Operations Manual

OPERATIONS 4-32
O&M of the MCC-545B PACKET DATA RADIO
12/2000
4.8.2.3 Automatic Master Selection
The MCC-545B has the ability to automatically select its Master based on an algorithm more
suited for LOS mobile networks. When a Remote has no online Master, it monitors all the other
units (Masters and Remotes) it can hear for a one minute period. All transmissions made by
those units are counted and the average detected RF level for the last two transmissions for each
unit is calculated. At the end of the one minute interval the Remote picks the best one from its
list to be its Master. The criteria for its choice are:
a) Count must be greater than or equal to SNP,NUP count.
b) Unit must have the highest detected RF level.
c) If several units have the same highest detected RF level, it will choose one with a different
ID than the previous Master.
d) For a Remote, only transmissions to a Master will be counted.
e) A Remote will prefer a BASE over a REPEATER and a REPEATER over another Remote.
The Remote chooses the best one, if there is one, clears all the other units out of its temporary
counting list and attempts to acquire that unit for the next SNP,NDOWN period. When no
successful exchange and acknowledgement have been made for the SNP,NDOWN period, the
choice process begins again.
The commands used are:
ID,NNNN,MM, AUTO, INIT
where NNNN is the Remote ID,
MM is the current Master,
AUTO is the mode option.
SNP,NUP,N
where N is the minimum number of counts per minute to be considered
SNP,NDOWN,D
where D is the maximum number of minutes to wait for a good exchange with current Master
before declaring it offline and starting to choose a new one.
4.8.3. Destination Considerations
Messages, position reports and data reports can be routed from any origin (Remote or Master) to
any other destination unit (Remote or Master). Messages can have multiple destination IDs
embedded in the report and position reports can have only a single destination ID embedded;
data reports cannot have any destination ID embedded. Moreover, the destination(s) can be
entered in the command for messages but position reports and data reports will look at the