Early Communication System (ECOMM) for ISS

The International Space Station (ISS) Early Communications System (ECOMM) was a Johnson Space Center (JSC) Avionic Systems Division (ASD) in-house developed communication system to provide early communications between the ISS and the Mission Control Center-Houston (MCC-H). This system allows for low rate commands (link rate of 6 kbps) to be transmitted through the Tracking and Data Relay Satellite System (TDRSS) from MCC-H to the ISS using TDRSS's S-band Single Access Forward (SSA/) link service. This system also allows for low rate telemetry (link rate of 20.48 kbps) to be transmitted from ISS to MCC-H through the TDRSS using TDRSS's S-band Single Access Return (SSAR) link service. In addition this system supports a JSC developed Onboard Communications Adapter (OCA) that allows for a two-way data exchange of 128 kbps between MCC-H and the ISS through TDRSS. This OCA data can be digital video/audio (two-way videoconference), and/or file transfers, and/or "white board". The key components of the system, the data formats used by the system to insure compatibility with the future ISS S-Band System, as well as how other vehicles may be able to use this system for their needs are discussed in this paper

Factors Affecting Resistance to Change: A Case Study of Two North Texas Police Departments

This study focuses on four common factors believed to affect resistance to change in public organizations. It contributes to existing literature by examining the effect of higher education and trust on the police officer's level of resistance to change and the effects of participation and communication on trust. 286 police officers from two north Texas towns responded to the survey. Regression analysis and bivariate correlations were used to determine the relationship between, resistance to change, and participation, trust, communication, information, and education and the relationship between trust and the other independent variable. The analysis failed to support previous research, which listed participation as the most important factor, but did support the concept that participation and communication improved trust

Space-to-Space Communications System

The Space-to-Space Communications System (SSCS) is an Ultra High Frequency (UHF) Time-Division-Multiple Access (TDMA) system that is designed, developed, and deployed by the NASA Johnson Space Center (JSC) to provide voice, commands, telemetry and data services in close proximity among three space elements: International Space Station (ISS), Space Shuttle Orbiter, and Extravehicular Mobility Units (EMU). The SSCS consists of a family of three radios which are, Space-to-Space Station Radio (SSSR), Space-to-Space Orbiter Radio (SSOR), and Space-to-Space Extravehicular Mobility Radio (SSER). The SSCS can support up to five such radios at a time. Each user has its own time slot within which to transmit voice and data. Continuous Phase Frequency Shift Keying (CPFSK) carrier modulation with a burst data rate of 695 kbps and a frequency deviation of 486.5 kHz is employed by the system. Reed-Solomon (R-S) coding is also adopted to ensure data quality. In this paper, the SSCS system requirements, operational scenario, detailed system architecture and parameters, link acquisition strategy, and link performance analysis will be presented and discusse

Factors Affecting Resistance to Change: A Case Study of Two North Texas Police Departments

This study focuses on four common factors believed to affect resistance to change in public organizations. It contributes to existing literature by examining the effect of higher education and trust on the police officer's level of resistance to change and the effects of participation and communication on trust. 286 police officers from two north Texas towns responded to the survey. Regression analysis and bivariate correlations were used to determine the relationship between, resistance to change, and participation, trust, communication, information, and education and the relationship between trust and the other independent variable. The analysis failed to support previous research, which listed participation as the most important factor, but did support the concept that participation and communication improved trust.