AZ DPS

I frequently monitor AZ DPS West and realize that the mobiles seem to switch between two repeaters that are transmitting on 460.300 MHz. FCC records indicate that two 460.30 repeaters exist at slightly different positions on South Mtn.

Can anyone explain how DPS decides which 460.30 MHz repeater to transmit from? Does DPS operate a voting system which votes on the mobile signal strength of the mobile transmissions and then decides which repeater to activate?

Aware that the mobiles can operate in the talk around mode on 460.300 Mhz.

Curious here,

I do believe that they have a voting system to switch to the appropriate repeater.
I'm guessing that the antennas are oriented more to the Valley on one, and more to the far west on the other.
I think it would make more sense to put the 2nd atop White Tanks, with the orientation (if they're using multi-bay folded dipoles with a cardioid pattern) to the west.

It's annoying when an officer brings up both repeaters, and interferes with himself, lol

John
Peoria

Yes, agree, seems as if DPS has a network that votes. Why not install Trak clocks on both transmitters and the astro tac and simulcast?

Have to agree with you on the orientation of the antennas on South Mtn. Guessing a low gain antenna is used for the repeater that provides coverage in the valley while the other transmitter might use a slightly higher gain antenna to reach out to the west. They do a pretty dam good job with the use of their UHF frequencies.

Have also heard the heterodyne caused by two transmitters firing up out of sync. Not sure if their investigators use encryption on the DPS UHF systems but if so then there is no PL when encryption is on and that might have done it. Regardless, thanks for taking the time to respond.

Don

I've not heard any encryption on the UHF CI channels 460.275 & 460.500. I've not ever heard 460.275 used at all, actually, with the exception of the regular CW ID'er, but 460.500 is frequently active with Zebra (GIITEM, Gang and Immigration Intelligence Team Enforcement Mission) and "Tac" units.

It's been reported that there are two encrypted DPS CI TG's on the RWC (2191 & 2192) and several encrypted TG's on the YRCS (1025-1027, maybe others, such as 1000).

I've heard signal strengths change drastically on Metro East, which probably signifies that they've switched sites, but I don't recall two sites coming on at the same time. Metro West and to a lesser degree Metro Central has had that problem, however.

But, then again, their system wasn't designed with the scanning public in mind, and if one officer misses a transmission from another, that's one of the reasons dispatchers are there for, to repeat/relay what one officer needs to communicate to another.

John
Peoria

Thank you, I am a new guy here and the information you provided was insightful and beneficial. I have to believe the DPS dispatchers have the option to monitor the repeater outputs or the mobile transmit signal that is received by the repeater or remote receivers.

Concur that DPS is using a voting system and all received signals from all sites in that system are directed to the voter via either, microwave, leased land lines or cross band repeaters. The dispatcher will always monitor the best signal and the voter will continuously vote on the received signal as it is being transmitted.

If the dispatch console is wire lined/microwaved to the repeater the dispatcher has the ability to always monitor incoming calls for assistance even if the dispatcher is transmitting, an awesome safety feature. Interesting to observe that FCC records indicate that DPS has talk around capability on all of their UHF dispatch channels and all of the talk around frequencies are authorized for statewide use.

Probably occurs seldom if ever but DPS officers could use a talk around frequency assigned to a repeater in the NW side of the state down in the SE side of the state. Its an option they probably don't opt for given they seemingly have other assignments for that use.

Again, thank you for clarifying some questions I had.

Don

Anything you ever want to know about the AZ DPS radio system (that he can divulge anyway) can be answered in the Yahoo Arizona Scanner group by a guy in there named Walter Howard. I don't know if he hangs out here also or not, but he's very knowledgeable about all things DPS radio. I believe he is a radio tech for the state (may be retired now though).

-AZ

I doubt they would switch to a different channel for talk around. Their dispatchers expect them to be on their district channel. If they ever did they would tell their dispatcher 10-52 to wherever.

Sent from my Nexus 7 using Tapatalk

Totally agree with your comment on district talk around, Have to assume DPS utilizes what is commonly called remote base stations and or monitor receivers that are normally positioned at repeater sites to receive talk around transmissions and are microwaved back to the dispatcher. Its all about officer safety for the DPS officers who have to deal with a lot of...knuckle heads.

Appreciate your feedback.
Don

I don't think the dispatchers can hear the officers when they go direct on the repeater output. I could be wrong.
The officers go direct when they want to coordinate traffic control or an accident investigation without tying up the district channel district wide, but they can still hear other officers and dispatch since they're on the output of the repeater.

Now, CID officers working a case might have gone direct on the output of a district channel away from that district in the past, in order to kind of hide from anyone who might be listening to the local district channel(s), or the main CID channels.
Now that they have their encrypted TG's on the RWC and YRCS, that practice may have fallen to the wayside.

