Michigan MPSCS talkgroup confusion

[peanutspecial]

Okay, so I kind of understand the concept of the MPSCS statewide system; the ability to have an interconnectability throughout the state, but there are some things that I just can't seem to grasp.

First, I thought that if interconnectibility across the state was possible, then why shouldn't my Pro-96 be able to listen to communications hundreds of miles away at my bidding? Later, having experimented with this idea for hours and hours, I found that I wasn't getting those results. Oh well, plenty of good local chatter, I thought. Still worth the $400.00 bucks.

BUT... today, on the Monroe Simulcast, I was hearing DNR Fire chatter from three different talkgroups, one from all the way up in Cadillac! Plus, there was some chatter from a talkgroup in Berrien County; somthing about a white step van from Canada that the Canadian Authorities were trying to follow, but lost around the I-94 - 127 interchange.

So now I'm confused. Is it possible to hear statewide chatter from a single MPSCS tower? Well, I guess the answer to that would be 'yes', since I heard talk from areas I had no business hearing with my handheld and 800 Mhz floppy. So, if I am able to hear statewide chatter, I guess the next logical question would be 'Can I control which talkgroups I am listening to?' Or, to put it another way, 'Can I hear communications from, let's say, in Ludington or Manistee from good ol' Ypsilanti?' 'Or listen to federal government talkgroups?'

This seems to be the concept of the MPSCS that I just can't grasp, and there are little resources available to explain this further; at least I haven't found any as of yet.

Can anyone help me out with this little issue?

I guess the second question I would have (which may be related somehow) is, what is the difference between a tower and a simulcast tower. Is the simulcast tower the big daddy that let's me hear statewide talkgroups, cause it was the Monroe Simulcast, not the closer Ann Arbor tower that gave me such entertainment this afternoon from voices afar.

Anyhow, I could use a bit of enlightenment from the experts I know are here.

Thanks much in advance.

[Josh]

You'll only hear talkgroups that radios within receiving/transmitting range of that tower are affiliated with.

Scanners do not transmit and therefore cannot affiliate with towers to allow distant talkgroups to be patched it. Also, local talkgroups like Monroe County, Detroit, etc... are only available on certain towers. Even if you had a Detroit PD radio out in... say.. Muskegon it may not be able to reach Detroit if the talkgroup isn't allowed to be on that site.

As for simulcast... it's simple... multiple sites transmitting at the same time in syncronization/phase in order to achieve better coverage over areas. Detroit has something like a 10 site simulcast setup such that there are ten sites with the same 28 frequencies transmitting the same information on the same frequencies at the same time, but the towers are spaced out for phasing and time-synchronized via GPS.

-Josh

[peanutspecial]

Gee Josh, when I said I wanted to hear from experts, I didn't mean confuse me even more! Nah, actually, I kind of understand what you mean, and I kind of thought that too all along, but was hoping a scanner with the ability to listen to statewide chatter was my dream come true.

Oh, well. But, that still doesn't answer why I was receiving a Cadillac and Berrien transmission today (or does it?). Is it because the Monroe Simulcast is subscribed to that talkgroup? If that's the case, does anyone know how to find out which towers are subscribed to what talkgroups?

Or did someone from the Monroe Simulcast patch into those talkgroups because they can? Hmmmm.

Or, am I just even more confused?

Now, everything is as clear as mud. lol

peanutspecial

[seamusg]

Originally Posted by peanutspecial

Okay, so I kind of understand the concept of the MPSCS statewide system; the ability to have an interconnectability throughout the state, but there are some things that I just can't seem to grasp.

First, I thought that if interconnectibility across the state was possible, then why shouldn't my Pro-96 be able to listen to communications hundreds of miles away at my bidding? Later, having experimented with this idea for hours and hours, I found that I wasn't getting those results. Oh well, plenty of good local chatter, I thought. Still worth the $400.00 bucks.

BUT... today, on the Monroe Simulcast, I was hearing DNR Fire chatter from three different talkgroups, one from all the way up in Cadillac! Plus, there was some chatter from a talkgroup in Berrien County; somthing about a white step van from Canada that the Canadian Authorities were trying to follow, but lost around the I-94 - 127 interchange.

So now I'm confused. Is it possible to hear statewide chatter from a single MPSCS tower? Well, I guess the answer to that would be 'yes', since I heard talk from areas I had no business hearing with my handheld and 800 Mhz floppy. So, if I am able to hear statewide chatter, I guess the next logical question would be 'Can I control which talkgroups I am listening to?' Or, to put it another way, 'Can I hear communications from, let's say, in Ludington or Manistee from good ol' Ypsilanti?' 'Or listen to federal government talkgroups?'

This seems to be the concept of the MPSCS that I just can't grasp, and there are little resources available to explain this further; at least I haven't found any as of yet.

Can anyone help me out with this little issue?

