Russian military single letter CW beacon L seen here with active grouping of D; P; S; A, F and L. A few audio glitches can also be heard. Typically these beacons are used throughout the HF spectrum for the purpose of providing location and propagation conditions. Each letter corresponds to a specific location. D Sevastopol, Ukraine; P Kaliningrad; S Severomorsk; C Moscow; A Astrakhan; F Vladivostok; K Kamchatsky; M Magodan; L Saint Petersburg.
Credit to Youtuber "SignalPhantom"