VHF UHF AWIN System Operation Explanation?

[tksanders3]

Hi All. I'm currently working with my county's OEM on getting some AWIN radios for the different agencies throughout the county. so that in the event of a large scale emergency all the county agencies can communicate with each other. We currently have several VHF repeater systems in place and I believe at least 1 UHF system. BUT i have to admit that my understanding of how each of these three systems actually work is sorely lacking. I was wondering if somebody could explain to me how each system works or at least direct me to someplace that does.

As far as radios go, I know enough about it to know i don't know much about it. as far as input frequencies and PL and DPL codes and what not. and I think its AWIN that has like DEC and HEX things and several frequencies.

basically i would like to know what goes on between me pressing my TX button and the sound coming out the other end. any help would be greatly appreciated.

Thanks in advance!!!!

 

[iamhere300]

Hi All. I'm currently working with my county's OEM on getting some AWIN radios for the different agencies throughout the county. so that in the event of a large scale emergency all the county agencies can communicate with each other. We currently have several VHF repeater systems in place and I believe at least 1 UHF system. BUT i have to admit that my understanding of how each of these three systems actually work is sorely lacking. I was wondering if somebody could explain to me how each system works or at least direct me to someplace that does.

As far as radios go, I know enough about it to know i don't know much about it. as far as input frequencies and PL and DPL codes and what not. and I think its AWIN that has like DEC and HEX things and several frequencies.

basically i would like to know what goes on between me pressing my TX button and the sound coming out the other end. any help would be greatly appreciated.

Thanks in advance!!!!

If almost all the county radios are already VHF, why depend on Awin for interoperability? Why not just use common VHF channels?

What county?

 

[poppafred]

Have you tried looking in the RadioRef Wiki?

Lots of good, basic info to be found there.

 

[tksanders3]

@poppafred: No I haven't looked at the radio ref wiki. I will do so. thanks.

@iamhere300: We do have some interop capability on our VHF system, but whether or not the different agencies are actually listening to those channels is another matter...Our county..(Marion County BTW) is a mostly rural mountainous area and so there isn't alot of money floating around to purchase radios and repeaters and the like. most agencies just make do with what they've got and stay in there own little world. also the VHF system coupled with the mountainous terrain makes for very spotty reception in the outlying areas of the county. I think the plan is to switch all our systems over to AWIN eventually, but there again is the money factor. getting a few AWIN radios now for each agency would provide a base to work on getting more in the future, as well as providing redundancy in case of a large scale disaster where the infrastructure may be compromised.

 

[bpckty1]

Check with your Motorola vendor. He may have a device you can put in your dispatcher's console that will connect the frequencies when needed. Plus, there are some portable devices that can be used in the field. I forget the names of the manufacturers, but an internet check should point you in the right direction.

 

[iamhere300]

@poppafred: No I haven't looked at the radio ref wiki. I will do so. thanks.

@iamhere300: We do have some interop capability on our VHF system, but whether or not the different agencies are actually listening to those channels is another matter...Our county..(Marion County BTW) is a mostly rural mountainous area and so there isn't alot of money floating around to purchase radios and repeaters and the like. most agencies just make do with what they've got and stay in there own little world. also the VHF system coupled with the mountainous terrain makes for very spotty reception in the outlying areas of the county. I think the plan is to switch all our systems over to AWIN eventually, but there again is the money factor. getting a few AWIN radios now for each agency would provide a base to work on getting more in the future, as well as providing redundancy in case of a large scale disaster where the infrastructure may be compromised.

Marion county? That explains a lot. No offense, but in the past they have listened to one Motorola shop against all advise otherwise. Fire and EMS on VHF, SO on UHF, Schools on low band, etc. The time they bid all new repeaters the shop convinced them to require DPL instead of just PL, This caused a BUNCH of volunteers to have to replace their privately owned mobiles and portables.

They put up like 4 fire repeaters, are they not getting coverage from those? They had a great tower site north of town, and I thought they had one found that was really going to perform well. One over by Pyatt was planned also.

Do you really think Awin will give you good coverage up there?

And if you must go Awin, Tait is less expensive than Motorola....

