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P L tones

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gewecke

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Do rail road companies use P L TONES? I am in NW Louisiana searching for L & N W railroad I found what sounds like RR 159.945. Dcs 351
Usually no, but they might in some areas. We have UPRR here and they don't. 73, n9zas
 
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#3
Yes - Some Do using PL/DPL for signalling which TX Site is being used, other for Repeater access, others for Bases only, some for Trains only, YMMV

Do rail road companies use P L TONES? I am in NW Louisiana searching for L & N W railroad I found what sounds like RR 159.945. Dcs 351
 

Railham_CJ

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Do rail road companies use P L TONES? I am in NW Louisiana searching for L & N W railroad I found what sounds like RR 159.945. Dcs 351
160.53000 BM CSQ L&NRR-ROAD Road Operations Gibsland, La. to McNeil, Ark. FM Railroad Pulled it from the Radioreference Railroad section of Louisiana.
 

Railham_CJ

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#8
To add confusion to the mix, at least one RR near me has gone to NXDN digital.
Railroads Scanner Frequencies and Radio Frequency Reference
Adrian & Blissfield
Operations

This is the new NEXEDGE TRS used by the Adrian and Blissfield Railroad Company that is currently being constructed. Long-term plans call for this digital radio system to be expanded to other railroad lines they operate in the state of Michigan:

Lapeer Industrial Railroad
Charlotte Southern Railroad
Detroit Connecting Railroad
Jackson & Lansing Railroad
Tecumseh Branch Connecting Railroad
 

PJH

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#10
ecps is correct.

To expand on it, for interchange purposes all comms are CSQ as the locomotive radios by default transmit that way do to selectable programming "on the fly".

Certain firmware BNSF Kenwood radios also support this.

In both cases, the locomotive radio can be preprogrammed with "home channels" that may include PL tones. This is typically limited to short line, switching and even some regional railroads as their locomotives are not subject to interchange and will remain on home rails.

As previously stated, you'd find it more common that for yard repeaters, or specific functions PL tones are not in wide spread use.

Conrail did add a PL tone to train defect detectors. The Motorola Railroad Spectra had a feature that could display a preformatted message on the display. The detector would transmit PL 127 (IIRC) with a no defects message and another PL tone if there was a defect. The display would change to reflect the same while the TDD was transmitting.
 

N9JIG

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#11
There are scattered use of PL tones on the rails. In the Chicago area there are a couple special use repeaters at or near Union Station that use PL or DPL. These include a carmen's channel in the yard and the police repeater in the station itself (which seemed to work well out into the far suburbs!).

The CSS&SB uses PL on 161.025 (173.8) when on Metra trackage I suspect this is so their HQ can hear them and not listen to the Metra-Electric trains.

I noted a couple towers that transmitted PL on their base radios but I suspect they were programming errors. Deval Tower transmitted a PL on the old Soo Line channel 161.085 years ago for a couple months, I came to find out they had replaced a bad base radio with a deskset after a lightening strike.

Conrail (and NS after they took over the line) had PL on the defect detectors in NW Indiana on the "Chicago Line". IIRC (It has been a few years...) they used 100.0 or 186.2 (depending on which detector) for no defects and a different one for defects detected.

While PBX systems are much less used these days they often used PL, at least on the inputs. I have also noted that many yard repeaters, especially with those using remote control switchers, have PL on the inputs but usually not on the outputs.

As far as locomotive radios I have rarely found then transmitting PL on road channels. In the year or so I have lived in Arizona I have only seen it a couple times. Once on the BNSF out of Wickenburg and once in the UP at Gila Bend, I suspect it was unintentional. Out on trips I occasionally see this from time to time but not on a regular basis.


While not PL, one used to be able to tell if a BN unit was being used on a train by hearing an MDC code at the end of the transmission. The area I lived in in Illinois was too far away to hear BN trains directly but it was common for BN units to lead on the Soo/WC/CN, EJ&E, or Milwaukee/Soo/CP/Metra MD-N lines on coal and run-thru and they almost always had MDC codes (Post). they never seemed to match the locomotive number though, since radios were swappable. I think this ended after the BNSF merger however since I don't hear them now. I suspect they used it more as a courtesy beep type system rather than as a true ANI.
 
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CT1396

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#12
I discovered Amtrak regularly using pl103.5 on 160.920 from what I can monitor of the northeast corridor, Springfield, and MRS lines.
 

PJH

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PBX systems may have had an output PL but not input. This was due to the locomotive radio limitation - and didn't matter as you needed the DTMF access codes to dial the company lines.

All legacy SP, UP, BN and SF systems are still setup this way (as I have used three of the four).

In addition, back "in the day" PL boards or options usually were not purchased by the railroads - due to cost and many radio models did not support it. The lunch box radios and early loco radios (usually four channels) just didn't support it.

Remember these were the days of channel elements and had to withstand the vibrating use. EEPROM or PROM based programming wasn't until the mid to late 80's in general - and the railroad spectra didn't pop up until the early 90's

Such radios cores were standard commercial radios with custom interfaces for the user, and with the exception of Riton, basically is still that way today (JEM, Nexterma and I beileve GE's).
 
