Mammoth/June Mountain Radio System Changes

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SCPD

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These ski areas have made many changes in their radio systems this winter. I'm just beginning to sort it all out. The biggest change is a plan (which may have been implemented already) to install a trunked system for June Mountain. They have licensed it for installation down in the town of June Lake, presumably so it will not interfere with the system on Mammoth Mountain. The June Lake system uses five frequencies that are also used in the Mammoth system.

The June Mountain ski area is located on the north side of a ridge that blocks the view of Mammoth Mountain from the June Lake area. The June Mountain ski area looks down on the June Lake area and so a trunked site in town should provide coverage for the ski area. What I can't figure out is how handheld and mobile radios (in grooming equipment) distinguish which system to affiliate with when on top of the ridge where the trunking sites on Mammoth Mountain and June Lake are simultaneously line of sight. I also presume that the radios from each ski area are interchangeable, which is why ridge top operation causes me to scratch my head. It can't be a smart zone type system as there is duplicate frequency use at the two adjacent sites.

Does anybody have any thoughts on how this would work?

The Mammoth Mountain trunked system employs the five frequencies discussed above plus a few others. The use of these other frequencies has been changing throughout the winter. I will attempt to sort this out as well and submit my findings to the database. In the meantime, anyone who comes to ski at Mammoth Mountain this winter that does not have a "control channel only" mode on their scanner will have some difficulties monitoring the trunked system.
 

karldotcom

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Are you sure they arent just linking the two resorts within one licensed system? The main Mammoth Transmitter appears to be on the top of the mtn....they could point a microwave link to the June Mtn site and simulcast....although I dont know if that would work during heavy snow.
 

SCPD

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They don't have any microwave licensed. The licenses for the Mammoth/June Ski Areas (both owned by Mammoth Mountain) show a trunked site on top of Mammoth Mountain in the upper gondola building and in the village of June Lake on the north side of Gull Lake. The June Lake site is completely blocked by a ridge nearly 3,000 feet higher than it so it is obvious that the systems are designed to operate independently.

I suppose the two sites could be linked via phone lines, but this would not be Mammoth Mountain's style, which is to do as much "in-house" as possible. They have never had an outside firm errect a chairlift or gondola, something that only the smallest of ski areas can possibly say. They have the largest parts warehouse for both commericial vehicles and snowcats between Reno and L.A. They have their own tractor-trailer rigs for picking up their own supplies from distant locations. They built and maintain their own phone system as well.

I will be visiting June Mountain on Monday and plan to monitor their old system and the newly licensed system in town. It is possible that the new system isn't installed yet, so the trip may not solve the mystery.

This is a great weekend to monitor the system at Mammoth Mountain. Town is about 99% full this holiday weekend so the trunked system is real busy. So far it appears that 3 of the 4 newly licensed 800 MHz frequencies have been added to this system. That would bring the total to 8 frequencies, allowing 7 simultaneous conversations. I will have more information after monitoring for a few more days.
 

zz0468

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They could be using a part 15 microwave link, in which case no license would show up. They could also be simulcasting the two sites, which would handle the frequency reuse problem very nicely. BTW, a properly designed microwave link wouldn't care if it's snowing or not.
 

SCPD

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I figured out the Mammoth Mountain system. I haven't been able to get up and figure out the new June Mountain system. They are not simulcasting as there isn't any June Mountain traffic being simulcasted on the Mammoth Mountain system. I doubt the systems are linked as it usually takes a very substantial microwave installation to survive the conditions found on the peaks in the Sierra Nevada. That is why I don't think it is an license exempt, Part 15, system, but I could be wrong as I'm not familiar with those systems.

I submitted what I found out about the Mammoth Mountain trunked system changes to the database and explained it all in a post to the "new information wanted" sticky thread.
 
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