Analog television | EPFL Graph Search

Analog television (analogue television) is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal. Analog signals vary over a continuous range of possible values which means that electronic noise and interference may be introduced. Thus with analog, a moderately weak signal becomes snowy and subject to interference. In contrast, picture quality from a digital television (DTV) signal remains good until the signal level drops below a threshold where reception is no longer possible or becomes intermittent. Analog television may be wireless (terrestrial television and satellite television) or can be distributed over a cable network as cable television. All broadcast television systems used analog signals before the arrival of DTV. Motivated by the lower bandwidth requirements of compressed digital signals, beginni

Switchable and Simultaneous Spatiotemporal Analog Computing with Computational Graphene-based Multilayers

Romain Christophe Rémy Fleury, Ali Momeni

In the past few years, analog computing has experienced rapid development but mostly for a single function. Motivated by parallel space-time computing and miniaturization, we show that reconfigurable graphene-based multilayerss offer a promising path towards spatiotemporal computing with integrated functionalities by properly engineering both spatial- and temporal-frequency responses. This paper employs a tunable graphene-based multilayers to enable analog signal and image processing in both space and time by tuning the external bias. In the first part of the paper, we propose a switchable analog computing paradigm in which the proposed multilayers can switch among defined performances by selecting a proper external voltage for graphene monolayers. Spatial isotropic differentiation and edge detection in the spatial channel and first-order temporal differentiation and multilayers-based phaser with linear group-delay response in the temporal channel are demonstrated. In the second section of the paper, simultaneous and parallel spatiotemporal analog computing is demonstrated. The proposed multilayers processor has almost no static power consumption due to its floating-gate configuration. The spatial- and temporal-frequency transfer functions (TFs) are engineered using a transmission line (TL) model, and the obtained results are validated with full-wave simulations. Our proposal will enable real-time parallel spatiotemporal analog signal and image processing.

2021

Plug-and-play TOF-PET Module Readout Based on TDC-on-FPGA and Gigabit Optical Fiber Network

Edoardo Charbon, Esteban Venialgo Araujo

Positron Emission Tomography (PET) scanner technology requires the use of a large number of PET detector modules that work in a parallel and synchronous manner. Moreover, system modularity is a desirable feature, that enables technology reutilization for different PET applications and geometries. Additionally, Time-of-Flight (TOF) PET requires a synchronization error, between the modules, below hundred picoseconds in order not to degrade the system level coincidence-resolving-time significantly. In a modular approach, every PET detector module, which typically is composed of a photodetector coupled to a scintillator, includes mixed-signal electronics and a data transmission system. If a host-based architecture is chosen for connecting all the modules to a central acquisition unit, a significant complexity is added at interconnection level and the modularity is reduced. This work aims to a full flexible and fast prototyping solution, where all the estimation methods are integrated in a Field Programmable Gate Array (FPGA), and the analog part is built with off-the-shelf components. An exploration and solution of module connection is proposed in order to reduce complexity and allowing full modularity. Every module hosts a FPGA that includes the data transmission resources and a multi-channel and high-performance Time-to-Digital Converter (TDC), with single-shoot channel precision below 12.5 ps r.m.s. In this way, it performs not only the timing measurement but also position and energy estimation, as well as independent data transmission. Furthermore, the connections are realized using optical fibers driven by Gigabit Transceivers (GT). In this way, we guarantee a physical link up to 8 Gb/s that makes feasible to sustain a global measure rate of 300 Mega measures per second. Moreover, the optical fiber link guaranties null electromagnetic interference that affects the analog stages or other sensitive parts.

IEEE2019

Plug-and-play TOF-PET Module Readout Based on TDC-on-FPGA and Gigabit Optical Fiber Network

Edoardo Charbon, Esteban Venialgo Araujo

IEEE2019