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Green Microwave and Satellite Communication Systems
Published in Gurjit Kaur, Akanksha Srivastava, Green Communication Technologies for Future Networks, 2023
Divya Sisodiya, Yash Bahuguna, Akanksha Srivastava, Gurjit Kaur
A transponder is an electronically controlled automatic device that transmits a received signal at various receiving, monitoring, amplifying, and retransmitting frequencies. It is mainly used for wireless communication. The word “sender” consists of two words: transmitter and transponder. Satellite communication channels are also called receivers because each channel is a separate transceiver or repeater. The transponder is not a single unit. It is composed of the duplexer, bandpass filter, broadband receiver, power amplifier, De-Mux in and Mux out, as shown in Figure 13.6. The duplexer is used to allow simultaneous transmission and reception. The duplexer is a bidirectional microwave gate that allows to receive the carrier signal from the antenna and transmit the carrier signal to the antenna. A basic bandwidth of 500 MHz is provided at C-band frequencies in the input link frequency range of 5.925 to 6.425 GHz. To reduce noise and interference, these frequencies are routed via a broadband bandpass filter (BPF). After that, it moved to a broadband receiver to give all channels with common frequency down conversion.
Satellites
Published in Mohammad Razani, Information, Communication, and Space Technology, 2017
The function of satellite transponders is the same as that of a radio relay repeater—that is, receive transmission from the Earth and retransmit to the Earth after frequency translation and amplification. Satellite resources are shared among many Earth stations, with different categories of standard A, B, C, D, E, and F, and therefore, with different satellite requirements. Other than the bandwidth, the parameters for a given transponder are 1. Saturation flux density (dBW/m2)2. Receive G/T (dB/oK)3. Saturation EIRP (dBW)
Satellite orbital parameters and outline satellite communication principles
Published in L. Tetley, D. Calcutt, Understanding GMDSS, 2012
Obviously, a satellite requires power for its operation. This power is derived from solar cells placed strategically around the satellite which convert solar energy to electrical energy. Batteries allow power to be maintained when a satellite is in earth shadow, during which time solar energy cannot be absorbed. A stabilization system is fitted which keeps the satellite fixed in its required orbital position and inclination with respect to the earth. Corrections for longitudinal and inclinational drift can be made using thrusters. Although these corrections are required only infrequently, the thrusters use fuel to obtain the corrections and the amount of fuel that can be carried is one of the factors to be taken into account when satellite operational lifetime is predicted. Transponders receive the up-link signals, translate the frequency and, after amplification, retransmit the signal to the receiving earth station. Additionally, there is a Telemetry, Tracking and Command (TT&C) system which operates in parallel with the communications system via the transponder. TT&C is for the reception of commands from the satellite control earth station and for relaying information about the satellite to the earth station. Reception of a signal and its retransmission could be via a single antenna (although there are usually many antennae fitted to a satellite). A single antenna may have a global beam coverage or, by making the antenna more directive, the beam could give a smaller zone beam coverage, or still smaller spot beam coverage. The transponders, antennae and all associated electronics comprise what is called the communications payload.
Understanding Redundancy Requirements in the Design of Non-Serviceable Systems
Published in Engineering Management Journal, 2022
Alejandro Salado, Aditya U. Kulkarni
Given that incorporating redundancies in space system design is a costly and time-consuming exercise, a significant question is whether redundancy requirements positively affect the solution space even when a reliability target at EOL for the space system has already been specified. While there are multiple research works on statistical analysis and modeling of space system reliability (Castet & Saleh, 2009; Guo et al., 2014), to the best of our knowledge, only J. Saleh et al. (2005) and J. H. Saleh and Marais (2006) have previously explored a research problem similar to ours. In their work, J. Saleh et al. (2005) and J. H. Saleh and Marais (2006) analyzed the impact of different redundancy configurations for transponders on a communications satellite on the revenue generated by the satellite. The results of their model showed that redundant transponders often do not justify their costs on communications satellites. Furthermore, J. H. Saleh and Marais (2006) suggest that perhaps there are other drivers in space system design that motivate redundancy requirements.
Multiple-period planning of Internet Protocol-over-Elastic Optical Networks
Published in Journal of Information and Telecommunication, 2019
Sridhar Iyer, Shree Prakash Singh
In view of the aforementioned, the new paradigm of Elastic Optical Network (EON) technology has emerged for OTNs in which, (i) on the basis of requirement(s), wider channels are created by combining spectrum units (or frequency slots (FSs)) and (ii) the use of multiple subcarrier(s) provisions increased flexibility in capacity allocation to heterogeneous demands (Napoli et al., 2015). The EONs (i) resort to use of flexi-grid switches and tunable (or flexible) transponders (or bandwidth variable transponders (BVTs)) and (ii) increase network efficiency, reduce network cost, and enable a reconfigurable OTN (Jinno et al., 2009). Furthermore, a mix of EON technology with IP layer re-configurability can alleviate the notion of ‘pay-as-you-grow’ in which, installation, continuous re-optimization, and upgradate in short cycles, of only some equipment are ensured. However, this require its conduction to be accurately co-ordinated between IP and optical segments.
Comparison of Cost, Power Consumption, and Spectrum Utilization in Protected Fixed- and Flexi-Grid Optical Networks
Published in IETE Journal of Research, 2018
Sridhar Iyer, Shree Prakash Singh
The key elements used in EONs include the (1) bandwidth variable transponders (BVTs), (2) bandwidth variable–optical cross connects (BV-OXCs), and (3) elastic (or flexible) frequency grids. The BVTs allow many demand-serving options by making a (a) decision on the MF, the bit-rate, and/or the spectrum, and (b) choice, which provides an adequate distance reaching performance [6]. Hence, efficient MFs together with advanced transmission techniques, such as multi-carrier optical orthogonal frequency division multiplexing (O-OFDM), are utilized [7], and further, the transmitted signal bandwidth and/or the bit-rate adaptation is achieved by modulation-level adjustment or by sub-carrier(s) allocation [6]. The BV-OXCs permit the creation of an optical route through the network by switching the transmitted signals within their frequency bandwidth to the appropriate switch output ports [2,6]. As a result, ITU-T has had to update the G.694.1 recommendation by including the flexible (or elastic) wavelength-division-multiplexed (WDM) grid definition [8].