I guess the second question I would have (which may be related somehow) is, what is the difference between a tower and a simulcast tower. Is the simulcast tower the big daddy that let's me hear statewide talkgroups, cause it was the Monroe Simulcast, not the closer Ann Arbor tower that gave me such entertainment this afternoon from voices afar.

Anyhow, I could use a bit of enlightenment from the experts I know are here.

Thanks much in advance.

MPSCS is a state wide system, but not all TG's can be broadcast on all towers all the time. There are over 1300 TG's on the system, at a 10% usage that would mean that each tower would have to have 130 channels available. THe system is a smart zone which means if a radio is affiliated with a tower it's TG' will be broadcast from that tower. Example is that I've heard someone from USCG CIS in Macomb County talking to someone in the Saulte in the UP on the Mt. Clemens tower. The system only broadcast the TG' on the towers where someone is there, not all towers. If a TG is setup to cover the whole state at one time, it will be broadcasted on all towers.
" then why shouldn't my Pro-96 be able to listen to communications hundreds of miles away at my bidding?"
Your PRO96 is a scanner not a radio on the system, a scanner CANNOT transmit on the control channel to tell the system you are there.

[Josh]

The DNR or whatever talkgroups you were hearing may have been statewide, or perhaps one of the state-wide talkgroups. What happened was someone's radio affiliated that talkgroup to your local tower and in doing so allowed/allows it to be heard. Radios have to reaffiliate the talkgroup over a certain period of time, which I think is programmable (which I think is typically be set at '24 hours'), so after the talkgroup time-out expires, you'll no longer be hearing it.

I remember when I got into digital scanning a couple years back and began monitoring the MSP system at times, it was I think fall of '02 where I was listening to Escanaba area DNR (from Wyandotte) talking about poachers the day before the hunting season began.

-Josh

[kirkman123]

I'm located near Marquette in the central U.P. The comments about various talk groups being "affiliated" with different towers is absolutely correct. For example, I hear all the local transmissions, all the time, as you'd expect. But in addition, I hear transmissions from the Dept of Corrections from all across the state. Also, I hear DNR on a regular basis from areas far beyond the U.P.

[peanutspecial]

So, if I'm understanding this correctly, listening on the MPSCS is kind of like DXing with shortwave by catching some bonus frequencies once in a while. But instead of a kick butt antenna, sweet propagation, and perfect timing, we are under the control of some person?

Is that right?

And now that I think about it, some of the chatter I was hearing yesterday was statewide talkgroups, but not all. Today, I am getting chatter from Kalamazoo Central Dispatch, which I was also getting earlier in the week. This digital stuff is pretty cool.

Thanks for everyone's help. I think I got it...kind of.

PeanutSpecial

[kirkman123]

Peanutspecial,

I'd say your statement about being under control of some person is correct. It just depends on who (talk group) has "permission" to be talking through a particular tower. I'm listening now, and I'm getting all the usual conversations between MSP post in Negaunee and troop cars in the area, but that's what I'd expect. I'm also hearing DNR officers from all over the state who are checking in with Lansing headquarters (who I am also hearing) as they go on duty. Dept of Corrections is another group that I'm hearing right now from locations both in the U.P. and Lower Michigan. I also get a lot of Dept. of Transportation far beyond the immediate area. I'm hearing DOT from the Copper Country right now and those trucks are over 100 miles away.

I love this 800 system.

Kirk

[Hoofy]

All the info above is correct. However some DNR officers check in service on a statewide tg. Those you could hear from any place in the state. If they use a local tg you wouldn't be able to hear them except on the local tower. Also the prisons and other groups use statewide tg's which can be heard anywhere in the state.

Some of what you hear is skip. I have heard traffic from around the state that can only be explained by skip. Also check to see that your scanner is operating in open mode which allows it to pickup tg's that are not programed into your scanner.

Good Luck.

[rdale]

"Also the prisons and other groups use statewide tg's which can be heard anywhere in the state. "

Again - ONLY IF SOMEONE ON YOUR TOWER IS AFFILIFATING WITH THAT TALKGROUP. Otherwise you will not hear them...

"Some of what you hear is skip. "

Not on a trunked system.

[Hoofy]

Why no skip on trunked system?

I believe that if it gets sent through the air it can be affected by atmospheric conditions. (ie skip or attenuation) A trunked system is nothing more than a complex computer controlled duplex repeater system. When that signal leaves the trs tower it can be received by anyone with a receiver on that frequency that is able to capture the signal.


I have talked half way across the country on 446.00 with 35 watts due to skip. Wheather it is a digital or analog signal should make no difference going through the atmosphere or being effected by the atmosphere.(skip)

I have received tg's from several hundred miles away that no one locally would have any reason to be affilliated with.

Hams have done some experimenting across Lake Supperior using microwaves ( a much shorter wave length) land found the signal went farther and stronger down closer to the water than from higher elevations directly above the water. Effectively that's skip.

