Site/talk groups relationship

[gcopter1]

New to Whistler, recent TRX-1 owner. Tweaking my scanner to get the most performance, I'm realizing something.

With Uniden, I make a favorite list that has the site I need for the talk groups I want to monitor off from that favorite list.

In Whistler, I import the system I want to monitor, which has 7 sites, but, I only need the one site where all the talk groups I want to monitor, are.

However, when I look into my TRX-1 Programming System, I go to trunked radio systems; trunked site info; site details, highlight my desired site and then I click on the talk group details, I find that no matter what site I highlight, the talk groups are all the same across.

Sure, not all of these talkgroups belong to one site in particular, I have tg's for police, fire and local government, but, how does the scanner knows what site to use for a particular talk group?

Another reason I ask this is because I'm concerned that the scanner might be wasting time looking for activity in the wrong site, thus slowing down the scan.

Of the current 7 sites, I've locked out all but two, the site used for local government talk groups and police.

Normally, my scanner would be on listening only to police. How do I ensure the scanner is not trying to look for those talk groups in the local government site?

 

[Ubbe]

The TRX-1 scans all frequencies in all sites for TG activity and will waste time if you only need to monitor one site.

Then you have to create another system exclusive for that site, or if you never want to use those other sites you could delete them.

/Ubbe

 

[troymail]

New to Whistler, recent TRX-1 owner. Tweaking my scanner to get the most performance, I'm realizing something.

With Uniden, I make a favorite list that has the site I need for the talk groups I want to monitor off from that favorite list.

In Whistler, I import the system I want to monitor, which has 7 sites, but, I only need the one site where all the talk groups I want to monitor, are.

However, when I look into my TRX-1 Programming System, I go to trunked radio systems; trunked site info; site details, highlight my desired site and then I click on the talk group details, I find that no matter what site I highlight, the talk groups are all the same across.

Sure, not all of these talkgroups belong to one site in particular, I have tg's for police, fire and local government, but, how does the scanner knows what site to use for a particular talk group?

Another reason I ask this is because I'm concerned that the scanner might be wasting time looking for activity in the wrong site, thus slowing down the scan.

Of the current 7 sites, I've locked out all but two, the site used for local government talk groups and police.

Normally, my scanner would be on listening only to police. How do I ensure the scanner is not trying to look for those talk groups in the local government site?

You didn't advise which system you are trying to monitor nor the type of Uniden radio you're talking about.

I'm going to assume this system and a Uniden 436/536 for this discussion.

When you import a trunked system with either the TRX-1 or a Uniden 436/536, the entire system - all sites, frequencies, and talkgroups are imported into the configuration with their respective programming software.

If desired, Whistler's EZ Scan software will allow you to select and import only the site(s) and groups of talkgroups that you want. By default, it will just import everything.

Once you copy the programming to the radio(s), there is really only one difference in the way each radio scans the system. The Whistler will look for, select, and stay on a site control channel that meets the decode threshold values. As long as the signal is solid and stable, it won't check other sites for control channels or activity. The Uniden x36 (and probably others) will just attempt to scan across all of the programmed sites for a control channel and activity.

In either case, without any custom programming or other action taken by the user, all of the imported talkgroups will be checked during scanning.

Without detailed knowledge of the whole system (very few people have this for any system), you cannot really know what (if any) talkgroups are limited to any given site. It is possible that the system designers and admins have some talkgroups limited to less than all system sites but you should probably assume that the talkgroups you want to hear are on all sites.

For sites - what typically (but not always) is import is which site or sites are in range for you current location. With some exceptions, typically one or two sites will be close to you and in range and those should be the sites you monitor. But rarely are two different user's situations the same.

Once your radio is monitoring the control channel on any given site, the only thing about programmed talkgroups that will slow down scanning would be the radio stopping on an active talkgroup that you don't care about. In those cases, you can just lockout those talkgroups when they pop up while scanning (you can always unlock them again later).

For the TRX, I generally follow a couple of standard practices for programming to allow total control over which site(s) I want to monitor:

• for multi-site systems, import the system and all talkgroups with all talkgroups assigned to a single scanlist
  
• import only the control channel frequencies (optional)
  
• include talkgroup and radio ID wildcards
  
• if there are talkgroups you do not want to monitor, lock them out in the programming software
  
• lockout all but one site for that programming
  
• duplicate the system, lockout a different site in the duplicated copy, and assign all of the talkgroups to a different scanlist
  
• repeat the duplication step until you have a copy of the system in a different scanlist for each site.

