the decision, as I recall it, was based on the fact that there's virtually no benefit to knowing whether a frequency is a "primary" or "secondary" CC.
A "fact" that isn't true. If I'm planning on doing some mobile analysis of a large SmartZone system, I'll program all of the unique control channel frequencies (into a conventional bank/system) and label them according to their usage; for example:
141.705 "141.705 23 8a 27a 38a"
...
142.590 "142.59 8 27 38 23a"
If I'm monitoring zone 8 and I can't RX the control channel on 142.59, I immediately know that something is up because the site isn't using its normal primary control channel.
Or if I'm just stepping through the channels to see what's in RX range from a given hilltop, 99.999% of the time the display tells me right away that I'm monitoring zone 8 when I stop on 142.59, because this system rarely uses its alternate control channels. It's a good thing I made my Fleetnet maps before this ill-advised choice was made.
As used in my area and in my experience, and evidently likely in Lindsay's view as well, alternate CCs are ones that cycle along with the "main" CC on a regular basis.
A poor definition IMO. A PCC is the RF channel pair on a SmartZone/OmniLink site that is
currently handling control channel duties. An ACC is an RF channel pair on a SmartZone/OmniLink site that has been programmed to handle control channel duties
and is currently capable of handling CC duties (e.g. isn't disabled/malfunctioning), but is
currently not carrying CC traffic. Cycling or not is immaterial.
On the SmartZone system you're most familiar with, all programmed control channels get equal time in the spotlight (PCC duty), so they should appear in the database in red. Red means that all of the control channels are essentially equals and if you don't program them all, you will lose the control channel on a regular basis.
On many other SmartZone systems, one channel is almost always the PCC while (typically) one other channel is almost always the ACC. When interference (RF signal but no ISWs) is detected on the PCC input, a zone will switch PCC and ACC channels until the interference goes away:
6:24:17 Neighbour zone #3 - North; PCC = 629 (866.7375 / PCN2)
6:24:17 Features: Digital and Analog voice, Wide area trunking
6:25:18 Neighbour zone #3 - North; PCC = 649 (867.2375 / PCN1)
6:25:18 Features: Digital and Analog voice, Wide area trunking
After one minute, the system reevaluated the noise problem and since it had abated, channel 1 was reinstated as the PCC and channel 2 went back to its normal ACC state.
Looky here:
http://home.ica.net/~phoenix/wap/Fleetnet/Fleetnet Zone 1.JPG
The King and Cayuga sites use the same two frequencies as control channels, but the preferred PCCs use different frequencies, as do the ACCs. If they didn't, those two sites would frequently be using the same RF channel as their PCC and any mobiles on the high ground north of King could (and would!) cause interference on Cayuga's PCC. An affiliation by a King unit would be made simultaneously on both sites - the zone controller would just love that.
By using Cayuga's preferred PCC frequency as King's normal ACC, transmissions by King units on Cayuga's PCC are kept to an absolute minimum (since King will use its ACC for voice comms only when all other channels are busy)
Those
preferred PCC and ACC frequencies should be identified with red and blue tags respectively; it shows that the system uses preferred PCCs rather than just rotating them. The distinction is very handy when a user happens to pick up a faint distant control channel on a scanner that doesn't display zone numbers (like a 246T) - when he scans the database listing for that system, the red entries are the likely candidates. With everything using blue, he has no idea which ones are ACCs and therefore likely not the zone he heard. This is not progress.
You're going to need to have these CCs in your programming all the time, for when the control channel DOES change to those frequencies.
That's not the point being debated here.
In my experience, the average site has 3 control channel frequencies that it rotates through (on a system which has a rotating CC).
For SmartZone systems, that seems to be the minority these days. If you look in the database at the large (and small) SmartZone systems in Ontario, Ohio, etc.,etc. you'll see that generally, each zone uses a single preferred primary control channel plus a single alternate. Oh wait, you can't - they're all blue now. So much for doing your own survey/analysis on how SmartZone systems are configured these days. Bad move...