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Wireless Personal Communications: A Perspective
Published in Jerry D. Gibson, The Communications Handbook, 2018
Similar comparisons can be made between PHS advanced cordless/low-tier PCS phones and advanced cellular/high-tier PCS pocketphones. New lithium batteries have permitted increased talk time in pock-etphones. Digital control/paging channels facilitate significantly extended standby time. Advances in solid-state circuits have reduced the size and weight of cellular pocketphone electronics so that they are almost insignificant compared to the battery required for the high power transmitter and complex digital signal processing. However, even with all these changes, there is still a very significant weight and talk time benefit in the low complexity PHS handsets compared to the most advanced cellular/high-tier PCS handsets. Picking typical minimum size and weight handsets for both technologies results in the following comparisons.
P
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
personal communications network (PCN) a telecommunications network designed to provide services to a person rather than a geographic location. The network may comprise a range of different technologies from end to end and contains within it intelligence to enable the communication to be directed to the appropriate terminal or device carried with the person. personal communications services (PCS) a mobile telephone service with an essential urban and suburban coverage characterized by low cost pocket terminals, communications at a price comparable to a cable telephone, and distribution of the services and products to the general public. This definition is independent of the technology used. PCS is the proposed next generation of wireless network services, providing voice communication services similar to today's cellular services, only with smaller cells, lower power, and cheaper rates. personal digital cellular (PDC) one type of digital cellular phone system. PDC is 800 MHz/ 1.5 GHz band, FDD, TDMA system, and it handles 1/4p shift QPSK modulated signal with 32 kbit/s. This cellular system was developed and operated in Japan. personal handy phone system (PHS) a digital microcell system designed in Japan that operates in the 1.9 GHz band. PHS provides cordless telephone or telepoint (q.v.) services similar to other
A study on transformation of multi-purpose dams into pumped storage hydroelectric power plants by using GIS model
Published in International Journal of Green Energy, 2021
Yıldırım Bayazıt, Recep Bakış, Cengiz Koç
PHS has become more preferred today because it provides advantages in terms of energy storage, the security of supply, system stability, as well as minimization of costs. As of 2018, 96% of 176 GW energy storage systems in the world consists of PHS systems. It is known that China has a PHS capacity of 32 GW, and Japan 28 GW, USA 22 GW, respectively; while in Europe, the PHS capacities consist of Spain with 8 GW, Italy 7.5 GW, Germany 6.5 GW, respectively (REN21 2019). Deane, Ó Gallachóir, and McKeogh (2010) reviewed the proposed developments in Europe, Japan, and the US by reviewing existing dams with newly installed power potentials of over 7,000 MW and new PHSs. In the study, it was reported that the majority of the transformation projects of existing dams into PHS are located in Europe, and the investment costs of these projects vary significantly. Similar to many examples around the world, initial investment costs and adverse environmental impacts can be reduced by using existing reservoirs into PHS projects. If the existing reservoir is a Hydroelectric Power Plant (HEPP), then it can be converted into a PHS scheme with a penstock and an upper reservoir at a reasonable cost in a convenient location nearby. However, if the existing reservoir does not belong to a HEPP, then an entirely new pumping and turbine installation, as well as the penstock and the second reservoir, will have to be added. This will cause the costs to grow. For this reason, it has been observed that the transformation projects are concentrated on the conversion of the existing HEPP to PHS systems. It should be noted that many of the existing dams, which are operated for other purposes such as flood, drinking, and potable water also have hydroelectric energy potential. Bakış (2006) conducted a study on the opportunities for generating electricity from multipurpose dams in 2006. In this study, it was determined that the dams which do not produce energy in their current form have energy production potential. However, many parameters need to be taken into account in the transformation of dam reservoirs operated for different purposes apart from HEPP. For example, during the conversion process of an irrigation dam to PHS, the amount of water taken for irrigation from the reservoir, as well as hydrological factors should be taken into consideration. For operating the PHS of a reservoir that serves more than one purpose, the reservoir volume must be operated optimally. In this study, only the criteria such as topographic and land use were taken into consideration, while transforming an existing reservoir into PHS. It is thought that this study can contribute to the optimum operation of the reservoir volume in future studies.