International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, we propose a receiver design for satellite ground station use which can demodulate a waveform without specific knowledge of the data rate, convolutional code rate, or line code used. Several assumptions, consistent with the Space Network operating environment, are made including only certain data rates, convolutional code rates and generator polynomials, and types of line encoders. Despite the assumptions, a wide class of digital signaling (covering most of what might be seen at a ground station receiver) is captured. The approach uses standard signal processing techniques to identify data rate and line encoder class and a look up table with coded sync words (a standard feature of telemetry data frame header) in order to identify the key parameters. As our research has shown, the leading bits of the received coded frame can be used to uniquely identify the parameters. With proper identification, a basic receiver autoconfiguration sequence (date rate, line decoder, convolutional decoder) may be constructed.

No description available.

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 / A Synthetic Beamforming antenna was built for Airborne Telemetry. Low-Noise Block-converters translated RF to IF suitable for direct analog-to-digital conversion. Then all telemetry functions were performed digitally via parallel FPGAs for 10 independent sources. Monopulse tracking and optimal diversity combination was performed using 4 antenna quadrants at two orthogonal polarizations. Novel estimation approaches drove digital demodulation, symbol- and bit- synchronization. Final telemetry outputs include: digital, analog (video), and analog IF (e.g., for downlink relay). This program has incubated several concepts that we believe have the combined potential to significantly improve the future of telemetry.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes an approach to the implementation of an IF sampling digital receiver for low data rate command and telemetry applications in the NASA Goddard Spaceflight Tracking and Data Network (STDN) and Air Force Space-Ground Link System (SGLS). The digital design is targeted for an FPGA-based implementation and was written entirely in VHDL. Several size and clock reduction techniques are described which were utilized due to limited gate-array resources and power. The system-level design architecture is described followed by a discussion of algorithms and performance of critical stages in the receiver chain. Bit error performance of the prototype receiver is also presented. Finally, although this design is specifically targeted for a narrowband command and telemetry application, the methodology forms the basis of a configurable receiver for higher data rate applications.

Les communications numériques ont évolué pour répondre à la demande des consommateurs pour accroître l'accès à la navigation Internet, TV, vidéo à la demande, jeux interactifs et de réseaux sociaux. Cette augmentation de débit est obtenue en utilisant des techniques avancées de traitement du signal, des modulations complexes, et des bandes passantes larges. Par conséquent, des récepteurs hautes performances, capables de traiter des signaux large bande, sont nécessaires pour les équipements d'infrastructure et de communication grand-public hauts de gamme. Les récepteurs à numérisation directe RF sont attrayants pour ces applications à large bande, mais plusieurs aspects doivent être étudiés afin de fournir des solutions performantes intégrées. Les principales contributions de cette thèse sont les suivantes: - l’analyse et la conception au niveau système des récepteurs à échantillonnage et numérisation directs RF : - l'analyse théorique de la distorsion non-linéaire large-bande, pour les stratégies d'échantillonnage passe-bas et passe-bande - l'analyse théorique des défauts des convertisseurs analogique-numérique haute-vitesse dans un contexte de réception large bande - la conception d'un conditionneur de signal RF optimisé pour une application câble, incluant: - un égaliseur RF programmable multi-pente, utilisant une seule inductance, avec son algorithme de contrôle - une boucle de contrôle de gain mixte combinant un détecteur RMS et un détecteur crête - contribution à la réalisation d'un produit récepteur RF multi-canaux, à numérisation directe, compétitif en consommation d'énergie, coût, et performances RF / The Holy Grail radio receiver architecture for Software Radio makes uses of direct RF digitization. The early RF signal digitization theoretically provides maximum re-configurability of the radio front-end to multiple bands and standards, as opposed to analog-extensive front-ends. In addition, in applications for which a large portion of the RF input signal spectrum is required to be received simultaneously, the RF direct digitization architecture could provide the most power-and-cost-effective front-end solution. This is typically the case in centralized architectures, for which a single receiver is used in a multi-user environment (data and video gateways) or in re-multiplexing systems. In these situations, this highly-digitized architecture could dramatically simplify the radio front-end, as it has the potential to replace most of the analog processing. In this Ph.D thesis, we study the trade-offs, from RF to DSP domains, which are being involved in direct RF digitization receivers. The developed system-level framework is applied to the design of a cable multi-channel RF direct digitization receiver. Special focus is provided on the design of an optimum RF signal conditioning, on the specification of time-interleaved analog-to-digital converter impairments, including clock quality, and on some algorithmic aspects (automatic gain control loop, RF front-end amplitude equalization control loop). The two-chip implementation is presented, using BiCMOS and 65nm CMOS processes, together with the block and system-level measurement results. The solution is highly competitive, both in terms of area and RF performance, while it drastically reduces power consumption.

