Coconino County SO simulcast on UHF?

[APSN556]

Has anyone heard any information about CCSO simulcasting on UHF? Today I have been hearing dispatch on 458.762 all one sided, and it appears to be a simulcast of 159.1500.

[mm]

I know that 453.7625 has been on the air for years, I listen to it all the time when all I have is my UHF saber with me but I haven't heard anything on the +5 meg input, but Prescott may be too far south to hear anything on the input.

I'd expect you to hear more traffic on 453.7625 as opposed to just dispatch on 458.7625, is it the same dispatch on the 453 and 458 frequencies that you hear ?

[Exsmokey]

I would guess that these frequencies are used to link to a remote base, most likely on Mt. Elden. The lower frequency is the down link and the upper frequency is the up link. I would be that if you looked up the FCC licenses of Coconino County you would find these frequencies listed as "FX1." The the lower frequency will have a lat and long listed that should correspond with the location of the remote base on Elden.

Knowing the geography of northern Arizona I would guess that there is some type of remote base or relay at Kendrick Peak as Mt Elden doesn't seem like it could link to the Coconino SO repeater on the south rim of the Grand Canyon, which I believe is located a Desert View or possibly Hopi Point. The SF Peaks would be in the way of Elden's line of sight to those repeaters. I seem to remember that Coconino County also has a repeater at Jacob Lake. That would also be blind to Mt. Elden. It could be linked to Kendrick also, but maybe Coconino Co. links to Jacob Lake by piggybacking on the state's microwave system or has a dedicated phone line to it. A bit of research of the county's FCC licenses would cast more light on how their repeaters are linked.

When the county first put a repeater on Kendrick I don't remember any UHF beam antennas, just a relatively short vertical on top of the lookout. It might not be the relay station I think it is. If the down link on the 453 frequency booms into Flagstaff locations then it is most likely coming from Elden.

Remote base UHF links can be set up in many ways, some have the down links repeat the up links and you can hear both sides of the conversation by just monitoring the down link frequency. The other advantage is that you can listen to everything the remote base is hearing on top of Mt. Elden, which is much more traffic than you will hear in town. The output power of UHF links is typically very low, probably 5 to 10 watts, so it is no surprise that the individual in Prescott is unable to hear the 458 frequency. Not only is the power low, but the beam or Yagi antenna from the SO's dispatch location, located at 7,000 feet in town, would be aimed 180 degrees in the opposite direction from Prescott.

As for Kendrick being able to link up with Jacob Lake this would be no problem. When I worked on the Kaibab National Forest from 1974 to 1978 and supervised the lookouts, we could often call the Dixie National Forest in southern Utah when the conditions were right. We had a battery operated pack set on the Coconino's frequency of 171.550, which was all simplex at the time (except for the repeater on East Pocket used to reach upper Oak Creek on the Sedona Ranger District). The Dixie's Forest Net was also on 171.550. We would try to call the Dixie on simplex and the output of the packsets was probably no more than 5-10 watts, but had a pretty tall vertical mounted on top of the lookout. The Coconino NF provided a radio to the Kaibab for use at Kendrick as the Elden remote base was blind to the west side of the Peaks and since neither the Kaibab or Coconino (National Forests) had repeaters then (except East Pocket) the people working the Kendrick lookout had to voice relay all the mobile traffic there back to the Coconino dispatcher. When lightning started igniting a lot of fires on both Forests Kendrick was difficult to work as the dispatcher and units from both Forests, neither one of which could hear each other, wanted to communicate with Kendrick. The seen area of this lookout was half on the Kaibab and half on the Coconino, so they spotted as many smokes on the Coconino as they did on the Kaibab. This paragraph is off topic, but since Kendrick is the location of one of the repeaters on the Coconino SO radio system, I thought some discussion of its importance and characteristics might be useful.

Radio in the southwest is very interesting due to the nature of the terrain, which is a lot of flat country with relatively small mountain ranges or individual peaks interspersed. Remote bases and repeaters are most often located on top of those ranges and peaks. The distances and paths that affect both reception and transmission of radio signals can be amazing.

[APSN556]

very interesting read exsmokey!

I plugged in the 463 freq and can only hear the officer side of the convo, where as on the 468 freq I only hear the dispatcher.

[mm]

Interesting because down here in Prescott, on 453.7625, I am hearing both dispatch and patrol units that are simulcast on 155.835, but only dispatch on 159.15 and nothing on 458.7625.

I'm at 5750 feet elevation and I can hear Eldon, Jacob lake and of course Williams plus the repeaters at the South Rim of the Canyon on my Motorola VHF and UHF Ht's with stock antennas.

[APSN556]

well this just gets stranger and stranger after reading MM's post. I'm a stones throw away from elden, its a 20 minute walk from my house, so you'd think i could hear both sides crystal clear, but thats not the case. Its either one or the other.

Example: I can hear dispatch calling 2 adam 54 on 468.7625, but can t hear 2 adam 54. On 463.7625 I can hear 2 adam 54 responding to the call, but not dispatch acknowleding him.

