What is the difference between ASQ & SQ?

ASQ means auto squelch. This type of squelch usually only works well on FM. If you used on AM, you might find that it cuts out the background noise, but that it also eliminates the ability to hear distant signals. We recommend using the regular squelch that you can manually adjust per your liking. On the SR-89MC the two squelch modes are SQ & ASQ.