User's Manual

1. Introduction
Description
The ASTRO Spectra compatible Vehicular Repeater System - Model 750 (VRS750) is a
mobile radio system component that provides on-site repeater capability between a
portable radio and a base station. 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.
Ordering Information
The VRS is a crossband repeater that operates on either UHF or VHF frequencies. The
repeater cannot be operated with a mobile radio operating in the same band as the VRS
unit.
The VRS RF platform is based on the HT750 synthesized transceiver. The VRS supports
one channel whose frequency and channel spacing can be programmed in the field. The
VRS remains a simplex repeater and as a result, the transmit frequency must be set equal
to the receive frequency. The VRS receives its programming information from the
ASTRO Spectra mobile at power-up. The ASTRO Spectra mobile supports the VRS
programming fields via ASTRO Customer Programming Software (CPS). For more
information, refer to “Programming,” Chapter ?.
The VRS is not compatible with ASTRO Spectra mobiles with the VSELP signaling
type.
When integrating a VRS with an ASTRO mobile with a Siren/PA, an additional interface
cable is needed (?). This cable allows the VRS to be connected to the Siren/PA. For more
information, refer to "Installation," Chapter 4.
When integrating a VRS with an ASTRO mobile with Dual Control heads, an additional
interface cable is needed (NKN6460A). This y-cable allows the VRS to be connected to
the ASTRO mobile with two control heads. For more information, refer to "Installation,"
Chapter 4.