[Exsmokey]

Originally Posted by APSN556

well this just gets stranger and stranger after reading MM's post. I'm a stones throw away from elden, its a 20 minute walk from my house, so you'd think i could hear both sides crystal clear, but thats not the case. Its either one or the other.

Example: I can hear dispatch calling 2 adam 54 on 468.7625, but can t hear 2 adam 54. On 463.7625 I can hear 2 adam 54 responding to the call, but not dispatch acknowleding him.

Chad, the frequencies involved are 453.7625 and 458.7625. You are hearing the deputies in the field (officers) on 453.7625 because it transmits the signal from the Mt. Elden remote base station down to the dispatcher. The remote base receives the signal on 155.835 (the repeater output) from one the four repeaters on that frequency located at Mt. Elden, O'Leary Peak (northwest of Sunset Crater), Mormon Mtn., and Schnebley Hill (near Sedona). At least those are the four repeaters shown on one of more of the 18 or so FCC licenses that Coconino County has been issued.

You hear the dispatcher only on 458.7625 because this frequency transmits from the Sheriff's dispatch center in Flagstaff up to the remote base on Mt. Elden. The remote base then transmits the signal on 159.150 to one of the four repeaters I listed. The 159.150 frequency is the repeater input.

The deputies transmit to the repeaters on the input of 159.150 and receive on 155.835. The repeater then hears the signal on 159.150 and transmits it on 155.835. It is then received by the Mt. Elden remote base and transmits the signal down to the sheriff's dispatch center on 453.7625. Now you have the process explained from both directions.

Both the dispatcher and the deputy select the repeaters they want to use by selecting a channel that carries the sub audible tone that opens up the receiver on each repeater. These receivers have a filter on them that only opens them up if the signal has the correct sub audible tone. Think of the tone as a type of password. There is a unique sub audible tone for each repeater so that only one repeater is transmitting at a time. Sub audible tones vary in frequency from 67.0 Hertz or cycles per second to 250 some Hertz or cycles per second. This is below the range of hearing for most people as the human voice can be as high as 20,000 Hertz.

This sub audible tone is carried on through the repeater output back to the remote base on Mt Elden and then onto the 453.7625 down link to the dispatch center. It is then used to have the dispatcher's console distinguish which repeater is being used. When the dispatcher replies the tone is carried on the 458.7625 up link to the remote base on Mt. Elden and is then transmitted with the 159.150 frequency to the repeaters. This tone and frequency then open up the receiver on one of the four repeaters, which in turn transmits the same signal on 155.835 along with the same sub audible tone that the dispatcher selected in the first place.

If you have one of the newer scanners (since about 2000) that is able to scan sub audible tones once the scanner has stopped on a particular frequency and if you know the tone of each repeater, you can then tell what repeater is being used.

It is important to note two things at this point. The deputies and the repeaters do not use any UHF or 450 to 470 MHz transmitters or receivers. Only the remote base does. So the deputies do not have UHF radios. Second, from Flagstaff you should be able to receive the Mt. Elden and Mormon Mtn. repeaters on 155.835. Depending on your location in Flagstaff, with the eastern portion of town being best, you can also hear O'Leary. Schnebley Hill is below the Mogollon Rim and you probably can't hear it.

This all applies to the 155.835 repeater system, which is the secondary repeater system for the sheriff, and as I understand it the primary repeater system for search and rescue. The 155.490 repeater system is the sheriff's primary system. It works in a similar manner except it uses a frequency of 453.9875 for the down link and 458.9875 for the up link. These are not only used to link Mt. Elden with the dispatch center, but to Bill Williams Mountain as well. Bill Williams is able to transmit to and receive the northern repeaters on the 155.490 system that are located at Hopi Point, Kendrick, Grand Canyon Airport, Bill Williams, Phinger Point near Page and Jacob Lake. The Mt. Elden remote base is used to receive and transmit to the repeaters on Jack's Peak, Mormon Mtn., Mt. Elden and Brookbank (Point or Peak located over near Holbrook or Winslow, I don't remember which). There is one more repeater licensed on 155.490 and it is at the Sedona Airport. I believe this one is controlled not by Mt. Elden or Bill Williams, put rather a link on Mormon Mtn. which is a little too complex to explain here. The input to the 155.490 repeaters is 159.210. Give 453.9875 and 458.9875 as well as 159.210 a try and see if your results are similar to the frequencies you originally asked about.

The neat thing about being able to hear the down link from a mountain top remote base is that you hear everything that remote base is receiving. In your case you can have your scanner in Flagstaff or in a location where the down link frequency can be received and is as if your scanner is on top of Mt. Elden.

Again the dispatcher speaks to Mt. Elden on 458.7625 and Mt. Elden speaks to the repeaters on 159.150. The repeaters speak to Mt. Elden on 155.835 and in turn speak to the dispatcher on 453.7625. If you have followed any of this you should be able to figure out why you hear the dispatcher only on the up link of 458.7625 and only hear the deputy on the down link of 453.7625. You can't hear both on only one of the UHF frequencies. It is as if there is one phone wire carrying a voice uphill to Mt. Elden and another phone line carrying the voices down from Mt. Elden. If you tap into one of the lines you are not going to hear both sides of the conversation. If you still don't understand, the only other way I know to explain it is to draw a picture of it in your immediate presence. Just pay me the gas money from Mammoth Lakes, California to Flagstaff, Arizona and $10/hour. I will try to fit it in to my schedule!

