SDS100/SDS200: Feature Request: Find best site, utilizing adjacent site resource, Motorola Trunked P25

[nokoa3116]

While monitoring a large P25 Phase 2 Trunked system while driving, it is difficult to find the appropriate site in range for the system. The system I am currently monitoring has not been fully discovered. As the Uniden device moves between site coverage constant site searching is needed.

Motorola radios have a feature, from my little understanding of it, it finds the best preprogrammed sites by measuring their signal strength. As the radio moves around and the site signal strength weakens, the radio utilizes the adjacent site resource, which provides the channels with some nearby sites. The radio then checks those sites' signal strength to find the best site, and switches to it. This allows the user to continue having access to the system. While a scanner is different, as it cannot affiliate with the system, some talkgroups may not be available in all sites. However I still believe that having this feature will be helpful for all large Motorola P25 trunked systems.

Currently, I select the site I know for the area that I am in, and hold it, but as I leave its reception area, I have to either switch and hold to the other site I know, or scan through my list of sites with some squelch settings in the hopes that it will lock into it and then I can hold the site. In my case it becomes an issue especially because I don't have all sites discovered. I have however have a lot of them, and should have all the ones in my area programmed, but still don't know exactly which site for which area.

I would love to see a feature like Motorola's. Similar to Uniden's "ID Searching" for talkgroups, have "Site Searching" for sites, and while scanning in search mode automatically switch sites using the site resource message from the control channel, and signal strength.

 

[donc13]

I doubt you'll ever see that in a hobby class scanner.

Talk groups on some systems can be locked out of or into a specific site(s) (can or cannot affiliate with certain sites) and that is flexible. The scanner however listens to a site, if a talk group you have in your list is active on that site, it airs it. It does that on a site to site basis and only has the capability to listen to 1 site at a time.

My guess is you're going to have to have a separate favorites list per talk group (with all nearby sites scanned) to do what I belive you want.

I could certainly be wrong though. 😊

 

[nokoa3116]

I doubt you'll ever see that in a hobby class scanner.

Talk groups on some systems can be locked out of or into a specific site(s) (can or cannot affiliate with certain sites) and that is flexible. The scanner however listens to a site, if a talk group you have in your list is active on that site, it airs it. It does that on a site to site basis and only has the capability to listen to 1 site at a time.

My guess is you're going to have to have a separate favorites list per talk group (with all nearby sites scanned) to do what I belive you want.

I could certainly be wrong though. 😊

I do mean to scan one control channel at a time, but when signal strength for the current control channel site becomes too weak, it runs through the list of adjacent site list provided by the current control channel, and finds a better one. I scan any talkgroup grants the control channel is broadcasting, "ID Searching" on Uniden. I know that if I wanted to follow a specific talkgroup this won't be helpful as it is available in some sites, and not others. In the specific instance I am referring to, each site covers such a small distance that many sites transmit the same talkgroups. Motorola does have preferred site options for talkgroups to do what you described.

 

[jtwalker]

This is what a GPS and location control does for you. Connects to the site (or sites) that is (are) closest on state-wide systems.

 

[Ubbe]

While monitoring a large P25 Phase 2 Trunked system while driving, it is difficult to find the appropriate site in range for the system. The system I am currently monitoring has not been fully discovered.

It seems to be a lot of software code to solve a temporary problem until a system has been fully discovered. And many systems seems to be simulcast from the start or are converted to it, so can't use any new developed feature for signal strength selection.

To me it looks to be a perfect job for DSD+ and a laptop. Take the discriminator signal from a scanner, TRX-1 or 2 has that from the earphone jack, or use a SDR dongle and SDR# to handle the frequency selection. Then look at the adjacent site info from DSD+ and look at SDR# for the sites signal strengths, or a scanners signal strength (TRX can be configured to use the signal bars in a much better way) to see which sites that are within coverage and which of them that are the strongest one that are used in the location you are currently in. The SDS100 cannot use a discriminator tap as the first available point where you have audio are after the DSP, where the audio are already filtered and limited in frequency range.

/Ubbe

 

[nd5y]

This is what a GPS and location control does for you. Connects to the site (or sites) that is (are) closest on state-wide systems.

That only works if all the sites are in the db and their locations are correct.

 

[natedawg1604]

This is what a GPS and location control does for you. Connects to the site (or sites) that is (are) closest on state-wide systems.

Lol not even close. The OP is talking about using the adjacent site table based on RSSI and BER levels to determine the strongest site signal. No scanner has this capability. I don't believe the Unications even have this yet. That's why some people use NAS Moto radios...

 

[jtwalker]

Lol not even close. The OP is talking about using the adjacent site table based on RSSI and BER levels to determine the strongest site signal. No scanner has this capability. I don't believe the Unications even have this yet. That's why some people use NAS Moto radios...

