This diploma thesis deals with the impact of pollutants on colour photography made by inkjet printing technology. There are summarized basic principles of inkjet printing, composition of inks and negative factors influencing the printout quality. The ozone was studied in the experimental part, because it has the stongest degrading effect of all common pollutants. The accelerated ageing test with changing the concentration of ozone and the time of exposure was performed. The test scales were made by using two different inks. The L*a*b* values and optical densities of selected fields were calculated from the reflectance spectra of 918 colour fileds. The colour gamut and its volume were calculated from the L*a*b* values. The changes of colour gamut volume correlated with the changes of optical densities. It emerged that using the colour gamut as the instrument of evaluation of the inkjet printout dyes degradation rate is eligible and it is suitable to recommend this method for the ozone accelerated tests.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Initial results of wideband channel sounding experiments sponsored by the Advanced Range Telemetry (ARTM) program are presented. Data collected at Edwards EAFB during the Winter 1998-1999, are analyzed in the frequency domain to estimate the number, strength, and delays of the significant multipath reflections observed during the experiments. We observe that the channel is adequately modeled using two or three multipath reflections. The multipath fade events are correlated with recorded bit error rates and transmitter location to provide a comprehensive overview of the channel characteristics. Summaries from two test flights are included where it is seen that the 2- and 3-ray channel models provide excellent models for the data. In general, the 3-ray model captures the essential features of the multipath interference. In this model the first multipath is a strong specular reflection with relative amplitude greater than 0.5 and relative delay in the 30 to 70 ns range. The second multipath is a much weaker reflection with relative amplitude less than 0.5 and relative delay in the 175 to 325 ns range.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the two main causes of fading encountered at test ranges. The first cause of fading results from nulls in the transmit antenna gain pattern. Variations in the received signal level are a result of changes in the gain pattern as the spatial relationship between transmitter and receiver change. The second cause of fading is due to multipath interference. This occurs when multiple copies of the transmitted signal with different delays arrive at the receiver and are phased relative to each other so that destructive interference occurs.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, a hybrid frequency division multiple access/code division multiple access (FDMA/CDMA) system in a Rician fading channel is described and analysis. The performance of the hybrid system is compared with a wideband CDMA system, which occupies the same total bandwidth. The results show that for DPSK modulation with a RIKE receiver, a hybrid system can have a greater capacity with a strong direct path component or a high signal to noise ratio (SNR). Otherwise, a wideband system remains optimal.

The presence of abnormally high signal levels beyond the horizon may be exploited for communication purposes. On the other hand, these high signal levels pose the threat of spatial co-channel interference. A long-term detailed investigation into the wideband characteristics of a typical transhorizon link was instigated by the Radiocommunications Agency (UK) to permit the compilation of the hitherto unknown channel parameter statistics. This thesis describes that investigation conducted at a frequency of 11.64 GHz on a 160 km transhorizon sea path between Cap d' Antifer (France) and Fort Widley (England). A channel sounder with a bandwidth of 31.25 MHz which allows the implementation of an automated time-critical continuous data acquisition strategy, is described in detail. The parametric estimation of time-domain model parameters, from measured channel transfer functions, in the context of multi path propagation is discussed. The Singular Value Decomposition Prony and Bayesian techniques are described in detail, having been chosen in preference to Fourier analysis because of their higher resolution potential. The deri vation and implementation of a novel Bayesian algorithm which incorporates prior knowledge concerning the channel parameters is presented. Multipath channel simulation data using differing channel models and varying signal-to-noise ratios has been generated and this data, together with field data, has been used to carry out a systematic and critical comparison between the Bayesian and the SVD_P approaches. It is shown that the Bayesian algorithm gives more accurate estimates of channel parameters, namely amplitudes and delays, especially when the signal-to-noise ratio is less than 30 dB. An 8 month long measurement campaign has generated a 110 Gbyte database of channel transfer functions. The estimated channel impulse response and the associated signal levels are used to discuss the underlying propagation phenomena on the link. It is shown that ducting propagation conditions occurred for a larger than expected period totalling 16% of the measurement time. This has been attributed to the dominance of surface ducting conditions in the summer. Troposcattering was found to be more prevalent in the winter. The risk of the channel being a source of interference was found to be greatest at about 20:00 GMT due to the presence of advection ducts and a minimum at about 10:00 GMT. Delay spread, Doppler spread, coherence bandwidth and fade depths have also been estimated from the database. The results show that there is a very strong correlation between these parameters and the wideband signal level. The median values of 35 ns and 6 Hz for the delay and Doppler spreads respectively, reveal that the transmission medium can be considered to be slowly varying. Coherence bandwidths greater than 250 MHz have been observed for 1 % of the time with a signal level of -2.7 dBf. Such a high value implies that to achieve acceptable interference levels on spatially aligned links, large frequency separations may well be required. Comparison with earlier CW investigation results (COST210 and follow-up research) show that the statistics of signal levels acquired from CW measurements also apply to wideband signals. However, there is a significant discrepancy between CW and wideband fading statistics due to frequency selective fading.

