Investigation on the Susceptibility to EMI of Second-Order ΔΣ Modulators

This paper analyzes the effects of radio frequency interference on second order ΔΣ modulators based on continuoustime (CT) and on discrete-time (DT) architectures. Specifically, Modulators used for the acquisition of sensor signals are targeted, which can operate with moderate clock rates due to the relatively small bandwidth of the signal to be acquired. A continuous wave interference with frequency above that of the modulator clock signal is superimposed onto the nominal input one with the purpose of evaluating the degradation of their performance, and more specifically their capability to demodulate out of band interference

A Wireless Communication System for Urban Water Supply Networks Based on Guided Acoustic Waves

The structural complexity of real-world pipeline networks makes it difficult to derive physics-based models of acoustic propagation. This work deals with the design of a communication system based on the propagation of acoustic waves in water-filled pipes. A method based on the experimental characterization of the communication channel is proposed. This approach is applied to an urban water distribution pipeline, and a black-box model representing its frequency response is obtained. The derived two-port model is used for the simulation of a complete communication system, comprising transmitter and receiver models, with the aim of using the water pipe as a wireless communication channel. It is shown that the choice of modulation parameters is critical in order to deal with issues such as the frequency selectivity of the channel and multipath wave propagation. A communication system is presented and the experimental results of the communicated data are provided

A Baseband Wireless VNA for the Characterization of Multi-Port Distributed Systems

Frequency characterization of spatially-large structures has become increasingly required, mostly in the fields of Structural Health Monitoring and Communication Systems based on non conventional media. When the ports of the system under measurement are far apart, methods based on traditional wired instruments become unattractive for field applications, due to the increased complexity, cost and signal integrity related issues. Aiming towards removing the wired connection from the ports of the system under test and the elaboration unit, the main issue to be dealt with is the time-synchronization of measurements at the ports. This contribution proposes a solution to such an issue by presenting a Wireless Vector Network Analyzer, suitable for the characterization of distributed systems. For this purpose, a wireless synchronization scheme is proposed, which is based on the disciplining of the signal sampling clock from the 1-Pulse-Per-Second reference signal. The proposed synchronization method reduces clock jitter at different ports at 1.13 μs over a 300 s observation interval. The hardware and software implementation of the system are detailed and experimental results proving its operation are provided

From Radio to In-Pipe Acoustic Communication for Smart Water Networks in Urban Environments: Design Challenges and Future Trends

The smart management of water resources is an increasingly important topic in today’s society. In this context, the paradigm of Smart Water Grids (SWGs) aims at a constant monitoring through a network of smart nodes deployed over the water distribution infrastructure. This facilitates a continuous assessment of water quality and the state of health of the pipeline infrastructure, enabling early detection of leaks and water contamination. Acoustic-wave-based technology has arisen as a viable communication technique among the nodes of the network. Such technology can be suitable for replacing traditional wireless networks in SWGs, as the acoustic channel is intrinsically embedded in the water supply network. However, the fluid-filled pipe is one of the most challenging media for data communication. Existing works proposing in-pipe acoustic communication systems are romising, but a comparison between the different implementations and their performance has not yet been reported. This paper reviews existing works dealing with acoustic-based ommunication networks in real large-scale urban water supply networks. For this purpose, an overview of the characteristics, trends and design challenges of existing works is provided in he present work as a guideline for future research

Decimation of Delta-Sigma-Modulated Signals Using a Low-Cost Microcontroller

2noΔΣ analog-to-digital converters (ADCs) are largely used in sensor acquisition applications. In the last few years, standalone ΔΣ modulators have become increasingly available as off-the-shelf parts. To build a complete ADC, a standalone modulator has to be paired with some advanced elaboration unit, such as a field programmable gate array (FPGA) or a digital signal processor (DSP), which is needed for the implementation of the decimation filter. This work investigates the use of low-cost, general-purpose microcontrollers for the decimation of ΔΣ-modulated signals. The main challenge is given by the clock frequency of the modulator, which can be in the range of a few MHz. The proposed technique deals with this limitation by employing two serial peripheral interface (SPI) modules in a time-interleaved configuration. This approach allows for continuous acquisition and elaboration of relatively high-speed, digital signals. The technique has been applied to a case study, and a data conversion system has been practically realized. The performance of the proposed filter is compared to that of a digital filter, present on board a commercial microcontroller, and the results of experimental tests are provided.openopenFishta M.; Fiori F.Fishta, M.; Fiori, F

New Challenges on the Electromagnetic Compatibility of Electric Vehicles

The massive use of electronics in modern electric vehicles poses new challenges to the coexistence of electric power units, analog and digital sensors and vehicle-to-infrastructure (v2i) communication systems. Indeed, power units like traction inverters or DC-DC converters have constantly improved over time in terms of power density and efficiency. However, this has led to increase the electromagnetic interference (EMI) they generate. In addition, the need of high capacity wireless and wired communication channels and the use of radars has increased the number of on board radio frequency and mm wave transmitters, which increase the level of electromagnetic pollution as well. Clearly, this renewed scenario poses new challenges to reduce the emission and increase the immunity to EMI of on board electronic units. In this context, the µEMC group has development some techniques aimed to reduce the electromagnetic emission generated by power modules, thus reducing the size of the EMI filters. For instance, it has been shown that a fine alignment of complementary switching voltages (see Fig. 1(a),(b)) reduces the conducted emission at low frequency (150kHz - 10MHz) significantly, as highlighted by the plot in Fig. 1(c) [1]. The group has also proposed solutions aimed to damp the oscillations resulting from fast switching based on resonant snubbers or active gate drivers [2,3]. For instance, the solution proposed in [3] allows one to damp the voltage oscillations triggered by hard switching at high frequency, as highlighted in Fig. 2. Regarding the immunity to EMI of analog front-end, since A/D converters based on ΣΔ modulation are increasingly used for signal conditioning, a study on the susceptibility of modulators [4] has been performed. Two second-order modulators have been considered, and the performance of Continuous-Time (CT) and Discrete-Time (DT) loops has been compared. Simulations have been carried out in different amplitude and frequency injection conditions showing that the DT modulator can be highly susceptible to RFI, resulting in a large offset voltage, as shown in Fig. 3(a). CT modulators showed to be more resilient to RFI, presenting a smaller offset voltage. However, spectral analysis showed even-order harmonic distortion in the presence of low frequency disturbances, as shown in Fig. 3(b)

Experimental Characterization of In-Pipe Acoustic Communication Channels Through Measurement of Pressure Transfer Functions

Communication systems based on in-pipe acoustic propagation have great potential to cover areas in which traditional infrastructure is unavailable. Characterization of the channel plays an important role in the design of any communication system. However, in case of spatially large channels, this aspect needs further investigations. In the present work, a method for the characterization of an acoustic channel is presented. This is based on the measurement of the complex transfer functions relating voltages and pressures at the channel ports. Such a technique was validated on a 75m long segment of a urban water distribution pipeline. The measurements assessed the frequency selectivity of the acoustic channel and the wave propagation speed. From experimental results, the response of the acoustic channel had an overall low-pass behavior, but it showed several deep notches at low frequency