[Exsmokey]

Originally Posted by mm

Interesting because down here in Prescott, on 453.7625, I am hearing both dispatch and patrol units that are simulcast on 155.835, but only dispatch on 159.15 and nothing on 458.7625.

I'm at 5750 feet elevation and I can hear Eldon, Jacob lake and of course Williams plus the repeaters at the South Rim of the Canyon on my Motorola VHF and UHF Ht's with stock antennas.

In Prescott you are probably hearing both Mormon Mtn. and Mt Elden, depending on which is in use at the time. You will hear both the dispatcher and the deputies on the repeater output of 155.835. You can then hear the Mt. Elden remote base on 453.7625 transmitting down to the dispatcher what it has received on 155.835. You can also hear the Mt. Elden remote base transmitting on 159.150 to one of the four repeaters as I listed in my post above. I'm surprised you can hear the repeater input of 159.150 from Prescott as the input is usually lower in power than the repeater output, which in this case is 155.835.

The reason you can't hear the dispatcher transmitting up to the Elden remote base on 458.7625 is because is is being transmitted from the sheriff's dispatch center in town. It isn't transmitted with much power because it doesn't take much power to reach the top of Mt. Elden, which can be seen from the dispatch center. The transmission on 453.7625 from the remote base on Mt. Elden has a similar or the same power as the one on 458.7625, but it can be heard from a greater distance because it is on a high mountain top. If I remember the elevation of Mt. Elden and I should as I've hiked up it about two dozen times, it is around 9,000 feet. I'm still surprised you can hear the signal on 453.7625 as its power is pretty low, like the up link which is only going to be, in most cases, around 10 to 20 watts.

I doubt you can receive the Schnebley Hill repeater from Prescott as Mingus Mountain and the adjacent ridge probably block anything located around Sedona. Your reception of the Jacob Lake repeater is amazing, but when I think about it there isn't much in the way between you and the Kaibab Plateau. The entire Colorado Plateau slopes upward from the south to the north and the elevation difference is probably the factor in you being able to receive Hopi Point on the south rim and the Jacob Lake on the Kaibab Plateau whose southern end is on the north rim of the Grand Canyon, with an elevation of 8,000 feet, about 1,000 feet higher than the south rim. You should try the National Park Service frequencies for Grand Canyon National Park. You would be able to hear the Hopi Point repeater, but not the Desert View repeater as it would be blocked by Bill Williams Mtn.and/or Mingus, and perhaps Kendrick and/or the SF Peaks. You should be able to pick up the northern net of the Kaibab National Forest. There are repeaters at Jacob Lake and Big Springs lookout and others I can't remember except Saddle Mountain, which is over near Nankoweep (sp?) Creek at the north end of the Marble Canyon portion of the Grand Canyon near the boundary line between the park and the forest. Again Bill Williams or the other peaks I mentioned would block Saddle Peak from Prescott.

You should also try the frequencies I gave Chad for the 155.490 system and see if you get similar results.

Now for both of you an explanation of what a remote base is might be helpful. It is just like any base station, except that it is controlled from a remote location using a link. The link can be UHF radio frequencies, 72 MHz radio frequencies, by microwave (which is carried on radio also, but at a real high frequency, such as 20,000 MHz and needs carefully aimed dish antennas to work), or by phone lines, either standard or fiber optic. It does not function like a repeater but more like a base station you will see in offices and stations such as sheriff's substations or ranger stations. The remote base is usually more powerful and larger than most bases you will see. Remote bases are frequently operated in the cross band mode, that is it will receive on one band and transmit on another. Some are operated simplex, with one frequency received and transmitted. The advantage of the remote base is that it can be located on a mountain top or other advantageous location to maximize the area it can reach.

I lived in Flagstaff from 1972 to 1978 while attending Northern Arizona University, where I graduated in 1975. I stayed after graduation and received a permanent appointment on the Kaibab National Forest in 1976. I had worked there as a seasonal since 1974. I was on the old Chalender Ranger District, now part of the larger Williams Ranger District. While I was living in northern Arizona I traveled a lot on backpacking trips and road trips both on the pavement and some very remote dirt roads. I got to know the area from Four Corners to the Verde River and then over to the California border fairly well. I also knocked around much of southern Utah while I was there. I got to know where repeaters and remote bases were by the use of my Forest Service radios and the scanners in my home and truck. At the time Coconino County was on low band with 39.180 as the primary (also the statewide law enforcement net) and 39.220 as a secondary, used mainly around the Flagstaff area. The DPS was still on VHF high and switched over to UHF a couple of years after I left.

There was a big fire near Prescott on the Prescott National Forest in 1972 that was made famous by the use of Air Force C5 cargo aircraft to transport Forest Service fire engines from California, thus reducing the travel time. I believe it was called the "Battlement Fire" or something similar. I'm rambling on about ancient history and will quit.