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Methods to improve reception during multipath fading of telemetry data received aboard ships participating in missile exercises include various diversity techniques. Among these techniques are polarization, angle, height, and frequency diversity. In this paper, a two-ray multipath model is used to investigate the various techniques and determine the merits of each. Possible ways of implementing the promising ones are discussed.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Telemetry propagation channel is modeled to predict PCM/FM telemetry receiving signal level at APG(Anheung Proving Ground), ADD(Agency for Defense Development). Channel model is composed of direct wave and reflected wave in sea surface, so-called 2-ray model. Our 2-ray model includes transmitting antenna radiation pattern, auto-tracking antenna radiation pattern, sea surface reflection coefficient and phase depending on incident angle. Vertical and horizontal polarized receiving signal strength is obtained from pre-calculated flight trajectory of transmitter. Calculated results are compared with measured data in real flight test. 2-ray channel model can predict almost identical receiving signal level and calculate starting point of multi-path fading effect. Using these results, receiving system can be moved to more proper position before flight test.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper will discuss the performance of pulse code modulation (PCM)/frequency modulation (FM) during frequency selective fading. Frequency selective fading occurs when the attenuation in part of the frequency band of interest is much greater than in the rest of the band of interest. The frequency selective fading model used in this paper assumes that two paths with different delays exist between the transmitter and receiver (multipath). The two-path model was simulated in the laboratory and the effects of frequency selective fading on the radio frequency (RF) spectrum and on the waveforms at the output of the FM demodulator were measured. A mathematical model was also used to predict the effects of frequency selective fading. The predicted waveshapes are compared with the laboratory data. A simple demodulator which alleviates the effects of frequency selective fading on PCM/FM at moderate signal-to-noise ratios (SNRs) will be described. This demodulator is created by detuning the telemetry receiver by a frequency equal to approximately one-half of the intermediate frequency (IF) bandwidth and using the receiver’s amplitude modulation (AM) detector output rather than the FM detector output. The performance of this offset AM demodulator will be compared with the performance of an FM demodulator. Frequency selective fades measured in real-world environments will be also presented.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper is the first of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data, collected at Edwards AFB, California at both L-Band and lower S-Band, were used to generate channel model. In Part 1, analytic and geometric considerations are discussed and the frequency domain modeling technique is introduced. In Part 2, the experimental results are summarized and a channel model composed of three propagation paths is proposed.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper is the second of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data were collected at Edwards AFB, California at both L-Band and lower S-Band. Frequency domain analysis techniques were used to evaluate candidate channel models. The channel model is composed of three propagation paths: a line-of-sight path, and two specular reflections. The first specular reflection is characterized by a relative amplitude of 70% to 96% of the line-of-sight amplitude and and a delay of 10 – 80 ns. This path is the result of “ground bounces” off the dry lake bed at Edwards and is a typical terrain feature at DoD test ranges located in the Western USA. The amplitude and delay of this path are defined completely by the flight path geometry. The second path is a much lower amplitude path with a longer delay. The gain of this path is well modeled as a zero-mean complex Gaussian random variable. The relative amplitude is on the order of 2% to 8% of the line-of-sight amplitude. The mean excess delay is 155 ns with an RMS delay spread of 74 ns.