Bandwidth efficient linear modulations require a pulse shape with finite support in the time domain while simultaneously achieving good spectral containment in the frequency domain. The square-root Nyquist pulse achieves zero intersymbol interference (ISI) at its matched-filter output but does so with infinite support in the time domain. This paper investigates three different methods for generating an FIR approximation of a square-root Nyquist pulse.

This paper summarizes the analysis of bit error rate data captured during flight tests designed to compare data-aided equalizers with SOQPSK-TG to unequalized and currently available blind, adaptive equalizers with SOQPSK-TG. The number of bit errors,on a second-by-second basis, are analyzed. The results are different for each test point. Given the uncertain behavior of the preamble detector for the data-aided equalizer and the differing channel conditions between the data-aided equalizer channel and the conventional serial streaming telemetry channel, we are unable to draw any firm comparative conclusions.

This paper investigates the performance of sparse minimum mean squared error (MMSE) equalizer for generalized time-reversed space-time block codes (GTR-STBC) in aeronautical telemetry. GTR-STBC equipped with MMSE equalizer performs the best trade-off between the signal-tonoise ratio and inter-symbol interference by allocating unequal power over aeronautical telemetry channels. However, aeronautical telemetry channels are in general consists of larger delay spreads which make the MMSE equalization of aeronautical channels with GTR-STBC computationally complex. Interestingly enough, in spite of larger delays aeronautical channels are made of few sparsely distributed multipaths and therefore their MMSE equalizers are highly compressible. In this paper, compressed sensing based greedy algorithm is used for the design of sparse MMSE equalizer and a convex curve-fitting algorithm is used to find the sub-optimum power allocation parameter at the same sparsity level for GTR-STBC. Our simulation results show that 75-90% of the non-zero equalizer taps can be reduced with a slight relaxation of the mean-squared error (or equivalentlyslight degradationof bit-errorrate performance). It isalso observedthat the optimum transmitter power profile for the sparse MMSE equalizer is different than that of the non-sparse equalizer.

Space-time coding (STC) for QPSK where the transmitted signals are received with the same delay is well known. This paper examines the case where the transmitted signals are received with a nonnegligible delay differential when the Alamouti 2x1 STC is used. Such a differential can be caused by a large spacing of the transmit antennas. In this paper, an expression for the received signal with a delay differential is derived and a decoding algorithm for that signal is developed. In addition, the performance of this new algorithm is compared to the standard Alamouti decoding algorithm for various delay differentials.

Data from ARTM channel sounding test flights is examined to characterize the dynamic channel behavior of aeronautical telemetry channels. The dynamic behavior is characterized using the Doppler power spectrum. The width of the Doppler power spectrum is the Doppler bandwidth of the channel which indicates the required bandwidth of adaptive detection techniques such as adaptive equalization, adaptive modulation, adaptive channel selection and adaptive error control coding. Data collected from ARTM Flight 11 suggest a Doppler bandwidth exceeding 6.7 Hz for the channel, but greater accuracy and resolution will only be possible with more data.

This paper describes the architecture, design, and performance of a dancing outfit equipped with LEDs and controlled by radio. The lights perform a "choreography" in synchronism with the music. The outfits were worn by a BYU dancing team (the "Cougarettes") for one of their dance routines.

Hybrid-ARQ schemes employ the simultaneous application of error-detection and error-correction to combat transmission errors in a data communications system. In this way automatic repeat request (ARQ) and forward error correction (FEC) schemes are combined to offer effective error control. The key to implementation is the identification of reliability information in the FEC decoding process which is used to alter the FEC decoding algorithm. Under certain channel conditions, the realized efficiency is superior to that of either FEC or ARQ.

This paper described the design and implementation of a prototype transmitter and a prototype demodulator/decoder for space-time coded SOQPSK-TG for aeronautical telemetry. The design exercise showed that the space-time coding concept can be reduced to hardware. The laboratory bit error rate tests showed that the performance of the prototype demodulator in a 2-transmit/1-receive antenna configuration is comparable to that of existing SOQPSK demodulators in a 1-transmit/1- receive antenna configuration.

This paper compares the bit error rate performance of a single channel equalizer with the bit error rate performance of a multi-channel equalizer (in the form of the time-reversed space-time block code) using channels derived from multipath channel measurements at Edwards AFB, California, and Cairns Army Airfield, Ft. Rucker, Alabama. The results show that the performance of the multi-channel equalizer is better than the single channel equalizer over the weaker channel, but worse than the performance of the single channel equalizer over the stronger channel. We conclude that the best approach for the informed transmitter is to apply all available power to a single antenna, whereas the best approach for the uninformed transmitter is to apply equal power with transmit diversity to the two available antennas.

This paper describes how to locate and remove periodically inserted preamble and ASM bit fields in the presence of the phase ambiguity caused by decision-directed PLLs used in most telemetry demodulators. The phase ambiguity is resolved by correlating rotated or delayed versions of the data with a stored template of the preamble and ASM bits. A finite state machine in conjunction with a FIFO is used to remove the preamble and ASM bits from the output bit stream.