Baseband Operation Research Articles

Synchronization and Optimal Operation of a 140 kVA Inverter in On-Grid Mode Using Mamdani Controllers in Cascade

This paper addresses the synchronization and operation of a 140 kVA inverter system connected to the main grid as part of a decentralized microgeneration system. The considerations for the supply of electrical energy stored in battery banks, mostly of photovoltaic origin, involve a study of the details of a rigid nonlinear system, which parallels the generation and distribution standards typical of hydroelectric and thermoelectric plants. Considering aspects related to power electronics operation, this paper presents both the modeling and the controlling aspects necessary to synchronize and ensure a stable operation of the microgeneration systems when connected to the main grid. Statistical processing was developed to guarantee synchronization between the systems without presenting electric shocks by simulating the magnetic link in asynchronous generators to meet this aim. The proposed model simulates the increase in power by a phase shift by maintaining a constant frequency based on a Chirp wave generator. The proposed process considers a generation power baseband operation. A Mamdani-type fuzzy proportional-integral controller is used to determine the power setpoint, which sets the Chirp generator phase shift setpoint, which includes a Mamdani fuzzy proportional-type controller. Both controllers are connected in a cascade. The applied correlational technique to achieve the synthesis of the sinusoid and the synchronization presented optimal performance when using 17 samples per signal period. The design of the transformer primarily, guaranteed a phase shift of −4.3018°, allowed for a THD below 2.75%.

4th order current-mode and transresistance-mode MOSFET-C low-pass filter for multi-standard receivers

This work presents a novel 4th order current-mode and transresistance-mode low-pass filter based on MOSFET-C architecture. Proposed filter's cut-off frequency can be easily adjusted from 15 MHz up to 45 MHz for the analog baseband filters used in multi-standard receivers. The main core circuit of the filter contains only 7 transistors in order to reduce chip area and power consumption. Also, the proposed 4th order architecture have dual outputs in different modes facilitating signal conversion and different signal operations. The proposed structure has (54.3 μm × 34.1 μm) chip area and post layout simulations are examined extensively to prove performance of the filter. Also, input referred noise (IRN) characteristics of the filter outputs are shown in order to overcome thermal noise effects worsening the performance of the filter. Power consumption changes from 195.8 μW up to 1.37 mW whereas cut-off frequency is varied from 15 MHz up to 45 MHz. Provided results show that the proposed filter scheme brings a promising opportunity to designers for the analog baseband operations in multi-standard communication receivers.

10 Clock-Periods Pipelined Implementation of AES-128 Encryption-Decryption Algorithm up to 28 Gbit/s Real Throughput by Xilinx Zynq UltraScale+ MPSoC ZCU102 Platform

The security of communication and computer systems is an increasingly important issue, nowadays pervading all areas of human activity (e.g., credit cards, website encryption, medical data, etc.). Furthermore, the development of high-speed and light-weight implementations of the encryption algorithms is fundamental to improve and widespread their application in low-cost, low-power and portable systems. In this scientific article, a high-speed implementation of the AES-128 algorithm is reported, developed for a short-range and high-frequency communication system, called Wireless Connector; a Xilinx ZCU102 Field Programmable Gate Array (FPGA) platform represents the core of this communication system since manages all the base-band operations, including the encryption/decryption of the data packets. Specifically, a pipelined implementation of the Advanced Encryption Standard (AES) algorithm has been developed, allowing simultaneous processing of distinct rounds on multiple successive plaintext packets for each clock period and thus obtaining higher data throughput. The proposed encryption system supports 220 MHz maximum operating frequency, ensuring encryption and decryption times both equal to only 10 clock periods. Thanks to the pipelined approach and optimized solutions for the Substitute Bytes operation, the proposed implementation can process and provide the encrypted packets each clock period, thus obtaining a maximum data throughput higher than 28 Gbit/s. Also, the simulation results demonstrate that the proposed architecture is very efficient in using hardware resources, requiring only 1631 Configurable Logic Blocks (CLBs) for the encryption block and 3464 CLBs for the decryption one.

Sensitive multi-species trace gas sensor based on a high repetition rate mid-infrared supercontinuum source.

