NDB – Non-Directional Beacon OW 397kHz – Stoughton MA USA

Location: 42.119598, -71.128304

City: Stoughton, MA USA

Freq: 397 kHz

Call: OW

Power: <25 Watts

Associated Airport: OWD

Today I visited the transmission site of non-directional beacon OW in Stoughton MA.  I knew I was going to be in the area so I allocated a little extra time for this nerd-venture.

The antenna on the left with the “top hat” is the NDB.  It sends out a transmission on 397 kHz consisting of the repeating morse code of the NDB’s identification call.  In this case it is sending  “OW” (dash dash dash, dot dash dash).  Navigational equipment on a plane receives signals from NDB’s and uses them to triangulate location.  Back in the day pilots did this manually with a directional antenna at their control.

The v-shaped antenna on the right is a separate navigational aide co-located at the site called an “outer marker”.  It sends a signal on 75 mHz straight up which is received by a plane notifying that it is in direct line for runway approach.

Here is a YouTube video of the audio transmission from OW.