Yosemite National Park

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SCPD

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My wife and I spent the afternoon in Yosemite today. This is the latest Tioga Pass has ever stayed open. I walked out onto the ice at Tenaya Lake. I didn't have time, but some other folks walked all the way across, while others ice skated across. Later I walked across the Lyell Fork of the Tuolumne River above Tuolumne Meadows.

The pass closed at 7 p.m. tonight in advance of two storms that are approaching the Sierra Nevada. We left about 4:30 p.m. and while there, with once exception, I heard nothing on the park frequencies. I heard something on the law enforcement frequency (166.850) and thought it might be on Mt. Hoffman, but could not see the screen of the scanner with my sunglasses on.

As I type I'm listening to the law enforcement frequency on tone 3 (131.8) on my PSR-500 sitting next to me in my living room! This has got to be the most incredible tropospheric ducting I've ever come across. I don't have my PSR-600 upstairs at my listening post where I have the 600 connected to an amplified antenna on the roof, rather I'm hearing this on my handheld using the stock rubber ducky. I've never tried to monitor Yosemite NP from Mammoth before. There are two major obstacles in between Mt. Hoffman and here, the San Joaquin divide and the Clark Range on the southeast boundary of Yosemite NP. These two obstacles are substantial with Lyell Peak, the highest point in Yosemite NP, being part of the latter obstacle. I would love to have this happen all summer long and on the park net as well, but I expect it won't last but a day or two.

The last time I was in Yosemite in July I didn't pick up anything on the law enforcement net while kicking back at Tuolumne Meadow for several hours. LE units in the high country of the park were using the park net (172.650). The park net repeater on Hoffman uses tone 3, so I expected the LE net repeater there to be on the same mountain. I'm pretty sure that the LE repeater on Hoffman must have been installed this summer. I would guess that LE repeaters have also been installed at the Wawona and Crane Flat electronic sites as well.
 

SCPD

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The signal on 166.850 her is too consistent in quality and strength for ducting to be a factor. That leaves two possibilities: first, I'm receiving Mt. Hoffman direct; second I'm hearing some type of extender. As for the first, I doubt that is possible. There are too many topographical barriers to make that possible unless there is a very unusual knife edge path. Narrowband is used by Yosemite and these signals are very hard to receive at long distances. I used to receive the Yosemite park net on Hoffman in Bridgeport, but I had an antenna mounted at a 35 foot height and I knew what was making this possible topographically.

The second, and more likely possibility, is that some sort of extender has been installed locally to serve the LE ranger(s ?) at Devils Postpile. They have good coverage on the Mammoth Mtn. .Repeater Inyo North Net. The Inyo dispatcher is quite capable doing LE dispatch. There is 24 hour coverage as the Inyo goes out of service in the evening. The FICC dispatches for Death Valley NP, Mojave National Preserve and Joshua Tree NP, the San Bernardino NF and the Calif. Desert District of the BLM. They are very capable LE dispatchers that provide service to these entities. It would seem that this arrangement would be cheaper, however, they have to compete with, at times, a lot of fire traffic on the Inyo Net.

Yosemite provide LE dispatching for Lassen Nation Park via VoIP. I'm wondering if a similar situation is at play to have the Yosemite LE net cover Devils Postpile. In that case the repeater has to be on Mammoth Mtn. It is a difficult time of year to figure this out. This summer will be the time to figure this out and report back later. If anyone else has some knowledge about this situation feel free to jump in.
 

inigo88

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I can't comment specifically on the location of where you're hearing this from, but can at least help you determine if it is the YNP LE net you're hearing. The LE net is used in the valley as well so I would guess they have repeaters in the usual park net locations plus the valley net locations (i.e. Sentinel Dome and Turtleback).

As for deciding whether it's YNP LE you're hearing, I noticed last time I was there that the law enforcement unit IDs in Yosemite differ from any other NPS agency I've monitored. Instead of the usual 3 digit numeric ID (i.e. 100s, 200s, etc.) LE protection rangers use a letter and a number, and the letter corresponds to the area of patrol: Victor for Valley, W for Wawona, etc. If you notice their patrol vehicles actually have the unit ID magnetically attached to the back bumper. For example, here's a valley unit:



As for the Lassen National Park units being dispatched by the Comm Center at Yosemite, as far as I know they use a completely different channel and it's either a separate dispatcher or the same dispatcher working two different channels. There was a thread here a while back where someone went to an old lookout tower up at Lassen and posted photos of the radio site there, and I believe they also explained some of the unit IDs and channel usage.
 
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SCPD

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I confirmed that I'm hearing Yosemite's law enforcement from the first reception. The contents of that reception was "Yosemite, Tango 11, Hoffman." My CTCSS search resulted with a tone of 131.8 and on a frequency 166.8500, the Yosemite LE net. This is the tone for Mt. Hoffman on the fire and park nets as well. I've never monitored this frequency in Mammoth before as reception was highly unlikely. After returning from Yosemite on 1/17 I forgot to remove my Yosemite list from my PSR-500 from scanning. The reception came as a complete surprise to me.

