BCD396XT multi-site trunking while traveling

[kolyur]

I'm a fairly new 396XT user and was hoping that someone could clarify a few things for me.

1. I listen to Ohio MARCS which is a multi-tower digital trunking system. If I'm traveling I need to be able to monitor multiple towers. I understand this can be done by either (a) creating multiple sites within the system and adding the corresponding control channel frequencies to each, or (b) putting all of the CC's for a group of towers into one site. From what I've read, (a) seems to be the preferred method, yes? I did some testing and it seems like putting all of the CC's into one site scans faster than setting them up individually, but I also read that this can cause the scanner to lock on to one tower and not switch when another comes into range. True?

2. What affects the amount of time it takes to scan through a system? I have a conventional system set up with 25 frequencies. Sometimes it takes about 1/4 second to scan through, but other times it hangs for up to 2 seconds before moving on (without locking on a frequency). I have the Hold Time for the system set to 0.

3. Is there a way to monitor or calculate the amount of time it should take to scan through a particular system? The specs say 100 channels/second, is that accurate? It would help to know this when planning systems and groups.

4. My understanding is that the difference between "ID Search" and "ID Scan" in a trunked system is simply that Search will locate *all* talkgroups with activity whereas Scan will just locate those that have been programmed in groups. It doesn't seem like ID Search mode increases the scan time, is that correct?

5. Freescan will only let me add 20 groups per system. This seems like a significant limitation for big systems like MARCS. Is the only workaround to create duplicate systems with the same sites but different groups?

I know these issues have been discussed in other threads but sometimes I have a hard time finding a clear answer. This forum has been a great resource, thanks for everyone's help.

 

[ofd8001]

1. Create separate sites for each tower location. You don't want to put all the CCs as one site. If you happen to be in an area that "hears" multiple sites, the scanner "listens" to the first active control channel it receives (per site) and disregards all others.

You should consider getting a compatible GPS device and connect it to your scanner. Using location based scanning (without getting into a lot of technical specifics), "turns on" sites that are close to your present location.

2 & 3. Scanning conventional systems and scanning trunked systems are two entirely different creatures. So comparing the time to scan a trunked system with scanning a conventional system is comparing apples to oranges.

4. You are correct with a slight addition. You can be ID Searching and if your scanner hits on a talkgroup you don't want to listen to, you can lock it out (temporarily or permanently). After locking-out talkgroups, they are by-passed as the ID Search continues.

5. As a new scanner user, it's pretty easy to confuse "systems", "sites", "groups" and "channels". A system can be programmed with up to 256 sites. Separate from these sites are groups. Groups would contain channels - in other words groups are clusters of channels. In a trunking system, channels are Talkgroup ID numbers and in a conventional system they are frequencies (noting that in conventional systems you do not have sites).

While you are limited to 20 groups (and this is a scanner limitation, not of the software you use to program the scanner), you can have up to 500 channels per trunked system. So if you divided this evenly by 20, that's 25 channels per group (but they don't have to be evenly divided some groups can be larger than others). For me I assign groups based on discipline, by that I mean I'll have a fire group, a police group, a statewide group, emergency management group.

If you do want to program the entire MARCS system (all I know about it is just now looking that the database reference), a couple of ways of doing this come to mind. One is to program by regions of the state with the sites and talkgroups from the region in a given system. Another is to duplicate systems but program by discipline (as in fire, state law enforcement, emergency management, etc.) Hopefully those more familiar with the MARCS system can offer better advice on this.

 

[ka3jjz]

Unless the database is incomplete, running in ID Search is really wasteful in terms of memory. Eventually as you lock out more items, eventually you will run afoul of the limit on how many items you can lock out. Running in ID Scan would, I suspect, be slightly faster and certainly more efficient. ID Search is fine when you are researching a system, but would be a royal pain if you are traveling a lot.

As to location based scanning - this article from our DMA FAQ explains it pretty well...

