Design and Validation of a Software Defined Radio Testbed for DVB-T Transmission

This paper describes the design and validation of a Software Defined Radio (SDR) testbed, which can be used for Digital Television transmission using the Digital Video Broadcasting - Terrestrial (DVB-T) standard. In order to generate a DVB-T-compliant signal with low computational complexity, we design an SDR architecture that uses the C/C++ language and exploits multithreading and vectorized instructions. Then, we transmit the generated DVB-T signal in real time, using a common PC equipped with multicore central processing units (CPUs) and a commercially available SDR modem board. The proposed SDR architecture has been validated using fixed TV sets, and portable receivers. Our results show that the proposed SDR architecture for DVB-T transmission is a low-cost low-complexity solution that, in the worst case, only requires less than 22% of CPU load and less than 170 MB of memory usage, on a 3.0 GHz Core i7 processor. In addition, using the same SDR modem board, we design an off-line software receiver that also performs time synchronization and carrier frequency offset estimation and compensation

Probability of Error of Linearly Modulated Signals with Gaussian Cochannel Interference in Maximally Correlated Rayleigh Fading Channels

We evaluate the probability of error of linearly modulated signals, such as phase-shift keying (PSK) and quadrature amplitude modulation (QAM), in the presence of Gaussian cochannel interference (CCI) and Rayleigh fading channels. Specifically, we assume that the fading channel of the CCI is maximally correlated with the fading channel of the signal of interest (SOI). In practical applications, the maximal correlation of the CCI channel with the SOI channel occurs when the CCI is generated at the transmitter, such as the multiuser interference in downlink systems, or when a transparent repeater relays some thermal noise together with the SOI. We analytically evaluate the error probability by using a series expansion of generalized hypergeometric functions. A convenient truncation criterion is also discussed. The proposed theoretical approach favorably compares with alternative approaches, such as numerical integration and Monte Carlo estimation. Among the various applications of the proposed analysis, we illustrate the effect of nonlinear amplifiers in orthogonal frequency-division multiplexing (OFDM) systems, the downlink reception of code-division multiple-access (CDMA) signals, and the outdoor-to-indoor relaying of Global Positioning System (GPS) signals

Joint Impact of Frequency Synchronization Errors and Intermodulation Distortion on the Performance of Multicarrier DS-CDMA Systems

The performance of multicarrier systems is highly impaired by intercarrier interference (ICI) due to frequency synchronization errors at the receiver and by intermodulation distortion (IMD) introduced by a nonlinear amplifier (NLA) at the transmitter. In this paper, we evaluate the bit-error rate (BER) of multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA) downlink systems subject to these impairments in frequency-selective Rayleigh fading channels, assuming quadrature amplitude modulation (QAM). The analytical findings allow to establish the sensitivity of MC-DS-CDMA systems to carrier frequency offset (CFO) and NLA distortions, to identify the maximum CFO that is tolerable at the receiver side in different scenarios, and to find out the optimum value of the NLA output power backoff for a given CFO. Simulation results show that the approximated analysis is quite accurate in several conditions

