RR Comms Current Status

[ComradeGlock]

The .pdf below is a fascinating (I think) look into the current status of US Railroad radio communications.

It’s an ex-parte filing made by the AAR in response to the FCC’s Docket 24-99 dated 6-12-24. A little technical, but it lays out exactly where the RR’s are today and their challenges going forward. (No prediction on VNB unfortunately).

Few highlights: RR’s want to increase the 450 Mhz EOT transmitter power from 8 watts to 30 watts. Apparently fishing equipment locators utilize 160.9 Mhz, which is smack dab in the middle of the Railroad band plan. To the AAR (logically), that’s a no-no. And there’s also a petition before the FCC (EWA Concurrence) which as near as I can tell (and over simplified) would eliminate frequency coordinators for VHF and UHF in favor of allowing individual entities to do it themselves.

This document covers all of the RR bands: 160Mhz, 220Mhz, 450Mhz, 900Mhz, and 6Ghz. But really expands on the 220Mhz band and its complexities and bandwidth problems.

 

[OpSec]

Interesting that they want to increase TXPO of EOTD's to 30w. I assume that given terrain and/or train length challenges they are having more difficulties than ever.

 

[ComradeGlock]

Train length was my first thought too. With Distributed Power, a 12,000'+ train is not uncommon on some roads. With an EOT at 8 watts tucked up behind a steel boxcar, it's hard to imagine much of a signal reaching the cab.

 

[AK9R]

Apparently fishing equipment locators utilize 160.9 Mhz, which is smack dab in the middle of the Railroad band plan. To the AAR (logically), that’s a no-no.

The AAR should be demanding that the FCC explain why fishing equipment locators were allowed to transmit there and what the FCC plans to do to alleviate the problem.

 

[ComradeGlock]

Well, apparently the FCC issued a Notice of Proposed Rulemaking - WT Docket No. 21-230 back in May of 2021 to address that very subject. In it they discuss the possibility of moving those locators to part of the AIS 1900-2000kHz band. The use of 160.9 was earlier recommended by the ITU: "the use of 160.900 MHz for non-navigation and non-safety AIS operations on a non-interference basis" (WRC-12, Geneva, Appendix 18). So far there doesn't appear to be any follow up activity to Docket 21-230.

What's probably more disconcerting is the EWA Conference Petition surrounding 160 MHz and 450 Mhz. (See the .pdf attached dated 3-23-23). They are seeking to amend the Part 90.35(b)(1)-(3) and 90.175(b) rules to eliminate "Primary Use" frequencies and do away with official frequency coordinators in those bands.

 

[ComradeGlock]

160.900 is also channel 2006 in the International VHF Marine Band as set by the ITU. The channel is not allowed to be used in US territorial waters and is "designated for autonomous maritime radio devices Group B that do not enhance the safety of navigation".

I did find the attached in response to Docket 21-230 from the "Land Mobile Communications Council" dated Sept 7, 2021 which more fully explains the AAR's strong interest in this issue.

 

[ComradeGlock]

For anyone interested in the future of Railroad comm's, take a look at what Siemens thinks it is.

Rail communications

 

[RRR]

That’s not “the future of Railroad comms” but limited use of something similar for other applications has been around for a while now. VHF is, and will be king for quite a while

 

[ComradeGlock]

VHF being king of what, voice comm’s? Sure, voice will stay where it is, moving to VNB when the Railroad's testing/approval of other data comms needs the bandwidth. The problem with data on VHF is moving large amounts of it thru a narrow bandwidth pipe (to be Federally mandated on VHF at some point) is difficult and slow.

SDR is not new technology, but putting it in a locomotive cab and replacing all of the single band radios with one SDR is new. And utilizing that SDR to move data by whatever frequency or protocol is the most spectrum efficient at any given time is definitely new.

Voice will always be essential to the day to day activity of a RR. But the “future of Railroad comms” is the collecting, distributing and processing of huge amounts of data to improve safety and customer service. I find it fascinating (ymmv) where the RR’s are headed with technology and what they are and will be capable of in the near to not so near future.