John
Peoria

Have not lived here long and have never actually heard an AZ DPS dispatcher communicate with an officer who was on a talk around channel. Seem to have good overlapping repeater coverage here and use their channels and systems effectively. Concur DPS CID slides over to an out of district talk around channel when they cant communicate on an encrypted talk group.

Question: Have seen some DPS units with VHF antennas on them. Do you know if they have the ability to communicate on 155.4475 MHz or any other VHF frequencies?

AZDon said:

Question: Have seen some DPS units with VHF antennas on them. Do you know if they have the ability to communicate on 155.4475 MHz or any other VHF frequencies?

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I have not seen a DPS vehicle with a VHF antenna. Are you sure it was not an ADOT or ADOT enforcement vehicle? ADOT uses the YRCS system in some areas of the state including Phoenix. ADOT uses VHF in rural areas. A lot of ADOT vehicles have both 700/800mhz and VHF.

The AZ DPS cars I have seen with a VHF -HI band antenna on it were rather loaded down with other antennas. Cars in question had the following antennas on one car: DPS UHF antenna; lo jack series 4 VHF antennas, two 800/700 MHz antennas and a quarter wave VHF antenna which was mounted on the trunk.

Will see if I can get a pic of one.

AZDon said:

The AZ DPS cars I have seen with a VHF -HI band antenna on it were rather loaded down with other antennas. Cars in question had the following antennas on one car: DPS UHF antenna; lo jack series 4 VHF antennas, two 800/700 MHz antennas and a quarter wave VHF antenna which was mounted on the trunk.

Will see if I can get a pic of one.

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I have seen this as well. I live down the street from the Westside Office at 111th & Peoria so the units are always passing the house. It seems the new ford units do not have the lo jack antennas on them but do have the UHF, 800/700 and a VHF. My thought is the VHF is for the VAIRS system, ADOT and or AOT enforcement.

Thanks for confirming that. The VHF antenna appears to be cut a little towards the high end, have to see what we can find out about it. Might just be a scanner antenna, will see if I can reach out to some old friends.

In NW AZ the dps cars are equipped with vhf radios to communicate/interoperability with other agencies like utah highway patrol, Kane county SO, MCSO (Mohave county SO)etc since Kane county is just north of the AZ state border

VAIRS/VLAW's, VTAC's, Fed-State LE and IR's, and/or other agencies (ADOT, State Lands, Game & Fish, Sheriff's Offices, etc) who are on VHF, as the vehicles can be used anywhere in the state, would be my guess.

John
Peoria

Oh, I just remembered, that VHF quarter wave antenna may be for the body mic worn by officers, to record audio during traffic stops, along with the video captured by the dash cam.

169.445, 170.245, and 171.905 are three of the most common frequencies in one list used by police dash cam manufacturers. (SWFD-10, page 234, circa 2009.) But, the list includes 30 frequencies between 169.445 and 210.000, so the actual frequency used could be any one of them.

John
Peoria

John,

That explains it! I thought the quarter wave was cut towards the high end of the band and mounting the VHF antenna on the trunk gives it some separation from the UHF antenna to avoid desense. Yes, for those of you out there that don't know the DPS UHF mobile radio would desense the VHF radio.

So how come all of the troops don't have a VHF antenna, perhaps they are mounted in the rear window. Thanks again John, that's a good explanation.

KB7MIB said:

I don't think the dispatchers can hear the officers when they go direct on the repeater output. I could be wrong.
The officers go direct when they want to coordinate traffic control or an accident investigation without tying up the district channel district wide, but they can still hear other officers and dispatch since they're on the output of the repeater.



John
Peoria

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I think it depends on the locations, antennas, etc. When I was working full time and we were on the old 450 UHF analog system we would often use the repeater output as a talk-around. With the 5 watt HTs we could talk to each other up to a mile or so away. Since we were on the output, we could always hear the dispatcher and other units. The dispatcher could generally hear us because of the good base station and a good receive antenna so we tried to keep things short and professional 'just in case'. With DPS repeaters covering probably hundreds of square miles, chances are pretty good the dispatchers wouldn't hear them. Our system covered the metro Phoenix area pretty well, but of course there were a couple of notorious dead spots.

Back to the original question, I have heard AZ DPS talking to the Cedar City Utah UHP dispatcher on the UHP VHF freq. They identify as "Arizona 156" etc.

I also can add that back in the 80s, Maricopa SO dispatchers could indeed hear "simplex" traffic on the old channel 8; sometimes in the wee hours they would interject when we thought nobody was listening....

I have a DPS question: Who/what would "Adam Frank 211" be??? I heard him in Phoenix on one of the Metro channels a couple of weeks ago.