There are lots of variations for how you program any given system into your scanner. For example, you might split your system/site talkgroup programming above even further such that for each site, you have a scanlist for various groups of users (i.e. fire/EMS, law, public works, etc.). For some of my programming, I've even split fire/ems even further such the dispatch, "routine" response, fireground, admin, etc. are all in separate scanlists. This way, I can enable, for example, only fireground talkgroups and the radio wil be quiet until a major response (structure fire, rescue, etc.) is dispatched ... and I almost always have law enforcement in separate scanlists and disabled until I want them on.

Bottom line is that you have to know the system and ultimately plan how you want to control what you are listening to at any given time. My programming has evolved over many years while the day-to-day system(s) I listen to haven't changed much if at all in a very long time.

The TRX-1 scans all frequencies in all sites for TG activity and will waste time if you only need to monitor one site.
/Ubbe

This is not really correct. For P25 systems such as Miami-Dade, the radio will search for an acceptable control channel frequency and as long as it is stable, the scanner will only monitor that frequency/control channel for active programmed/unlocked talkgroups. It will switch to the assigned voice frequency for the active talkgroup and then return to the previous known control channel frequency.

 

[wa8pyr]

The TRX-1 scans all frequencies in all sites for TG activity and will waste time if you only need to monitor one site.

This is not really correct. For P25 systems such as Miami-Dade, the radio will search for an acceptable control channel frequency and as long as it is stable, the scanner will only monitor that frequency/control channel for active programmed/unlocked talkgroups. It will switch to the assigned voice frequency for the active talkgroup and then return to the previous known control channel frequency.

True, and it's pretty annoying behavior. GRE models like the PSR500 had the capability to check all control channels in a scan pass; why GRE did away with that capability in the PSR800-type scanners (which has carried down to it's descendants) is a head-scratcher.

For that reason, I generally import the desired system with all sites and talkgroups in the area I want to monitor, get my scan lists set up, then create copies of that system, each one named for a specific county. Each system has all sites locked out except the highest-profile or busiest site for that county. Treating each site as a different system means I hear a lot more stuff more reliably.

Kind of annoying to have to waste memory space like that, though.

 

[gcopter1]

I'm going to assume this system and a Uniden 436/536 for this discussion.

Correct about that.

I received the radio this past Tuesday. As I read thru the forums, every now and then, I would find mention of assigning a site to a scan list (???) Surprised me since I have not seen this in the programming software.But it got me thinking; maybe the reason why my radio takes so long to hear any activity is because it is going thru all the sites trying to lock on to a control channel.

As for tg's living in more than one site, yes, this has been discussed in the group. But it is generally recommended to just program the known one site they're usually assigned to.

Thanks for your reply, very informative.

 

[troymail]

Correct about that.

I received the radio this past Tuesday. As I read thru the forums, every now and then, I would find mention of assigning a site to a scan list (???) Surprised me since I have not seen this in the programming software.But it got me thinking; maybe the reason why my radio takes so long to hear any activity is because it is going thru all the sites trying to lock on to a control channel.

As for tg's living in more than one site, yes, this has been discussed in the group. But it is generally recommended to just program the known one site they're usually assigned to.

Thanks for your reply, very informative.

You don't necessarily "see" this in the programming software because it's something you can do but not something there as an explicit function or "easy button" that allows or enables it. The software will let you do lots of things but you need to get creative... at least the software allows for that creativity.

How many sites you program depends on your usage - location, etc. If you're stationary and can only receive a single site from your location, then of course it probably makes sense to only program a single site. It would be different if you are able to readily receive more than one site from your location and/or travel with the radio to other locations (site footprints).

As far as the time it takes for the radio to find a site, etc - most systems these days are simulcast in one form or another - or a mixed of simulcast sites and standalone (the latter of which are less trouble receiving). P25 simulcast sites can be difficult to receive on scanners - regardless of vendor.

Even with only one simulcast site programmed, I have to find a specific spot to place my radio(s) to receive it. It could be a matter of inches.

Many times, it's even easier for me to receive a more remote site than the site "footprint" that I am current located in because of the effects of simulcast.

In an effort to overcome that issue, for me, it takes a combination of all of:

• a single site in the programming,
• programming only the active control channel frequency (not all CCs - just the active one), and
• find that "right spot" to place my radio on a desk, etc.

Even with these steps, it's still a challenge.

 

[Ubbe]

The TRX-1 scans all frequencies in all sites for TG activity and will waste time if you only need to monitor one site.

Then you have to create another system exclusive for that site, or if you never want to use those other sites you could delete them.

/Ubbe

The assumption where wrong but at least the solutions where correct

/Ubbe

 

[rwier]

deleted

 

[troymail]

The assumption where wrong but at least the solutions where correct

/Ubbe

True.

