Meteor Communications Corporation MCC-545C, Operation And Maintenance, Page: 46 / 88

OPERATIONS 4-10
MCC-545C PACKET DATA RADIO
12/2000
IMPORTANT
The MCC-545C limits the usable frequency range to a 2 MHz bandwidth. If frequencies are to
be changed outside this bandwidth then hardware modifications must also be made to the MCC-
545C.
If the synthesizer is unable to establish phase-lock when the SYNTH,ON command is entered,
the MCC-545C will respond UNLOCKED to the request and turn off the TX key. It will try
once a minute thereafter to establish phase-lock. If it fails, the message Synthesizer unlocked
will be displayed; if it succeeds, the MCC-545C will respond LOCKED and turn on the TX key.
4.2.9 Defining Data Relays
The ambient noise conditions at a remote station site may sometimes be excessive and a poor
communication path to the Master Station will result particularly if the remote station is
operating in a meteor burst mode. To overcome this problem, another MCC-545C may be
placed in a nearby quiet location and used as relay station between the MCC-545C at the noisy
site and its master station. When used as a relay, the MCC-545C will concentrate the data
reports it receives from one or more neighboring remote sites and forwards the data to the Master
Station.
When used in the relay mode,, the MCC-545C must be defined as a Master Station. The relay
will then receive MCC-550C sensor data GROUP reports (see MCC-550C Operations Manual),
repackage them and forward them to the Master Station. A relay can handle a total of sixteen
GROUP reports. These reports can be in any combination; i.e., four groups from each of four
Remote units, one group from each of sixteen Remote units or any combination in between.
Substitution tables must be established in both the relay unit and also at the Master Station to
manage the relay function.
When a designated GROUP report is received at the relay, it will substitute its own ID and group
number in the report as defined in its substitution table and forward the data to a MCC-520B
Master Station using the MCC-550C RF format rather than the standard MCC-545C message
format. When the relayed data is received at the MCC-520B it reconstructs the original data
report based on its own substitution table and route the report as required.
The following command is used to define the entries in the substitution table for a relay unit:
SUBST,relay_id,relay_group,remote_id,remote_group
where: relay_id is the relay unit's ID
relay_group is the data group report number at the relay
remote_id is the originating Remote unit's ID
remote_group is the data group report number at the originating Remote unit