Mojave Nat'l Preserve - Database

[es93546]

Within the last 1-3 weeks a revision to the database listing for Mojave National Preserve was made to show the following:

169.9875 out / 164.0875 in

Tones:

110.9 Kelso
123.0 Clark Mtn.

Some years back I was advised by a person at the visitor's center that the tones were as follows:

T1 110.9 Providence Mtn.
T2 123.0 Clark Mtn.
T3 131.8 Christmas Tree Pass

Within a year or two I had driven enough in that area to confirm all the tones and locations. This tone plan was shared with me as I'm related to the person that owned the Kelso Train Station property, which was later donated to the National Park Service. I'm not sure without this "in" I would have been given the info when I asked the question. Anyway, I trusted the info due to this connection. The submission of "Kelso" for Tone 110.9 is likely Providence Mtn. as it is the closest high point to the train station and a repeater right at Kelso doesn't make sense. So I believe the listing should show the mountain, not the train station location. It's been a few years, but I confirmed that location for the tone, 131.8. I think I submitted this information just after confirming it. I think there is sufficient info to list the tones as I show above, per the NPS employee.

What do others think here? I'm not sure of the validity of the info someone else submitted recently.

 

[mcjones2013]

Per the database administrator handbook, input tones are not to be listed in the database.

Only output frequency tones shall be entered in the RR database. Do not enter input frequency tones except in the case of Amateur Radio frequencies (where known).

 

[avdrummerboy]

As the one who submitted the recent info, I can say that it came from an Interop bank in a radio, and the channel is listed as Kelso. My guess would be that it is for users to know which channel to use in which geographic area, not necessarily which mountain top repeater they are utilizing, as most end users don't really care so much as the radio works when keyed up. That being said, you are most likely correct in terms of the repeater site location and the database can surely be changed to reflect that. As to input tones, I've seen that a great many repeaters simply pass through the input tones, therefore there is a good chance that the listed output tones will also happen to be input tones. I know this isn't always the case, for example the county fire VHF repeaters in SBD County having one output tone with many input tones, but for many NPS and USFS repeaters I see this to be the case.

 

[es93546]

As the one who submitted the recent info, I can say that it came from an Interop bank in a radio, and the channel is listed as Kelso. My guess would be that it is for users to know which channel to use in which geographic area, not necessarily which mountain top repeater they are utilizing, as most end users don't really care so much as the radio works when keyed up. That being said, you are most likely correct in terms of the repeater site location and the database can surely be changed to reflect that. As to input tones, I've seen that a great many repeaters simply pass through the input tones, therefore there is a good chance that the listed output tones will also happen to be input tones. I know this isn't always the case, for example the county fire VHF repeaters in SBD County having one output tone with many input tones, but for many NPS and USFS repeaters I see this to be the case.

Many federal natural resource agencies pass the input on to the output. Your point is well taken. I seem to remember that Mojave NP passed their on. I know Yosemite and Death Valley do. Joshua Tree NP has a multicast system with only one input and input tone, which then uses a voter to select which repeater carries the signal and all repeaters transmit the same signal to all points in the park. Whatever the output tone of the repeater should be shown in the database as it helps the listener determine what repeater is being heard.

When I got the info from the NPS employee the radio showed Providence, Clark and XMAS Tree on the radios channel plan taped to the battery of the King radio. Nearly all the radios of the USFS I've looked at, as well as written channel plans, the repeater location is shown. The 2021 R5 Frequency Guide lists the repeater location and the associated tones. Based on this, I respectfully disagree that users don't really care so much about the repeater location given that location being the standard of how channel plans are printed. Some local unit user's guides will list each repeater by location then show what areas each repeater covers.

 

[f40ph]

All 3 MNP repeaters send tone 1 (110.9) on their output freq.

 

[es93546]

All 3 MNP repeaters send tone 1 (110.9) on their output freq.

Either I recalled incorrectly or there have been some changes since I was last down there specifically to monitor and test their system. Whatever, the effect is the same. Thanks for letting me know.

As the one who submitted the recent info, I can say that it came from an Interop bank in a radio, and the channel is listed as Kelso. My guess would be that it is for users to know which channel to use in which geographic area, not necessarily which mountain top repeater they are utilizing, as most end users don't really care so much as the radio works when keyed up. That being said, you are most likely correct in terms of the repeater site location and the database can surely be changed to reflect that. As to input tones, I've seen that a great many repeaters simply pass through the input tones, therefore there is a good chance that the listed output tones will also happen to be input tones. I know this isn't always the case, for example the county fire VHF repeaters in SBD County having one output tone with many input tones, but for many NPS and USFS repeaters I see this to be the case.

The terrain of the preserve is such that I don't think they can cover the northeastern portion of it from Providence and from Clark so it makes sense that XMAS tree would be the logical choice for another repeater. However, this is speculation on my part, they may have found that they only needed two of the three repeaters the installed many years ago. I'd love to swing by there when we travel to Arizona this fall sometime, if Covid in Arizona allows us to.

 

[Tower5153]

As of March 2021

 

[AM909]

Assuming channel 14 above, "DVP Repeater", is Death Valley National Park, there's a discrepancy with the RRDB page, which shows the repeater output freq as 170.1 instead of 171.1.

Also, I don't know how common it is, but should there be a mention at Air Plan of potential use of tone 1 (110.9) on 168.625? I realize it's unusual to listen to a guard channel with anything other than CSQ, but the tone is shown in Cal-IFOG, too.

