DTRS P25 System Load

[bayrisch]

I've been curious about this. I regularly monitor several agencies using the 868.8375 (Chevron) control channel. Everytime the control channel assigns a receive frequency, it is always some 1Mhz multiple of ***.3125, between 850Mhz and 860 Mhz. Does anybody know how many transmissions may occur simultaneously for any given control channel?

Mark

 

[MikeyB]

I've been curious about this. I regularly monitor several agencies using the 868.8375 (Chevron) control channel. Everytime the control channel assigns a receive frequency, it is always some 1Mhz multiple of ***.3125, between 850Mhz and 860 Mhz. Does anybody know how many transmissions may occur simultaneously for any given control channel?

Mark

That's going to depend on how many channels are assigned to that site. In the database, each site has it's associated channels listed. I imagine you could have as many transmissions as there are channels minus 1 for the control channel and maybe another one for data or something. Some sites have 15+ channels and some have 5.

 

[wlmr]

I've been curious about this. I regularly monitor several agencies using the 868.8375 (Chevron) control channel. Everytime the control channel assigns a receive frequency, it is always some 1Mhz multiple of ***.3125, between 850Mhz and 860 Mhz. Does anybody know how many transmissions may occur simultaneously for any given control channel?

Mark

Each site in the trunking system you're talking about uses a single control channel assigning voice traffic to the voice channels at that site. The limit for your site is the number of installed radios. Someone who has info on your specific site can say what the total number of frequencies is, I haven't looked for that info. There is a limit to the maximum number of radios at a site Motorola will support. I would be suprised if your site has the max.

 

[jimmnn]

Are you in Colorado WLMR and familiar with the statewide DTRS?

Jim<

 

[bayrisch]

Thanks

I didn't realize that a given agency had access to all of the published frequencies for a given site. Is that right?

Mark

 

[jimmnn]

I didn't realize that a given agency had access to all of the published frequencies for a given site. Is that right?

Mark

That's correct in most situations except Cherry Creek School Buses for example have priority to the 700MHz portions of Smoky Hill for example.

Mark have you tried watching the afflilations screen of pro96com it's real time and can give you a very good idea what's happening on the site.

Jim<

 

[bayrisch]

Web Address

Jim,

Do you have the actual web address? I assume you're talking about the web and not the scanner itself. I tried pro96.com...

Mark

 

[rckydenver]

Mark, this is program that decodes the P25 digital.

 

[jimmnn]

Jim,

Do you have the actual web address? I assume you're talking about the web and not the scanner itself. I tried pro96.com...

Mark

No it's a program called pro96com that actually decodes the P25 digital signal, are you using a Pro-96 or 2096 or PSR-500? It only decodes from those radios.

Produces files like the one attached to this message.

Jim<

 

[rckydenver]

Mike Vander Veer program works pretty good, seeing where in future program that is may decode the p36 and maybe edacs. Can't wait for that. And also the GRE 600.

 

[wlmr]

Each site in the trunking system you're talking about uses a single control channel assigning voice traffic to the voice channels at that site. The limit for your site is the number of installed radios. Someone who has info on your specific site can say what the total number of frequencies is, I haven't looked for that info. There is a limit to the maximum number of radios at a site Motorola will support. I would be suprised if your site has the max.

Update-found some info that states that the sites can have 18 or 28 channels (depends on which types of infrastructure are installed at the site). Simulcast (don't believe used in Colorado) can have up to 30 channels. You have to subtract the control channel to know the max # of voice channels.

By the way, the place to get the PRO96COM software is by searching the yahoo groups for PRO96COM. Well worth it if you have a Pro96 scanner or the new GRE one!

 

[mpg0515]

Thanks for the info, from wherever you are? I am so glad we have so many outside experts to the State of Colorado.......

Thanks again,

Mike

Update-found some info that states that the sites can have 18 or 28 channels (depends on which types of infrastructure are installed at the site). Simulcast (don't believe used in Colorado) can have up to 30 channels. You have to subtract the control channel to know the max # of voice channels.

By the way, the place to get the PRO96COM software is by searching the yahoo groups for PRO96COM. Well worth it if you have a Pro96 scanner or the new GRE one!

 

[jimmnn]

Mark, what specific site(s) are you interested in? They each vary in number of frequencies available for affliation.

