Academic literature on the topic 'SOQPSK'

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada<br>We study simple trellis-based detectors for SOQPSK that have a minimal level of complexity. In particular, we show that the state complexity can be cut in half relative to previous approaches—from 4 states down to 2—with asymptotically optimum performance. We give two possible means of achieving this: the pulse amplitude modulation (PAM) technique and the pulse truncation (PT) technique; both of these techniques make use of recent advances in SOQPSK technology based on a continuous phase modulation (CPM) interpretation of SOQPSK. The proposed simplifications are significant since trellis-based SOQPSK detectors are 1–2 dB superior to widely-deployed symbol-by-symbol detectors. These performance gains come at the expense of complexity, and the proposed 2-state detectors minimize this expense. Thus, these simple detection schemes are applicable in settings where high-performance and low complexity are needed to meet restrictions on power consumption and cost.

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<br>This paper presents the results of laboratory experiments using a commercial-off-the-shelf software defined radio to demodulate SOQPSK-TG for aeronautical telemetry. Using the NI USRP N210 and Zynq™ processor, we achieved 900 kbits/s demodulation and found that the USRP N210 has a signal sensitivity of -71 dBm at a BER of 10⁻⁶.

This paper investigates a fractionally-spaced decision-feedback equalization technique for Shaped Offset Quadrature Phase Shift Keying (SOQPSK). The kernel of the block-based feedback algorithm is to estimate the intersymbol interference and cancel it from the samples used to make the bit decisions. This process refines the bit estimates sequentially, thereby increasing the probability of obtaining accurate estimates. The simulated bit error rate performance of the decision-feedback technique shows a 1 dB improvement over MMSE-equalized SOQPSK-TG over channels derived from multipath channel measurements at Cairns Army Airfield, Ft. Rucker, Alabama and Edwards AFB, California.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada<br>Shaped offset quadrature phase shift keying (SOQPSK) is a highly bandwidth efficient modulation technique used widely in military and aeronautical telemetry standards. It can be classified as a form of continuous phase modulation (CPM), but its major distinction from other CPM schemes is that it has a constrained (correlated) ternary data alphabet. CPM-based detection models for SOQPSK have been developed only recently. One roadblock standing in the way of these detectors being adopted is that existing symbol timing recovery techniques for CPM are not always applicable since the data symbols are correlated. We investigate the performance of one CPM-based timing error detector (TED) that can be used with SOQPSK, and apply it to the versions of SOQPSK used in military (MIL-STD SOQPSK) and telemetry group (SOQPSK-TG) standards. We derive the theoretical performance limits on the accuracy of timing recovery for SOQPSK, as given by the modified Cramer-Rao bound (MCRB), and show that the proposed TED performs close to these bounds in computer simulations and is free of false-lock points. We also show that the proposed scheme outperforms a non-data aided TED that was recently developed for SOQPSK. These results show that the proposed scheme has great promise in a wide range of applications due to its low complexity, strong performance, and lack of false-lock points.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California<br>Shaped Offset QPSK (SOQPSK), as proposed and analyzed by Terrance Hill, is a family of constant envelope waveforms that is non-proprietary and exhibits excellent spectral containment and detection efficiency. Detection results using the filtering found in conventional OQPSK demodulators have been published for two variants of SOQPSK, namely SOQPSK-A and –B. This paper describes a method of synthesizing an optimal linear detection filter, with regard to bit error probability (BEP), and presents the resulting performance.

<p>Beroende på i vilken miljö man har tänkt att använda trådlös kommunikation behöver man hitta en modulationsteknik som passar under rådande förhållanden. I början på 1980-talet utvecklade den Amerikanska militären en modulationsteknik som kallas för Shaped BPSK (SBPSK) avsedd att tillämpas i kommunikationslänkar med satelliter. Vidareutveckling av SBPSK ledde sedan fram till en förbättrad variant kallad Shaped Offset QPSK (SOQPSK). På senare år har denna modulationsteknik börjat användas i civila tillämpningar och vidareutvecklats ytterligare för att ge den än bättre prestanda. År 2004 antogs SOQPSK som en modulationsteknik i den internationella flygplanskommunikationsstandarden, IRIG-106. Versionen av SOQPSK som antogs i IRIG-106 har flera bra egenskaper som t. ex. dess spektraltäthet. Detta gör denna typ av modulationsteknik lämpad för kommunikationslänkar med bl.a. flygplan, satelliter och rymdsonder (‘deep-space’).</p><p>Målet med examensarbetet har varit att implementera algoritmer för att skicka och ta emot SOQPSK-modulerade signaler. Dessa algoritmer skulle utvecklas i VHDL för att sedan syntetiseras och programmera en FPGA. Uppgiften har givits av Syncore Technologies AB i Linköping.</p><p>Arbetet har resulterat i fungerande implementationer både i mjukvara och hårdvara. Hårdvarulösningen är verifierad att klara bithastiheter upp till 30 Mbit/s. Teoretisk information om allmän modulering/demodulering och specifikt kring SOQPSK behandlas i rapporten. Uppbyggnaden av en teoretisk sändar- och mottagarmodell utformad för SOQPSK-kommunikation beskrivs också i rapporten för att ge en bättre helhetsbild av implementationen som utförts.</p><p>Arbetets syfte är att ligga till grund för Syncore AB som utvecklar en kom- munikationslänk med SOQPSK-kompatibilitet.</p>

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<br>This paper presents algorithms for estimating the frequency offset, multipath channel coefficients, and noise variance of iNET-formatted SOQPSK-TG. The estimators compare the received signal samples corresponding to the iNET preamble and attached sync marker (ASM) bits to a locally stored copy of the SOQPSK-TG samples corresponding to the same. The mean and variance of the three estimators over ten test channels derived from channel sounding experiments at Edwards AFB is presented. The results show that usable estimates are achievable.

In this paper we compute a lower bound, namely the dependence testing (DT) bound, on the maximum achievable rates (expressed in bits/channel use) with military standard shaped-offset quadrature phase shift-keying (SOQPSK-MIL) and aeronautical telemetry SOQPSK (SOQPSK-TG) schemes over additive white Gaussian noise (AWGN) channels under finite code blocklength, probability block error and equiprobable input constraints. The DT bound results for SOQPSK-MIL and SOQPSK-TG are used to lower bound their respective spectral efficiencies (expressed in bits/s/Hz). We simulate a serially concatenated convolutional code (SCCC) using SOQPSK-MIL as the inner code, and show that it performs within 1:1 dB of the SOQPSK-MIL DT bound for various coding rates. The numerical results also demonstrate the performance loss compared to the channel capacity due to the finite blocklength constraint.

This paper describes the use of a phase lock loop (PLL) to compensate for and remove a residual frequency offset when using data-aided estimators to equalize SOQPSK-TG. The problems of multipath and residual frequency offset will be shown my example. An equalizer followed by a PLL will be shown to be a viable option to mitigate multipath and residual frequency offset by example.

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<br>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).