With any programming, you'll want to always try to optimize as much as possible. Otherwise, potentially, the radio will spend (waste) lots of time rotating through stuff you don't need or care about.

Most subscriber (police officer, firefighter, etc.) radios are parked on only a single channel/talkgroup at any given time. Scanners will allow you to scan the entire spectrum and/or database (sort of) if you allow it. However, in doing so, the radio will stop on all kinds of garbage and you'll likely never hear anything you are really interested in hearing by doing so.

 

[gcopter1]

Couldn't reply earlier, as I was at work. In my line of work, I drive a bus on a fixed route. So that, I can actually get a feel for, where my system of interest, fails...at least in the scanner world.

Prior to me getting the TRX-1, I've always used Uniden scanners. With the advent of P25 and LSM, reading here and there, found out that commercial equipment could "solve" the simulcast blues.

At one point, I bought off e-Bay, a Harris radio. That was all and good except that, I did not own the programming software. Any changes to suit my listening needs, involved sending the radio to the vendor who would accommodate my requests...for a fee.

Enter the Unication G4 pager.

Not scanner, a pager, but oh how wonderful it was that I could at the end of the day, plug it into my pc and make changes with the included programming software. I could program a site, talk groups, and be in blissful LSM free, scanning.

As ownership time with the Unication went by, I started noticing that, as wonderful and better it was at handling LSM, there where still times when transmissions were unintelligible. Not necessarily because of the Unication, but because their own radios and or system lay out, sucked.

Additionally, the Unication, because it is designed as a pager, and not a scanner, left me wanting more control, like, holding on to a talk group, or skipping a talk group blathering encrypted stuff, adding a delay, etc.

Sold the Unication and got the Whistler. After 35 years of exclusively using Uniden, I thought I would never understand their programming architecture, I tried sometime ago downloading the software and couldn't understand how it actually worked. Owning the Unication gave me a bit more perspective and helped me understand better Whistler's way of programming a scanner.

Today at work, thinking about my experience and reading here and there, got the idea that maybe, adding another site to scan, might help with my perceived lack of activity. On the one hand I was worried this extra sites, would slow my scan, but, hey, why should I worry, I'm a hobbyist, I've got to try!

Thanks to the simplicity of the Whistler (yes, even after 35 years of dealing with Unidens and the damned QK system, I now find/think Whistler is more simple to use), I was able to browse objects, find the locked out sites, unlock and put them back into the scan.

Is too early for me yet to decide whether this helped or not. However, as I left work, I noticed the scanner stopping on a site that I would never ever dreamed of it been used for my talk group of interest!

I'm now at home, fired up my 536 searching ID's in those "unused" sites, launched Unitrunker as well looking for activity there.

I want to understand something about simulcast.

Each site is one radio tower, correct? So that, if a talk group is carried in more than one site, this is the cause for LSM, one signal arriving at the same time to the radio, from different places. Can one site have multiple towers?

Thanks to; troymail, Ubbe, wa8pyr, for your comments and time responding. I'm sure to have more questions later on...

 

[Ubbe]

Simulcast means that a TG are always simultaniously broadcasted from all sites.

As I understand a frequency license can be very expensive in US, not so much in europe as an annual license here are something like $50, so this is pretty much an isolated US phenomen.

As you have noticed it can work well for most of the time but the solution is costly, maybe there are Motorola licenses involved or complicated hardware, that makes it unrealistic to implement in a scanner. As the towers transmit on the same frequency it will generate doppler problems when you travel towards a site, that will increase the RF freqcuency, and moving from a site that will decrease the frequency, and create herrendous heterodyne interferencies. Also when stationary it can cancel out signals totally when they are received out of phase from two towers.

When you write multiple towers I guess you mean transmitters/channels and yes there must be many frequencies/channels at one site, otherwise the capacity of the system would be very limited. So it is very dependent on the type of usage you expect from the users in the system, large coverage, few TGs used at the same time, if it will be wortwhile to use simulcast with its system problems.

/Ubbe

 

[KR3LC]

...
Each site is one radio tower, correct? So that, if a talk group is carried in more than one site, this is the cause for LSM, one signal arriving at the same time to the radio, from different places. Can one site have multiple towers?...

Each "site" can have more than one tower. In my state's statewide system my county is listed as a site but in fact it has maybe 6 transmitter sites set up for simulcast as one site. Many other counties on this system are arranged in a similar manner.

 

[troymail]

Ok - this is long but it's important to understand how these systems work, why you see (or don't see) what you are seeing, and reasons why in some cases, you have little control over some aspects of the hobby.

