To: Maurice Winn who wrote (29748 ) 8/7/2020 8:41:34 PM From: pcstel 1 RecommendationRecommended By Maurice Winn
Read Replies (1) | Respond to of 29986 Ahhh!! The good ole' days Maurice.....gildertech.com "[B]eyond the bold and ingenious concept (Russ Daggatt of Teledesic calls Iridium “the real pioneer of LEOs”), the system suffers from technical flaws. Were it not for Globalstar, perhaps these flaws would not have become evident until after the 66 birds were aloft. A far simpler and cheaper solution, Globalstar uses 48 satellites with no links between them. Each functions as a “bent pipe” transponder, receiving signals from a phone on the ground and passing them back to any gateway within the satellite’s 1,500-mile-wide footprint, linked to locally available telephone networks… Globalstar has capital costs (at $1.8 billion) onehalf Iridium’s, circuit costs one-third Iridium’s, and terminal costs (at $750 each) one-fourth Iridium’s. With no intelligence in space, Globalstar relies entirely on the advance of intelligent phones and portable computer devices on the ground; it is the Ethernet of satellite architectures. Costing one-half as much as Iridium, it will handle nearly 20 times more calls. The advantages of Globalstar stem only partly from its avoidance of complex intersatellite links. Originating several years before spread-spectrum technology was thoroughly tested for cellular phones, Iridium employs time division multiple access (TDMA), an obsolescent system that requires exclusive command of spectrum but offers far less capacity than code division multiple access, [which uses all the assigned spectrum for every call]. Iridium could fly only if it offered radically superior performance or capacity. But TDMA dooms it to generally inferior performance and capacity." In the end.. Iridiums Intersatellite Links are what defined it's success.. And so it goes, PCSTEL