PTC side of track Antenna Tower - mast - pole

[Cameron314]

Can't say I've ever seen a 900mhz folded dipole. The one in the picture sure isn't one.

 

[MCWKen]

This is a typical Union Pacific installation. Off to the right of course is the signal/switch com, a 900 mhz yagi. I have seen a few where they use a fold down 'tower', but most are of a steel or wood pole.

 

[ak7an]

220 Mhz folded dipoles.. allows each signal location to talk to each other. Has nothing to do with taking to the trains.. That is done via cell or sat and those signals come from the PTC server that is integrated with the CAD system at a central location. The 900 MHz is for CTC control and indications for the Central CAD. Each Signal location talks to the PTC server via cell.
UP Signal Tech..
Ed
AK7AN

 

[iceman977th]

220 Mhz folded dipoles.. allows each signal location to talk to each other. Has nothing to do with taking to the trains.. That is done via cell or sat and those signals come from the PTC server that is integrated with the CAD system at a central location. The 900 MHz is for CTC control and indications for the Central CAD. Each Signal location talks to the PTC server via cell.
UP Signal Tech..
Ed
AK7AN

For a UP signal tech, you sure are spreading a lot of wrong information, along with most everyone else on this post.

Without knowing the exact layout of the location posted in the OP's post, it's hard to exactly say, but here's a good place to start. As Tom said, you won't see folded dipoles in the 900MHz band, they just aren't practical, not to mention the pictures shown in this topic clearly shows dipole elements that are tuned for the VHF band. So, they are either tuned for 160-161MHz for voice communication or VHF codeline control (ARES protocol or similar) or they are tuned for the 220-222MHz band for the ITC network (which contains crucial PTC data)

Judging from the OP's callsign, they are in WA, which leads to BNSF and UP as the primary network operators. Both are notorious for using multiple forms of codeline control, including ATCS, Genisys, and ARES. ATCS and Genisys are primarily 900MHz based, where ARES was commonly found on VHF frequencies. So, it's possible that if this was not used for voice, it may have been used for codeline control of signals/switches.

Judging by the photo posted, those elements are shorter than typical VHF voice elements, so it's a good assumption that the antenna is tuned for 220MHz, which would be used by the ITC network. Without knowing the exact location of the OP's photo, we should assume that it's either used for 1. transmitting vital data to the PTC system in the cab (signal/switch info, etc) or 2. it could be used for wayside codeline control. Both western railroads are fast-paced converting their network to migrate their codeline control into the ITC network, allowing PTC and wayside functions to exist on one system, eliminating the need for multiple protocols and systems, especially legacy systems that have been in use for upwards of 30 years.

The railroads have already spent billions of dollars on their investment into PTC, so it makes sense to take full advantage of the system, especially with the upcoming deadline to migrate frequencies in the 900MHz band coming up fast. Unfortunately that means that the information is also not going to be as available as ATCS data was, since it is spread across multiple frequencies and reported to be encrypted, but that's the unfortunate state of the world we live in.

Mike

 

[AK9R]

...especially with the upcoming deadline to migrate frequencies in the 900MHz band coming up fast.

Who imposed the deadline? The FCC? The railroads?

 

[nd5y]

FCC rebanded the 935-940/896-901 MHz band.

FCC Enables Broadband Deployment in the 900 MHz Band

Establishes Negotiation-Based Framework to Transition Six Megahertz to Broadband Use while Preserving Spectrum for Continued Narrowband Operations

www.fcc.gov

Page 41 of this .pdf talks about the AAR allocations.

https://docs.fcc.gov/public/attachments/FCC-20-67A1.pdf

 

[iceman977th]

Who imposed the deadline? The FCC? The railroads?

As ND5Y said, the FCC. Long story short, those bands are being re-banded for broadband deployment. In exchange for kicking off the current ATCS channels, AAR receives 896.000-896.125 and 935.000-935.125 on their nationwide ribbon license. If used in 12.5k steps, that equates to 10 channels each. So, realistically, they come out with more bandwith, but less spacing. But, the railroads seem to share interest in merging into one system versus two.

Mike

 

[ak7an]

For a UP signal tech, you sure are spreading a lot of wrong information, along with most everyone else on this post.

Without knowing the exact layout of the location posted in the OP's post, it's hard to exactly say, but here's a good place to start. As Tom said, you won't see folded dipoles in the 900MHz band, they just aren't practical, not to mention the pictures shown in this topic clearly shows dipole elements that are tuned for the VHF band. So, they are either tuned for 160-161MHz for voice communication or VHF codeline control (ARES protocol or similar) or they are tuned for the 220-222MHz band for the ITC network (which contains crucial PTC data)

Judging from the OP's callsign, they are in WA, which leads to BNSF and UP as the primary network operators. Both are notorious for using multiple forms of codeline control, including ATCS, Genisys, and ARES. ATCS and Genisys are primarily 900MHz based, where ARES was commonly found on VHF frequencies. So, it's possible that if this was not used for voice, it may have been used for codeline control of signals/switches.

Judging by the photo posted, those elements are shorter than typical VHF voice elements, so it's a good assumption that the antenna is tuned for 220MHz, which would be used by the ITC network. Without knowing the exact location of the OP's photo, we should assume that it's either used for 1. transmitting vital data to the PTC system in the cab (signal/switch info, etc) or 2. it could be used for wayside codeline control. Both western railroads are fast-paced converting their network to migrate their codeline control into the ITC network, allowing PTC and wayside functions to exist on one system, eliminating the need for multiple protocols and systems, especially legacy systems that have been in use for upwards of 30 years.

The railroads have already spent billions of dollars on their investment into PTC, so it makes sense to take full advantage of the system, especially with the upcoming deadline to migrate frequencies in the 900MHz band coming up fast. Unfortunately that means that the information is also not going to be as available as ATCS data was, since it is spread across multiple frequencies and reported to be encrypted, but that's the unfortunate state of the world we live in.

Mike

SO... I never said the folded dipoles were 900 MHz, 220 MHz, and I posted what their intended use is.... I work on the UP system all the time, it is what I do, and I know what I say is accurate.
I put it out there that I was a Signal Technician so as to not hide my credentials, please enlighten us as to yours..
This I know, and do not assume what each antenna is used for.