Radio communications study on noise threshold reduction. Task 3 - Oscillator stability in a tracking system Final report

Oscillator stability in range and range rate tracking syste

Special studies of AROD systems, concepts and designs Final report

Design and evaluation of development model for airborne range and orbit determination syste

Multipath performance of a TDRS system employing wideband FM VHF signals

An approximate theoretical analysis is presented for the effects of specular reflection multipath on the performance of a one-way tracking and data relay satellite-to-user link. The analysis pertains to the wideband FM system employing a sinusoidal subcarrier to achieve spectrum spreading. Bounds on multipath effects are derived for receivers with and without limiters and for data modulated on the carrier or the subcarrier. For data modulation, performance is evaluated in terms of an additive lowpass signal at the data detection filter. Doppler and range tracking performance is evaluated in terms of root-mean-square (RMS) error of carrier frequency in a carrier PLL and rms phase jitter in a subcarrier PLL

SNR behavior of coherent phase demodulators. Radio communications study on noise threshold reduction Final report

Signal to noise ratio analysis at outputs of three coherent phase detectors for radio noise threshold reduction stud

Multipath signal model development

The development and use of mathematical models of signals received through the multipath environmental of a TDRS-to-user spacecraft link and vice versa are discussed. The TDRS (tracking and data relay satellite) will be in synchronous orbit. The user spacecraft will be in a low altitude orbit between 200 and 4000 km

Part I - Application of ultra-stable oscillators to one-way ranging systems. Part II - Fluctuation spectra of ultra- stable oscillators - Measurement and estimation Final report

Application of ultrastable oscillators to one-way ranging systems - Measurement technique for determining phase fluctuation spectrum of highly stable oscillator

Special studies of AROD system concepts and designs

Signal processing techniques for range and range rate measurements in airborne range and orbit determinatio

Intermodulation distortion from receiver non-linear phase characteristics Final report

Computation of intermodulation distortion levels produced by telemetry system predetection filte

Simulation of the TDRS multipath environment

Design principles and implementation methods are discussed for simulating the propagation path between a tracking and data relay satellite and a mission spacecraft. The emphasis is on multipath and Doppler simulation but additive disturbances are also considered. The recommended form of the simulator is fed separately with the unmodulated carrier, the unmodulated subcarriers (or spread-spectrum components) and the data signals. The perturbations are also introduced separately; then successive modulation operations are performed. The simulator is segmented into elements that perform the various functions of direct and specular multipath, diffuse fading, Doppler shift and delay spread. Delay spreads are realized by discrete delays operating on baseband signals. Doppler simulation and ionospheric or diffuse multipath fading are applied to individual paths before or after modulation of the carrier by delayed baseband signals. Block diagrams are presented on how the different elements are combined to create a complete channel simulator

System for the measurement of oscillator instability

System for measuring phase and frequency fluctuations of high precision oscillator