For example Site 101 is 7, Site 105 is 13 and Site 313 is 7.

Jim<

 

[bayrisch]

Thanks Jim

I think my questions have been answered. Each site will support a given number of frequencies. My understanding is that any user of that site will have use of any and all frequencies assigned to that site. If there are a dozen frequencies available, not including control channels, then you could have a dozen users transmitting at the same time. If the number of transmissions exceeds the number of available frequencies, then you are going to have service deficiencies at given sites. I monitor southern metro P25 systems on the Chevron site. When you consider that Douglas County, Arapahoe County and the cities of Parker, Castle Rock, Englewood, Greenwood Village, Littleton, Glendale, Sheridan and a few other municipalities feed into that site, in a real emergency, it would appear to me, that things could get bogged down pretty fast, at least on the particular site which I monitor...

Mark

 

[jimmnn]

I think my questions have been answered. Each site will support a given number of frequencies. My understanding is that any user of that site will have use of any and all frequencies assigned to that site. If there are a dozen frequencies available, not including control channels, then you could have a dozen users transmitting at the same time. If the number of transmissions exceeds the number of available frequencies, then you are going to have service deficiencies at given sites. I monitor southern metro P25 systems on the Chevron site. When you consider that Douglas County, Arapahoe County and the cities of Parker, Castle Rock, Englewood, Greenwood Village, Littleton, Glendale, Sheridan and a few other municipalities feed into that site, in a real emergency, it would appear to me, that things could get bogged down pretty fast, at least on the particular site which I monitor...

Mark

You've got it exactly correct Mark those "service deficiencies" you speak of are referred to as busy signals.

Can you make the scanner meeting in Parker on Sunday? You could see real time a screen of the affilations on Chevron for example, it's pretty interesting to watch actually.

The other thing you need to remember is with those agencies you mention they have lots of other site options for the radios to automatically select if they receive a busy signal (Castle Rock, Franktown, Littleton, Glendale, Golden, West Creek, Smoky Hill etc) also other small modifications occur to limited volume such as all CSP radios being not allowed to affliate with Chevron.

I would assume an MCI in a more rural area where they only have one DTRS site option, and normally less channels on that avaialble site to be more of an issue.

It's interesting to watch Thorodin and Golden especially on a busy Friday night or during a snow storm for example and the affliations screen fills frequently.

Jim<

 

[bayrisch]

Real-time Monitoring

Jim,

The pro96 software that's been referred to...that's used in conjunction with GRE or RS scanners? Is there a website available where you can see the freq assignments as they occur realtime?

I would love to come to the scanner meetings on a regular basis, but have conflicts on Sundays. I've certainly learned a lot from reading everybody's posts, exploring WIKI and asking a lot of questions.

Thanks again -

Mark
Parker, CO

 

[jimmnn]

The software is called Pro96Com and no it's not web based, unless you log into one of my computers and watch the desktop, and it works with Pro-96, 2096 and GRE-500 on 9600baud control channels only.

Stop by and see Erik anytime I'm sure he's be happy to show you it working.

Jim<

 

[GrayJeep]

Pro96Com

The software is called Pro96Com and no it's not web based, unless you log into one of my computers and watch the desktop, and it works with Pro-96, 2096 and GRE-500 on 9600baud control channels only.

Stop by and see Erik anytime I'm sure he's be happy to show you it working.

Jim<

Since the program is free and it's the standard that folks here are using I downloaded and installed it and have been watching it for a few nights.
Pretty cool stuff!

Picked up 2 talkgroups that aren't identified in the Colo DTRSL TGID list.
Am expecting to have to use it to figure out Larimer County when the county moves.

Free software that works.... try it!

NW0U

 

[jimmnn]

Believe these were your unknown questions Ron.

4058 Northern Colorado Water Admin
4059 Northern Colorado Water Dispatch
4060 Northern Colorado Water East
4061 Northern Colorado Water West


Jim<

 

[wlmr]

Thanks for the info, from wherever you are? I am so glad we have so many outside experts to the State of Colorado.......

Thanks again,

Mike

I'm not a resident of Colorado, but -

I did stay at a Holiday Inn there once!

Actually, I have I-25 from New Mexico to Denver, and I-76 from Denver to Nebraska fairly well memorized. The route from important point A and important point B travels through Colorado.