International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / The bit rates of telemetry systems are increasing rapidly. Higher bit rates occupy more spectra and result in decreased link margin. The major signal parameters that affect the spectral occupancy and bit error probability (BEP) of binary pulse code modulation (PCM)/frequency modulation (FM) signals are the bit rate, code, premodulation filter, and peak deviation. The measured spectral occupancy is also affected by the spectrum analyzer (or other measurement equipment) settings. Additional parameters that affect the BEP include the receiver intermediate frequency (IF) filter, the FM demodulator, and the bit detector. This paper will present the effects of these parameters on the measured 99% and -60 dBc bandwidths and the BEP of binary PCM/FM telemetry signals. Normalized BEP and bandwidth curves will be presented.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Commercial FQPSK-B receivers traditionally use symbol-by-symbol detection and have a 2 dB Eb=No loss relative to ideal QPSK at a bit error rate (BER) of 10^(-5). An enhanced FQPSK-B receiver using a Viterbi algorithm (VA) to perform trellis decoding is simulated and shown to have a 1.2 dB Eb=No improvement over symbol-by-symbol detection for 10^(-5)5 BER at the cost of increased complexity. A simplified Viterbi receiver with a reduced trellis and significantly less complexity is introduced with only a slight BER degradation compared to the full Viterbi receiver. In addition, a theoretical bit error probability expression for the symbol-by-symbol FQPSK-B receiver is derived and compared with simulation results.

Abstract Radio link adaptation, multiple antenna techniques, relaying methods and dynamic radio resource assignment are among the key methods used to improve the performance of wireless communication networks. Opportunistic resource block (RB) allocation in downlink orthogonal frequency division multiple access (OFDMA) with limited feedback is considered. The spectral efficiency analysis of multiuser OFDMA with imperfect feedback path, multiple antenna methods and relaying methods is a particular focus. The analysis is derived for best-M feedback methods and for a RB-wise signal-to-noise ratio (SNR) quantization based feedback strategy. Practical resource fair round robin (RR) allocation is assumed at the RB assignment, i.e., each user gets the same portion of the available RBs. The fading of each RB is modelled to be independent and identically distributed (IID). This assumption enabled a communication theoretic approach for the performance evaluation of OFDMA systems The event probabilities related to the considered OFDMA systems are presented so that the feedback bit error probability (BEP) is a parameter in the expressions. The performance expressions are derived for the BEP in the case of binary phase-shift keying (BPSK) modulation and single antenna methods. Asymptotic BEP behavior is considered for the best-M feedback methods when the mean SNR tends to infinity. The system outage capacity and the average system spectral efficiency are investigated in the case of multiple antenna schemes. Antenna selection and space-time block coding (STBC) are considered in multiple antenna schemes when each RB is allocated exclusively to a single user. Simple OFDMA-spatial division multiple access (SDMA) schemes are also analyzed when zero forcing (ZF) detection is assumed at the receiver. Relay enhanced dynamic OFDMA with single and multiple antennas at each end is considered for fixed infrastructure amplify-and-forward (AF) relaying methods. The average spectral efficiency has been derived for the best-M and RB-wise one bit feedback schemes, antenna selection and STBC methods. The best choice for a combination of multiple antenna scheme and feedback strategy depends on several system parameters. The proposed analytical tools enable easy evaluation of the performance of the investigated schemes with different system parameters. The fundamental properties of the combinations of feedback and multiple antenna schemes are extensively studied through numerical examples. The results also demonstrate that the analytical results with idealized IID fading assumption are close to those obtained via simulations in a practical frequency selective channel when RBs are selected properly. Dynamic RB allocation is attractive for practical OFDMA systems since significant performance gain over random allocation can be achieved with a practical allocation principle, very low feedback overhead and an imperfect feedback channel.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / One of the charters of the Advanced Range Telemetry (ARTM) program was to develop more spectrally efficient waveforms while trying to maintain similar performance to the legacy waveform, Pulse Code Modulation/Frequency Modulation (PCM/FM). The first step toward this goal was the ARTM Tier I family of waveforms which include Feher patented, quadrature phase shift keying, -B version (FQSPKB) and shaped offset quadrature phase shift keying, Telemetry Group version (SOQPSK-TG). The final step was development of Tier II, an even more spectrally efficient waveform, multi-h Continuous Phase Modulation (CPM). This paper characterizes the performance of this waveform when applied in an airborne telemetry environment and, where appropriate, comparisons are made with existing Tier 0 and Tier I waveforms. The benefits, drawbacks, and trade-offs when applying this waveform in an airborne environment will also be discussed.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / When designing transmitters for quadrature modulation schemes, the designer always tries to achieve good balance and symmetry of the in-phase (I) and quadrature (Q) branches of the modulator in terms of amplitude, phase, and offsets. Perfect balance between modulators is ideal but rarely if ever achieved. The Advance Range Telemetry (ARTM) program has placed indirect specifications on the remnant carrier and sideband levels which are controlled by modulator imbalance. These specifications will govern the ARTM programs first generation of Feher’s patented quadrature phase shift keying, version B (FQPSK-B) [9] airborne telemetry transmitters. The ARTM Program has also adopted test procedures for quantifying these modulation imbalances. This paper looks at the effects of modulator imbalances on spectral occupancy and bit error probability of the airborne telemetry link. It also outlines how these imbalances influence the levels in one of the ARTM specifications. Recommendations are presented based on the measured data for higher bit rate telemetry systems.

