A comparison between coherent and noncoherent mobile systems in large Doppler shift, delay spread, and C/I environment

The performance and implementation complexity of coherent and of noncoherent QPSK and GMSK modulation/demodulation techniques in a complex mobile satellite systems environment, including large Doppler shift, delay spread, and low C/I, are compared. We demonstrate that for large f(sub d)T(sub b) products, where f(sub d) is the Doppler shift and T(sub b) is the bit duration, noncoherent (discriminator detector or differential demodulation) systems have a lower BER floor than their coherent counterparts. For significant delay spreads, e.g., tau(sub rms) greater than 0.4 T(sub b), and low C/I, coherent systems outperform noncoherent systems. However, the synchronization time of coherent systems is longer than that of noncoherent systems. Spectral efficiency, overall capacity, and related hardware complexity issues of these systems are also analyzed. We demonstrate that coherent systems have a simpler overall architecture (IF filter implementation-cost versus carrier recovery) and are more robust in an RF frequency drift environment. Additionally, the prediction tools, computer simulations, and analysis of coherent systems is simpler. The threshold or capture effect in low C/I interference environment is critical for noncoherent discriminator based systems. We conclude with a comparison of hardware architectures of coherent and of noncoherent systems, including recent trends in commercial VLSI technology and direct baseband to RF transmit, RF to baseband (0-IF) receiver implementation strategies

A novel scheme to aid coherent detection of GMSK signals in fast Rayleigh fading channels

A novel scheme to insert carrier pilot to Gaussian Minimum Shift Keying (GMSK) signal using Binary Block Code (BBC) and a highpass filter in baseband is proposed. This allows the signal to be coherently demodulated even in a fast Rayleigh fading environment. As an illustrative example, the scheme is applied to a 16 kb/s GMSK signal, and its performance over a fast Rayleigh fading channel is investigated using computer simulation. This modem's 'irreducible error rate' is found to be Pe = 5.5 x 10(exp -5) which is more than that of differential detection. The modem's performance in Rician fading channel is currently under investigation

FQPSK Doubles Spectral Efficiency of Telemetry: Advances and Initial Air to Ground Flight Tests

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaFQPSK is the abbreviation for Feher Quadrature Phase Shift Keying (FQPSK) patented systems [1]. Digcom, Inc. licensed FQPSK products demonstrated significant spectral saving and RF power efficient robust BER performance advantages. These bit rate agile modems and Non Linearly Amplified (NLA) transceivers, DSP and hardware implementations, and in some instances “software-radios” (20kb/s to more than 100Mb/s) and RF frequency agile (from 150MHz to more than 40GHz) developments and systems have recently been demonstrated and deployed. The spectral efficiency, i.e., data throughput capability of the 1st generation of FQPSK, as demonstrated in initial Advanced Range Telemetry (ARTM) flight tests, approximately doubles while 2nd generation “FQPSK-2” systems have the potential to quadruple the spectral efficiency of operational PCM/FM telemetry systems and be backward compatible with the 1st generation of FQPSK technologies. It is also demonstrated that the spectral efficiency advantage of FQPSK over that of NLA power efficient GMSK, OQPSK and QPSK modulated transceivers is in the 50% to 300% range and that the potential spectral efficiency advantage of FQPSK-2 over GMSK [1] is in the 200% to 500% range. Based on extensive multi-year studies of alternative solutions for spectral and RF power efficient, robust BER performance systems, several commercial US and international organizations, AIAA, CCSDS, NASA, ESA, CCSDS and various programs of the US Department of Defense (DoD) concluded that FQPSK offers the most spectrally efficient high performance-high speed proven technology solutions and recommended FQPSK standardization for several data links. Initial DoD-ARTM Program Office Air-to-Ground L-band and S-band jet airborne telemetry Test and Evaluation (T&E) data, obtained during the summer of 1998 are briefly highlighted. These include simultaneosly tested FQPSK and PCM/FM. In these tests the following ARTM objectives have been demonstrated: (a) FQPSK approximately doubles the spectral efficiency of currently operational PCM/FM; (b) The Data Link Performance of these two systems is comparable. The American Institute of Aeronautics and Astronautics (AIAA) draft modulation standard recommended to the DoD, NASA and CCSDS, was approved by the AIAA [23]. The AIAA standard recommends “that FQPSK modulation be immediately adopted as the interim increment–1 standard.”International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Digital/analog microwave transmission study