Now I can't determine where this extender or additional repeater is located. My guess is Mammoth Mountain and the use is for the one or two law enforcement officers (Protection Rangers) at Devils Postpile National Monument (DPP). This monument had been a unit in the Sequoia-Kings Canyon National Parks management organization, but now has its own park superintendent.

The letter-number combination unit designators started at Yosemite about 8-10 years ago. The other National Park unit using this system is Grand Canyon National Park. There might be more, but I haven't monitored enough NPS units in the last 10 years to find out if there are more. This system only applies to protection rangers in each park's visitor and resource protection branch. The system in Yosemite is based on ranger district/sub-district units. Tango is the Tuolumne sub-district, Mike for the Mather district and Whiskey for the Wawona district. the Valley district has several letters in use. There are letters for each shift and other valley functions. There are other letters for park wide law enforcement functions. There was a thread about this some years back where many posters reported their observations about the designator system.

The letter on the back bumper is not likely the unit designator for the ranger inside the car. Yosemite and other large national parks do not have a vehicle assigned to each ranger, unless the duty station is somewhat remote. There are far more rangers in Yosemite than there are vehicles and they are shared by shifts and days of the week.

I have not monitored Lassen National Park in 10 years, during which time the law enforcement dispatch function was moved from the Susanville ECC (Cal Fire, U.S. Forest Service, BLM, Lassen NP fire and some local fire districts) to Yosemite NP. I'm not sure what the arrangements are for staffing. I don't think the LE traffic load at Lassen is enough to require a dispatcher be dedicated to it full time. Sequoia Kings dispatches for Pinnacles and I'm sure, in the case of this very small unit, that workloads did not have to be adjusted. In the case of Lassen/Yosemite some workload adjustments and funding from Lassen probably occurred. Of course, the LE net for Lassen is used.

The last two paragraphs are conjecture on my part based on the experience I gained working for the USFS. That experience included working closely with Yosemite for 7 years.
 
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SCPD

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By the way inigo88, nice picture. I think the number on the vehicle is similar to a shop number as used by municipal police departments and the CHP. I will have to see if LE vehicles outside the valley are marked in a similar fashion. It will be this summer before I can get over there again.
 

leonzo

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I volunteered at Yosemite during the summer of 2006. At that time there was talk of the dispatchers at Yosemite doing dispatch for several other National Parks. This is just conjecture on my part but are you close to another national park that is being dispatched by Yosemite? If so there is a chance that for dispatcher conveience they have patched different parks in together so when someone transmits on the Yosemite frequency it is being re-transmitted on another parks frequency that Yosemite is dispatching for. Just a thought....
 

SCPD

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Devils Postpile National Monument is the likely reason this repeater is installed somewhere in the Mammoth Lakes area. I'm thinking it links into Mt. Hoffman somehow. That is the only LE repeater I'm receiving over here. I think they may be using a VoIP link (voice over Internet Protocol). VoIP is used to link the Lassen NP radio system to Yosemite. or so I've heard. I don't believe the listed input frequency is correct.

Devils Postpile was using the Inyo NF net for dispatch services. The Inyo has been using the Federal Interagency Communications Center in San Bernardino for overnight coverage. I think the Postpile wanted a net where they weren't competing with fires and other incidents.

I'm not sure what other National Parks Yosemite could be dispatching for. The Whiskeytown National Recreation Area is one possibility as the other NPS units in northern California have their own dispatch center with the exception of Pinnacles and they are dispatched by Sequoia-Kings and Lassen.

In the Lassen situation Yosemite controls the Lassen's net. Yosemite does not patch the other parks onto their net.
 
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ecps92

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Much of the NPS [from what I have been told] is now VOIP for linking and access to the various repeaters. I have even heard the Radios Techs can remote in from anywhere, which is interesting.

Devils Postpile National Monument is the likely reason this repeater is installed somewhere in the Mammoth Lakes area. I'm thinking it links into Mt. Hoffman somehow. That is the only LE repeater I'm receiving over here. I think they may be using a VoIP link (voice over Internet Protocol). VoIP is used to link the Lassen NP radio system to Yosemite. or so I've heard. I don't believe the listed input frequency is correct.

Devils Postpile was using the Inyo NF net for dispatch services. The Inyo has been using the Federal Interagency Communications Center in San Bernardino for overnight coverage. I think the Postpile wanted a net where they weren't competing with fires and other incidents.

I'm not sure what other National Parks Yosemite could be dispatching for. The Whiskeytown National Recreation Area is one possibility as the other NPS units in northern California have their own dispatch center with the exception of Pinnacles and they are dispatched by Sequoia-Kings and Lassen.

In the Lassen situation Yosemite controls the Lassen's net. Yosemite does not patch the other parks onto their net.
 
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