Parkes radio science system design and testing for Voyager Neptune encounter

The Radio Science System installed at Parkes, Australia for the Voyager Neptune encounter was specified to meet the same stringent requirements that were imposed upon the Deep Space Network Radio Science System. The system design and test methodology employed to meet these requirements at Parkes are described, and data showing the measured performance of the system are presented. The results indicate that the system operates with a comfortable margin on the requirements. There was a minor problem with frequency-dependent spurious signals which could not be fixed before the encounter. Test results characterizing these spurious signals are included

DSN radio science system design and testing for Voyager-Neptune encounter

The Deep Space Network (DSN) Radio Science System presently implemented within the Deep Space Network was designed to meet stringent requirements imposed by the demands of the Voyager-Neptune encounter and future missions. One of the initial parameters related to frequency stability is discussed. The requirement, specification, design, and methodology for measuring this parameter are described. A description of special instrumentation that was developed for the test measurements and initial test data resulting from the system tests performed at Canberra, Australia and Usuda, Japan are given

The Mars Observer Ka-band link experiment

The Ka-Band Link Experiment was the first demonstration of a deep-space communications link in the 32- to 35-GHz band (Ka-band). It was carried out using the Mars Observer spacecraft while the spacecraft was in the cruise phase of its mission and using a 34-meter beam-waveguide research and development antenna at the Goldstone complex of the DSN. The DSN has been investigating the performance benefits of a shift from X-band (8.4 GHz) to Ka-band (32 GHz) for deep-space communications. The fourfold increase in frequency is expected to offer a factor of 3 to 10 improvement (5 to 10 dB) in signal strength for a given spacecraft transmitter power and antenna size. Until recently, the expected benefits were based on performance studies, with an eye to implementing such a link, but theory was transformed to reality when a 33.7-GHz Ka-band signal was received from the spacecraft by DSS 13. This article describes the design and implementation of the Ka-Band Link Experiment from the spacecraft to the DSS-13 system, as well as results from the Ka-band telemetry demonstration, ranging demonstration, and long-term tracking experiment. Finally, a preliminary analysis of comparative X- and Ka-band tracking results is included. These results show a 4- to 7-dB advantage for Ka-band using the system at DSS 13, assuming such obstacles as antenna pointing loss and power conversion loss are overcome

The Impact of Cell Phone Texting During Aerobic Exercise on Measures of Cognition

International Journal of Exercise Science 12(5): 646-656, 2019. This study assessed the effect of cell phone texting during a 30-minute bout of cycle ergometer exercise on measures of cognition (i.e., reaction time and accuracy). Twenty-eight college students participated in two conditions (cell phone and no cell phone). Reaction time and accuracy were assessed pre- and post-exercise with the use of the Stroop test. Reaction time was significantly worse (p \u3c 0.001) in the cell phone condition from pre- (1003.75 ± 178.04 ms) to post-exercise (1124.46 ± 238.55 ms). Reaction time was significantly better (p \u3c 0.001) in the no cell phone condition from pre- (1107.71 ± 229.54 ms) to post-exercise (953.86 ± 177.42 ms). Accuracy was significantly worse (p = 0.01) in the cell phone condition from pre- (97.61 ± 2.32) to post-exercise (94.04 ± 7.88). Accuracy was significantly better (p \u3c 0.001) in the no cell phone condition from pre- (94.82 ± 4.42) to post-exercise (97.39 ± 2.42). In conclusion, using your cell phone for texting can interfere with the cognitive benefits associated with reaction time and accuracy that are developed from participating in aerobic exercise