I know what the OP is suggesting, and can't imagine adding the overhead to a scanner to have it evaluate the signal strength of all neighbors on every pass through a site. My comment was, GPS is as close as you are going to get to what you want, at least currently.

 

[JoeBearcat]

Lots of reading into the request. I read it as using the control channel adjacent site info to evaluate it for alternates to scan.


Pretty niche, but I will put it on the list. Do I understand the request correctly?

 

[natedawg1604]

Lots of reading into the request. I read it as using the control channel adjacent site info to evaluate it for alternates to scan.


Pretty niche, but I will put it on the list. Do I understand the request correctly?

Yeah, roaming for the strongest site based on the adjacent site table, and with reference to BER and RSSI values, just like XTS/APX radios have been doing for decades.

 

[JoeBearcat]

Roaming is a different issue. I understood it as using adjacent sites when the local site is lost (which is not RSSI-based roaming).

It would almost be like an auto-programming of the trunk system - perhaps a different type of trunk system discovery.

 

[nokoa3116]

Yeah, roaming for the strongest site based on the adjacent site table, and with reference to BER and RSSI values, just like XTS/APX radios have been doing for decades.

Roaming is a different issue. I understood it as using adjacent sites when the local site is lost (which is not RSSI-based roaming).

It would almost be like an auto-programming of the trunk system - perhaps a different type of trunk system discovery.

I am not certain as to what exactly Motorola APX does behind the scenes with the adjacent site table. I was for some reason under the impression that it utilizes the adjacent site data to more easily find a closer site when reception to the current site is poor.

When traveling with the radio and the current locked site signal becomes weak, use the adjacent site table to get nearby sites and then go through them to find the best site to lock into based on RSSI. Motorola has the options to limit certain talkroups to certain sites, with a "preferred site" option. The purpose for this however is for affiliation while roaming between sites. Motorola has an option to "Ignore Site Resource Preference" which I assume is what is pulling the information from the adjacent site table.

I would like a feature that will allow the scanner to act similarly to what Motorola does. Allow scanner to to hold to "BEST SITE" versus scan all sites, or hold a specific site, this will automatically switch sites based on what was described above. Additionally you described an auto programming of the trunk system, I would love to see this in the system discovery also, to help find sites. I had used Trunk Discovery before to find talkgroups, but it could be great if you can also find sites with it as well. Using the adjacent site table you can do that.

The "dream" for me with the Uniden is while driving with the scanner, it will always be monitoring the system, while locking to the best site available every time, and when encountering new sites from the adjacent site table, save them into the system . I know that Uniden has the GPS module that is designed to help with this, however it won't work if I don't have the sites programmed/ or discovered.


Here are some quotes from the CPS help pages.

"Coverage Type (Trunking System, General)
SmartZone operation allows the radio to determine through Received Signal Strength Indication (RSSI) polling samples, the best Trunking Site to be used for SmartZone-enabled Trunking channels."

"Ignore Site Resource Preference (Trunking Personality, Preferred Sites)
Enables the radio to ignore site resources information received in adjacent Control Channel Outbound Signal Words (OSWs), i.e., if the site has ASTRO, 12 Kbit Secure, or Analog Clear repeaters. The feature applies for the current Trunking Personality and only when operating in SmartZone operation.

If disabled, the radio selects sites based on this site resources information. For example, if a radio has selected an ASTRO Talkgroup."

 

[KevinC]

I am not certain as to what exactly Motorola APX does behind the scenes with the adjacent site table. I was for some reason under the impression that it utilizes the adjacent site data to more easily find a closer site when reception to the current site is poor.

When traveling with the radio and the current locked site signal becomes weak, use the adjacent site table to get nearby sites and then go through them to find the best site to lock into based on RSSI. Motorola has the options to limit certain talkroups to certain sites, with a "preferred site" option. The purpose for this however is for affiliation while roaming between sites. Motorola has an option to "Ignore Site Resource Preference" which I assume is what is pulling the information from the adjacent site table.

I would like a feature that will allow the scanner to act similarly to what Motorola does. Allow scanner to to hold to "BEST SITE" versus scan all sites, or hold a specific site, this will automatically switch sites based on what was described above. Additionally you described an auto programming of the trunk system, I would love to see this in the system discovery also, to help find sites. I had used Trunk Discovery before to find talkgroups, but it could be great if you can also find sites with it as well. Using the adjacent site table you can do that.

The "dream" for me with the Uniden is while driving with the scanner, it will always be monitoring the system, while locking to the best site available every time, and when encountering new sites from the adjacent site table, save them into the system . I know that Uniden has the GPS module that is designed to help with this, however it won't work if I don't have the sites programmed/ or discovered.


Here are some quotes from the CPS help pages.

"Coverage Type (Trunking System, General)
SmartZone operation allows the radio to determine through Received Signal Strength Indication (RSSI) polling samples, the best Trunking Site to be used for SmartZone-enabled Trunking channels."

