Narrowbanding (Replaces April 19th Letter)



Revised: Replaces April 19th letter


Dear Colleague:

I am writing to you today to follow-up on Narrowbanding requirements that are mandated by the Federal Communications Commission (FCC).  The Federal Transit Administration (FTA) reminds transit operators that FCC began a series of proceedings, beginning in 1992, to address the issues of Narrowbanding, also referred to as “Refarming.”  These requirements, announced in December 2004, mandated that all non-Federal public safety licensees using 25 kHz radio systems migrate to narrowband 12.5 kHz or lower channels by January 1, 2013.

The proceedings impact all Part 90 land mobile radio users in frequency bands between 150-174 MHz and 421-512 MHz who currently use 25 kHz wideband channels.  This relates to radio systems traditionally used by transit operators for communications between dispatchers and drivers, by transit police using radios and walkie-talkies, and for basic data oriented services such as automated vehicle location (AVL).  The FCC mandate may have severe impacts on selected radio communications unless affected transit operators retune their equipment, reengineer their systems, make modifications to their FCC licenses, or in some cases, replace their entire radio systems by the cut-off date.

The FTA advises all affected transit operators to start assessing the inventory of their current systems and determine if they are impacted by the FCC ruling.  This may result in operators requiring new or modified licenses and to update, modify or replace their equipment to bring systems into compliance.  The radio systems that do not meet the FCC’s requirements face possible loss of radio communication, substantial fines, or revocation of licenses. 

As of January 1, 2011, the FCC is no longer granting applications to expand existing or new systems for 25 kHz channels.  Additionally, beginning January 1, 2013, land mobile radio systems must operate the narrowband by migrating to at least 12.5 kHz efficiency technology.  Based on FCC guidance, any of the following meet the 12.5 kHz equivalent efficiency requirement:

• One voice path in a 12.5 kHz channel
• Two voice paths in a 25 kHz channel
• Data operations on channels greater than 12.5 kHz must employ data rates greater than  4.8 kbps per 6.25 kHz channel, such as 19.2 kbps per 25 kHz channel

The FTA is working closely with the transit industry and stakeholders on the Narrowbanding issue, and FTA is coordinating with the American Public Transportation Association and the National Transit Institute to help organize training sessions and webinars on Narrowbanding.  In addition, FTA is exploring other opportunities to increase transit agency awareness of this issue.

To find more background information on this important topic, please visit FTA’s website at:  If you have any questions, please do not hesitate to contact Raj Wagley, General Engineer, Office of Technology at (202) 366-5386 or

I look forward to working with you on this effort now to avoid any interruptions in transit service to our riding public.


                                                                                                                                                           Sincerely yours,


                                                                                                                                                           Vincent Valdes
Associate Administrator, Research, Demonstration and Innovation