No description available.

CMOS technology is particularly attractive for commercialization of ultra wideband (UWB) radios due to its low power and low cost. In addition to CMOS implementation, UWB radios would also significantly benefit from a radio architecture that enables digital communications. In addition to the normal challenges of CMOS RFIC design, there are two major technical challenges for the implementation of CMOS digital UWB radios. The first is building RF and analog circuitry covering wide bandwidth over several GHz. The second is sampling and digitizing high frequency signals in the UWB frequency range of 3 GHz to 10 GHz, which is not feasible for existing CMOS analog-to-digital converters. In this dissertation, we investigate the two technical challenges at the circuit level and the system level. We propose a systematic approach at the circuit level for optimal transistor sizing and biasing conditions that result in optimal noise and power matching over a wide bandwidth. We also propose a general scheme for wideband matching. To verify our methods, we design two single-stage low noise amplifiers (LNAs) in TSMC 0.18µm CMOS technology. Measurement results from fabricated chips indicate that the proposed LNAs could achieve as high as 16 dB power gain and as low as 2.2 dB noise figure with only 6.4 mA current dissipation under a supply voltage of 1.2 V. At the system level, we propose a unique frequency domain receiver architecture. The receiver samples frequency components of a received signal rather than the traditional approach of sampling a received signal at discrete instances in time. The frequency domain sampling leads to a simple RF front-end architecture that directly samples an RF signal without the need to downconvert it into a baseband signal. Further, our approach significantly reduces the sampling rate to the pulse repetition rate. We investigate a simple, low-power implementation of the frequency domain sampler with 1-bit ADCs. Simulation results show that the proposed frequency-domain UWB receiver significantly outperforms a conventional analog correlator. A digital UWB receiver can be implemented efficiently in CMOS with the proposed LNA as an RF front-end, followed by the frequency domain sampler. / Ph. D.

International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, Nevada / Digital processing techniques and related algorithms for receiving and processing space vehicle downlink signals are discussed. The combination of low minimum signal to noise density (C/No), large signal dynamic range, unknown time of arrival, and high space vehicle dynamics that is characteristic of some of these downlink signals results in a difficult acquisition problem. A method for rapid acquisition is described which employs a Fast Fourier Transform (FFT). Also discussed are digital techniques for precise measurement of space vehicle range and range rate using a digitally synthesized number controlled oscillator (NCO).

Approved for public release, distribution is unlimited / This thesis is a continuation of the design and development of a three-dimensional 2.4 GHz digital phased array radar antenna. A commercial off-the-shelf quadrature modulator and demodulator were used as phase shifters in the digital transmit and receive arrays. The phase response characteristic of the demodulator was measured and the results show that the phase difference between the received phase and transmit phase is small. In order to increase the bandwidth of the phased array, a method of time-varying phase weights for linear frequency modulated signal was investigated. Using time-varying phase weights on transmit and receive give the best performance, but require the range information of the target. It is more practical to use time-varying phase weights on only one side (transmit or receive but not both), and constant phase weights on the other side. The simulation results showed that by using time-varying phase weights, the matched filter loss is not as severe as it is when using the conventional fixed weights technique. It was also found that this method is only effective for small scan angles when the time-bandwidth product is large. The approach to implement time-varying phase weights on transmit using commercial components such as direct digital synthesizer and quadrature modulator is discussed. / Civilian, Ministry of Defense, Singapore