We present a multi-species trace gas sensor based on a high-repetition-rate mid-infrared supercontinuum source, in combination with a 30 m multipass absorption cell, and a scanning grating spectrometer. The output of the spectrometer is demodulated by a digital lock-in amplifier, referenced to the repetition rate of the supercontinuum source. This improved the detection sensitivity of the system by a factor 5, as compared to direct baseband operation. The spectrometer provides a spectral coverage of 950 cm-1 (between 2.85-3.90 µm) with a resolution of 2.5 cm-1 in 100 ms. It can achieve noise equivalent detection limits in the order of 100 ppbv Hz-1/2 for various hydrocarbons, alcohols, and aldehydes.

Analysis of the Actual Power and EMF Exposure from Base Stations in a Commercial 5G Network

In this work, monitoring of the transmit power for several base stations operating in a live 5G network (Telstra, Australia) was conducted with the purpose of analyzing the radio frequency (RF) electromagnetic field (EMF) exposure levels. The base stations made use of state-of-the-art massive MIMO antennas utilizing beamforming in order to optimize the signal strength at the user’s device. In order to characterize the actual EMF exposure from 5G base stations, knowledge of the amount of power dynamically allocated to each beam is therefore of importance. Experimental data on the spatial distribution of the base stations’ transmit power were gathered directly from the network by extracting information on the radio and baseband operations. Out of more than 13 million samples collected over 24 h, the maximum time-averaged power per beam direction was found to be well-below the theoretical maximum and lower than what was predicted by the existing statistical models. The results show that assuming constant peak power transmission in a fixed beam direction leads to an unrealistic EMF exposure assessment. This work provides insights relevant for the standardization of EMF compliance assessment methodologies applicable for 5G base stations.

A high-quality digital radio-frequency capacitor microphone with improved dynamic range.

Capacitor microphones are widely used to transduce sound waves into electrical voltages. The converting capacitor can either be operated in baseband (audio-frequency) or passband (radio-frequency, RF). A baseband operation can use a straightforward circuit implementation while a passband operation becomes more complex. The advantage of operating the capacitor in passband is a drastically lowered sensor impedance leading to superior performance, especially at high humidity levels. In this work, a digitized RF microphone is presented. Measurements prove the microphone to exceed commercial state-of-the-art small-diaphragm capacitor microphones in signal-to-noise ratio. Additionally, as the signal is digitized before demodulation, the electrical low-frequency 1/f-noise is circumvented. Furthermore, an all-digital gain ranging approach is presented, which is especially suited for the proposed system. The approach increases the system's dynamic range by digitally adjusting and correcting the microphone's sensitivity.

Near‐band digital predistortion for wideband power amplifiers with mmWave non‐contiguous carrier aggregation

A near-band digital predistortion technique is proposed to linearise a wideband power amplifier (PA) with millimetre wave (mmWave) non-contiguous carrier aggregation (CA). The proposed method employs low-bandwidth linearisation architecture to only focus on the in-band compensation and part of the out-of-band (OOB) distortion suppression, which largely alleviate the bandwidth limitation for baseband operation. Experiments have been carried out on an mmWave PA with the centre frequency of 41 GHz. Good measurement results can be achieved when the PA is excited by a very wideband modulated signal with 1001 CA configuration and the total bandwidth of 640 MHz.

Application of Digital Signal Processing in USRP Satellite Signal Detection

The Universal Software Radio Peripheral development technique is designing and implementing radio frequency based systems. The distinctiveness originates from the interchangeable daughterboard within the USRP. The system is designed around the Xilinx Vertex 3 FPGA chip. This means C++, Python, and VHDL can be used to program this device. The project consists of creating a receiver. The objective of the project is to research and comprehend the hardware functionalities of the USRP. The purpose is to create codes in C++ and Python to implement receiving capabilities of the device. The goal of this project was to design a GPS receiver that is capable of recording the L1 signal from a DirecTV satellite. The USRP is used a lot for research. This project consisted of more than just one method. We used GNU Radio Companion and Matlab/Simulink. GNU Radio is open source for building software defined radios. It is also known as GRC. While using GRC the USRP1 was the device used. This software has rapid development. It runs in Ubuntu, a Linux operating system. Within this software there are logic blocks. Each block consists of information to create a flow graph. The flow graph builds and generates the program. Simulink can be compared to GRC. They both have logic blocks that have to be connected to run. Simulink can be used to create a transmitter or a receiver for software radio development and signal processing. Software-defined radio can only be defined if its baseband operations can be completely defined by software. A SDR converts digital to analog signals. The USRP can also convert digital signals from a computer to Radio Frequency Signals (RF). This software is one way to communicate between hardware and software.

