Service manual

1-1
March 2000
Part No. 001-3139-502
INTRODUCTION
SECTION 1 INTRODUCTION
1.1 DESCRIPTION
The Voter System is an additional feature of the
Multi-Net System that allows receiver voting. The
voter system is used in Wide Area systems that require
simultaneous RF coverage over an area not capable of
coverage by a single repeater site. The Voter System
is also used to assist the RF coverage of a system
using portables where a single receiver cannot cover
the area, but a single transmitter site is sufficient for
outgoing coverage.
1.2 MAIN COMPONENTS
The Voter System consists of at least one or more
of the following modules. See Figures 1-1 and 1-3 for
a Local Site and Figures 1-2 and 1-4 for a Remote Site
and Figure 1-6 for a 5-channel voter system block
diagram.
1.2.1 RECEIVER DECODER MODULE
See Section 2 (8000/8900) or Section 3 (2008/2009).
The 800 or 900 MHz Receiver Decoder Module
(RDM) is the Receiver and Interface board. The
RDM decodes the subaudible data and four levels of
Received Signal Strength Indication (RSSI) plus the
condition of the squelch line, open or closed, from the
receiver. In the Remote site information is then
passed from the RDM, to the RMM, to the Local Site
CDM and then to the RVM. In the Local Site, the
RDMs are hard wired to the RVM.
The Multi-Net System is capable of handling 30
channels and the Voter System is capable of handling
32 voted receiver sites, the maximum number of
RDMs is 960
.
1.2.2 RECEIVER MULTIPLEXER MODULE
The Receive Multiplexer Module (RMM), in the
Remote Site, receives RSSI data from multiple RDMs
and multiplexes the information onto a single line to
be transmitted to a CDM at the Local Site.
Each RMM is capable of handling 10 RDMs,
with 3 RMMs required per 30 channel site. With 3
RMMs per site (maximum) and 32 voted receiver
sites, the maximum number of RMMs is 3 x 32 = 96
(see Section 4
).
1.2.3 CENTRAL DE-MULTIPLEXER MODULE
The Central De-Multiplexer Module (CDM), in
the Local Site, receives the multiplexed data from the
Remote Site RMM or directly from the RDM at the
Local Site and de-multiplexes the information to the
appropriate line to send to the RVMs (see Section 5
).
A CDM is connected to each Remote Site RMM,
therefore, 96 CDMs are the maximum number for a
Voter System. A CDM is not required for the Local
Site RDMs, these are hard wired to the RVM.
1.2.4 CHANNEL RECEIVER VOTER MODULE
The Channel Receiver Voter Module (cRVM), at
the Local Site, receives audio directly from the RDMs
at both the Local and the Remote Sites. The cRVM
receives the RSSI level directly from the Local Site
RDMs and through the CDMs for Remote Sites. The
cRVM compares the different sites and selects the
audio from RDM with the best RSSI value. The
cRVM connects the selected audio to the Repeater
(see Section 6)
.
Each cRVM can handle the audio from 4-RDMs
and the RSSI level information from 1-Local RDM
and 3-CDMs (or 4-CDMs). There can be 32 possible
Voter Sites; divide this by 4 and 8 is the maximum
number of RVMs required (1-cRVM and 7-slave
RVMs) per channel. For a 30 channel system with 32
Voter Sites, the maximum number of RVMs required
is 240 (30-cRVMs and 210-slave RVMs).
As stated above, a cRVM can have 4 audio/data
inputs (channels). If a fifth site is added, a slave RVM
is added to each cRVM to accommodate the fifth site.