Russia annexes Crimea and less than 48 hours later voices can be heard on the UVB-76 number station.
Not sure what to make of this but we highly doubt it has anything to do with "ionospheric research".
UVB-76 number station:
"UVB-76, also known as The Buzzer, is the nickname given by radio listeners to a shortwave radio station that broadcasts on the frequency 4625 kHz.[1] It broadcasts a short, monotonous About this sound buzz tone (help·info), repeating at a rate of approximately 25 tones per minute, for 24 hours per day. On very rare occasions, the buzzer signal is interrupted and a voice transmission in Russian takes place.[2] It has been active since at least the late 1970s or early 1980s, when the first reports were made of a station on this frequency.[1][3] Its origins have been traced to Russia, but although several theories with varying degrees of plausibility exist, its actual purpose remains unknown to the public."
VIDEO:
SOURCE