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 / The optimum detector for shaped offset QPSK (SOQPSK) is a trellis detector which has high complexity (as measured by the number of detection filters and trellis states) due to the memory inherent in this modulation. In this paper we exploit the cross-correlated, trellis-coded, quadrature modulation (XTCQM) representation of SOQPSK-TG to formulate a reduced complexity detector. We show that a factor of 128 reduction in the number of trellis states of the detector can be achieved with a loss of only 0.2 dB in bit error rate performance as compared to optimum at P(b) = 10^(-5).

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / Off-line software based signal analysis can be a valuable tool for detailed examination of transmitter signal characteristics. This paper describes the Advanced Range Telemetry (ARTM) Constant Envelope (CE) offset quadrature phase shift keying (OQPSK) modulation analyzer. It was developed expressly for evaluation of FQPSK-B^(1), FQPSK-JR and shaped OQPSK transmitter signals. Rationale for its creation, underlying assumptions, computation methods, and examples of its data products are presented.

Multipath is one of the dominant causes for link loss in aeronautical telemetry. Equalizers have been studied to combat multipath interference in aeronautical telemetry. Blind equalizers are currently being used with SOQPSK-TG. The Preamble Assisted Equalization (PAQ) project studied data-aided equalizers with SOQPSK-TG. PAQ compares, side-by-side, no equalization, blind equalization, and five data-aided equalization algorithms: ZF, MMSE, MMSE-initialized CMA, and frequency domain equalization. This thesis describes the GPU implementation of data-aided equalizer algorithms. Static lab tests, performed with channel and noise emulators, showed that the MMSE, ZF, and FDE1 show the best and most consistent performance.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / SOQPSK-TG is a highly bandwidth-efficient constant-envelope modulation so that it has been applied in aeronautical telemetry widely. We develop a simple detection of SOQPSK-TG which is based on a modified OQPSK detection. The simple detection has the advantages of low complexity and good performance. And it's also suitable for other varieties of SOQPSK and FQPSK.

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 / The ARTM Tier 1 waveforms include two versions of Feher patented QPSK (FQPSK-B and FQPSK-JR) and a version of shaped offset QPSK (SOQPSK-TG). In this paper we examine three common detector architectures for the ARTM Tier 1 modulations: a symbol-by-symbol detector, a cross correlated trellis coded modulation (XTCQM) detector, and a continuous phase modulation (CPM) detector. We show that when used to detect Tier 1 modulations, these detectors perform well even without knowledge of the modulation used by the transmitter. The common symbol-by-symbol detector suffers a loss of 1.5 dB for SOQPSK-TG and 1.6 dB for FQPSK-JR in bit error rate performance relative to the theoretical optimum for these modulations. The common XTCQM detector provides a bit error rate performance that is 0.1 dB worse than optimum for SOQPSK-TG and that matches optimum performance for FQPSK-JR. The common CPM detector achieves a bit error rate performance that is 0.25 dB worse than optimum for SOQPSK-TG and that approximately matches optimum for FQPSK-JR. The common XTCQM detector provides the best bit error rate performance, but this detector also has the highest complexity.

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 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 / SOQPSK-TG is a highly bandwidth-efficient constant-envelope modulation so that it has been applied in airspace telemetry widely. We compare four types of coherent detectors for SOQPSK-TG, which are optimal detector, pulse truncation (PT) detector, standard OQPSK detector and modified OQPSK detector. The simulation and analysis results indicate that PT detector has the advantages of low complexity and good performance, so it has more practicality value.

In aeronautical telemetry, the multipath interference usually causes significant performance degradation. As the bit rate of telemetry systems increases, the impairments of multipath interference are more serious. The constant modulus algorithm (CMA) blind equalizer is effective to mitigate the impairments of multipath interference. The CMA adapts the equalizer coefficients to minimize the deviation of the signal envelope from a constant level. This paper presents the performances of the CMA blind equalizer applied for PCM-FM, PCM-BPSK, SOQPSK-TG and ARTM CPM in aeronautical telemetry.

In this thesis, frame synchronization for iNET formatted SOQPSK-TG communications is considered. Frame synchronization for M-ary linear modulations (MQAM, MPSK, etc.) are known in the literature using pilot detection methods, but are based on a signal model that does not apply to SOQPSK-TG. Maximum likelihood frame synchronizers are derived for an SOQPSK-TG system following assumptions found in the literature. The analysis shows that a reinterpretation of known detectors operating on the samples of the received waveform and locally stored samples of the pilot is the optimum approach for this case. Simulation results for an AWGN channel and several multipath channels verify the performance of the synchronizers.

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 / Hardware implementing forward error correction (FEC) is currently available for utilization by the airborne telemetry system designer. This paper will discuss the potential benefits along with drawbacks when using this technology. Laboratory testing is supplemented with real-world flight testing. Performance results comparing FEC and non-FEC systems are presented for both IRIG-106 Pulse Code Modulation/Frequency Modulation, PCM/FM, (or Continuous Phase Frequency Shift Keying, CPFSK, with filtering, or ARTM Tier 0) and Shaped Offset Quadrature Phase Shift Keying, Telemetry Group version (SOQPSK-TG or ARTM Tier I) waveforms.