The Experts below are selected from a list of 34785 Experts worldwide ranked by ideXlab platform
T.e. Parker - One of the best experts on this subject based on the ideXlab platform.
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Earth Station errors in two-way time and frequency transfer
IEEE Transactions on Instrumentation and Measurement, 1997Co-Authors: F.g. Ascarrunz, Steven R. Jefferts, T.e. ParkerAbstract:We have investigated the Earth Station errors in two-way time transfer. A 3.7-m Earth Station and a very small aperture terminal Earth Station were used in these experiments along with a transponder located on a mountain about 10 km away. The temperature coefficient of the receive delay for the 3.7 m NIST Earth Station was (-150/spl plusmn/30) ps/K, and the temperature coefficient for the transmit delay was (-50/spl plusmn/10) ps/K. The overall temperature coefficient for the Earth Station was (100/spl plusmn/30) ps/K. Aside from environmental errors there are apparent changes in delay due to characteristics of the modulation/demodulation scheme. Apparent delay changes due to nonlinearity effects in the Earth Station were as high as 10 ns. The errors due to code dependence and third code interference were sometimes as high as 3 ns.
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Earth Station errors in two-way time transfer
Proceedings of 1996 IEEE International Frequency Control Symposium, 1Co-Authors: F.g. Ascarrunz, Steven R. Jefferts, T.e. ParkerAbstract:We have investigated the Earth Station errors in two-way time transfer. A 3.7 m Earth Station and a very small aperture terminal (VSAT) Earth Station were used in these experiments along with a transponder located on a mountain about 10 km away. The temperature coefficient of the receive (RX) delay for the 3.7 m NIST Earth Station was found to be -150 /spl plusmn/30 ps//spl deg/C and the temperature coefficient for the transmit (TX) delay was -50/spl plusmn/10 ps//spl deg/C. The overall temperature coefficient for the Earth Station was 100/spl plusmn/30 ps//spl deg/C. Aside from environmental errors there are apparent changes in delay due to characteristics of the modulation/demodulation scheme. Apparent delay changes due to non-linearity effects in the Earth Station were as high as 10 ns. The errors due to code dependence and third code interference were as high as 3 ns.
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Measurements of Earth-Station delay instabilities using a delay-calibration device
Proceedings of the 1999 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium (Cat. No.99CH363, 1Co-Authors: F.g. Ascarrunz, T.e. Parker, Steven R. JeffertsAbstract:Delay calibrators were used to measure delay instabilities in the two-way satellite time-and-frequency-transfer Earth Stations at NIST. Data from the calibrators suggests that the dominant source of Earth-Station instabilities is group delay errors due to coherent interference and not physical-delay changes. The delay the calibrators measure is correlated utilize instabilities in the Earth Stations but cannot always be used to improve the performance of the system because the correlation factor may be variable.
J. Miller - One of the best experts on this subject based on the ideXlab platform.
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Earth-Station engineering
Satellite Communication Systems, 1999Co-Authors: J. MillerAbstract:This Chapter has identified the major subsystems of a satellite communications Earth Station, has described some of the factors leading to the selection of particular items of equipment, discussed siting matters and interference problems, and looked at testing, acceptance and ongoing maintenance aspects. Although, out of necessity, the approach has been brief, it is hoped that this Chapter has given the reader an insight into some of the likely design challenges associated with Earth-Station engineering.
F.g. Ascarrunz - One of the best experts on this subject based on the ideXlab platform.
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Earth Station errors in two-way time and frequency transfer
IEEE Transactions on Instrumentation and Measurement, 1997Co-Authors: F.g. Ascarrunz, Steven R. Jefferts, T.e. ParkerAbstract:We have investigated the Earth Station errors in two-way time transfer. A 3.7-m Earth Station and a very small aperture terminal Earth Station were used in these experiments along with a transponder located on a mountain about 10 km away. The temperature coefficient of the receive delay for the 3.7 m NIST Earth Station was (-150/spl plusmn/30) ps/K, and the temperature coefficient for the transmit delay was (-50/spl plusmn/10) ps/K. The overall temperature coefficient for the Earth Station was (100/spl plusmn/30) ps/K. Aside from environmental errors there are apparent changes in delay due to characteristics of the modulation/demodulation scheme. Apparent delay changes due to nonlinearity effects in the Earth Station were as high as 10 ns. The errors due to code dependence and third code interference were sometimes as high as 3 ns.
