Motor rumbling and distant muffled voices, could be used for a nearly empty bus or subway station. Voice talking in middle.
August 16th, 2019
Number Stations
websdr_recording_start_2018-03-12T19_09_37Z_4590.0kHz
March 12th, 2018
Tuning the radio at some stations, it contains hiss and noise characteristic of old radios when you search for available stations.
August 16th, 2015
Of hundreds of navigation beacons for spaceships all have different signal characteristics.
January 31st, 2014
Radio tuning sound on AM frequency.
October 16th, 2010