User's Manual

14 68P80801H45-1 1/20/2002
Base Radio EBTS System Manual - Vol 2
QUAD Channel 900 MHz Base Radio Overview
QUAD Channel 900 MHz Base Radio Theory of Operation
The QUAD Channel 900 MHz BR operates with other site controllers and
equipment and must be properly terminated. The following description assumes
such a configuration. Figure 6 show an overall block diagram of the QUAD
Channel 900 MHz BR.
Power is applied to the DC Power inputs located on the QUAD Channel 900 MHz
BR backplane. The DC Power input is connected if -48 VDC or batteries are used
in the site.
Power is applied to the BR by setting the Power Supply power switch to the ON
position. Upon power-up, the QUAD Channel 900 MHz BR performs
self-diagnostic tests to ensure the integrity of the unit. These tests, which include
memory and Ethernet verification routines, primarily examine the EX / CNTL.
After completing self-diagnostic tests, the QUAD Channel 900 MHz BR reports
alarm conditions on any of its modules to the site controller via Ethernet. Alarm
conditions may also be verified locally. Local verification involves using the
service computer and the STATUS port located on the front of the QUAD Channel
900 MHz EX / CNTL.
The software resident in FLASH on the EX / CNTL registers the BR with the site
controller via Ethernet. After BR registration on initial power-up, the BR software
downloads via resident FLASH or Ethernet and executes from RAM. The
download includes operating parameters for the QUAD Channel 900 MHz BR.
These parameters allow the QUAD Channel 900 MHz BR to perform call
processing functions.
After software downloads to the BR via Ethernet, FLASH memory stores the
software object. Upon future power-ups, the software object in FLASH loads into
RAM for execution.
The BR operates in a TDMA (Time Division Multiple Access) mode. This mode,
combined with voice compression techniques, increases channel capacity by a
ratio of as much as six to one. TDMA divides both the receive and transmit
signals of the BR into six individual time slots. Each receive slot has a
corresponding transmit slot. This pair of slots comprises a logical RF channel.