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Earth Station errors in two-way time transfer
Proceedings of 1996 IEEE International Frequency Control Symposium, 1Co-Authors: F.g. Ascarrunz, Steven R. Jefferts, T.e. ParkerAbstract:We have investigated the Earth Station errors in two-way time transfer. A 3.7 m Earth Station and a very small aperture terminal (VSAT) Earth Station were used in these experiments along with a transponder located on a mountain about 10 km away. The temperature coefficient of the receive (RX) delay for the 3.7 m NIST Earth Station was found to be -150 /spl plusmn/30 ps//spl deg/C and the temperature coefficient for the transmit (TX) delay was -50/spl plusmn/10 ps//spl deg/C. The overall temperature coefficient for the Earth Station was 100/spl plusmn/30 ps//spl deg/C. Aside from environmental errors there are apparent changes in delay due to characteristics of the modulation/demodulation scheme. Apparent delay changes due to non-linearity effects in the Earth Station were as high as 10 ns. The errors due to code dependence and third code interference were as high as 3 ns.
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Measurements of Earth-Station delay instabilities using a delay-calibration device
Proceedings of the 1999 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium (Cat. No.99CH363, 1Co-Authors: F.g. Ascarrunz, T.e. Parker, Steven R. JeffertsAbstract:Delay calibrators were used to measure delay instabilities in the two-way satellite time-and-frequency-transfer Earth Stations at NIST. Data from the calibrators suggests that the dominant source of Earth-Station instabilities is group delay errors due to coherent interference and not physical-delay changes. The delay the calibrators measure is correlated utilize instabilities in the Earth Stations but cannot always be used to improve the performance of the system because the correlation factor may be variable.
Hitomi Murakami - One of the best experts on this subject based on the ideXlab platform.
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120 140 mbit s portable hdtv codec and its transmission performance in a field trial via intelsat satellite
Signal Processing-image Communication, 1992Co-Authors: Shuichi Matsumoto, Hitomi MurakamiAbstract:Abstract This paper describes a portable HDTV digital codec and its transmission performance obtained in a transpacific field trial via an INTELSAT satellite with a transportable small Earth Station. This portable codec is designed for transmitting HDTV programs including 4 channels of high quality sound via a 72 MHz bandwidth transponder in an INTELSAT satellite, or via an ISDN H 4 channel in an optical fiber submarine cable. In order to realize the portable hardware for practical applications, the codec employs bit-reduction techniques whose algorithms are extremely simple from the viewpoint of hardware construction but are effective in achieving a high coding picture quality. From the results obtained in the field trial, it is concluded that an end-to-end international digital transmission of HDTV programs, wherein HDTV programs can be directly transmitted from the place of an event to a theater, is commercially viable using the codec in conjunction with the small Earth Station.
Abbas Jamalipour - One of the best experts on this subject based on the ideXlab platform.
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an implementation of multichannel multi interface manet for fire engines and experiments with winds satellite mobile Earth Station
Wireless Communications and Networking Conference, 2016Co-Authors: Yasunori Owada, Norihiko Katayama, Byeongpyo Jeong, Kiyohiko Hattori, Kiyoshi Hamaguchiv, Masugi Inoue, Kenichi Takanashi, Masafumi Hosokawa, Abbas JamalipourAbstract:We propose a novel communication system for an emergency fire response team, which provides Internet service on the way to and in the disaster area. The system is composed of a multi-interface mobile ad-hoc network (MANET) router, a Global Positioning System (GPS) receiver, and two Wi-Fi interfaces with directional antennas, which can be easily attached to the roof of a vehicle. The front-side Wi-Fi interface of the vehicle is operated in the infrastructure mode, and the rear-side interface is operated in the access point mode. Different channels are assigned to each AP interface of the vehicles. Infrastructure-mode Wi-Fi interfaces automatically scan and connect to an appropriate AP interface and create MANET links. Some experiments using this wireless system with the WINDS satellite mobile Earth Station and nine fire engines were conducted in Ebetsu, Hokkaido. We measured the TCP throughput and confirmed that a throughput of more than 10 Mbps was able to be obtained by most of the node pairs. In addition, high-vision video streaming was able to be successfully transmitted to the streaming server on the Internet through MANET and satellite communication links while they were platooning.
