To: JBruin who wrote (254 ) 12/29/1997 8:39:00 PM From: David G. Read Replies (1) | Respond to
Wireless Telecommunications 101 Can you or anyone who knows, explain the fundamentals with regard to the different types of communications standards, e.g., pcs, analog. What is the difference between Iridium's standard and that of Nextel? com Analog - The traditional method of modulating radio signals so that they can carry information. AM (amplitude modulation) and FM (frequency modulation) are the two most common methods of analog modulation. Analog modulation techniques have been around for more than 50 years and offer a proven, known method of using analog, but the switch to digital is already underway. Analog signals are not as clear as digital signals.Digital modulation - A method of encoding information for transmission that will eventually replace analog transmission. Digital modulation reduces voice to binary code -- the zeros and ones of computer language. At the receiving end, the information is reconverted. Digital transmission offers stronger reception, less static, greater call handling capacity, fewer dropped calls, improved call privacy, and the potential for additional voice and data service such as fax and computer data transmission. aulds-garner.com interdigital.com PCS - Personal Communications Service - A new generation of wireless-phone technology that introduces a range of features and services surpassing those available in analog-and digital-cellular phone systems. PCS provides the user with an all-in-one wireless phone, paging, messaging, and data service having a greatly improved battery-standby time. Within the U.S., the 1.9 GHz band has been allocated for PCS systems; the allocated spectrum is 120 MHz wide and is licensed as two 30 MHz segments for the 51 major trading areas, and three 10 MHz segments for the 493 basic trading areas. Global transmission with PCS presents some hurdles to overcome.webproforum.com ieee.org Mobile Satelites - a new generation of wireless technology that intends to provide global personal satellite based communications via handheld terminals, providing the user with an all-in-one wireless phone, paging, messaging, fax and data service to anywhere in the world . Iridium will be the first of its kind. GlobalStar will be the second, which is about 18 months behind Iridium. Iridium handsets will be sold for $2000-3000 US. The number of subscribers to this system is expected to be in the region of 1 million, which equates to $2-3 billion in handset sales. ee.surrey.ac.uk ddi.co.jp ee.surrey.ac.uk or ee.surrey.ac.uk or iridium.com
