Engineering topics

Tsang, C. S.

Publications and source records attributed to Tsang, C. S..

6 records

NASA NTRS1986

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.

Lindsey, W. C.↗

NASA NTRS1985

Shuttle Communications and Tracking Systems Modeling and TDRSS Link Simulations Studies

An analytical simulation package (LinCsim) which allows the analytical verification of data transmission performance through TDRSS satellites was modified. The work involved the modeling of the user transponder, TDRS, TDRS ground terminal, and link dynamics for forward and return links based on the TDRSS performance specifications (4) and the critical design reviews. The scope of this effort has recently been expanded to include the effects of radio frequency interference (RFI) on the bit error rate (BER) performance of the S-band return links. The RFI environment and the modified TDRSS satellite and ground station hardware are being modeled in accordance with their description in the applicable documents.

Chie, C. M.↗

NASA NTRS1983

User manual of the CATSS system (version 1.0) communication analysis tool for space station

The Communication Analysis Tool for the Space Station (CATSS) is a FORTRAN language software package capable of predicting the communications links performance for the Space Station (SS) communication and tracking (C & T) system. An interactive software package was currently developed to run on the DEC/VAX computers. The CATSS models and evaluates the various C & T links of the SS, which includes the modulation schemes such as Binary-Phase-Shift-Keying (BPSK), BPSK with Direct Sequence Spread Spectrum (PN/BPSK), and M-ary Frequency-Shift-Keying with Frequency Hopping (FH/MFSK). Optical Space Communication link is also included. CATSS is a C & T system engineering tool used to predict and analyze the system performance for different link environment. Identification of system weaknesses is achieved through evaluation of performance with varying system parameters. System tradeoff for different values of system parameters are made based on the performance prediction.

Tsang, C. S.↗

NASA NTRS1983

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.

Lindsey, W. C.↗

NASA NTRS1983

Orbiter global positioning system design and Ku-band problem investigations, exhibit B, revision 1

The shuttle Ku-band Costas loop lock detector output signal appears to vary about the lock detection threshold (the lock detect flag is on and off) shortly after the carrier acquisition starts. Real time computer simulation was performed to obtain the signal output from the low pass filter of the lock detector. Based on this simulation, it appears that the oscillation of in-lock and out-lock is related to tracking process and is not caused by the sweep acquisition algorithm.

Lindsey, W. C.↗

NASA NTRS1981

The effects of transmitter/receiver clock time base instability on coherent communication system performance

The purpose of this paper is to present a model and associated analysis of the deleterious effects which both transmitter and receiver data clock time-base instability have on bit error probability. The types of time-base instability modeled and analyzed include bit jitter (epoch jitter), bit jitter rate (time interval jitter) and data asymmetry. The bit error probability is determined as a function of the statistical characteristics of the time-base instability, the data transition density, the signal-to-noise ratio in the bit rate bandwidth and the mechanizations of both the data bit detector and bit synchronizer. Numerical results are provided.

Chie, C. M.↗