FPGA-Based Realisation of SDR with OFDM Tranceiver

Software-defined radio architecture is the key point of next generation communication systems in which some of the functional units are designed as software on a reconfigurable processor. This paper proposes the physical layer architecture of SDR with modified orthogonal frequency division multiplexing (OFDM). One of the main drawbacks of OFDM is that its high peak-to-average reduction (PAPR) ratio. The PAPR can be reduced using filtering and adaptive peak windowing method with Kaiser window. The adaptive window method finds the positions of maximum peak values using a peak detector in the signal and applies the window function with variable parameter. The radix 2 scalable N point FFT algorithm is used in the system. The mapping of the information signal is done with BPSK, PSK, and 16 QAM modulation. According to the signal-to- noise ratio (SNR) value, the type of modulation can be selected. Decoding of the OFDM signal in the receiver is done with Viterbi decoding algorithm. The communication system simulation is done in MATLAB and the baseband operations are implemented on Xilinx FPGA. Defence Science Journal, Vol. 65, No. 3, May 2015, pp.233-239, DOI: http://dx.doi.org/10.14429/dsj.65.6011

Mitigating Time Interval Error (TIE) in High-Speed Baseband Digital Transports: Design for Delay Compensation at Baseband Infrastructure of Smart-Phones Using Fractal Dispersive Delay-Lines

A major concern in modern smart-phones and hand-held devices is a way of mitigating the time interval error (TIE) perceived at high-speed digital transits along the traces of the circuit-board (rigid and or flexible) used in baseband infrastructures. Indicated here is a way of adopting a planar fractal inductor configuration to improvise the necessary time-delay in the transits of digital signal phase jitter and reduce the TIE. This paper addresses systematic design considerations on fractal inductor geometry commensurate with practical aspects of its implementation as delaylines in the high-speed digital transports at the baseband operations of smart-phone infrastructures. Experimental results obtained from a test module are presented to illustrate the efficacy of the design and acceptable delay performance of the test structure commensurate with the digital transports of interest.

Development of a PC-Based Software Receiver for the Reception of Beidou Navigation Satellite Signals

Beidou is the Global Navigation Satellite System (GNSS) being developed in China, with the aim to provide a global navigation service that is similar to the Global Positioning System (GPS) and Galileo navigation systems. In this paper, it is demonstrated that through the flexibility and re-configurability of a PC-based software receiver in which the baseband operations are realized in terms of software, it is possible to acquire, track, and demodulate Beidou satellite signals even when only a limited amount of information is known. Further, with the Beidou interface control document now available, the proposed PC-based software receiver can be easily adapted to perform navigation functions. This research lays the foundation for the further development of navigation receivers and exploration of multi-GNSS applications.

High-Throughput, Low-Power Software-Defined Radio Using Reconfigurable Processors

A new, low-power software-defined radio baseband supports up to 600 Mbps. Wireless LAN and WiMax are implemented on a dynamically reconfigurable processor that's fully utilized in the baseband operation. Power is estimated at 500 mW in a 40-nm CMOS design. The platform also permits fast runtime switching between multiple wireless standards.

Operational amplifier immune to EMI with no baseband performance degradation

An operational amplifier (opamp) input stage achieving a high degree of immunity against electromagnetic interference (EMI) is presented. Unlike previously proposed topologies, the novel circuit does not show any significant penalty in baseband operation. The effectiveness of the proposed solution and its robustness to mismatch and process variations is tested by simulations performed with reference to the AMS C35 0.35 µm CMOS technology.

EDA toolbox for VHF Data Link system simulation

Commercial communication systems design software is usually shipped with libraries and toolboxes covering standards like GSM or UMTS. For designing aeronautical communication systems such ready-to-use libraries are rare. Low-level elements and functional blocks have to be adopted and used instead. In this paper a toolbox consisting of system elements for the use with electronic design automation software was developed. It enables radiofrequency design engineers to perform system level simulations using specialised components dedicated to aeronautical communication. For this, functional blocks within the physical layer of VHF Data Link were defined and made available. They cover basic radio frequency (RF) baseband operations as well as modulation, demodulation and power-ramp functionality. The library was tested and verified with a VHF Data Link Mode 4 signal generation application as well as with a VHF Data Link Mode 2 system simulation set-up. While the toolbox presented in this paper is intended to speed up development cycles by providing ready-to-use VHF Data Link functional blocks to radiofrequency system engineers, it is also a useful tool in signal generation and receiver testing.