Résumé : L'objet de cette thèse est l'étude de nouvelles méthodes d'utilisation du réseau micro-onde en vue de la transmission simultanée de signaux numériques et analogiques et ce d'une manière efficace. Compte tenu des contraintes pratiques, nous montrons que la transmission en bande large des données conduit à une augmentation de la capacité de transinformation par un facteur de près de cinq (5) par rapport aux techniques usuelles à bande étroite. Comme point principal, on démontre théoriquement et vérifie expérimentalement sur une section du réseau canadien qu'il est possible de transmettre 1.544 Mbits/sec, soit au-dessus de 960 canaux FDM, soit au-dessous de 840 canaux du même type, avec un système F.M. normalement conçu pour 960 canaux. Une étude conceptuelle des systèmes hybrides de même qu'une analyse détaillée des deux configurations DAY (data above voice) et DUV (data under voice) est aussi présentée. Ceci a nécessité la dérivation de la densité spectrale de puissance pour des données aléatoires à niveaux multiples de même que 1'analyse des performances des récepteurs digitaux en présence de bruit gaussien coloré. Des critères d'évaluation pour les systèmes hybrides ont dû être définis pour en arriver à obtenir une évaluation quantitative. Cette partie de notre travail a été rendue possible par l’utilisation d'un programme pour simuler sur ordinateur les systèmes micro-ondes analogues et digitaux. Différentes méthodes de comparaisons pour les systèmes hybrides ont alors été introduites. Finalement, quelques autres problèmes associés à la transmission hybride sont abordés. On a d'abord examiné les différentes configurations possibles dans le cas d'un système à diversité de deuxième ordre, avec une attention particulière pour les combineurs de type "commutation sélective" (SS) et "gains égaux" (EG). De plus, une approche nouvelle à la question de l'évaluation d'un "pilote" et du bruit de façon digitale est proposée. Toute cette discussion nous mène à la conclusion que pour des rythmes de transmission élevés les combineurs de type "digital" et à "rapport maximum" sont les plus prometteurs pour le futur. On considère enfin le problème, souvent négligé mais extrêmement important, de la transmission d'un canal de service. Nous proposons ici une méthode d'insertion du canal de service pour les systèmes complètement digitalisés ou encore hybride de type DUV, méthode qui nécessite un minimum d'investissement. En résumé, le point le plus important qui a été établi dans ce travail c'est que les systèmes DUV et DAY sont tous les deux réalisables, ce qui contredit les prédictions de certaines autorités en la matière qui maintenaient que 1es systèmes DAY ne fonctionneraient pas sur un réseau F.M. On a même montré que les systèmes DAY possèdent suffisamment d'avantages par rapport aux systèmes DUV pour constituer une des techniques les plus prometteuses pour les prochaines années.||Abstract : New and efficient microwave system utilization methods for simultaneous wideband digital and analog signal transmission are presented. In particular, it is shown that a Data Above Voice (DA V) system employing a 1.544 Mbit/s data channel above 960 Frequency Division Multiplex (FDM) channels and a Data Under Voice (DUV) system having a 1.544 Mbit/s data channel below 840 FDM channels, are practical hybrid systems. Theoretical models of hybrid transmission are discussed and the DAV and DUV methods are compared. In order to enable quantitative system studies hybrid system evaluation criteria are defined and the power spectrum of multilevel random data as well as the performance of digital receivers in additive coloured gaussian noise environment is derived. A digital computer simulation and a conceptual hybrid system design procedure are described, while field measurement result's on an 8 hop 6 GHz system are compared favourably with theoretical predictions. Finally, other problems associated with hybrid transmission are discussed. Different baseband diversity configurations are analyzed and particular attention is given t-o the Selective Switching or Equal Gain combiner. For service channel transmission in dedicated digital and DUV microwave systems a somewhat complex but highly practical method is introduced. This method is expected to result in significant hardware and cost- savings

