Itronix Duo-Touch, Начало работы

Страница: 43 / 106

PC Card Radios
Your Duo-Touch supports several PC Card radios:

CDMA 1xEV-DO/1xRTT (850/1900Mhz)

GSM / GPRS (900/1800Mhz and 1900Mhz)
See the PC Card Radio manufacturer for more information on using each radio.
Read About CDMA
CDMA is a digital cellular technology that enables multiple users to share the same radio spectrum at
the same time without compromising quality or security. It does this by encoding each conversation
with a unique digital code called Pseudo-Random Code Sequence (PRCS). It then breaks up the
conversation and spreads it over many frequencies. The conversation is reassembled on the end using
the PRCS. This spread-spectrum technique requires less power and enables greater capacity than
analog radios. It also enables each call to be secure and free from interference.
Along with excellent voice support, CDMA offers three types of data services:

SMS sends, receives and acknowledges short text messages similar to a two-way pager.

Circuit-switched data enables dial-up modem connections over the cellular network at speeds
up to 14.4 kbps.

Packet-switched data provides Internet Protocol connectivity at speeds up to 153 kbps.
Read About GSM / GPRS
Global System for Mobile Communications (GSM) is a digital cellular technology that uses Time
Division Multiple Access (TDMA) where up to eight simultaneous calls can coexist on the same radio
frequency. GSM is a globally accepted standard that gives mobile users quality, secure voice and data
transmission worldwide. Along with voice support, GSM provides data support including Circuit
Switched Data and Short Message Service (SMS).
General Packet Radio Service (GPRS) adds value to the GSM network by providing high-speed
wireless Internet and data communication using instant connections. The user can send and receive
data immediately without dial-up modem connections and at much greater speeds than available with
traditional GSM networks. GPRS uses packet switching technology where the data is broken up into
smaller, related
“
packets
”
before transmitting and reassembling the content at the other end. This
means radio resources are only used when actually transmitting and receiving, freeing bandwidth for
more users.