"Ignore Site Resource Preference (Trunking Personality, Preferred Sites)
Enables the radio to ignore site resources information received in adjacent Control Channel Outbound Signal Words (OSWs), i.e., if the site has ASTRO, 12 Kbit Secure, or Analog Clear repeaters. The feature applies for the current Trunking Personality and only when operating in SmartZone operation.

If disabled, the radio selects sites based on this site resources information. For example, if a radio has selected an ASTRO Talkgroup."

A MSI subscriber will check the ACL every 5 seconds and sample the signal strength of CC's in that list. It leaves the current CC for about 80 milliseconds to do this. It will switch sites based on several criteria, some of which are adjustable in CPS.

 

[Jay911]

A MSI subscriber will check the ACL every 5 seconds and sample the signal strength of CC's in that list. It leaves the current CC for about 80 milliseconds to do this. It will switch sites based on several criteria, some of which are adjustable in CPS.

I don't have a source, but I thought I heard waaaaaay back that implementing a feature like this in a scanner would get too close to whatever patents either Motorola or other bodies (standards developers?) had on the process. I was under the impression that specifically not sampling signal strength of adjacent sites and moving to the strongest signal was part of what allowed scanner manufacturers to avoid getting sued into oblivion for being able to 'trunk track' various protocols. Of course, I could be wrong, but that's what I seem to recall being suggested from many, many years ago, like Greg Knox era.

 

[KevinC]

I don't have a source, but I thought I heard waaaaaay back that implementing a feature like this in a scanner would get too close to whatever patents either Motorola or other bodies (standards developers?) had on the process. I was under the impression that specifically not sampling signal strength of adjacent sites and moving to the strongest signal was part of what allowed scanner manufacturers to avoid getting sued into oblivion for being able to 'trunk track' various protocols. Of course, I could be wrong, but that's what I seem to recall being suggested from many, many years ago, like Greg Knox era.

That's possible. I'm not a lawyer, I'm only a lowlife technical guy.

 

[wtp]

this is what the 396XT had/has
Multi-Site Trunking - lets you program the scanner to share trunked system IDs across multiple sites without duplicating IDs, and turn each site on and off independently so that you can select the best site to scan for your area.

but you still have to do the work.

 

[JoeBearcat]

A MSI subscriber will check the ACL every 5 seconds and sample the signal strength of CC's in that list. It leaves the current CC for about 80 milliseconds to do this. It will switch sites based on several criteria, some of which are adjustable in CPS.

Correct, but there is a wrinkle. The subscriber unit will also affiliate with the new site if it switches so the TG can be heard. A scanner has no way to do this, so it would have to evaluate the signal strength and the active TG list (taking about a full second to do that). Worst case, no subscriber unit is affiliated and that TG you were monitoring would not be heard. Of course, if you only do this after the current site is lost (not RSSI evaluation) then it would be the best chance to continue monitoring that TG. It's not a perfect solution, but it's the best you can do without affiliation for this case.

 

[nokoa3116]

Correct, but there is a wrinkle. The subscriber unit will also affiliate with the new site if it switches so the TG can be heard. A scanner has no way to do this, so it would have to evaluate the signal strength and the active TG list (taking about a full second to do that). Worst case, no subscriber unit is affiliated and that TG you were monitoring would not be heard. Of course, if you only do this after the current site is lost (not RSSI evaluation) then it would be the best chance to continue monitoring that TG. It's not a perfect solution, but it's the best you can do without affiliation for this case.

A site provides a list of all of its currently active TGs?


A feature where the scanner can auto lock to the best received site would also help. No need to necessarily use, or worry about the adjacent site messages. Having to scan through more than 100 sites where maybe only 3 top are in range takes a bit of time.

Maybe even poll the sites occasionally to find the ones in range, and then scan only through those, until the next poll.

 

[Ubbe]

A feature where the scanner can auto lock to the best received site would also help. No need to necessarily use, or worry about the adjacent site messages. Having to scan through more than 100 sites where maybe only 3 top are in range takes a bit of time.

Maybe even poll the sites occasionally to find the ones in range, and then scan only through those, until the next poll.

An adjacent site list have maybe 5 sites that it then needs to check which one that are the strongest. Without that list the scanner needs to scan through all 100 sites to find those that are the strongest. As you already mentioned it is not a good idea. And when you move to another location and loose coverage it will at some point need to scan all those 100 sites once more to find another set of strong sites. It's either GPS controlled scan or you manually select zip code or set GPS coordinates that seems to be the most suitable solution, and for unknown and newly discovered sites you program those with an approximate location and an extra large range.

UPMan already tried to reduce the house keeping time to focus on scanning, so we don't want house keeping to take away any more time from scanning.

/Ubbe

 

[JoeBearcat]

A site provides a list of all of its currently active TGs?

Not exactly. The radios affiliated to that site tell it which ones they are using. If that includes one that is not currently broadcast, it will be broadcast until the last unit using that TG leaves that site.