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Opensky Radio System Basics

radio system digital radio communication system tdma wireless communication

This tutorial covers the basics of the Opensky Radio System. It outlines the features of the Open Sky radio developed by Harris Corporation and explains how the system works.

What is Opensky Radio System?

The Opensky Radio System is a digital radio technology that supports both voice and data transmission on the same frequency channel using the TDMA (Time Division Multiple Access) technique. Voice and data are carried in different time slots.

It uses Voice over IP (VoIP) technology and operates in the 700 MHz, 800 MHz, or 900 MHz bands. This wireless radio communication system was originally developed by M/A Com Inc., which was later acquired by Tyco Electronics. The Tyco Electronics wireless system division (formerly known as M/A COM) was subsequently acquired by Harris Corporation.

Features of Open Sky Radio

The following table lists the key specifications of the Open Sky radio system:

SpecificationsOpensky Radio System
Radio Technology TypeDigital
Access TechniqueTDMA
Frequency of operation700/800/900 MHz
AMPS Band Frequency
Channel Bandwidth25KHz
Number of time slots/channel4
Aggregate Data rate19.2 Kbps

Working of Opensky Radio System

Opensky Radio System Image Alt: Opensky Radio System

Let’s understand the working of the Opensky Radio System as shown in Figure 1.

As shown, dedicated downlink (869 MHz to 894 MHz) and uplink (824 MHz to 849 MHz) bands are used, similar to the AMPS system.

  • In the Opensky Radio System, 25 Watt repeaters are installed on the cell sites.
  • All Opensky handsets or phones use a single frequency and any time slot out of four per channel to communicate with the repeater and establish a voice or data call with another Opensky handset.
  • Each Opensky handset uses a unique IP address for data communication within the network. Moreover, it uses SLIP/PPP protocols for establishing the connection needed for data applications.
  • Encryption is used for the data payload to provide secure communication.
  • Both voice and data calls can run simultaneously over the radio. When a voice call is received on the Opensky handset while a data call is in progress, the voice call will be answered without interrupting the ongoing data call.