A new digital receiver was built for the Ooty Radio Telescope (ORT). This new digital receiver system functionally replaces many systems custom-built for various applications at ORT. The thesis presents the receiver design, tests conducted, contributions made, revisions to the receiver architecture and future scopes. The novelty of the receiver design is in treating the ORT as an array of 22 antenna elements. Simulation studies were carried out to analyze the array performance of ORT. The IF signals are digitized and processed by a combination of multiple FPGAs and computers. Major transport of data in the receiver is through high speed serial communication. Programs were developed for configuration, control, data acquisition and off-line analysis. The functionality of the proposed digital receiver was verified through laboratory tests. The proposed receiver enables several new modes of operation of the ORT and field tests were carried out to verify these features of the system. These tests are briefly described below. The radio waves received on earth from celestial sources are extremely weak and their presence can only be detected by sensitive receivers associated with large radio telescopes. The resulting vulnerability of such observations to the ever increasing presence of radio frequency interference has prompted us to to develop new procedures to identify RFI at ORT through time and frequency domain analysis. The digital receiver has also been used in carrying out RFI study at ORT module level for the first time. Our study demonstrates that a major challenge to realizing the full potential of the ORT will be to detect weakly interfering RFI features and occasionally appearing RFI spikes and correct for their contamination in the observations. The examples provided by our analysis of data collected using the digital receiver are very useful for interpreting the data obtained during sensitive spectral line observations and has already enabled several new studies, the most notable being a sensitive recombination line survey conducted using our digital receiver at ORT as part of another research work. A spectral line emission detection procedure using our receiver has been evolved and an example result obtained by observing a region is presented in the thesis. Formation of phased array of ORT modules using the digitized IF signal is discussed and its implementation is verified through observation of celestial sources. An important requirement for proper phasing of the array is the calibration of differential delay/phase variations across the modules of the ORT, for which a powerful method was implemented based on the cross correlation of signals arriving at the 22 modules. This new method employs Hilbert Transform technique to introduce phase information in the sampled signal and the estimated delay and phase corrections are found to be consistent and repeatable. An interplanetary scintillation observation was made with the phased array and the resultant fluctuation spectra obtained are presented. Several pulsar observations and continuum sources have been observed and the results are presented. Another notable feature of the proposed digital receiver is the enhanced field of view which will lead to a reduced observing time observing extended regions. The improved spectral and temporal resolutions have also been demonstrated by the observations presented in the thesis. In particular, the single pulse observations of pulsars reported in the thesis were enabled by the high time resolution supported by the receiver.. The present work also demonstrated the digital beam formation with ORT modules in arbitrary directions. The digitally synthesized beam was compared within the first null positions of the central analog beam (beam-7) of ORT and the result is reported in the thesis. The new digital receiver enabled all the above mentioned analyses which were carried out for the first time at ORT. The results of the field trials emphasized the need for future observations to include RFI monitoring and characterization as part of the observing strategy and continuously evolve the algorithms for RFI mitigation by using different statistical signatures of the celestial signals. The need for providing a layer of buffering and preprocessing before the final beam formation or correlation is emphasized. To facilitate such development in the future, the final operational system provides for software based correlator which can be developed using the algorithms presented in this thesis. This transforms our original target of a reconfigurable platform to a much more flexible re-programmable platform. In particular, this simplifies the application of windowing functions and polyphase filters to control the beam shapes to (a) reduce beam dilution effects and, (b) to enhance RFI rejection by side lobe suppression. Such techniques can be used to reduce spectral leakage and reduce the effect of RFI on adjacent frequency channels in critical observations. Our receiver is adequate for realizing the maximum potential of the IF signals entering the receiver room. Any further enhancement of the ORT spectral coverage and instantaneous sky coverage will require telescope's front end modification and digitization of signals at the RF stage. The real time processing capabilities can be further enhanced by using multi-core processors and multi gigabit ethernet interfaces that are starting to appear as commodity hardware. Thus the present work opens up several new avenues for future work.