UHF Santa Monica Mountains National Recreation Area UHF Link

[iscanvnc2]

I recently came across 410.9125 PL203.5 which appears to be a 2-way link between the Santa Monica Mountains National Recreation Area (SMMNRA) VHF-Hi repeaters and dispatch. This has been verified by monitoring 410.9125 & 2 of the SMMNRA repeaters simultaneously with 3 scanners.

Dispatch IDs as “Santa Monica”. Just a while ago they were called by LE75. Transmissions are very infrequent, maybe hours apart.

Before entering into the RRDB, it would be nice to have more info on the exact use of 410.9125 to best enter it into the DB.

 

[iscanvnc2]

5:23 PM "Resource 724 out of service".
This is only the second transmission I've heard since my original post two hours ago. The other I heard from another room and couldn't copy.
My point being how scare transmissions are. Hopefully over the weekend things will pick up.

 

[ecps92]

See what you hear on 419.9125
is 410.9125 the downlink from the Mountain Top [ie Remote RX] or is this the uplink from the Dispatch site ?
it could [YMMV] be only a remote from one site [Repeater]

Keep monitoring and see if you get more than one tone.
Out east [my area] these are CSQ and the PL changes depending on the Repeater they wish to Access

I recently came across 410.9125 PL203.5 which appears to be a 2-way link between the Santa Monica Mountains National Recreation Area (SMMNRA) VHF-Hi repeaters and dispatch. This has been verified by monitoring 410.9125 & 2 of the SMMNRA repeaters simultaneously with 3 scanners.

Dispatch IDs as “Santa Monica”. Just a while ago they were called by LE75. Transmissions are very infrequent, maybe hours apart.

Before entering into the RRDB, it would be nice to have more info on the exact use of 410.9125 to best enter it into the DB.

 

[iscanvnc2]

Thanks ecps92 for the 419.9125 MHz tip. I should have thought of it myself.

With one scanner on 172.525, one on 410.9125, the third on 419.9125 here are the analog results:
1. 410.9125 (PL203.5) & 172. 525 (PL 110.9) transmissions are simultaneous, both dispatch & mobile.
2. 419.9125 (PL 110.9) is dispatch only and precedes 410 &172.

Assume dispatch initiates an exchange. It will be heard first on 419, delayed on 410 & 172 through the exchange.
Mobiles are heard on 172 & 410, but NOT 419.

So it appears that 419.9125 is the uplink & 410.9124 the down link.

Now to find the NACs when they go P2 5 which is extremely rare.

 

[ecps92]

So to add one more Freq for you
if 410 is the downlink, you should only get the PL/NAC from the Repeaters, so it they only have one [110.9] then you are fine
if 419 is the uplink, you should only get the PL for the Repeater they are accessing, so with that said, it will vary if multiple Rptrs
the 16x.xxxx input for that repeater is likely using 203.5 [older notes,etc, but is 164.1625 still the input ?]

so the next question becomes, what Repeater uses 203.5 as the input ?

Thanks ecps92 for the 419.9125 MHz tip. I should have thought of it myself.

With one scanner on 172.525, one on 410.9125, the third on 419.9125 here are the analog results:
1. 410.9125 (PL203.5) & 172. 525 (PL 110.9) transmissions are simultaneous, both dispatch & mobile.
2. 419.9125 (PL 110.9) is dispatch only and precedes 410 &172.

Assume dispatch initiates an exchange. It will be heard first on 419, delayed on 410 & 172 through the exchange.
Mobiles are heard on 172 & 410, but NOT 419.

So it appears that 419.9125 is the uplink & 410.9124 the down link.

Now to find the NACs when they go P25 which is extremely rare.

 

[iscanvnc2]

Sorry for the delay in replying. Partly due to infrequent, brief transmissions.
I now am using four scanners.
Repeater input is the same, 164.1625/PL 110.9, for all three repeaters (169.7875, 171.725, 172.525).
My notes from ages ago, as well as RR DB, show PL 127.3 for 169.7875. Apparently this has changed to PL 110.9.
My notes and current monitoring show no PL 203.5 in connection with SMMNRA.

 

[es93546]

Keep in mind that dispatch is located at Fox Field in Lancaster. Dispatch used to identify as "Angeles," which is the USFS Angeles National Forest dispatch center. It is a 24 hour center year round. I don't think the change in dispatch ID reflects a change in dispatch locations though. The California Interagency Mobilization Plan of 2021 shows that Fox Field is doing the dispatching for the SMMNRA. I will look to see if this has changed when the 2022 version comes out in a couple of months.

Prior to the switch in UHF federal band frequency allocation most downlinks repeated the uplink. However, since the new allocation of uplinks always being 9 MHz higher in frequency I haven't found one system where the uplink is repeated on the downlink.

I would think that there is more than one UHF hop from Fox Field to the repeaters on Castro, Laguna and Solstice, the electronic sites my information currently shows for the NRA's radio system. This unless there is a microwave link from Fox to the remote base that controls this system.

My notes show the following:

169.7875/162.2375 T12 (127.3) Solstice - Park Net
171.7250/164.1625 T1 (110.9) Laguna - Park Net
172.5250/164.1625 T1 (110.9) Castro - Park Net
172.5250/ ? NAC 455 Digital Park Net
172.5750/ ? T1 (110.9) Park Net - Location?

