https://www.youtube.com/watch?v=oDOcgLQ5RSU
https://hackaday.com/2015/10/29/secret-radio-stations-by-the-numbers/
Audio from other QRG, but monitored by me
today without Jamming, px listened from 15.30 - 15.59 UTC
last 4 minutes the same usual "ending instrumental music"
-- not a real Interval Signal, but often used --