Genetsko oplemenjivanje masline

In the last decade significant progress has been made in developing successful olive cloning techniques, although some difficulties still remain such as that with establishing sterile cultures in vitro and morphogenesis from mature tissue of cultivars. More work is required, although significant advances have also been made in shoot regeneration from petioles of in vitro grown shoots of several cultivars (Mencuccini and Rugini, 1993). However, the regeneration ability is still low for use in biotechnological applications. The novel strategy of the «double regeneration», developed to achieve somatic embryos in olive cv. Canino and Moraiolo may also be applicable in other cultivars. This technique can be generalised since at present it is essential for inducing and maintaining shoot morphogenic callus in other species such as cherry, apple, and pear (Gutiérrez Pesce et al., 1998; Rugini e Muganu 1998; Abdollahi et al., 2005). Gene transfer techniques offer a more powerful strategy for genetic improvement in respect to traditional breeding methods. It allows the introduction into one genotype, one or a few pieces of genetic information without drastic modifications of the general characteristics of the plant. Transformation techniques have been developed, by using somatic embryogenesis, and transgenic plants, with some desirable agronomic traits, have already been generated in one cultivar. At present field trials, approved by the Italian Health Minister, are conducted on transgenic rolABC, and osmotin plants. From transgenic olive plants, similar to kiwi transgenic plants with rolABC genes we expect plants with large root systems, compact vegetative habitus, smaller number of flowers per plant, and high rooting ability of cuttings. In plants over-expressing osmotin gene, we expect a higher tolerance to some fungi. Many genes have already been isolated from several species, which may be introduced in olive singly or associated with others. Transformation experiments with multiple genes (chitinase + osmotin + PR1) are in progress in our laboratory in order to increase fungal resistance. Antibacterial genes (thionin, cecropin, attacin, etc.) against Pseudomonas syringae and genes for modifying the pattern of fruit ripening (ethylene, PG) are only a few examples of the potential of genetic manipulation to improve olive. A high content of di-hydroxiphenols could confer the valuable bitter taste in the olive oil. Agrobacterium-mediated gene transfer seems to be the most efficient method in olive. The molecular techniques should not aim only to make clear the phylogenesis of the genus, but also to clone useful genes and promoters in olive. To facilitate this work, biotechnology, long-term breeding programs and biochemical research should be closely linked to achieve the objectives quickly.U zadnjem desetljeću učinjen je znatan napredak u razvijanju uspješnih metoda kloniranja maslina iako će neke poteškoće ostati, kao utvrđivanje sterilnih kultura in vitro i morfogeneza iz zrelog tkiva kultivara. Potrebno je još raditi, makar je učinjen znatan napredak i u regeneraciji izbojaka iz petiola uzgojenih in vitro od nekoliko kultivara (Mencuccini i Rugini, 1993). Međutim, mogućnost regeneracije još je uvijek mala za biotehnološku primjenu. Nova strategija "dvostruke regeneracije", razvijena kako bi se dobili somatski embriji masline cv. Ganino i Moraiolo mogu se primijeniti i u drugim kultivarima. Ova se tehnika može generalizirati jer je danas bitna za induciranje i održavanje morfogenskog kalusa izbojka u drugim vrstama kao što su trešnja, jabuka i kruška (Gutierrez Pesce et al. 1998; Rugini e Muganu, 1998; Abdollahi et al., 2005). Tehnike transfera gena pružaju snažniju strategiju za genetsko oplemenjivanje u odnosu na tradicionalne uzgojne metode. One omogućuju uvođenje u jedan genotip jedne ili više genetskih informacija bez drastičnih modifikacija općih značajki biljke. Razvijene su tehnike transformacije primjenom somatske embriogeneze i transgenske biljke određenih poželjnih agronomskih svojstava i već su proizvedene u jednom kultivaru. Upravo se provode pokusi na terenu, koje je odobrio talijanski Ministar zdravstva, na transgenskim rolABC i osmotinskim biljkama. Od transgenskih biljaka masline, slično transgenskim biljkama kivija s genima rolABC, očekujemo biljke velikog sustava korijena, zbijenog vegetativnog habitusa, manjeg broja cvjetova po biljci i velike sposobnosti sadnica za ukorijenjenjem. U biljaka preizraženog osmotinskog gena očekujemo veću tolerantnost na neke gljive/gljivice. Izolirani su već mnogi geni iz nekoliko vrsta, što se mogu introducirati pojedinačno ili zajedno s drugima. Pokusi transformacije s mnogostrukim genima (chitinase + osmotin + PRL) su u tijeku u našem laboratoriju, kako bi se povećala otpornost na gljivice. Antibakterijski geni (tionin, cecropin, atacin itd.) protiv Pseudomonas syringae i geni za modificiranje uzorka zriobe voća (etilen, PG) samo su neki primjeri potencijala genetske manipulacije za oplemenjivanje masline. Visok sadržaj dihidroksifenola mogao bi prenijeti dragocjen gorki okus maslinovog ulja. Prijenos gena posredstvom agro-bakterija čini se najdjelotvornijom metodom u masline. Cilj molekularnih tehnika ne bi trebao biti samo razjašnjenje filogeneze gena nego i kloniranje korisnih gena i stimulatora u maslini. Da bi se taj posao olakšao potrebno je usko povezati biotehnologiju, dugoročne uzgojne programe i biokemijska istraživanja radi brzog postizanja ciljeva

Optimisation of regeneration and maintenance of morphogenic callus in pear (Pyrus communis L.) by simple and double regeneration techniques

