Service manual

CHANNEL RECEIVER VOTER MODULE (cRVM)
6-2
March 2000
Part No. 001-3139-502
6.4 RSSI
The RVM evaluates the RSSI levels from the dif-
ferent receiver Sites and selects the receiver with the
best RSSI level. If the RVM is a Slave RVM (sRVM)
it creates a Status Message and passes on the RDM
with the best RSSI level. This message is sent to the
Channel RVM (cRVM). A cRVM is capable of han-
dling up to 7-sRVMs and the cRVM option is switch
selectable (see 6-5). The cRVM evaluates the RSSI
levels from the different receiver Sites and selects the
receiver with the best RSSI level. This level is then
evaluated with the RSSI levels received from sRVMs.
The cRVM creates and sends a Receive Call Order
with the best receiver to the Multi-Net Logic Module
(MLM) via a separate 9600 baud or 2400 baud
RS-232 line depending on the setting of S5, section 6
(see Table 6-1). The RVM passes the best selected
RDM audio to the MLM.
When the receiver with the best RSSI level is
from a sRVM, the cRVM sends a System Order to this
sRVM. The System Order contains the necessary
information to connect the audio properly.
The time to receive the information from the
different RDMs, decode the data, vote for the best
RDM and pass the information to the MLM is less
than 120 milliseconds.
The RVM continues to evaluate the updated RSSI
levels received. The cRVM selects a better RDM if
there is an RDM that has a better RSSI level than the
one selected.
6.5 PRIORITY OF SITES
The RVM can be programmed from the SMM to
give a priority to each of the RDMs connected to it.
The priority is a two-level priority, normal (0) or low
(1), which is written to EEPROM address 0. The
upper 4-bits are unused.
Assuming a mobile transmits and the call is
received by two Sites with the same RSSI value, if one
Site has a low priority and the other a normal priority,
the RVM chooses the normal priority for the call.
6.5.1 PRIORITY PROGRAMMING
To program the priority of the Sites, go into the
SMM under Manual Device Control (F2). In the Man-
ual Device Control menu select the Receiver Voter
Control (F6). In the Receiver Voter Control menu
select RVM Memory Management (F1). Select write
mode and go to EEPROM location. Enter location “0”
and the hex (0xh) value of the priority byte. The prior-
ity byte consists of 8-bits with only the lower four bits
being used. See Figure 6-2
.
Figure 6-2 PRIORITY BYTE CONFIGURATION
6.6 SWITCH SETTINGS
Refer to the RVM board alignment points dia-
gram (Figure 6-4) and cRVM board alignment points
diagram (Figure 6-5) for the location of switches and
sections.
NOTE: See Appendix A to D for frequencies and Figure
6-3 for an example of switch settings for 800 MHz
Channel 100.
Figure 6-3 CHANNEL 100 SWITCH SETTINGS
1
O
N
2
3
4
5
6
7
8
4
O
N
3
2
1
4
O
N
3
2
1
S6
S7
S
5