SmarTrunk Systems, Inc. - Exploring the ST-510

When a call request arrives at a SmarTrunk II controller, a short data packet will be sent from the controller's RS-232 data port to the ST-422 board which serves as the switch gate for that controller. Immediately, this packet is processed by the ST-310 which decodes all information such as subscriber number, required service, etc. Once the subscriber ID is decoded, the program will access the main database looking for the subscriber profile and checking if the service request is valid for that particular subscriber.

If the requested service was a mobile-to-mobile call, the system software will search for the profile and status of the called party, checking if the party is busy or free and if this type of call is valid for the called party. If so, the ST-310 will send a new data packet to each site in the network where the called party is authorized to roam.

At this moment, one SmarTrunk II controller in each of those sites will look for the acknowledgment signal from the called party. If the called party is out of range or his radio is turned off, the caller party will be disconnected.

If the called party is within range, the ST-310 opens an audio path from the original controller (calling party) to the second controller (called party) in a process which requires no more than one-half second beyond the normal SmarTrunk II signaling time. If the called party answers, the conversation takes place as normal. If the called party does not answer within a programmed time, the calling party will be disconnected.

When either party ends the call, all resources are set free and the call information is reported to the call record account memory.

In smaller networks, it is often possible to have a single ST-310 Firmware-based Multisite Switch support multiple repeater sites. In this example of a ten channel system, the ST-310 and the SmarTrunk controllers are all located at Site B, with the remote repeaters at Sites A and C connected only by audio links (i.e., no data link is required). Different roaming areas may be defined which correspond to the different repeater sites.

For many applications, this may be the most economical scenario because only one ST-310 switch is required to support the entire network. However, there must be a separate audio link for each repeater at the remote site(s).

This service allows customers to locate any subscriber in the entire network simply by dialing the subscriber's number. For this searching process, the system will use only one free channel in each roaming area, and only the two channels supporting the call (one at each site) will remain in use until the call ends. The entire searching process requires only a half second more than the standard SmarTrunk II signaling time.

The definition of the roaming areas and the associated subscriber profiles will be automatically edited using the comprehensive Configuration software included with the system.

In some applications it may be necessary to place one or more channels in a shadow area to obtain wider RF coverage. In order for all controllers to be connected to the network, it is necessary to place a link between each channel and the ST-310.

One of the ways to cover a remote area is to leave the SmarTrunk controller at the primary site and place a remote repeater at the remote high-site.

In this case, all the signaling between the repeater and the controller will be carried by a link. The SmarTrunk controller remains close to the switch, so the audio and data connection will be only wires.

In this application, the Rx-Tx delay in the radio link must be less than100 mSec.

In another case, the repeater and the controller are located at the remote high-site, but audio and data is carried by a link to the main ST-510 switch. In this case, a data and audio link must be used for each channel, which may increase the cost of the linking equipment.