The purpose of our work was to improve the regeneration capacity of leaf explants and the maintenance of shoot morphogenesis in callus of six pear cultivars: Abate Fetel, Conference, Dar Gazi, Harrow Sweet, Kaiser and Williams, by altering the composition of both regeneration and proliferation media of explant donor shoots, and choosing the right type of explant. Regeneration capacity of leaf explants collected from in vitro shoots has been improved in the majority of cultivars also due to shoot preconditioning. For the first time, long term morphogenic callus production and maintenance have been established in some cultivars by a “double regeneration”. Using this technique, morphogenic callus of two cultivars, ‘Dar Gazi’ and ‘Conference’, was maintained for several subcultures but only when they were initiated from small leaflets – less than 2–3 mm long – which had been collected from the neoformed adventitious buds. MS medium [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassay with tobacco tissue culture. Physiol. Plant. 15, 473–497] proved to be an efficient regeneration medium by stimulating adventitious buds, while the explants of all cultivars, except for Kaiser, showed a high regeneration capacity when they were collected from shoots proliferated on modified QL medium [Quoirin, M, Lepoivre, P., Boxus, P., 1977. Un premier bilan de dix annees de recherche sur les cultures de meristemes et la multiplication in vitro de fruitiers ligneux. Compte rendu des recherches, Station des Cultures Fruitieres et Maraicheres de Gembloux (1976–1977), 93–117]. This medium conferred leaf expansion, overcoming 90% of regeneration in explants of cv Dar Gazi and Williams. Well expanded leaves were obtained and collected by rooting the shoots, while regeneration percentage was not improved and the number of adventitious shoots was increased in most cultivars, reaching up to 10 shoots per explant. When cefotaxime at 200 mg/l, which is normally effective in controlling Agrobacterium, was used for genetic transformation, regeneration percentage and number of shoots per explant (in leaf explants collected from rooted shoots) were increased and a uniform bud regeneration on all the leaf surface was promoted.L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.co

Olea

The genus Olea contains about 30 species were grouped into three subgenera, Tetrapilus, Paniculatae, and Olea (cultivated olive and wild relatives), found in Asia, Australia and Asia, Africa and Europe, respectively. The species O. europaea L. includes six subspecies: Olea europaea L. ssp. europaea (the Mediterranean olives); O. e. laperrinei (distributed in Saharan massifs of Hoggar, Aïr, Jebel Marra in Algeria); O. e. cuspidata (which moved from South Africa to Egypt, East Australian areas and Hawaii, and from Arabia to northern India and Southwest China); O. e. guanchica (Canary Islands); O. e. maroccana (southwestern Morocco); and O. e. cerasiformis (Madeira). Using molecular markers, it has been ascertained that the Mediterranean olives include the cultivated types (O. europaea L. ssp. europaea var. sativa), the true wild oleaster (O. e. e. var. sylvestris), and the feral form olevaster from seedlings raised from seeds of the cultivated types. The oleaster has a narrow range of distribution and it is often mistaken for olevaster. Recolonization of the Mediterranean basin by Oleaster occurred after the last glacial event, from refuges located in both eastern and western Mediterranean basin areas toward southern Europe. Oleaster is a source of rootstock for propagating new improved cultivated varieties. Cultivated and wild forms have the same diploid chromosome number (2n = 46) and are fully interfertile. Triploid and tetraploid genotypes have been isolated from cultivated O.e.e., but polyploid forms have been found in endangered natural populations of O. e. guancica (tetraploid) and O. e. maroccana (hexaploid). Individual oleaster trees showing superior performance for size and/or oil content of fruit were selected empirically during olive domestication and propagated vegetatively as clones using cuttings that were planted directly or, more recently, grafted onto indigenous oleasters. Genetic markers linked for most important agronomic traits, such as size of the tree, content of secondary products of fruit, flowering induction, oil quality, and biotic and abiotic resistance, will help introgression by conventional breeding of oleaster trait-enhancing genes into cultivated olive. Successful results were difficult to achieve due to both the complex genetic basis of the traits to be improved and the long juvenile period of the progenies that delays the expression of the target traits. In vitro techniques to regenerate doubled haploids from hybrids or somaclonal variation induction may complement classical breeding procedures. Genetic transformation could speed up the development of new genotypes, and transgenic olive plants with modified growth habit and putative induced disease resistance are being tested under filed conditions. However, the development of an efficient regeneration method from mature tissue is the limiting factor for the routine application of this technology to olive genetic improvement.La pubblicazione originale è disponibile sul sito dell'editore http://www.springerlink.co