Rice, Michael; Tinubi, Oluwasegun (International Foundation for Telemetering, 2010-10)
The concept of a range area network dedicated to the reception of telemetry from airborne test articles is explored. The range area network consists of ground-based radios that receive telemetry packets from an airborne test article and relay those packets through the network to a data sink (e.g., the main telemetry display and processing center). The network may use either "dumb" nodes or "smart" nodes and this choice presents a trade-off involving node complexity, network bandwidth, and required RF power. Using a somewhat idealized, but nonetheless realistic example at the Edwards AFB complex and link budgets based on the emerging iNET standard, we show that a network consisting of just 6 nodes reduces the L-band airborne transmitter power to 6W and the ground-based transmitters to 3W. If the airborne transmitter is restricted to 1W at L-band, then coverage can be provided by a grid of 50 nodes.
Rice, Michael; Perrins, Erik (International Foundation for Telemetering, 2015-10)
This paper deals with the problem of producing the best bit stream from a number of input bit streams with varying degrees of reliability. The best source selector and smart source selector are recast as detectors, and the maximum likelihood bit detector (MLBD) is derived from basic principles under the assumption that each bit value is accompanied by a quality measure proportional to its probability of error. We show that both the majority voter and the best source selector are special cases of the MLBD and define the conditions under which these special cases occur. We give a mathematical proof that the MLBD is the same as or better than the best source selector.
Wardle, Mason (International Foundation for Telemetering, 2005-10)
The PAM representation was used to formulate a reduced-complexity detector for the Enhanced Flight Termination System (EFTS) whose performance is 5.6 dB better than limiter-discriminator detection when no phase noise is present and 3.4 dB better in the presence of expected phase noise in EFTS.
Nelson, Tom; Rice, Michael; Jensen, Michael (International Foundation for Telemetering, 2005-10)
When using two antennas to transmit telemetry from an airborne platform, self interference results when both transmit antennae are visible to the receive antenna. This self interference can lead to link outages and severe distortion, especially as data rates increase above 5 Mbits/sec. Space-time coding can be used to provide transmit diversity to overcome this self interference problem. This paper describes the results of experiments (conducted at Edwards Air Force Base, California, USA) using FQPSK-JR waveforms coded with ARTM Tier-1 Space-Time Block Code.
Swenson, Brian; Rice, Michael (International Foundation for Telemetering, 2012-10)
A discrete-time channelizer based on a polyphase filter bank and suitable for use with aeronautical telemetry is described. The discrete-time approach reduces the number of continuous-time components - and the need to maintain and calibrate these components. Channel selection is accomplished by changing a single parameter that defines a small part of the system.
Afran, Md. Shah (International Foundation for Telemetering, 2015-10)
This paper presents a frequency domain equalization (FDE) technique for aeronautical telemetry channels. The FDE has significantly lower computational complexity compared to its time-domain counterpart, however both are found to exhibit almost identical performance. A cyclic prefix is generally needed to implement the FDE. In this paper, we exploit the repetition of iNET preamble and ASM bits in place of cyclic prefix.
Rice, Michael; Lei, Qiang (International Foundation for Telemetering, 2005-10)
This paper presents the results of land-based SHF channel modeling experiments. Channel modeling data were collected at Edwards AFB, California at S-Band, X-Band and Ku-band. Frequency domain analysis techniques were used to evaluate candidate channel models. A graphical user interface (GUI) was developed to search for the optimum channel parameters. The model parameters corresponding to different frequencies were compared for multipath events captured at approximately the same locations. A general trend was observed where the magnitude of the first multipath reflection decreased as frequency increased and the delay remained relatively unchanged.
Perrins, Erik; Rice, Michael (International Foundation for Telemetering, 2004-10)
The ARTM Tier-2 waveform, called “ARTM CPM” in IRIG 106-04, has almost three times the spectral efficiency of PCM/FM and approximately the same detection efficiency. The improved spectral efficiency comes at the price of computational complexity in the receiver. The optimum receiver requires 128 real-valued matched filters and keeps track of the waveform state with a trellis of 512 states and 2048 branches. Various complexity reducing techniques are applied and the resulting loss in detection efficiency is quantified. It is shown that the full 512-state trellis is not required to achieve the desired detection efficiency: two different 32-state configurations were found to perform within one tenth of a dB of optimal. Noncoherent techniques are also evaluated. It is shown that the required complexity can be quite large to achieve a respectable detection efficiency. One noncoherent technique performed within 1.9 dB of the optimal with only 64 states, which is significant when considering the additional complexity savings of not having to track the carrier phase.
Liu, Kejing; Rice, Michael (International Foundation for Telemetering, 2003-10)
This paper derives the maximum likelihood (ML) symbol timing estimator for a frequency non-selective multiple-input, multiple output (MIMO) channel assuming linear modulation and known data and known channel gains. The non-frequency selective fading assumption means the multipath delay spread is small so that the symbol time delay is the same across all receive antennas. Both a closed-loop and an approximate open-loop architecture are demonstrated. The open-loop or “batch” estimator is based on a polyphase filterbank implementation of the derivative matched filter.
Rice, Michael; Davis, Adam; Bettwieser, Christian (International Foundation for Telemetering, 2002-10)
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.
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