 

[iamhere300]

Check with your Motorola vendor. He may have a device you can put in your dispatcher's console that will connect the frequencies when needed. Plus, there are some portable devices that can be used in the field. I forget the names of the manufacturers, but an internet check should point you in the right direction.

It does not need a Motorola vendor. Any decent shop can provide a bridge.

The issue comes with so many VHF frequencies they use up there, desense and intermod at the dispatch center when a bridge is set up there can be extreme and make it unusable.

 

[rxbob]

Here in Lincoln County, we have a county wide vhf system with 3 repeaters for the FD's, all paging and cross-county talking is done there. That system replaced 4 vhf's, 2 low bands, and a uhf. OH, forgot about two departments that didn't have radios. Now we slowly gathering awin radios and the county purchased a vhf to awin patch system. It has one large base and two field units. I've seen it, it's 6 foot tall and blue, but I couldn't tell you much more than that. The OEM says somebody form Hot Springs is going to train a few of us how to use it.

 

[tksanders3]

Yeah that sounds about par for the course for Marion County. Now don't quote me on this but i'm fairly sure that we only have 1 VHF Fire/EMS repeater north of town there. I'm no authority on this by any means, hence my asking questions here. I know how to use the radio, but i haven't the foggiest how it works.

that repeater works fairly well in the central part of the county, but as you start getting further away or down in a valley it goes downhill quick. our original repeater equipment took a hit from lightning so we've been working off a backup for awhile now.

when i worked in dispatch i remember that the console only had 1 spot for the fire radio, it had a light that blinked as long as the repeater had the channel open. and there were about 6 spots for the UHF for the SO channel that would blink when that repeater was open. that may explain where the other repeaters went. which is ironic considering that even with all those repeaters they still have worse coverage than the FD's 1 VHF repeater. probably has to do with the longer wavelength being able to roll up and over hills better.

as far as awin coverage...i would like to think that it's better than what we have now. I worked for the NPS Buffalo River once, and they used awin radios for the entire river. i heard a guy do a radio check from Fayetteville when i was in the roughest, backwoods part of Marion County. I mean it doesn't get any harder to get radio service than where i was and it was clear as a bell.

I'm pretty sure that OEM is also working on getting a bridge for our mobile command center that would tie in all the systems together, but that's another project.

What i originally wanted to know is how these systems worked so that when i'm asked I can provide an intelligent response. I know..I'll put how i think they work and you guys can correct me.

Im pretty sure this is wrong but i think VHF and UHF works by me pressing my TX button then my handheld transmits my traffic on the repeater's out frequency(for short range)as well as transmitting the dpl and my traffic on the repeater's input frequency. then if the dpl is correct the repeater takes my traffic, bumps up the power and puts it out on the output frequency walking out the lower power transmission from my handheld as they are on the same frequency.

My understanding of awin is very limited, but if i press my TX button on awin it takes my traffic and slices it up and transmits different chunks of it on 6 or 7 different pre-determined frequencies and the instructions for putting them back together as well as my radio's id number are put out of the broadcast frequency. each transmission is picked up by the awin repeater and broadcast to every awin repeater statewide but the only radios that will hear it are the ones that are programmed to search for the right pieces in the right order (same talkgroup).

while all the other information is great and i'm learning alot from you guys, this is really what i'd like to know, the correct way that the above happens as im sure im nowhere near what actually happens.

Thanks again guys

 

[iamhere300]

My understanding of awin is very limited, but if i press my TX button on awin it takes my traffic and slices it up and transmits different chunks of it on 6 or 7 different pre-determined frequencies and the instructions for putting them back together as well as my radio's id number are put out of the broadcast frequency. each transmission is picked up by the awin repeater and broadcast to every awin repeater statewide but the only radios that will hear it are the ones that are programmed to search for the right pieces in the right order (same talkgroup).

while all the other information is great and i'm learning alot from you guys, this is really what i'd like to know, the correct way that the above happens as im sure im nowhere near what actually happens.

Thanks again guys

VERY simply put.

When you push the button on the AWIN radio, it sends a request to the tower for a "channel". The tower assigns that frequency, and then tells all the other radios on that talkgroup what frequency to go to. When they unkey they may be assigned another frequency for the next keyup.

Only the towers that have active radios on that talkgroup will transmit.

