Ku-band system design study and TDRSS interface analysis

The capabilities of the Shuttle/TDRSS link simulation program (LinCsim) were expanded to account for radio frequency interference (RFI) effects on the Shuttle S-band links, the channel models were updated to reflect the RFI related hardware changes, the ESTL hardware modeling of the TDRS communication payload was reviewed and evaluated, in LinCsim the Shuttle/TDRSS signal acquisition was modeled, LinCsim was upgraded, and possible Shuttle on-orbit navigation techniques was evaluated

Satellite Emission Range Inferred Earth Survey (SERIES) project

The Global Positioning System (GPS) was developed by the Department of Defense primarily for navigation use by the United States Armed Forces. The system will consist of a constellation of 18 operational Navigation Satellite Timing and Ranging (NAVSTAR) satellites by the late 1980's. During the last four years, the Satellite Emission Range Inferred Earth Surveying (SERIES) team at the Jet Propulsion Laboratory (JPL) has developed a novel receiver which is the heart of the SERIES geodetic system designed to use signals broadcast from the GPS. This receiver does not require knowledge of the exact code sequence being transmitted. In addition, when two SERIES receivers are used differentially to determine a baseline, few cm accuracies can be obtained. The initial engineering test phase has been completed for the SERIES Project. Baseline lengths, ranging from 150 meters to 171 kilometers, have been measured with 0.3 cm to 7 cm accuracies. This technology, which is sponsored by the NASA Geodynamics Program, has been developed at JPL to meet the challenge for high precision, cost-effective geodesy, and to complement the mobile Very Long Baseline Interferometry (VLBI) system for Earth surveying

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Low power, reduced complexity filtering and improved tracking accuracy for GNSS

This thesis addresses the power consumption problems resulting from the advent of multiple GNSS satellite systems which create the need for receivers supporting multi-frequency, multi-constellation GNSS systems. Such a multi-mode receiver requires a substantial amount of signal processing power which translates to increased hardware complexity and higher power dissipation which reduces the battery life of a mobile platform. During the course of the work undertaken, a power analysis tool was developed in order to be able to estimate the hardware utilisation as well as the power consumption of a digital system. By using the power estimation tool developed, it was established that most of the power was dissipated after the Analog to Digital Converter (ADC)by the filters associated with the decimation process. The power dissipation and the hardware complexity of the decimator can be reduced substantially by using a minimum-phase Infinite Impulse Response (IIR) filter. For Global Positioning System (GPS) civilian signals, the use of IIR filters does not deleteriously affect the positional accuracy. However, in the case where an IIR filter was deployed in a GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS) receiver, the pseudorange measurements of the receiver varied by up to 200 metres. The work undertaken proposes various methods that overcomes the pseudorange measurement variation and reports on the results that are on par with linear-phase Finite Impulse Response (FIR) filters. The work also proposes a modified tracking loop that is capable of tracking very low Doppler frequencies without decreasing the tracking performance

A TDM synchronization system for multiple access satellite communication

Time Division Multiple Access /TDMA/ system for satellite communication with ground station syste

A Non-Data-Aided and Non-Phase-Based AFC Method for MPSK DS/CDMA Transceivers Used in Digital Broadcasting

Due to its high-performance broadcast capability, M -ary phase-shift-keying (MPSK) direct sequence code division multiple access (DS/CDMA) technique is widely used in terrestrial and satellite communications to provide wired/wireless services such as audio broadcasting, video broadcasting and high-speed data transmission. However, both coherent and noncoherent MPSK modulation schemes are sensitive to the carrier frequency offset (CFO) incurred by transceiver oscillator instability and/or Doppler shift. In this paper, a nondata-aided and nonphase-based automatic frequency control (AFC) method for MPSK DS/CDMA transceivers is proposed. Different from phase-based AFC approaches, which utilize the frequency-offset-induced phase rotation and suffer from the modulo- 2π phase ambiguity, the proposed method exploits the frequency-offset-induced power degradation and has a wide tracking range of twice the symbol rate, which is independent of the phase keying number as well as the spreading code length. To shorten the tracking time of AFC, the improved steepest descent algorithm and the reshaped S curve are employed. Due to its wide tracking range, short tracking time and low implementation complexity, the proposed AFC method is attractive for terrestrial and satellite-based digital broadcasting.published_or_final_versio

Space Shuttle/TDRSS communication and tracking systems analysis

In order to evaluate the technical and operational problem areas and provide a recommendation, the enhancements to the Tracking and Data Delay Satellite System (TDRSS) and Shuttle must be evaluated through simulation and analysis. These enhancement techniques must first be characterized, then modeled mathematically, and finally updated into LinCsim (analytical simulation package). The LinCsim package can then be used as an evaluation tool. Three areas of potential enhancements were identified: shuttle payload accommodations, TDRSS SSA and KSA services, and shuttle tracking system and navigation sensors. Recommendations for each area were discussed