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#16
In the New York area NYCTA has used PL on RTC and PD since the mid 80's, Metro North has used PL on Rail Traffic and PD channels since the 90's,and LIRR and New Jersey Transit all have PL but not sure when they added it.
I would like to see a Nationwide PL used to correct for some of the noise that's created by Fax Machines, LED and CFL bulbs and other sources. Narrow Banding in 2013 would have been a perfect opportunity to do that, but that was missed due to the laziness of a number of RR that travel our territiory.

Qutoe"I think 159.945 is a business/industrial frequency but in Louisiana
it's licensed as such to Louisiana & Northwestern RR"

We have numerous licenses that are plain old business channels, sometimes it's the only ones available in large markets like NYC
 

N9JIG

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#17
In the last 25-30 years I have been listening to railroad radio I have never seen a PBX system with PL on the output, only the input. The idea is to avoid having the output of one PBX repeater from activating a distant repeater. Thus the inputs use PL and the output does not. This is much the same on many other railroad band repeaters.

Since there are a limited number of channels this is very important. When conditions are up these repeaters can activate a CSQ input hundred of miles away.

PBX systems may have had an output PL but not input. This was due to the locomotive radio limitation - and didn't matter as you needed the DTMF access codes to dial the company lines.

All legacy SP, UP, BN and SF systems are still setup this way (as I have used three of the four).

In addition, back "in the day" PL boards or options usually were not purchased by the railroads - due to cost and many radio models did not support it. The lunch box radios and early loco radios (usually four channels) just didn't support it.

Remember these were the days of channel elements and had to withstand the vibrating use. EEPROM or PROM based programming wasn't until the mid to late 80's in general - and the railroad spectra didn't pop up until the early 90's

Such radios cores were standard commercial radios with custom interfaces for the user, and with the exception of Riton, basically is still that way today (JEM, Nexterma and I beileve GE's).
 

PJH

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#18
I can tell you with 100% certainty that all the remaining (and looking at my old work stuff) that the PBX systems on UP, SP, ATSF and BN from Kansas to the left coast was DTMF activated for the closest tower. The few existing DRGW ones are also DTMF (should see the old stuff still at tower sites on TP).

Each area (if PBX equipped) had a different activation DTMF sequence. This prevent the other towers from coming online.

Again, locomotive radios and field radios would have been useless to use these as PL tones were not programmed in. This would only leave site specific vehicles to use these towers and leave train crews and regional/system gangs without a means to use the interconnect.

Because of the influx of new radios and narrowbanding (though a few stragglers out there) some site and area specific operations are using PL tones and repeaters. These can only be used by locally issued radios.

Recently out my way the railroad came out with area wide repeaters for conductors in the mountains. Initially these too were DTMF only repeaters but after some changes, they can be turned on by DTMF or PL tone.

NS and CSX only currently use DTMF PBX activated sites that I have come across and in the current TT's.

There may have been site specific uses, but by no means was it a common feature due to radio limitations when they were installed.

There are conductors I have met that still have their 8channel MX300's that were issued many moons ago.

The general accession on radios by "on ground" personell that would be using them (including MOW) was the PT500, MX300, MT500, MT1000, HT1000, MT2000, Kenwood 7180, NX210 and similar models.

Mobiles were of similar vintage and equivenelt models.
 

N9JIG

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#19
My point was that there is no reason (and the railroads didn't and generally don't) use PL's on the output of the PBX repeaters or bases, especially when/if the repeater uses CSQ on the input. This would be backwards of common sense and defeats the purpose of PL use in general.

It is possible that you misconstrued the post and saw DTMF when it was PL under discussion. You are absolutely correct in that most PBX repeaters were (are?) DTMF activated, few if any used PL on the input and even fewer would use PL on the output and they would almost never use CSQ on the input with PL on the output.

Now, there are some other railroad repeaters out there that do use PL either on the input only or on both the input and output, these are mostly yard or special purpose uses, not PBX.

PBX systems were/are mostly pretty generic repeaters or remote bases with controllers that used DTMF and interconnected with the railroads internal phone system, some of them also allowed access to the PSTN ("Bell") with special access codes.

I don't recall hearing any PBX systems that muted the DTMF tones on the output, I usually was able to decode them pretty easily with my various DTMF decoders.
 

PJH

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My point was that there is no reason (and the railroads didn't and generally don't) use PL's on the output of the PBX repeaters or bases, especially when/if the repeater uses CSQ on the input. This would be backwards of common sense and defeats the purpose of PL use in general.
It was used buy Telecommunications to determine which site was being brought up for range adjustments. Telcom radios were programmed with PL's on those channels (and others) and drive around to adjust coverage or major site changes. It was a poor mans way to do it when proper equipment wasn't available. As an output PL didn't matter for CSQ radios - no big deal. Many were also set for PL passthru.

We recently turned down a legacy system that was interconnected to four different states. Amazing on how long the old Motorola MICOR and MSF5000's lasted and well they performed
 
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