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 / Typical airborne test platforms use multiple telemetry transmit antennas in a top and bottom configuration in order to mitigate signal shadowing during maneuvers on high dynamic platforms. While mitigating one problem, this also creates a co-channel interference problem as the same signal, time delayed with differing amplitude, is sent to both antennas. Space-Time Coding (STC) was developed with the intention of mitigating this co-channel interference problem, also known as the "two antenna problem". Lab testing and preliminary flight testing of developmental and pre-production hardware has been completed and documented. This is the first test dedicated to assessing the performance of a production STC system in a real-world test environment. This paper will briefly describe lab testing that preceded the flight testing, describes the airborne and ground station configurations used during the flight test, and provides detailed results of the performance of the space time coded telemetry link as compared against a reference telemetry link.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Since the waveform was first developed by the Advanced Range Telemetry Program (ARTM) and adopted by the Range Commanders Council Telemetry Group (RCC/TG), receiver/demodulators for the ARTM Continuous Phase Modulation (CPM) waveform have undergone continued development by several hardware vendors to boost performance in terms of phase noise, detection performance, and resynchronization time. These same results were initially presented at the International Telemetry Conference (ITC) 2003 when hardware first became available supporting this waveform, at the time called ARTM Tier II. This paper reexamines the current state of the art performance of ARTM CPM receiver/demodulators available in the marketplace today.

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.

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 / In some flight test scenarios the telemetry link is noise limited at long slant ranges or during signal fade events caused by antenna pattern nulls. In these situations, a mitigation technique such as forward error correction (FEC) can add several decibels to the link margin. The particular FEC code discussed in this paper is a variant of a low-density parity check (LDPC) code and is coupled with SOQPSK modulation in the hardware tested. This paper will briefly cover lab testing of the flight-ready hardware then present flight test results comparing a baseline uncoded telemetry link with a LDPC-coded telemetry link. This is the first known test dedicated to this specific FEC code in a real-world test environment with flight profile tailored to assess the viability of an LDPC-coded telemetry link.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The Nova HYPERMOD demodulator operates in three modes, the classic pulse-code modulation/frequency modulation (PCM/FM), sometimes known as continuous phase frequency shift keying (CPFSK) mode, shaped offset quadrature phase shift keying (SOQPSK) mode, and continuous phase modulation (CPM) mode. Of interest to this paper is SOQPSK mode which is a waveform similar to the Advanced Range Telemetry (ARTM) Tier I waveform, Feher’s Quadrature Phase Shift Keying, B version (FQPSK-B) revision (Rev) A1. Also considered is another variant, FQPSK-JR. This paper will outline the cross compatibility and resynchronization speed of these waveforms based upon ARTM-adopted demodulator performance tests. The results of these laboratory tests comparing the HYPERMOD demodulator, the enhanced Tier I demodulator, and the current Tier I reference demodulator, both from RF Networks, will be presented.