Digital-carrier multi-band user codes for baseband UWB multiple access

The growing interest towards ultra-wideband (UWB) communications stems from its unique features such as baseband operation, ample multipath diversity, and the potential of enhanced user capacity. But since UWB has to overlay existing narrowband systems, multiple access has to be achieved in the presence of narrowband interference (NBI). However, existing baseband spreading codes for UWB multiple access are not flexible in handling NBI. In this paper, we introduce two novel spreading codes that not only enable baseband UWB multiple access, but also facilitate flexible NBI cancellation. We construct our codes using a single carrier or multiple carriers (SC or MC), which can be implemented with standard discrete-cosine transform (DCT) circuits. With our SC/MC codes, NBI can be avoided by simply nulling undesired digital carriers. Being digital, these SC/MC codes give rise to multi-band UWB systems, without invoking analog carriers. In addition, our SC/MC codes enable full multipath diversity, and maximum coding gains. Equally attractive is their capability to reduce the number of interfering users, with simple matched filter operations. Comprehensive simulations are also carried out to corroborate our analysis.

Low-IF topologies for high-performance analog front ends of fully integrated receivers

When it comes to integratability, the zero-intermediate frequency (IF) receiver is an alternative for the heterodyne or IF receiver. In recent years, the zero-IF receiver has been introduced in several applications, but its performance cannot be compared to that of the IF receiver yet. This lower performance is closely related to its baseband operation, resulting in filter saturation and distortion, both caused by DC-offsets and self-mixing at the inputs of the mixers. The low-IF receiver has a topology which is closely related to the zero-IF receiver, but it does not operate in the baseband, only near the baseband. The consequences are that, as for the zero-IF receiver, the implementation of a low-IF receiver can be done with a high degree of integration, however, its performance can be better. In this paper, the fundamental principles of the low-IF receiver topology are introduced. Different low-IF receiver topologies are synthesized and fully analyzed in this paper. This is done by applying the complex signal technique-a technique used in digital applications to the study of analog receiver front ends.

Design and development of c.c.d. programmable transversal filters

This paper examines the potential of integrated-circuit-based programmable transversal filters for baseband operation. The emphasis is on compact processors with an eventual aim of a single chip, monolithic (design suitable for a variety of signal-processing applications. Before hardware developments are treated, trade-offs between serial and parallel configurations of convolver are considered, together with their respective component requirements. It appears that for complete integration of a transversal filter module, the parallel approach is preferred. A study is made of the circuit elements of a particular realisation of an integrated analogue convolver in c.c.d./m.o.s. technology. All aspects of the design are considered and the description is focused around a prototype 64-stage programmable transversal filter. Several such units could be cascaded giving this integrated approach an enormous potential in applications where space and power are crucial, and high computing precision is not essential.

Linear minimum variance filters applied to carrier tracking

A new approach is taken to the problem of tracking a fixed amplitude signal with a Brownian motion phase process. Classically, a first-order phase-lock loop (PLL) is used; here, the problem is treated via estimation of the quadrature signal components. In this space, the state dynamics are linear with white multiplicative noise. Therefore, linear, minimum-variance filters, which have a particularly simple mechanization, are suggested. The resulting error dynamics are linear at any signal/noise ( S/N ) ratio unlike the classical PLL. During synchronization, and above threshold, this filter with constant gains degrades by 3 percent in output rms phase error with respect to the classical loop. However, up to 80 percent of the maximum possible noise improvement is obtained below threshold where the classical loop is nonoptimum, as demonstrated by a Monte Carlo analysis. Filter mechanizations are presented for beth carrier and baseband operation. An interesting bandpass filter interpretation is given.

High-speed electro-optic diffraction modulator for baseband operation

A new kind of laser-beam modulator is described. An interdigital electrode structure deposited on an electro-optic crystal is used to produce a spatially periodic electric field which diffracts the laser beam within the crystal. Baseband operation is possible, and optical-pulse risetimes of 1.5 ns have been observed. The required drive power is only 7.5 nJ per pulse at 25 V, but this could be improved by scaling. The measured extinction ratio is 25 dB and this varies by less than ±1dB for a 10 K temperature change. The form of the modulator lends itself to inclusion in thin-film optical circuits.