Motorola VRS750, Service Manual, Page: 52 / 104

40
Non-Priority VRS
Rules
A priority VRS is placed into non-priority mode when one of the
following occurs:
1. It receives a Single Tone burst at the fixed frequency of 847.5 Hz.
2. During a base-to-portable repeat, it receives a VRS/portable
frequency RF signal without proper PL during the PPI.
When a VRS goes from priority to non-priority, the internal delay state
changes from 0 to 1. Upon subsequent reception of Single Tone bursts
(that is, other VRS units activate in the same coverage area), the non-
priority unit will increase delay states up to a maximum of 7. While in
non-priority, the following occur:
Portable-to-Base Non-Priority Operation
1. Upon reception of a portable frequency RF signal with proper PL,
the VRS will determine if the mobile of another VRS system is
repeating the signal.
2. For the prioritization routine to function, all of the mobiles with
a VRS must be able to receive other mobile transmissions, either
directly (TX=RX), or on a trunked system (TX
≠
RX), or through a
base repeater (TX
≠
RX) in conventional modes with the <Base
Repeater> feature enabled. For conventional non-repeater
dispatch systems (TX
≠
RX), the Mobile Detector must be enabled
for the prioritization routine to function properly.
3. The VRS will determine if the mobile of another VRS system is
repeating the portable signal by steering the mobile to the mode
corresponding to the received PL. If, within one delay state
(at least 600 ms for conventional, at least 900 ms for <Base
Repeater>, and at least 1.5 seconds for trunking), the mobile in
the non-priority VRS system does not receive the repeated signal,
it will countdown from the current delay state.
4. Upon reaching delay state 0, the non-priority VRS will become
the priority VRS and start repeating. The maximum delay for a
non-priority VRS to countdown into priority is 4.2 seconds for
conventional, 6.3 seconds for <Base Repeater>, and 10.5 seconds
for trunking.
5. If the VRS does detect another VRS system repeating within the
delay state, it will stop the countdown process and stay non-
priority.
Base-to-Portable Non-Priority Operation
1. Upon reception of a repeatable base signal, the non-priority VRS
will monitor for a VRS-to-portable transmission from another VRS
system (that is, a signal on the portable frequency without proper
VRS access PL).
2. If, within one delay state, the VRS does not receive the repeated
signal, it will countdown from the current delay state.