I don't live in southern California and haven't monitored the system since the last time I was down there in 2012. I assume Laguna and Castro, given that the input frequency and tone are the same have a mobile voting system. Also, the listing of a repeater on 172.5750 with an unknown input frequency using Tone 1 would indicate another voted repeater. Why "Solstice" has a different input frequency and tone is another mystery or is an error. I don't recall where I got this information.

The infrequent radio traffic reflect the smallish number of employees the NRA has. There is a shocking decline in the number of rangers, both protection and interpretive, helping manage the National Park System.

OPTIONAL SOAPBOX MATERIAL: I wish a higher priority was placed on purchasing land inside the NRA boundary. Each time a private parcel is developed, the values of having the land in public ownership is lost, the open space is degraded, the Congress established the NRA here to prevent this. I grew up in southern California and used to hike and drive in the area, but I moved away 47 years ago. I imagine the amount of development would be a shock to me if I returned. There is a fund that provides for federal land purchases, part of the royalty from oil and gas leases. Most years this fund is 800 million to 1 billion dollars. It sounds like a lot of money, but the demand is very high given the number of private inholdings within the boundaries of National Parks, National Forests, National Wildlife Refuges, the BLM's National Conservation Lands System and similar.

 

[es93546]

There is one more possibility for dispatch that I thought of considering the "Santa Monica" dispatch ID. I wonder if the dispatching is now being done by the Sequoia-Kings Canyon NP (SEKI) dispatcher at Ash Mountain (SEKI HQ). "Sequoia" as the dispatcher is known as at SEKI, is providing service for Pinnacles NP and when contacting the SEKI dispatcher they use the ID of "Pinnacles." I think it is possible that SEKI could use the Pinnacles net without a computer link from SEKI, but with a remote base on a nearby peak. I would not surprise me if the Santa Monica Mountains NRA is using the SEKI dispatcher. Channel Islands is recently confirmed to be using them. The NPS tends to favor providing dispatch services for their own units. Obviously there has to be some type of radio over internet protocol employed for these Channel Islands and SMMNRA, which are both shielded by topography from Ash Mountain. If this is the case I wonder where the UHF uplink transmits from.

 

[iscanvnc2]

You are correct about CINP being dispatched by "Sequoia". Listen to them all the time. For the last 15 minutes CI units on the various islands have been signing off.

Since SEKI dispatch IDs as "Sequoia" for CINP, why wouldn't they do the same if dispatching for SMMNRA?

Working on reply to your previous message. Standby.

 

[iscanvnc2]

Es93546 posted several factors I was about to bring up. I don’t “babysit” SMMNRA. It’s one of umpteen agencies I scan. As long as things go along as usual it can be months (years?) before changes are noted and you begin investigating.

For instance it was only recently that a realized dispatch ID switched from “Angeles” to “Santa Monica”.

Question: Has Angeles National Forest dispatch center always been at Fox Field? If not, where did it move from & when?

The notes of Es93546 are the same as the RR DB & are repeated here with my comments.

169.7875/162.2375 T12 (127.3) Solstice - Park Net
Tone is (110.9)

171.7250/164.1625 T1 (110.9) Laguna - Park Net
Not heard. Formally loud & clear with other two VHF repeaters. Discontinued?

172.5250/164.1625 T1 (110.9) Castro - Park Net
OK

172.5250/ ? NAC 455 Digital Park Net
Digital extremely rare. Not heard in days. NAC 455 last I heard.

172.5750/ ? T1 (110.9) Park Net - Location?
Never heard.

 

[es93546]

The Angeles Dispatch Center has been at Fox Field for at least 30 years. It's been over 40 since the Angeles National Forest moved out of its Forest Supervisor's Office in Pasadena. When it was there it answered to "Pasadena." I had a supervisor when I worked on the Kaibab NF in Arizona, who had transferred from the Angeles. When I transferred into California, but on the Toiyabe NF in Region 4, in 1981 all the R5 forest dispatchers were ID'ing using the forest name. I then transferred into R5 in 1988 and the dispatch center was at Fox Field then. Due to budget constraints the Angeles moved their forest supervisor's office to Arcadia where they owned some property. I think the dispatch center was located there for a short period. Since they have had a air operations center at Fox since Moses got out of boot camp, moving dispatch there was a good move. However, you can't just drop in for a visit as easily as you could when it was in the supervisor's office. There has been a great deal of moves, colocations, and consolidations in dispatch centers in the 40 plus years I've been in California, but the Angeles Dispatch Center has remained much the same for all of it.

I wonder how it links to the SMMNRA system from Fox. I don't think any of my insider notes show the NPS system, just the USFS system. I will look just in case.

 

[iscanvnc2]

Very interesting about the Angeles Dispatch Center. Thanks, es93536 for history lesson.
I agree with your statement that it would take more than a single hop from Fox to reach SMMNRA re;eaters and a combination of microwave wi

 

[iscanvnc2]

Very interesting about the Angeles Dispatch Center. Thanks, es93536 for history lesson.
I agree with your statement that it would take more than a single hop from Fox to reach SMMNRA re;eaters and a combination of microwave with the UHF links is most likely. Assuming microwave is used to reach ANF repeaters, it would make sense to include SMMNRA traffic to one of their mountain top sites and switch to UHF. At least one of the ANF repeaters booms in here in Venture.

If ANF was using UHF, you would think it be in the RR DB.

Sorry about the inadvertent "send".