Motorola VRS750, Service Manual

Page: 31 / 104

19
VRS Operation
3
General
The VRS is a crossband repeater that repeats either UHF or VHF
portable transmissions though a VHF, UHF, or 800 MHz ASTRO
mobile. The repeater cannot be operated with a mobile radio operating
in the same band as the VRS unit. In multiple-VRS sites, the VRS uses
a priority algorithm to prevent other VRS units from repeating. In this
mode, only the highest priority VRS will serve multiple portable users.
This prevents interference problems associated with multiple VRS
units in proximity to one another.
Control Unit
The VRS may be enabled/disabled from the ASTRO mobile radio’s
remote-mounted W4, W5, W7, or W9 control head (see Figure 17).
The VRS button may occupy any of the indicator button positions.
Field programming determines the exact position. The VRS requires an
ASTRO radio with a remote-mount control head.
When the VRS is turned on, the indicator illuminates and, after
transmitting the Single Tone burst, the words “
VRS BOTH ” (indicating
the In-Car Monitor mode) will be displayed momentarily. The
indicator remains on for as long as the VRS is on.
When the VRS unit is activated, it transmits Single Tone on the
portable frequency, and assumes the priority (active) repeater state.
The Single Tone frequency is fixed at 847.5 Hz. For proper operation,
all VRS units to be used in the same system must be programmed with
Figure 17. Typical ASTRO Control Head with VRS
Dir
MPL VRS
Siren
XMIT BUSY
DIM
Wail Yelp Hi-Lo
Mon ExRad
Rcl Sql Del
Pri
Non
Pri
Mode Vol Sel Home
1 2 3
4 5 6
7 8 9
* 0 #
MODE ROCKER
HOME BUTTON
Astro
PA