This paper presents the results of a study covering measurement and characterization of the wide-band impulsive noise present in a digital TV radio channel. Measurements were conducted at a frequency of 762 MHz in different outdoor and indoor environments using vertical and horizontal polarization. The measurement system was built on commercial equipment only. The calibration process, which is an important stage of this kind of measurements, is described. To analyze the measurements the impulsive noise has been modeled as a pulse train where the pulse amplitude, pulse duration and elapsed time between pulses are considered random variables. It has been found that the pulse duration and elapsed time between pulses is not dependent on the antenna polarization while the pulse amplitude is, especially in the case of the noise generated by a fluorescent lamp. It has also been found that the pulse duration of the noise measured in the outdoor environments presents some clustering features and is correlated with the pulse amplitudes. This correlation may be caused by a RF noise bandwidth that is larger than the bandwidth of the measurement system. The noise in busy streets presents larger pulse durations, larger amplitude, and shorter elapsed time between pulses that the noise measured in a pedestrian area. Several statistical tests have been done to find the distribution function that best fits these random variables. Power Rayleigh, lognormal, exponential, Poisson, and Gamma distributions have been tested. According to the assessment carried out, none of the distribution functions is adequate to model the pulse amplitudes or the elapsed time between pulses, while the pulse duration seems to be Gamma distributed.

No abstract

Signal amplification at the polymer optical fiber low-loss window of 650 nm is reported in an SU8 rib waveguide coated with Rhodamine-640 doped poly(methyl methacrylate). A signal beam is end-fired into the facet of a 7×100μm waveguide and amplified by top pumping of the 2-μm-thick cladding region with a pulsed pump source focused into a 9-mm-long stripe. A gain of 14dB and a minimum signal-to-noise ratio of around 2 dB are achieved in a 15-mm-long device with a low threshold pump intensity of 0.25μJ∕mm2, which is an order of magnitude lower than previously reported.

We report optical signal amplification in a solid-state dye-doped polymer with a rib waveguide structure. A 625nm pulsed signal and a collinear 575nm pump are coupled into a 1μm×120μm poly(methyl methacrylate) waveguide doped with 1% by weight Rhodamine 640 dye. Depending on the signal intensity, a maximum optical gain in the 21–26dB range is obtained from a 1.2-cm-long device, accompanied by a signal-to-noise ratio in the 9–16dB range.

We demonstrate a procedure for fabricating micro-structured organic light-emitting diodes (micro-LEDs) based on so-called breath figure (BF) pattern formation. In the latter process water vapour is condensed on the surface of a spread polymer solution to form droplets that close pack into ordered arrays and that transfer the BF pattern into the resulting solid thin polymer film. Here, we generate a silicone elastomer negative replica of the BF pattern and use it as a master for solvent-assisted micro-moulding of an insulating polymer layer deposited on top of a PEDOT:PSS covered indium tin oxide (ITO)-coated glass substrate. By spin coating a light-emitting polymer blend film on top of the micro-structured insulator, we obtain micro-structured polymer LEDs with dimensions defined by the BF pattern.

We report on the triplet spectra and dynamics in two types of oligomeric films deposited by two different techniques: thermal evaporation and spin coating. The different molecular arrangement in both films is manifested in a red shift of the absorption, PL, and T1-Tn absorption spectra of the sublimated film relative to the spin-coated one. Triplet recombination dynamics studied with steady-state photoinduced absorption (PA) spectroscopy follow a dispersive bimolecular recombination model away from the trap filling regime. We obtained values for the triplet bimolecular recombination ratio (beta) of 3.4 x 10 (-14) and 1.1 x 10 (-15) cm3 s (-1) for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films.

No abstract

The multiservice uplink capacity and the interference (intracellular and intercellular) statistics (mean and variance) of the sectors of cigar-shaped wideband code-division multiple access (WCDMA) microcell are studied using a model of 5 highway microcells in rural zone. The two-slope propagation loss model with lognormal shadowing is used in the analysis. The capacity and the interference statistics of the microcell are studied for different sector ranges, antenna side lobe levels, standard deviation of the power control error, breakpoint distance, and different intersites correlation coefficient. It is shown that reducing the antenna side lobe level increases the sector capacity. Also, it is shown that the sector range that gives the quasi the maximum sector capacity is in the order of 800 to 1200 m.