I'll need some proof that trunked signals are not affected by skip. I'm certainly not as knowledgeable as trained radio personel but my basic knowledge of radio propogation is based on my firsthand knowledge and common sense. What is HF radio if it isn't skip.

I operate my scanner with virtually every control channel in the state of michigan programed into it and scan in the open mode. Therefore any tg from any tower that my scanner can capture and decode I can hear. I'm not limited to a few tg's.

We had some guys out in the middle of Lake Superior breakdown in a boat and the only thing they had was a cell phone. The tower that picked them up was in lower michigan which relayed the info to the local Coastguard. (Skip)

[peanutspecial]

So, and this is the last question I think I have on this topic; I am REALLY interested in hearing chatter from Feds and such; you know, DEA, FBI, Border Patrol, etc. Is that going to be possible from Ypsilanti? I have yet to hear these talkgroups using the Ann Arbor, Monroe Simulcast, Western Wayne, and Eastern Wayne frequencies. Then again, maybe these groups don't have much to say.

Again, thanks to all for explaining the technical jargon. You've all been a great help.

PeanutSpecial

[seamusg]

Originally Posted by peanutspecial

So, and this is the last question I think I have on this topic; I am REALLY interested in hearing chatter from Feds and such; you know, DEA, FBI, Border Patrol, etc. Is that going to be possible from Ypsilanti? I have yet to hear these talkgroups using the Ann Arbor, Monroe Simulcast, Western Wayne, and Eastern Wayne frequencies. Then again, maybe these groups don't have much to say.

Again, thanks to all for explaining the technical jargon. You've all been a great help.

PeanutSpecial

Western Wayne and Eastern Wayne are not part of MPSCS therefore no. Just because a system is 800 mhz and MOT does not make it MPSCS.

[rdale]

"Why no skip on trunked system?"

Because your radio is set to go to a voice frequency when the control channel tells your radio that there is activity on that frequency. So while it's possible the voice freq could skip into your area, as long as you are monitoring in trunked mode the trunk controller knows nothing about it (since the input won't skip, just the output) and it will never tell your scanner that a signal exists.

"no one locally would have any reason to be affilliated with."

Could be someone driving through. When I go to Otsego Lake, there's a fire officer from Livingston Co that takes his radio when he goes on a trip and I'll hear all their comms just fine from 200+ miles away...

- Rob

[Hoofy]

""Because your radio is set to go to a voice frequency when the control channel tells your radio that there is activity on that frequency. So while it's possible the voice freq could skip into your area, as long as you are monitoring in trunked mode the trunk controller knows nothing about it (since the input won't skip, just the output) and it will never tell your scanner that a signal exists.""

I guess I'm really dense.

Are you saying that the control channel can't skip?

Are you saying that even to hear a local tower I have to hear the input to that tower?

I'm not talking about skip from one tower to another tower. I'm talking about skip from a tower to my scanner.

""Could be someone driving through. When I go to Otsego Lake, there's a fire officer from Livingston Co that takes his radio when he goes on a trip and I'll hear all their comms just fine from 200+ miles away...""

No one just drives through here. We are at the end of the road.

[rdale]

"Are you saying that the control channel can't skip?"

No, but odds of the control channel AND all the associated voice channels skipping at the same time are not good.

"Are you saying that even to hear a local tower I have to hear the input to that tower?"

No. I'm saying if your local tower is going to be affected by skip, it would only happen if it could hear the input (and inputs are too weak to skip.)

"No one just drives through here. We are at the end of the road."

That may be, however in the end the story is the same - there is a radio in your area affiliating with that talkgroup.

[tutakt]

""Could be someone driving through. When I go to Otsego Lake, there's a fire officer from Livingston Co that takes his radio when he goes on a trip and I'll hear all their comms just fine from 200+ miles away...""

Is this much the sam a a cellular phone that transmits a signal to the local cell to tell the system where the phone is?

[seamusg]

Originally Posted by tutakt

""Could be someone driving through. When I go to Otsego Lake, there's a fire officer from Livingston Co that takes his radio when he goes on a trip and I'll hear all their comms just fine from 200+ miles away...""

Is this much the sam a a cellular phone that transmits a signal to the local cell to tell the system where the phone is?

Each radio on the system affilliates with a tower by sending a message to the tower when it is turned on, when it changes talkgroup or moves into another tower area. And the main computer in Lansing gets all of this information and directs the traffic on the system. If you have a PRO96 or PRO2096 and PRO96COM, you could see this. I often hear a person in Sault Ste. Marie talking to another person in St. Clair Shores on TG 2690.

[rdale]

"Is this much the sam a a cellular phone that transmits a signal to the local cell to tell the system where the phone is?"

Yes.

[Hoofy]

Okay, I understand what you're saying now. Sometimes it takes a while to soak in.

As remote as it is I'm still thinking that skip has a higher percentage chance than a visitor in the area with a radio.

Thanks for all the good info.