ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / This paper considers the joint selection of the source code rate and channel code rate in an image telemetry system. Specifically considered is the JPEG2000 image coder and an LDPC code family. The goal is to determine the optimum apportioning of bits between the source and channel codes for a given channel signal-to-noise ratio and total bit rate, R(total). Optimality is in the sense of maximum peak image SNR and the tradeoff is between the JPEG2000 bit rate R(source) and the LDPC code rate R(channel). For comparison, results are included for the industry standard rate-1/2, memory-6 convolutional code.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Since becoming an ANSI standard in 1994, Fibre Channel has matured into a high-speed reliable data communication solution. Fibre Channel uses point-to-point, arbitrated loop, or switched topologies, to provide a wide range of options for data storage and highspeed data transfer applications. Unlike Gigabit Ethernet, Fibre Channel supports protocols such as HIPPI-FP, SCSI and IPI, allowing for greater flexibility when designing systems. However, the wide range of options supported in the Fibre Channel standard can be the source of misunderstanding and incompatibility. This paper intends to clear up some of the misconceptions about Fibre Channel by presenting the current standard and discussing how Fibre Channel can be used in data acquisition systems. Since these systems often require extremely high throughput for routing data, as well as high speed data storage to long term media, solutions are not often cut and dry. This paper will give examples of how using different layers of the Fibre Channel protocol will meet the needs of today’s data acquisition requirements. It provides a brief overview of Fibre Channel technology and identifies the different types of Fibre Channel products available. It provides examples of how commercial-off-the-shelf (COTS) products can be used to build data acquisition and storage systems requiring throughputs of up to 90 Mbytes per second on a single fiber. Additionally, it shows how multiple fibers can be used to achieve much higher data rates.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A PC-based space channel error simulator that includes differing forward and return data links, independent statistical characterization of the data links, and link propagation delay has been developed. The LabVIEW programming language has been used to configure this containing all of the error generation and processing in software. The simulator is used for testing networking protocols in a simulated space channel environment and can be used for other types of channels as well. This paper describes the design goals, hardware configuration, software, and testing of the simulator. This technique allows for rapid development and validation of the simulator.

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.

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International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / This paper summarize range error caused by instability of transmission characteristics and change of signal frequency and amplitude. On the basis of transmission system's modulation-demodulation combined characteristic, amplitude-frequency characteristics even symmetry, phase-frequency characteristics odd symmetry, phase orthogonality of demodulator, author analyses influence of factors on range accuracy. And formulas of phase of ranging tone are derived. Using these formulas, the many factors having influence on drift range error may be calculated, and range accuracy can be improved. Above conclusion has been testfied and applied in TT&C system for years.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Underwater acoustic (UWA) telemetry requires wideband waveforms for anti-multipath which are simultaneously easy to equalize and demodulate. The Walsh/m-sequence waveforms proposed here are robust to multipath and with appropriate time-guard bands do not require equalization. For example, in the UCSB prototype acoustic modem, a data rate of 133 bps is achieved using 8-ary Walsh signaling with an 11.2 msec. symbol duration. Demodulation is performed using noncoherent detection, and hence accurate phase tracking, which is difficult to achieve in the UWA channel, is not required. However, telemetry from unmanned underwater vehicles (UUVs) is more problematic due to large Doppler shifts resulting from platform motion. A new receiver algorithm based on Matching Pursuits is proposed which combines channel and Doppler shift estimation. Symbol-error rate (SER) simulation results are presented for the UWA modem under realistic Doppler/multipath conditions.

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.

The traditional model of cryptography examines the security of the cipher as a mathematical function. However, ciphers that are secure when specified as mathematical functions are not necessarily secure in real-world implementations. The physical implementations of ciphers can be extremely difficult to control and often leak socalled side-channel information. Side-channel cryptanalysis attacks have shown to be especially effective as a practical means for attacking implementations of cryptographic algorithms on simple hardware platforms, such as smart-cards. Adversaries can obtain sensitive information from side-channels, such as the timing of operations, power consumption and electromagnetic emissions. Some of the attack techniques require surprisingly little side-channel information to break some of the best known ciphers. In constrained devices, such as smart-cards, straightforward implementations of cryptographic algorithms can be broken with minimal work. Preventing these attacks has become an active and a challenging area of research. Power analysis is a successful cryptanalytic technique that extracts secret information from cryptographic devices by analysing the power consumed during their operation. A particularly dangerous class of power analysis, differential power analysis (DPA), relies on the correlation of power consumption measurements. It has been proposed that adding non-determinism to the execution of the cryptographic device would reduce the danger of these attacks. It has also been demonstrated that asynchronous logic has advantages for security-sensitive applications. This thesis investigates the security and performance advantages of using a network-based asynchronous architecture, in which the functional units of the datapath form a network. Non-deterministic execution is achieved by exploiting concurrent execution of instructions both with and without data-dependencies; and by forwarding register values between instructions with data-dependencies using randomised routing over the network. The executions of cryptographic algorithms on different architectural configurations are simulated, and the obtained power traces are subjected to DPA attacks. The results show that the proposed architecture introduces a level of non-determinism in the execution that significantly raises the threshold for DPA attacks to succeed. In addition, the performance analysis shows that the improved security does not degrade performance.