System configuration by only system id

[Jay911]

With all due respect, the benefit, in that case, sounds very minimal. Scanners already do control channel only trunking. Telling it that it should only stop on systems which match the sysid entered doesn't have that much of a plus, IMO, to warrant its inclusion. You could do the same thing by doing a Control Channel Only search and hitting 'resume' every time you don't get the one you want.

There'd have to be a lot more functionality included in order to make this useful enough for most people.

 

[WayneH]

nonposter, are you aware that a system ID is not continually sent out over the control channel and to sample *every* transmission would take a long time? System IDs are sent every three seconds. There are some situations where the sysid can be acquired quicker but this feature is only useful for SmartZone systems. And if it misses the sysid then what? You have greater chances of remaining on the CC looking for it versus continuing to scan. This adds a hell of a lot of time. Are you going to devote an expensive scanner to this? Considering a feature like this is only good for travelling you'll probably never be in an area long enough to find what you want since the scanner will take so long to search.

From a manufacturer's perspective this isn't great for marketing or for R&D to figure out. And since it's easy enough to search and find new CCs with current technology this feature probably wouldn't last long on the table. It's not *that* helpful when you look at the technical side of it.

 

[nonposter]

nonposter, are you aware that a system ID is not continually sent out over the control channel and to sample *every* transmission would take a long time? System IDs are sent every three seconds.

Ok, let's do some quick calculations.

If the system id is sent every 3 seconds on each control channel, then the average amount of time to until the next control channel is sent when starting to monitor a control channel is 1.5 seconds.

I think I can "hear" 3 Motorola trunked systems from my house. For the sake of argument, let's double that.

Modern scanners can scan 100 frequencies per second. There are 920 channels for 800MHz Type II systems, and 479 channels for 900Mhz (according to the batlab page mentioned earlier). For simplicity, let's assume there are 1000 channels to search through, so 1000 frequencies. A modern scanner would require 10 seconds to search through all of these frequencies to find any with a carrier.

How many of those channels would have active carriers? I don't have a good guess. Let's say 100 channels have carriers.

How long would it take to determine if a channel with a carrier is a data channel (including control channels)? 0.1 seconds each? Probably less. The channels which are active and are control or data channels could be determined in 10 seconds.

If the scanner is in range of 6 systems, 6 channels are control channels. But, we wouldn't need to look through all of the channels. On average, the control channel for the system we want would be found after checking 3 of the channels. At 1.5 seconds each, that is only 4.5 seconds.

Adding it all up, that's 24.5 seconds, on average. Of course, the worst case scenario would have longer times.

Once a control channel is found for the system we want, it and the adjacent control channels (see earlier posts) could be stored in flash memory. The next time you turn your scanner on in while you are within range of any of the "last known" control channels, the scanner could be monitoring in a few seconds: if there are 4 adjacent sites, that's 5 channels total. The average time to find one of these sites is (2.5 channels * 1.5 seconds) 3.75 seconds. If you haven't moved, the scanner would start with the last known control channel used, so the time to re-verify the control channel would probably be around 1.5 seconds.

All of the above would happen with no user input, other than the band (800MHz) and system id being programmed into the scanner.


Does it take longer than 24.5 seconds to type in all of the control channel frequencies for a system in existing scanners?

 

[Jay911]

Does it take longer than 24.5 seconds to type in all of the control channel frequencies for a system in existing scanners?

To give you the benefit of the doubt, let's say that the scanner user is in a new, unfamiliar location, and hasn't programmed it via the computer (which is what I'd do 999 times out of 1000 - especially since the scanners these days have an insane amount of memory and can be programmed once before I leave my house).

How many control channels are you worried about entering? Not counting the "add new system" keypresses, all you have to do is key in one frequency and hit Enter. Maybe two or three if you have a system that rolls its CC every few hours. As others have said, there is no time gained with your plan - even if you luck out and hit the data packet containing the sysid every time as soon as you start scanning that frequency.

Couple that with the fact that, as mentioned previously, this has no benefit to any systems except Motorola 800/900 systems, and there's no point. Besides all this, the Motorola channel numbering has no bearing on this issue.

 

[nonposter]

...this has no benefit to any systems except Motorola 800/900 systems...

At home, I program my scanner with a certain system id for a system in my area. When I start scanning, the scanner finds the system. I know the system will be scanned when I travel to any other location which is covered by that system. (By entering only control channel frequencies, the only way I can verify that it will be scanned is if the frequency I programmed is an active control channel and if my scanner can hear that control channel.)


At a certain location, system A's site is using control channel frequency X, and a different system, system B, has a site using control channel frequency Y. At a different location, the situation is the opposite: system A's site is using control channel frequency Y, and system B's site is using control channel frequency X. I want to scan one talkgroup on each system, and the talkgroup ids are different. I don't believe there is a way I can program my scanner to scan both systems at both locations, without changing configuration when I travel between the two locations. If the scanner was programmed with each system's system id, it would be able to scan both systems at both locations.



For users who use a program to copy configuration from RR's database to their scanner, including control channel frequencies, there would be no difference from how it works today.

For users who don't use a program to copy configuration from RR's database to their scanner, they would be able to enter the system id instead of any control channels frequencies. It would be easier to enter system id, and there would be fewer opportunities for errors.

 

[bassmkenk2508]

...this has no benefit to any systems except Motorola 800/900 systems...

I disagree with your statement that there are no benefits to scanning by system id.

He said no benefit except for Motorola 800/900 systems.

You forgot what your quote said... :roll: