NDB - Non-Directional Beacons
pictured: NDB and Outer Marker located in Waco, TX
NDB's were the predecessors to the VOR system, more commonly used. NDB offers a non-precision approach because you have no way of knowing the exact distance from the plane to the beacon, unlike VOR DME systems.
NDB is still used by those flying under VFR conditions. Receiving equipment is less expensive and easier to use than VOR, and range can extend further since it uses the longwave 150-500 khz band.
Many NDB's are situated at the Outer Marker (covered on another page) which is located approximately 5 miles from the airport. But some are located by themselves, at the airport.
The wire between the 2 poles is actually the NDB antenna, and the orange V-shaped antenna is the Outer Marker Beacon.
Click below to hear some NDB signals I have received:
CDI - Cedar Hill, TX (broadcasts warning about high towers)
FT - Ft. Worth, TX (as recieved in Hot Springs, AR)
GLS - Galveston, TX (as received in Hot Springs, AR)
Strange one here - the AD Addison, Texas NDB/Outer Marker is located in a gas pipeline facility.
Note the V-shaped Outer Marker, and the wire antenna between the poles for the NDB broadcasts.
This is FT in Fort Worth, Texas. It's an NDB and Outer Marker for Meacham Field.
I heard this one over 300 miles away in Hot Springs, AR. Hear it locally and from Hot Springs above!
Try other navigational aids
Fly me out of here, this sucks