I am hearing this sound again on 853.6000 ID: 03-135 it only last for a few minutes or up to 5 minutes then goes off then appears on a different HC frequency. Time I am hearing it is about 20 minutes and now. Are the engineers testing the sites? I know yesterday District 4 had problems and another county did as well. I don't know how to describe the sound I just know it's a sound.