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The Space System
Published in Ron Burch, Resilient Space Systems Design: An Introduction, 2019
The ground segment consists of a satellite operations center (SOC) from which satellite operations are planned, managed, and executed. Sometimes a mission planning segment is depicted separately, but usually the SOC is the control point for the system, and particularly for the satellite constellation. The ground segment also includes terrestrial gateways that communicate directly with the satellites over RF communications links to send and receive data. Links that transmit data to the satellite are referred to as uplinks, while those used by the satellite to transmit data to the ground are called downlinks. These gateways must be in line-of-sight view of the satellites during these data transfers and are usually connected to the network segment for retransmission of the data to other locations. The gateway sites are often distinguished by large antennas, some of which must track moving satellites throughout the contact time. Some space systems, such as imaging systems, also include a separate data processing center to process received raw data prior to dissemination of processed imagery to users. These functions are usually considered a part of the ground segment, as are any additional ground-based data processing and data dissemination functions.
Mission Concept and Trade-Off Study
Published in Shen-En Qian, Hyperspectral Satellites and System Design, 2020
The ground segment provides the means for controlling and monitoring the space segment, planning image acquisitions, receiving image data, processing the image data into higher level products, and interacting with the user community.
Analysis of Amplitude Scintillation and Positioning Error of IRNSS/GPS/SBAS Receiver for Heavy Rainy Days
Published in IETE Journal of Research, 2023
Mitchell Prajapati, Abhishek Rawat, Divyash Kumbhani
India Regional Navigation Satellite System (IRNSS) has two main components: Space segment and Ground segment. IRNSS satellites send signals to ground receiver with the carrier frequency of 1.17 and 2.49 GHz. IRNSS provides standard positioning services to public and precise positioning to military applications [1]. The IRNSS/GPS/SBAS receiver receives signal in L1, L5 and S band. The diffraction due to ionospheric irregularities is variable in nature with different carrier frequencies; this may result in amplitude and phase scintillation. Scintillation occurs due to electron density variation in the ionosphere when signal passes through it. Amplitude scintillation degrades the amplitude of carrier to noise ratio and phase scintillation changes the phase of navigation signal. Degradation of signal can affect the performance of navigation receiver from precise positioning accuracy to loss of data. Ionospheric delay and positioning error are highly proportional to total electron count present in ionosphere. As the signal is affected by strong scintillation, the receiver will face the loss of lock with the satellite. The effect of scintillation is highly dependent on weather, geographical location, solar radiation and geomagnetic disturbances. So it is required to analyze the effect of scintillation at various geographical locations. Various researchers have investigated the effect of amplitude scintillation at low and high equatorial region, anomaly crest regions, and equatorial ionization anomaly region under various solar and magnetic activities, and weather conditions. Many researchers have studied GPS scintillation events at various locations, but a few have done it on IRNSS as it is a newly developed Indian satellite-based navigation system.
Smartphone-Based Telemedicine Supported by Pico-Satellite Constellation
Published in IETE Journal of Research, 2019
Omar Ben Bahri, Nissen Lazreg, Kamel Besbes
The ground segment consists of a ground station connected to the administrator server which encompasses a network of broadcasting service. The communication system of the ground station consists of the S-band for downlink at frequency equal to 2.2 GHz. After being received from the ground station, the data are distributed through the Internet. For low energy consumption, the uplink commands can be set to operate at a frequency of 145 MHz with 1200 kbps bit rate. The specifications of the downlink budgets are illustrated in Table 7.
A Brief Review on mm-Wave Antennas for 5G and Beyond Applications
Published in IETE Technical Review, 2023
Paikhomba Loktongbam, Debasish Pal, A. K. Bandyopadhyay, Chaitali Koley
The internet of things (IoT) applications are to be evolved into the Internet of Space Things (IoST), covering things on the ground and in the air and space [211]. The IoST may consist of a ground segment (network of ground stations, on-earth sensing devices, client premises) and a space segment [network of Space-station, satellites, CubeSats, Unmanned Aerial Vehicles (UAVs) and near-earth sensing devices].