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By Iven Simon

Cellular Digital Packet Data (CDPD) systems was one of the previous advanced wireless data transmission technology. Generally used as a tool for business, law enforcement communications and operations. But after the introduction of GPRS Technology on the mobile networking, all the hopes around CDPD technology diminished. Today this protocol is only exist as a memory.

About CDPD

CDPD is a specification for supporting wireless access to the Internet and other public packet-switched networks. Data transmitted on the CDPD systems travel several times faster than data send using analog networks. CDPD is an open specification that adheres to the layered structure of the Open Systems Interconnection (OSI) model. CDPD supports both the Internet's Connectionless Network Protocol (CLNP).


  • 19.2 kbps raw data transfer rate
  • Full duplex transceiver
  • 600 mW transmit power
  • Integrated TCP/IP protocol stack
  • Proven technology
  • Compact size
  • Rugged aluminum case
  • LEDs show status of CDPD operation
  • Mounting brackets
This features are very low rated on today. But belive me this was one of the most top rated on its time.

Application Interfaces

Standard interfaces include:

  • AT command serial character streams (uses embedded TCP/IP stack)
  • Host TCP/IP stack communicates with Raven using SLIP
  • Windows 95/98/NT Dial-Up Networking communicates with Raven using PPP
In addition, several protocol conversions (Modbus, Opto22, BSAP) have been implemented to allow hosts to communicate with RTUs over CDPD without modifying the host or remote software.

Working of CDPD
CDPD network implements a technique called channel hopping. The way this works is that when a CDPD mobile data unit desires to initiate data transmission, it will check for availability of a cellular channel. Once an available channel is located, the data link is established. As long as the assigned cellular channel is not needed for voice communications, the mobile data unit can continue to transmit data packet bursts on it.

To know more about CDPD technology, Visit: Here

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