Now, there are announcement talkgroups, that would transmit on each and every tower, but they are seldom used as they will be a tremendous drain on the number of conversations that can be handled.

It does not "slice up" and send it out.

Consider that trunking came from the telephone world. If you go to the hospital, there are hundreds of telephones, but there may only be 10 outside lines. You dial 9, is like the PTT, requesting a talkpath. If there is one available, then it is granted and you talk.

If there is not one available, you have to wait.

 

[rxbob]

Have you had the Awin class that DIS offers? They have maps and diagrams that explian awin in leymans terms. As for our vhf system we have 3 repeaters all have the same input and output frequencies different pl tones on input. The choice is based on location. My handheld and my moblie have all 3 pl's programmed in. The downside is that means I have 3 channels with the same frequenices. All of the repeaters output have the same pl so you can hear the others without swapping channels. We still have dead spots though, especially in the hills south of Star City. But, once you get in the Delta you can talk anywhere.

 

[tksanders3]

now that's what I'm talking about. that makes alot of sense. was i close on VHF? talking it out with you guys is really helping me out with my ignorance problem. haha. I thought i heard about some sort of an awin class coming up i might look into.

@iamhere300 the way you talk about awin makes me think the system isn't as good as i thought it was. are there any concerns you have about it i should know about? and thanks for all your info so far.

 

[iamhere300]

now that's what I'm talking about. that makes alot of sense. was i close on VHF? talking it out with you guys is really helping me out with my ignorance problem. haha. I thought i heard about some sort of an awin class coming up i might look into.

@iamhere300 the way you talk about awin makes me think the system isn't as good as i thought it was. are there any concerns you have about it i should know about? and thanks for all your info so far.

It works well. But, coverage is your issue in your area. The only tower in your county is at Pyatt. 800/700 range is less than VHF. Think about it.

 

[wrr20891]

The only tower in your county is at Pyatt. 800/700 range is less than VHF. Think about it.

Yes, but you are not limited to using only that tower. Hickman Knob in Baxter County provides good coverage on the east end of Marion County. Likewise, Backbone Mountain in Searcy County provides a good signal in the south end of Marion County.

 

[iamhere300]

Yes, but you are not limited to using only that tower. Hickman Knob in Baxter County provides good coverage on the east end of Marion County. Likewise, Backbone Mountain in Searcy County provides a good signal in the south end of Marion County.

Please... Although I don't have any experience with the Backbone site, Hickman Knob being north of Mt Home I have tons of experience with, at 800 Mhz. 17.9 air miles from Yellville, you can't expect in the hills and hollows to have reliable portable coverage.

Mobile coverage would be better, but to expect it to be reliable in 95% of the county from those three sites? Nope.

 

[wrr20891]

Mobile coverage would be better, but to expect it to be reliable in 95% of the county from those three sites? Nope.

The AWIN system, like the ASP 800 MHz system before it, was never designed to provide 95% portable coverage in any County in the State. The system design was for 90% coverage, 90% of the time for mobile radios. I don't know of anyone doing a study to see what the average portable coverage percentage is, but it would be interesting to see.

If you have tons of experience with the Hickman Knob site, I'm sure you have observed the radios select that site until you get somewhere between Miller's and George's Creek. The radios usually will switch to the Pyatt site from there on west. They also stay on Hickman until you get north of Summit on 14 where they'll switch to Pyatt, and south on 14 until you get n the shadows of Hall Mountain where they usually switch to Backbone.

I'm not sure if your experience is with an AWIN radio or a scanner. I have no idea what the scanners do, but this is what the AWIN radios themselves do.

 

[poppafred]

You were pretty close on the VHF.

There are two different ways of getting your signal out from a base. Hardline link to the repeater or radio link. Hardline ties directly into the repeater and it is like using a mike attached to the repeater itself. Radio links can be either a VHF transmitting on the input freq of the repeater or a microwave link. They are probably using a VHF rig in the building, microwave setups are not cheap. Microwave would have a receiver and transmitter on the microwave frequency at both ends, at the base and at the repeater site. A VHF base rig runs off a 110v. power supply and looks like another mobile to the repeater. Since that is cheaper, that is probably what they are doing.