SPECTRAL EFFICIENCY OF COMMERCIAL WIRELESS AND TELEMETRY SYSTEMS IS DOUBLED WITH IRIG 106-00 STANDARDIZED FQPSK AND IS QUADRUPLED WITH FQAM

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaAdvances in spectrally efficient Feher’s Quadrature Phase Shift Keying (FQPSK) and Feher‘s Quadrature Amplitude Modulation (FQAM) patented technologies, commercial and government “dual-use” FQPSK products and Test & Evaluation (T&E) results are highlighted in this overview paper. US and international customer requirements/systems, programs and recent deployments and standardization programs are also described. FQPSK doubles the spectral efficiency of PCM/FM Telemetry and of Feher patented Gaussian Minimum Shift Keying (GMSK or FGMSK) and of alternatives, while FQAM quadruples the spectral efficiency of these systems. The predominant focus of this presentation is on an overview and advances of IRIG 106-00 standardized FQPSK technologies. FQAM systems will also be described. Use of FQPSK for applications such as telemetry, data links, clear mode, TDMA ,CSMA and CDMA, OCDMA, WCDMA as well as OFDM – COFDM will be included in the presentation.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Digital/analog microwave transmission study

Résumé : L'objet de cette thèse est l'étude de nouvelles méthodes d'utilisation du réseau micro-onde en vue de la transmission simultanée de signaux numériques et analogiques et ce d'une manière efficace. Compte tenu des contraintes pratiques, nous montrons que la transmission en bande large des données conduit à une augmentation de la capacité de transinformation par un facteur de près de cinq (5) par rapport aux techniques usuelles à bande étroite. Comme point principal, on démontre théoriquement et vérifie expérimentalement sur une section du réseau canadien qu'il est possible de transmettre 1.544 Mbits/sec, soit au-dessus de 960 canaux FDM, soit au-dessous de 840 canaux du même type, avec un système F.M. normalement conçu pour 960 canaux. Une étude conceptuelle des systèmes hybrides de même qu'une analyse détaillée des deux configurations DAY (data above voice) et DUV (data under voice) est aussi présentée. Ceci a nécessité la dérivation de la densité spectrale de puissance pour des données aléatoires à niveaux multiples de même que 1'analyse des performances des récepteurs digitaux en présence de bruit gaussien coloré. Des critères d'évaluation pour les systèmes hybrides ont dû être définis pour en arriver à obtenir une évaluation quantitative. Cette partie de notre travail a été rendue possible par l’utilisation d'un programme pour simuler sur ordinateur les systèmes micro-ondes analogues et digitaux. Différentes méthodes de comparaisons pour les systèmes hybrides ont alors été introduites. Finalement, quelques autres problèmes associés à la transmission hybride sont abordés. On a d'abord examiné les différentes configurations possibles dans le cas d'un système à diversité de deuxième ordre, avec une attention particulière pour les combineurs de type "commutation sélective" (SS) et "gains égaux" (EG). De plus, une approche nouvelle à la question de l'évaluation d'un "pilote" et du bruit de façon digitale est proposée. Toute cette discussion nous mène à la conclusion que pour des rythmes de transmission élevés les combineurs de type "digital" et à "rapport maximum" sont les plus prometteurs pour le futur. On considère enfin le problème, souvent négligé mais extrêmement important, de la transmission d'un canal de service. Nous proposons ici une méthode d'insertion du canal de service pour les systèmes complètement digitalisés ou encore hybride de type DUV, méthode qui nécessite un minimum d'investissement. En résumé, le point le plus important qui a été établi dans ce travail c'est que les systèmes DUV et DAY sont tous les deux réalisables, ce qui contredit les prédictions de certaines autorités en la matière qui maintenaient que 1es systèmes DAY ne fonctionneraient pas sur un réseau F.M. On a même montré que les systèmes DAY possèdent suffisamment d'avantages par rapport aux systèmes DUV pour constituer une des techniques les plus prometteuses pour les prochaines années.||Abstract : New and efficient microwave system utilization methods for simultaneous wideband digital and analog signal transmission are presented. In particular, it is shown that a Data Above Voice (DA V) system employing a 1.544 Mbit/s data channel above 960 Frequency Division Multiplex (FDM) channels and a Data Under Voice (DUV) system having a 1.544 Mbit/s data channel below 840 FDM channels, are practical hybrid systems. Theoretical models of hybrid transmission are discussed and the DAV and DUV methods are compared. In order to enable quantitative system studies hybrid system evaluation criteria are defined and the power spectrum of multilevel random data as well as the performance of digital receivers in additive coloured gaussian noise environment is derived. A digital computer simulation and a conceptual hybrid system design procedure are described, while field measurement result's on an 8 hop 6 GHz system are compared favourably with theoretical predictions. Finally, other problems associated with hybrid transmission are discussed. Different baseband diversity configurations are analyzed and particular attention is given t-o the Selective Switching or Equal Gain combiner. For service channel transmission in dedicated digital and DUV microwave systems a somewhat complex but highly practical method is introduced. This method is expected to result in significant hardware and cost- savings