Location Based Scanning - The RadioReference Wiki

HTH...Mike

 

[jking54]

I've just recently began experimenting with straight up ID Scan on my BCD996XT with all of my trunked systems and it seems much better for me over ID search mode in terms of ridding the channels of unwanted stuff like road crews etc., useful for obvious warranted conditions but most of the time not so. But, now with my new GPS I'd imagine with ID Scan would be even more of an added benefit?

 

[jking54]

1. Create separate sites for each tower location. You don't want to put all the CCs as one site. If you happen to be in an area that "hears" multiple sites, the scanner "listens" to the first active control channel it receives (per site) and disregards all others.

You should consider getting a compatible GPS device and connect it to your scanner. Using location based scanning (without getting into a lot of technical specifics), "turns on" sites that are close to your present location.

...

So if I understand you correctly, if I have several groups who came in under a system/site sharing the same antenna, then it's best to split them all up in heir own separate sites/group?

 

[UPMan]

Channel groups and system sites are two different things and can have two completely different sets of coordinates. Channel groups are the comms used on the system and are typically centered on a town (or portion of a town). Sites are the radio antennas that channels groups use (but a channel could be carried on one or more sites simultaneously, or different sites at different times). Sites are usually centered on the physical location of the antenna.

 

[jking54]

Channel groups and system sites are two different things and can have two completely different sets of coordinates. Channel groups are the comms used on the system and are typically centered on a town (or portion of a town). Sites are the radio antennas that channels groups use (but a channel could be carried on one or more sites simultaneously, or different sites at different times). Sites are usually centered on the physical location of the antenna.

Hi UPMan, thanks for the response. Yes I know that they are different entities, channel groups and sites, but what I was attempting to find out is whether or not it would be more efficient for scanning or not missing much from either group if they were split up. I have a few sites with several groups and wondered if I'm missing more than I should if they were all together as such.

 

[UPMan]

It sounds like you are mixing/matching some terms. Sites don't have any groups (systems have channel groups). Not sure what you are proposing to split up (or what is all together, now).

 

[jking54]

It sounds like you are mixing/matching some terms. Sites don't have any groups (systems have channel groups). Not sure what you are proposing to split up (or what is all together, now).

Perhaps due to bit of a misunderstanding here, actually it's how I have them arranged for viewing(highlighted), where my Systems are first, then the site and all the channel groups are under that, all of which are trunked P25 Standard. I wasn't being clear enough so my apologies on that and say that I don't quite follow then what was said in post #2 above.

 

[UPMan]

There was a lot said in #2. Did you not understand any of it, or is there a particular part you need clarification on?

 

[jking54]

There was a lot said in #2. Did you not understand any of it, or is there a particular part you need clarification on?

What I quoted above in #5

 

[UPMan]

In light of the definition of the various terms, your question doesn't make sense. Sites and channel groups are independent. Channel groups are based on jurisdictional boundaries. Sites are based on antenna locations. One site could service multiple channel groups. One channel group could appear on multiple sites.

 

[jking54]

In light of the definition of the various terms, your question doesn't make sense. Sites and channel groups are independent. Channel groups are based on jurisdictional boundaries. Sites are based on antenna locations. One site could service multiple channel groups. One channel group could appear on multiple sites.

No worries, I'm new to scanning and not much of this makes sense to me right now either, sorry to have wasted your time.

 

[ofd8001]

There is a tremendous learning curve to scanning. First one has to get his arms around how trunking systems work generally, then trunking systems with multiple sites and how they are different from conventional systems.

Then the next phase is learning how the "new way" of programming scanners works. They are complicated.

Rest assured, however that most every scanner listener has started off with zero knowledge and we've come to learn these things over time.

That's the good thing about these message boards and those haunting these forums like to help. We are very fortunate to have the Uniden Product Manager (UPMan) who watches these things and wants us to get the most out of our scanners. He's been exceptionally helpful to me and others and his efforts are appreciated.

Please feel free to post questions you may have. There are several ways of explaining things and some times an alternate way may be more helpful than the original.