UHF repeaters are the same hardware wise, different frequencies (of course).

 

[iamhere300]

The AWIN system, like the ASP 800 MHz system before it, was never designed to provide 95% portable coverage in any County in the State. The system design was for 90% coverage, 90% of the time for mobile radios. I don't know of anyone doing a study to see what the average portable coverage percentage is, but it would be interesting to see.

If you have tons of experience with the Hickman Knob site, I'm sure you have observed the radios select that site until you get somewhere between Miller's and George's Creek. The radios usually will switch to the Pyatt site from there on west. They also stay on Hickman until you get north of Summit on 14 where they'll switch to Pyatt, and south on 14 until you get n the shadows of Hall Mountain where they usually switch to Backbone.

I'm not sure if your experience is with an AWIN radio or a scanner. I have no idea what the scanners do, but this is what the AWIN radios themselves do.

My experience is with other 800 Mhz repeaters on the same tower, and other radio systems on that same knob, as well as others close by.

You are right - it is 90/90. Normally agencies strive for 95/95, but Arkansas elected for a lower bar, mainly because of funding. The old system was no where near as good as the new system.

Missouri for example has a better DAQ requirement, and mandates 95/95 for mobiles. (we will see how that ends up working) Missouri of course is a VHF system.

I just don't see a county like Marion getting the rural FD's to all start to use AWIN with mobiles. Counties in similar situations tend to try to depend on portables, and then they complain about coverage issues. I see a LOT more portables out there than mobiles in many rural counties.

 

[hitophikers]

AWIN and FD's - Not a Good Mix

Over the years, I have read numerous posts about AWIN (type) digital systems that have had very bad results when used by Fire Departments.

It seems that P25, like most digital-based systems, tries to digitally eliminate background noise like noise cancelling headphones used by air passengers. But when this happens to a fireman in a burning structure with all their head gear on, it may also eliminate VOICE frequencies. The muffled sound inside a helmet coupled with the normal voice range of a male, sometimes gets cancelled, putting the fireman in a burning structure in danger if he can not be clearly understood. The result is that they may not be heard or even hear safety commands from outside.

I read about one city that forced an AWIN (type) system on their FD's, based on the Motorola salesmen assurance of safety, against the Chief's wishes and concerns, . After a close call, they ditched the digital system and returned to their reliable VHF system. Luckly, it was still in place.

Something to discuss with other fire departments that have been there before committing your firemen to a potentially dangerous system.

And in large cities with "canyons" of high rise building, where maybe 10 VHF/UHF repeaters covered the city, when going to digital they had to double the number and still could not get positive coverage inside most buildings that they had coverage in with analog systems.

The problem is like the HDTV we all now have, it's DIGITAL and that means the ones and zeros have to add up to the checksum or the result is nothing. It's called error checking. You either have information transmitted that checks out or from a weak signal with missing data it doesn't and nothing is transmitted. No such thing as a "snowy" picture anymore. Digital radio is the same way. It either works or it doesn't.

I'm sure there are those that will loudly disagree with me and that is their right. I'm just stating what I have read and especially heard in operation on my P25 scanners.

 

[iamhere300]

Over the years, I have read numerous posts about AWIN (type) digital systems that have had very bad results when used by Fire Departments.

It seems that P25, like most digital-based systems, tries to digitally eliminate background noise like noise cancelling headphones used by air passengers. But when this happens to a fireman in a burning structure with all their head gear on, it may also eliminate VOICE frequencies. The muffled sound inside a helmet coupled with the normal voice range of a male, sometimes gets cancelled, putting the fireman in a burning structure in danger if he can not be clearly understood. The result is that they may not be heard or even hear safety commands from outside.

I read about one city that forced an AWIN (type) system on their FD's, based on the Motorola salesmen assurance of safety, against the Chief's wishes and concerns, . After a close call, they ditched the digital system and returned to their reliable VHF system. Luckly, it was still in place.

Something to discuss with other fire departments that have been there before committing your firemen to a potentially dangerous system.
.

Digital has no business in a burning building, nor repeater transmissions should be used on a fireground.

Fireground operations should stay analog, narrowband.

That said, any of the AWIN radios can have analog programmed also.