Batboard

Hi all!

I have a few question about SmartZone.

We have received few Astro Sabers attached to Motorola trunking system (protocol type II, coverage type SmartZone). This system covers big city and contains 10 sites. Sites linked among themselves via wires. Each site have 1 invariable control channel and many voice channels.

Questions:

1. Astro Sabers currently programmed with one Trunking system and only one frequency in Control Channel list. But this Astro Sabers can work in any site! Yes! I have checked it by pressing Site Display/Search button. Transcever can be attached to site 1, site 3, site 5, or site 7 & etc.

How it's possible? But others 9 control channels are not present at the frequency list! How transceivers get to know about existence of others of 9 sites?.

'Smart' functions, like is Full Spectrum Control Channel Scan, Dynamic Regrouping are disabled.

2. By what principle Astro Saber chooses control channel? I have noticed that when I am near to a site (less than 0.5 mile to antenna farm!), transceiver often (but not always!) continues to work with the remote site (located more than 8-10 miles to antenna farm). It is strange. Why transceiver it is not switched to the nearest and much more powerful site? And why it is impossible to be switched to more powerful site by pressing Site Display/Search button?

It seems to me that it would be better to choose the most powerful site. But why AS does not do it?

Menu Preferred Sites contains only one line where None is selected.

P.S.
Excuse for silly questions. Reading of articles on RR's Wiki has not helped to get answers to them: (

1) You have to be careful with the word "site" as applied to a SmartNet system. You can have multiple sites all simulcasting on the same control channel, or you could have multiple sites each with their own control channel (but sharing the same SysID) (in which case you have a SmartZone system). For that reason, the term "site" can be ambiguous, and it is preferable to use the term "zone," where a zone is defined as a unique combination of SysID and control channel(s).

2) If your system is a SmartZone system, different zone should not share a common control channel (at least unless they are separated sufficiently to preclude coverage overlap under any circumstances). It follows that if your AS is programmed with only one control channel, it cannot be operating on a SmartZone system.

3) Once a SmartZone programmed subscriber has affiliated on a zone, it will not seek to change zones until the signal of the affiliated zone drops below a set of parameters programmed into the radio, one of which is signal strength. And so long as the zone you're affiliated on is reaching you with a sufficiently strong signal, the fact that some other zone might be closer is irrelevant to system performance.

In a SmartZone (SZ) system there are one or more sites. These sites make up a Zone. Depending on the release version of the system there can be a maximum of seven (7) Zones. A site can be made up of a single physical location that has RF channels, or a simulcast site that has a number of physical locations operating on the same RF channels. The simulcast group of subsites is considered a single site to the system. Each site, single or simulcast subsystem are connected to a single Zone. Within the Zone is a Zone controller. Management terminals connected to the Zone controller are used to manage the system. One of the abilities of the management software within the Zone is to program the Zone controller with information about each site. The zone controller is told which sites are adjacent to each other.

When a subscriber radio is first turned on, it looks in its control channel list for a valid control channel on one of the sites within the Zone. After it finds the control channel, it monitors that control channel constantly unless it has voice traffic. Each control channel, one at each site, sends data about the adjacent sites and what frequency the control channel is on at those adjacent sites. The subscriber radio gets this list and saves it in it's memory. The subscriber radio then makes quick switches to those other sites control channel frequencies and takes samples of the signal strength of those adjacent site control channels. If the signal strength is higher by a significant amount the subscriber radio will switch to that stronger site.

Therefore, as your radio moves about the Zone, some sites will become stronger and the one you are on gets weaker and your radio switches to stronger sites as it travels around. When you press the SITE button, you will see the site name and its relative signal strength indicator (RSSI). This RSSI number is what the level of the control channel is at the site you are on.

Once the the subscriber radio moves to another site, it gets new adjacent site information about whatever sites are nearby. The radio remembers those new sites and frequencies in order to determine again later on if it needs to switch again. This is why the radio really only needs on control channel frequency to get the process started. Normally, the subscriber radio would have all possible control channels of each site in the zone programmed into the radio. But is is not absolutely required.

I hope that helps,

Dennis