E F Johnson Company 2425770 Benutzerhandbuch

9-2 

Viking Portable 600 Radio Operating Manual

For the radio to access data service on a trunking system, it must be a valid user on the 
system and it must be affiliated to an RF site. Once this is accomplished, the radio must 
request data services from the trunked system through the process of context activation; a 
data registration of the radio with the system. Context activation is initiated from the radio. 
In an EFJohnson radio, context activation is automatically initiated when the user selects a 
P25 trunking system with either data registration enabled or OTAR enabled. During a 
context activation, the radio attempts to access a packet data channel (PDCH) at the site 
and send it its request for data services. If the context activation is successful, the radio 
will receive a response containing a IP address. This IP address will be used by the radio 
as a source IP address for all inbound data messages sent, and is used by the host 
application as the destination IP address for all outbound data messages. If for some 
reason the context activation fails, the radio will not be allowed to use data services on the 
trunked system. If a PPP link is established between the portable computer and radio 
without the radio context activated, any data transmitted by the computer to the radio is 
ignored.