ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / This paper addresses the air-to-ground communication problem, where multiple transmit antennas are used on the aircraft to combat multi-path interference. The channel is assumed to have a line-of-sight component and a single ground reflection. Multiple input multiple output (MIMO) techniques can be used in this situation, to increase the reliability and data rate. In this paper we discuss how the MIMO channel capacity changes, with the aircraft antenna configuration, altitude, velocity, range, and a number of other parameters. For comparison, the MIMO results are compared to systems which have single antennas at the transmitter, at the receiver, or at both ends.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / This paper will present the results of experiments to characterize the performance of a blind, adaptive constant modulus algorithm (CMA) equalizer in simulated telemetry multipath environments. The variables included modulation method, bit rate, received signal-to-noise ratio, delay of the indirect path relative to the direct path, amplitude of the indirect path relative to the direct path, and fade rate. The main measured parameter was bit error probability (BEP). The tests showed that the equalizer usually improved the data quality in the presence of multipath.

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 / Adaptive modulation is a communication technique capable of maximizing throughput while guaranteeing a fixed symbol error rate (SER). However, this technique requires instantaneous channel state information at the transmitter. This can be obtained by predicting channel states at the receiver and feeding them back to the transmitter. Existing algorithms used to predict single-input single-output (SISO) channels with recurrent neural networks (RNN) are extended to multiple-input multiple-output (MIMO) channels for use with adaptive modulation and their performance is demonstrated in several examples.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The turbo code is a block code even though a convolutional encoder is used to construct codewords. Its performance depends on the code word length. Since the invention of the turbo code in 1993, most of the bit error rate (BER) evaluations have been performed using large block sizes, i.e., sizes greater than 1000, or even 10,000. However, for telemetry and command, a relatively short message (<500 bits) may be used. This paper investigates the turbo-coded BER performance for short packets. Fading channel is also considered. In addition, biased channel side information is adopted to improve the performance.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, orthogonal wavelets are employed to produce multiscale signaling. It is shown that signaling using these functions is bandwidth efficient compared other signaling schemes, including SFSK and GMSK. For signaling in Rician fast fading channel, it is also shown that scaling functions is superior in term of achieving low level of probability of error. Even for multiscale signaling, the level probability of error achieved by using wavelet is lower than conventional flat-top signaling. The benefits are largest for channels with small B(D)T , in which the degradation due to fading is most severe.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Design and performance evaluation of a low-complexity equalizer for recently standardized spectral efficient Feher patented quadrature phase shift keying (FQPSK) system [1] over multipath fading channel is presented. The implementation based on a Feher patented equalizer (FE) [1] is of a structure with three branches, which are individually used to compensate for a moving fade notch with different locations. These branches are switched by the control signal that is generated based on pseudo-error on-line detection technique. It is demonstrated that for typical aeronautical telemetry RF frequency selective fading channels, having delay spreads in 20 – 200 ns range, the adaptive FE reduces the number of statistical outages by more than 60% without the need for training bits and without increasing the receiver synchronization time.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Parameterized data from ARTM channel sounding test flights are used to derive a parameter-based estimate of the scattering function. The Doppler bandwidth and Doppler spread, important measures of channel dynamics, can be estimated from such a scattering function. Data collected from ARTM Flight 11 suggest that the Doppler bandwidth is larger than 6.7 Hz. Even for very small collections of parameterized data, surprising agreement is shown to non-parametric scattering function estimates. This confirms modeling assumptions and offers a way to achieve significant reductions of storage requirements.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / In an effort to determine a more accurate characterization of the multipath fading effects on telemetry signals, the BYU telemetering group is implementing an inexpensive data acquisition system to measure these effects. It is designed to measure important signals in a diversity combining system. The received RF envelope, AGC signal, and the weighting signal for each beam, as well as the IRIG B time stamp will be sampled and stored. This system is based on an 80x86 platform for simplicity, compactness, and ease of use. The design is robust and portable to accommodate measurements in a variety of locations including aircraft, ground, and mobile environments.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper presents a mathematical model for Coded Orthogonal Frequency Division Multiplexing (COFDM) in frequency selective multipath encountered in aeronautical telemetry. The use of the fast Fourier transform (FFT) for modulation and demodulation is reviewed. Error control coding with interleaving in frequency is able to provide reliable data communications during frequency selective multipath fade events. Simulations demonstrate QPSK mapped COFDM performs well in a multipath fading environment with parameters typically encountered in aeronautical telemetry.

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / Fading estimation in wireless communication systems depend on an expected fading model and assumptions about the channel itself. The bit error rate (BER) performance of the communication system is affected by how closely the assumptions made in de- signing the estimation technique match the deployment environment. Any unforeseen disturbances or hindrances in the environment deteriorate the BER performance of the system when the estimation system is not designed to combat the same. To combat such obstacles, estimation techniques must either be reinforced with modular systems which combat such observed types of disturbances, or be redesigned as a whole considering such observations of disturbances. In this paper a modular scheme to detect and combat sinusoidal variation in fading power is developed and tested by employing the developed scheme in a multiple-input-multiple-output (MIMO) wireless communication system which adopts Space-Time Block Coding (STBC) techniques.