 

[KK6ZTE]

Assuming channel 14 above, "DVP Repeater", is Death Valley National Park, there's a discrepancy with the RRDB page, which shows the repeater output freq as 170.1 instead of 171.1.

Also, I don't know how common it is, but should there be a mention at Air Plan of potential use of tone 1 (110.9) on 168.625? I realize it's unusual to listen to a guard channel with anything other than CSQ, but the tone is shown in Cal-IFOG, too.

It's standard procedure to program Guard with a TX tone (110.9) only. Air units have the option to receive with a tone if they're getting interference.

 

[es93546]

Also, I don't know how common it is, but should there be a mention at Air Plan of potential use of tone 1 (110.9) on 168.625? I realize it's unusual to listen to a guard channel with anything other than CSQ, but the tone is shown in Cal-IFOG, too.

It's standard procedure to program Guard with a TX tone (110.9) only. Air units have the option to receive with a tone if they're getting interference.

Up until the last year or two, the "Interagency Standards for Fire and Fire Aviation Operations," commonly referred to as "The Redbook" stated that National Air Guard was to be programmed with a tone of 110.9 (national standard Tone 1) in both the transmit and receive sides of all radios with this frequency. I rid my travel notebooks of all previous versions of portions of the Redbook and the "National Interagency Aviation Frequency Guide," plus other memos showing the nationally used frequencies. I was going to quote these sources to show that Tone 1 is required on the receive side, but the latest sources just state "A Continuous Tone Coded Squelch 1 System (CTCSS) tone of 110.9 Hz must be used when transmitting on the 2 National Air Guard Frequency." I hadn't noticed this subtle change or when, prior to 2020 it became effective. I know Air Guard required it on TX and RX, but it was only required for TX on "National Flight Following" on 168.6500. This difference used to make me wonder why, but without that difference I have a new mystery. How many pilots are able to reprogram their VHF-FM radios to enable code guard or PL on the receive side when they experience interference? My impression is that commercial pilots are pretty radio savvy, but I still have to ask the question.

Assuming channel 14 above, "DVP Repeater", is Death Valley National Park, there's a discrepancy with the RRDB page, which shows the repeater output freq as 170.1 instead of 171.1.

As far as I know, the "Park Net" at Death Valley NP is still 170.1000. The 2021 USFS R5 Frequency Directory it shows 171.5000. Is this an error or has a change been made? I think it is an error as Sequoia-Kings Canyon uses this frequency for its multicast "Frontcountry Net." It is a 4 hour drive to Furnace Creek from my place, but there is a small area south of me about a 20-25 minute drive where I can hear Rogers Peak on this net. "When I get a chance . . . . "

I have noted an error on a previous page of that directory that I've noticed for 3-4 years. This year's version of the guide has an email address for the person who puts this guide together who asks for help "maintaining and improving the accuracy of this guide . . . " I'm going to listen to DVP to confirm 170.1000 or 171.7000 and pass along any other errors I've found, at the same time.

 

[AM909]

@Tower5153: From where was the image you posted (regarding the 170.1/171.1 discrepancy)?

 

[AM909]

This was possibly the source for the existing DV DB info, with which some here may be familiar.

 

[KK6ZTE]

How many pilots are able to reprogram their VHF-FM radios to enable code guard or PL on the receive side when they experience interference? My impression is that commercial pilots are pretty radio savvy, but I still have to ask the question.

They don't have to. The TDFM-9000 radio system will have one of it's (up to 6) decks devoted to GUARD, and that radio will only have two channels programmed, GUARD with receive tone squelch, and GUARD without.

The last radio module is dedicated to Air Guard. It has only two channels: 1 – Air Guard (168.6250 & 110.9 TX) and 2 – Air Guard RtTt (168.6250 & 110.9 RX/TX).

 

[Tower5153]

@Tower5153: From where was the image you posted (regarding the 170.1/171.1 discrepancy)?

It’s from the 2021 R5 Radio Guide

 

[es93546]

They don't have to. The TDFM-9000 radio system will have one of it's (up to 6) decks devoted to GUARD, and that radio will only have two channels programmed, GUARD with receive tone squelch, and GUARD without.

Thanks for that info!

 

[ME801]

Unless DVP has changed their freq since 2103 (when I transferred out of DVP) the mountain top output is 170.100.
I'm now retired from NPS, when I was at DVP the SysAdmin retired and I was voluntold that I would have the collateral duty of Communication Manager overseeing the radio and SatComm system and I was the primary POC with San Bernardino (FICC). I just found one of my old codeplugs and verified the freq.

 

[AM909]

Unless DVP has changed their freq since 2103 ...

Can you confirm you meant 2013, or was it 2003? Thanks.

 

[ME801]

My mistake, 2013. And yes we shared frequencies with other federal land management agencies.

 

[inigo88]

Can confirm along with the others, I was recently visiting the area and the DVP REPEATER output is still 170.100. Looks like the screenshot of that frequency directory has a typo (which does happen).

 

[AM909]

Can confirm along with the others, I was recently visiting the area and the DVP REPEATER output is still 170.100. Looks like the screenshot of that frequency directory has a typo (which does happen).

I'd be concerned that that typo has been loaded into radios somewhere, either because a radio load file was used as for the source of that guide, or someone downstream of it has used it. Assuming @Tower5153 meant the USFS 2021 R5 Radio Guide, perhaps they, or someone else with a contact in their radio shop, will let them know about it. I'd hate for someone to find the error when needing to use a radio that's been mis-programmed.