ZETRON 748, Техническое руководство

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Operation
50 025-9368H
Call Clear Down
Once the call has been established, it is just like any other interconnect call, various control timers
are running and programmed disconnect sequences are now valid.. Clear down of the call can be
initiated by any of the normal methods, expiration of the Call limit or Mobile activity timers,
detection of 2
nd
dial tone or six cycles of busy tone or reception of mobile or telco disconnect codes.
Since two Model 748's are now handling the call, either one is capable of initiating call clear down,
and will send the telco disconnect code to the other.
The destination or called Model 748 handles the call just like any other phone originated
interconnect call. The originating or calling Model 748 handles the mobile activity timer differently
based on how the call was setup. If the Interconnect Gateway function of the repeater panel user
database was used, then the mobile activity reset value is twice the transmit hold time for the
originating tone/code. If short sign-on is used, then the normal mobile activity timer is used. If no
DTMF is available to the mobiles, then a shorter time out period would be desired.
System Setup
Multi-channel capability is required of the radios used in these systems, the question then becomes
are they DTMF capable. When using sub-audible for site selection, the number of channels required
goes up exponentially with sites. A simple two site system requires four channel radios, a three site
system requires nine channel radios. When using the short sign-on method of site selection, the
number of channels required is equal to the number of sites supported. For a simple two site system,
using sub-audible for site selection can work quite well. Three or more sites really need DTMF to
help simplify the operation, both for the system operator and the users.
In a typical system, you want incoming calls (those from other sites) to be received on the regular
dispatch channel. This allows all radios in the receiving user group to hear the incoming call and be
able to answer. You may also find that programming the equipment type to Talkback for incoming
calls, allows the originating mobile to “voice hail” out on the destination system, thus operating
more like a dispatch call.
In a typical system you will have more than one user group on it. For each user group, you will need
an interconnect user for each site you wish to support. One for receiving incoming calls (phone to
mobile), plus one for each of the other sites (mobile to phone). The user programming for originating
a gateway call is specific to both the function and site. This prevents you from using the same
interconnect user for more than one site and also from receiving incoming phone to mobile calls.
Once a system has been designed, a single Model 748 can be programmed with all the required
system and user data. This can then be downloaded and then uploaded or cloned into the other
Model 748’s on the system.
Four Site Example
This example has four sites to be linked together using the Interconnect Gateway feature of the
Model 748. We will be using Short sign-on with sub-audible validation for site selection. The field
units required to support this system are multi-channel( at least four channel), DTMF capable radios.
Each site is on a different RF channel. User groups are separated by sub-audible tone/code. Short
sign-on allows all user groups on the system to select or access the four sites in the same way.