum CMOS process using newly designed circuits including linear VGAs, RMS detectors, and current-mode computation circuitry. Simulation and measurement results verify that the new AGC circuit converges with gain error less than 1dB to the desired level within 5.6 mus

A Joint Scheme of AGC and Gain/Phase Mismatch Compensation for QPSK DCR

This paper presents a simple gain/phase blind compensation algorithm with an automatic gain control (AGC) function for the adoption of the AGC function and compensation for gain/phase imbalances in quadrature phase shift keying (QPSK) direct conversion receivers (DCRs). The AGC function is interactively operated with the compensation algorithm for gain/phase imbalances. By detecting the gain sum and difference values between the I-channel and Q-channel, the combined AGC and gain imbalance compensation algorithm provides a simpler DCR architecture.