First, "site" and "simulcast" are overloaded terms and must be considered based on the context of the use of the terms.

It is true that a single tower/transmitter is sometimes refer to as a "site". However, for most of the conversations here - particularly when talking about simulcast distortion, this use should probably be ignored (for now).

In the context of these systems, a "site" represents an area of coverage. This could be a building, town, or entire county.

A "site" might be (but does not have to be) a single tower/transmitter. I believe Motorola sometimes refers to these standalone sites/towers as an "ASR".

A "simulcast site" means that there are multiple (at least two but probably more) towers/transmitters that provide coverage for a given area of coverage. That is - when a frequency is active in that "site", all of the towers that are part of that "site" transmit at the same time.

A system may consist of a combination of all of these. That is, the system could be a single tower/transmitter "site", one large "simulcast site", or a combination of both types.

"Simulcast" isn't a new thing - analog systems have done that for many years. The problem is that digital processing in the radios is less tolerant of the variations in the amount of time it takes for the signal to arrive at the radio from each transmitting tower in the "site".

The context of the term "simulcast" must also be considered in the context of the way it is being used. As Ubbe said, "simulcast" is also sometimes used to mean that a particularly talkgroup is transmitted over all geographic simulcast sites/areas. While it is true that some talkgroups are "simulcast" over all "sites" ("simulcast site" or standalone site), you cannot assume they are operate in that fashion.

Now, many analog systems simulcast as one big simulcast site across the intended area of coverage. For various reasons, newer systems can't always operate in the same way and must be broken down into multiple simulcast sites to provide the same coverage.

In my area, some counties did install systems with a single large P25 simulcast site while others split their systems into two sites (for example, one site called "north" and the other site called "south").

My state system consists of a combination of "simulcast sites" and standalone ASR sites. In many cases, the "simulcast sites" roughly equate to an area of coverage for each county. Some of these county coverage simulcast sites are augmented by a few standalone sites as well - typically near the edges of the county and state. I am not an expert but my guess as to why this is done is to fill a gap coverage area and/or limit the range of that particular signal since it's near the state boundaries.

As far as talkgroups and when they are active in any given "site" (simulcast or standalone)....

Obviously, if you only have a single simulcast site that covers the entire intended area of coverage, all talkgroups are going to be transmitted on every tower/transmitter in the simulcast site.

If the system consists of more than one site (simulcast or standalone), knowing which "site" will carry any given talkgroup is far less clear. Every system is going to be different. It is possible that for a system, all talkgroups might be carried over all sites. However, this is somewhat inefficient in terms of frequency usage.

The easiest way to understand this is an example in a state system.

Some counties are using the state system to provide their jurisdiction with public safety (and other) radio services. Under normal conditions, there is no reason for the system to carry this activity over every "site" over the entire state. Therefore, these talkgroups are likely limited (under normal operating conditions) to "sites" in that county and perhaps sites in the immediate area.

There might also be talkgroups that are regional which may be typically "allowed" over a larger group of sites or maybe the entire system. However, in at least some cases (probably many), that does not mean they will nor will they be active 100% of the time. In many cases, for the talkgroup to be active on a site that it is "allowed" to be used, a subscriber radio might need to be actively both in (affiliated with) that given "site" and switched to that talkgroup before you'll hear it on the system. Keep in mind that under these circumstances, the opposite could occur as well -- the talkgroup might be active on that site one minute and then suddenly go silent the next... the user may have switched to a different talkgroup and/or left that "site" footprint and entered an adjacent site.

These comments are only based on my experiences and I like everyone else as always learning. Every system is going to be different. I recently learned that there are some multi-site systems that are essentially overalys - that is - in one case, the system's two sites cover the entire city - one might be used for public safety and the other used for city services. Interestingly, some talkgroups are carried on both "sites" while most talkgroups remain on their respective "site".

As I said, I am always learning so I welcome input from others that helps to make these concepts more clear and/or offer other perspectives or examples.

 

[Ubbe]

Simulcast sites that share the same frequencies must broadcast all calls on all sites.

As there is such a big impact on the ratio between maximum number of active talk groups relative to number of transmit sites compared to a standard multi frequency system you'll need to keep the number of TGs down. By using seperate cells of sites that have non simulcast frequencies and place the sites where it's only a local need like in a small city with mostly local users, and have only some TG's common with the simulcast system, you can somewhat compensate for the capacity loss in a pure simulcast system.

The system designer must be skilled at his work to make the right decisions in presales or it will backfire and the supplier needs to take the system back and/or pay huge fines for a system that doesn't work.

/Ubbe

 

[gcopter1]

A lot to digest. Thanks to all for clearing up my lack of knowledge.


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