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iO1000 Detailed Service Manual - OVERVIEW
CHAPTER 1
OVERVIEW
INTRODUCTION
The iO1000
Detailed Service Manual
contains the information necessary to iden-
tify and fix problems in the iO1000 OEM Module. This unit is based on digital
technology and is designed to operate on integrated Digital-Enhanced Network
(iDEN) systems.
Service for the iO1000 unit is based on the substitution method: a faulty part is
replaced by a working one, providing quick service to the customer. For example,
if the battery is faulty, it is replaced. If the unit requires more complete testing or
service than is available at the basic level, it is sent to the field-level service facil-
ity, serviced, and returned to the iDEN Customer Care Center (ICC).
Note:
Before operating or testing this unit, please read the
Safety and General
Information
section in the front of this manual.
Digital Modulation Technology
The iO1000 is an 806-866 MHz unit that can operate in three modes:
dispatch
,
interconnect
, and
multi-service
. It uses two digital technologies: Quad 16QAM
and Time Division Multiple Access (TDMA).
Quadrature Amplitude Modulation (QAM)
is a modulation technique that trans-
mits information by altering the amplitude and phase of the radio frequency (RF)
signal. Data is converted into complex symbols, which alter the RF signal and
transmit the information. When the signal is received, the amplitude and phase are
converted back into symbols and then into the original data.
In 16QAM, each of the 16 possible combinations of four bits is converted into a
unique amplitude and phase. The traditional 25 kHz channel used for two-way
radios is split into four 16QAM signals (subcarriers) that are transmitted simulta-
neously. This technique can transmit 64 kbps in a single 25 kHz channel.
The signal spectrum of the Quad 16QAM is shown in Figure 1 on page 2.