Motorola VRS750, Service Manual

Page: 13 / 104

1
Introduction
1
Description
The VRS750 Vehicular Repeater System is a mobile radio system
component that provides on-site repeater capability between a
portable radio and a base station (see Figure 1). The VRS gives the
portable user the equivalent range of a mobile radio with the flexibility
of a portable. The VRS is not an ASTRO-capable radio; instead, it is
designed to interface with an ASTRO Spectra
®
mobile radio. It can only
transmit and receive clear analog transmissions.
The VRS receives transmissions on the portable radio’s transmit
frequency with the proper access PL, and passes these portable signals
to the mobile radio. The mobile radio re-transmits the signals to the
base station on the mobile radio’s transmit frequency.
NOTE: These transmissions have the mobile’s ID, not the
portable’s.
Similarly, base station signals received by the mobile radio are sent to
the VRS and re-transmitted to the portable radio. The VRS does not
provide local repeater capability (received portable signals are not
repeated on the portable receive frequency).
The VRS-to-portable and portable-to-VRS communications are limited
to clear analog only. This is a simplex-only interface; the VRS cannot
receive and transmit simultaneously. The base station-to-mobile and
mobile-to-base communications protocol is not limited to analog
only. Rather, this interface is limited by the features and functions of
the ASTRO Spectra and the base.
Figure 1. VRS750 Vehicular Repeater System
SPEAKER
CONTROL HEAD
ASTRO MOBILE
VRS750
HKN6153A
MOBILE
MICROPHONE