[Scan-DC] DTMF ? Tone on 154.145 (Balto City FD VHF Simulcast)

[Gene McAvoy]

Over the past week I have noticed an extended tone on the Baltimore City VHF
Simulcast freq.  I haven't heard it on the 1616 TG channel.
Doesn't appear to be related to any dispatch traffic. Anybody have an idea
of what might be going on there?
Also doesn't appear to be associated with any sort of radio testing.

Any clues?

Gene / KG7XD
Odenton, MD