PSEUDO ERROR DETECTION IN SMART ANTENNA/DIVERSITY SYSTEMS

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaAn implementation of a Pseudo Error Detection (PSED) system is presented and its performance in conjunction with smart antenna and smart diversity systems tested and evaluated. Non redundancy, instant response and relative simplicity make the Pseudo Error Detectors excellent real time error monitoring systems in smart antenna and smart diversity systems. Because of the Non-redundant Error Detection mechanism in Pseudo Error Detectors, we can monitor the error quality without any coding or overhead. The output of the pseudo error detector in AWGN, selective fading Doppler shift and other interference environments is directly correlated to the BER and BLER. This direct correlation makes it a great tool for online error monitoring of a system and can have numerous applications In a PSED the Eye diagram from the demodulator is sampled once per symbol. By monitoring and comparison of the eye at sampled intervals at different thresholds, we would know if an error has occurred. By integrating this result over a period of time we can get the averaged error level. The results provided in this paper were obtained and verified by both MatLab simulations using dynamic simulation techniques and hardware measurements over dynamic channels.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

PERFORMANCE OF FQPSK TRANSCEIVERS IN A COMPLEX REAL-LIFE INTERFERENCE ENVIRONMENT

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThe Bit Error Rate (BER) performance of FQPSK modulated signals in the presence of the Co-Channel Interference (CCI) and Additive White Gaussian Noise (AWGN) is evaluated and improved. A Non- Linearly Amplified (NLA) FQPSK modulated signal with the data rate of 1Mb/s and carrier frequency of 70 MHz is interfered with a sinusoidal signal at different frequencies. As the relative distance of the center frequency of the Co-channel interference (CCI) changes, different BER are obtained. The effect of the CCI decreases as the CCI center frequency moves away from the center of the modulated signal. In order to improve the BER in the presence of the CCI, a hard limited filter is added at the receiver input. The hard limited filter has a different amplification factor for different signal strength. As a result, the amplification factor for the CCI, which is normally a weaker signal, is smaller than the actual signal. This means that the signal is amplified more than the interference and as a result the CCI is suppressed and the BER rate improves. The results of both simulations and measurements are obtained for different CCI center frequencies, before and after the improvements.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

ADAPTIVE FAST BLIND FEHER EQUALIZERS (FE) FOR FQPSK

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe performance of novel experimental blind equalizers suitable for a large class of applications including telemetry systems and other wireless applications is described. Experimental hardware research of these adaptive patent pending Feher Equalizers (FE) confirms computer simulated data [1]. A two-ray RF selective faded telemetry channel has been simulated. A dynamically changing channel environment with a selective fade rate in the 1Hz to 50Hz range has been constructed by laboratory hardware. The Test and Evaluation (T&E) setup had RF frequency selective dynamic notch depth variations in the Power Spectral Density (PSD) within the band of the signal of up to 15dB. As an illustrative example of the adaptive equalizer capability we used a 1Mb/s rate Feher patented FQPSK [1] Commercially Of The Shelf (COTS) product. Both hardware experimental results as well as simulation indicate substantial performance improvement with the utilization of the FE. It is demonstrated that the FE improves for a large class of frequency selective faded systems the Bit Error Rate(BER) from 10^-2 to 10^-6. Similar performance improvements are presented for the Block Error Rate (BLER).International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection