Efficient TV white space filter bank transceiver

Future devices operating in the TV white space (TVWS) spectrum will require to access different bands at different locations and times in order to avoid interference to incumbent users, requiring agility and sufficient spectral masks to satisfy regulators. Further, with very high-speed ADCs and DACs becoming reality, the purpose of this paper is to present a transceiver front-end capable of simultaneously up- and downconverting a significant portion of the UHF band. The proposed approach takes a two-stage filter-bank conversion for implementation on state-of-the-art FPGAs. We present three different parameterisations, which are compatible with the 40 TVWS channels between 470 and 790MHz in Europe, and compare them in terms of complexity and latency

Design considerations for a filter bank based TVWS transceiver

This paper discusses the design of a filter bank based transceiver capable of simultaneously up- or downconverting the entire TV white space (TVWS) frequency band. The spectral mask requirements favour a filter bank based approach, whereby RF sampling and the use of an FPGA for digital up- and down-conversion dictates a two-stage approach. Some of the design considerations, including filter design approaches, are discussed in this contribution

TVWS filter bank transceiver on OMAP-L137 evaluation module

Communications devices operating in the TV white space (TVWS) spectrum will be strictly regulated, requiring compliance with spectral masks to protect incumbent users and sufficient frequency agility to allow access to numerous frequency bands at different times and locations. Therefore, future designs operating at radio frequency (RF) have been proposed. The purpose of this paper is to demonstrate an implementation of such a transceivers at a scale-down frequency implemented on the OMAP--L137 evaluation module, whereby the RF link can be replaced by the device's audio I/O, thus enabling easier observation and algorithm testing for students

Digital RF multiplexing for a TVWS transceiver implementation

Future devices operating in the TV white space (TVWS) spectrum will require to access different bands at different locations and times in order to avoid interference to incumbent users, requiring agility and sufficient spectral masks to satisfy regulators. In order to realise radio devices capable of this, we briefly review design efforts on a radio transceiver capable up- and downconverting the 40 8MHz TVWS channels residing between 470MHz and 790MHz. While we briefly address the overall proposed structure, the aim of this contribution is to address the practical issues of interfacing data conversion devices sampling at RF to state-of-the-art FPGAs which can then perform the digital operations required for up- and downconversion

Partially reconfigurable TVWS transceiver for use in UK and US markets

With more and more countries opening up sections of unlicensed spectrum for use by TV White Space (TVWS) devices, the prospect of building a device capable of operating in more than one world region is appealing. The difficulty is that the locations of TVWS bands within the radio spectrum are not globally harmonised. With this problem in mind, the purpose of this paper is to present a TVWS transceiver design which is capable of being reconfigured to operate in both the UK and US spectrum. We present three different configurations: one covering the UK TVWS spectrum and the remaining two covering the various locations of the US TVWS bands

Novel B(Ar')2(Ar'') hetero-tri(aryl)boranes: a systematic study of Lewis acidity

A series of homo- and hetero-tri(aryl)boranes incorporating pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, and pentachlorophenyl groups, four of which are novel species, have been studied as the acidic component of frustrated Lewis pairs for the heterolytic cleavage of H2. Under mild conditions eight of these will cleave H2; the rate of cleavage depending on both the electrophilicity of the borane and the steric bulk around the boron atom. Electrochemical studies allow comparisons of the electrophilicity with spectroscopic measurements of Lewis acidity for different series of boranes. Discrepancies in the correlation between these two types of measurements, combined with structural characterisation of each borane, reveal that the twist of the aryl rings with respect to the boron-centred trigonal plane is significant from both a steric and electronic perspective, and is an important consideration in the design of tri(aryl)boranes as Lewis acids

A plant homologue to mammalian brain 14-3-3 protein and protein kinase C inhibitor

We have isolated cDNA clones of Spinacea oleracea L. and Oenothera hookeri of 930 and 1017 base pairs, respectively. The open reading frame deduced from the Oenothera sequence codes for a protein of a calculated molecular mass of 29 200. The primary amino acid sequence exhibits a very high degree (88%) of homology to the 14-3-3 protein from bovine brain, and protein kinase C inhibitor from sheep brain. Subsequently the plant protein was partially purified from leaf extract. The partially purified plant protein inhibited protein kinase C from sheep brain in a heterologous assay system. The active fraction consisted of 5–6 different polypeptides of similar molecular size. One of these proteins crossreacted with a peptide-specific antibody against protein kinase C inhibitor protein from sheep brain

Exploring structural and electronic effects in three isomers of tris{bis(trifluoromethyl)phenyl}borane: Towards the combined electrochemical-frustrated Lewis pair activation of H2

Three structural isomers of tris{bis(trifluoromethyl)phenyl}borane have been studied as the acidic com- ponent of frustrated Lewis pairs. While the 3,5-substituted isomer is already known to heterolytically cleave H2 to generate a bridging-hydride; ortho-substituents in the 2,4- and 2,5-isomers quench such reactivity through electron donation into the vacant boron pz orbital and steric blocking of the boron centre; as shown by electrochemical, structural and computational studies. Electrochemical studies of the corresponding borohydrides identify that the two-electron oxidation of terminal-hydrides occurs at more positive potentials than observed for [HB(C6F5)3]−, while the bridging-hydride oxidizes at a higher poten- tial still, comparable to that of free H2

Wideband TV white space transceiver design and implementation

For transceivers operating in television white space (TVWS), frequency agility and strict spectral mask fulfilments are vital. In the UK, TVWS covers a 320 MHz wide frequency band in the UHF range, and the aim of this paper is to present a wideband digital up- and down converter for this scenario. Sampling at radio frequency (RF), a two stage digital conversion is presented, which consists of a polyphase filter for implicit upsampling and decimation, and a filter bank-based multicarrier approach to resolve the 8MHz channels within the TVWS band. We demonstrate that the up- and down-conversion of 40 such channels is hardly more costly than that of a single channel. Appropriate filter design can satisfy the mandated spectral mask and control the reconstruction error. An FPGA implementation is discussed, capable of running the wideband transceiver on a single Virtex-7 device with sufficient word length to preserve the spectral mask requirements of the system

An Electrochemical Study of Frustrated Lewis Pairs: A Metal-free Route to Hydrogen Oxidation

[Image: see text] Frustrated Lewis pairs have found many applications in the heterolytic activation of H(2) and subsequent hydrogenation of small molecules through delivery of the resulting proton and hydride equivalents. Herein, we describe how H(2) can be preactivated using classical frustrated Lewis pair chemistry and combined with in situ nonaqueous electrochemical oxidation of the resulting borohydride. Our approach allows hydrogen to be cleanly converted into two protons and two electrons in situ, and reduces the potential (the required energetic driving force) for nonaqueous H(2) oxidation by 610 mV (117.7 kJ mol(–1)). This significant energy reduction opens routes to the development of nonaqueous hydrogen energy technology