I believe you are talking about an IR Emitter. If that is the case, on most receivers, it is to the right of the red record light. To test, you can put a piece of tape or something to block that area and see if your remote works. If it does not, that's where the IR sensor is. Hope this helps.
David, AT&T Community Specialist
AT&T Customer Care
Need help with an account specific question? Post a new question here on the forums by clicking the "Ask a Question" button. For additional support, please visit us at our AT&T services hub. Follow us on: Twitter @ATTCares and @DIRECTVService
*I am an AT&T employee, and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
A single thickness of tape will often not block IR signals into the IR receiverof the set top. In some cases, it actually only dampens it enough to improve accuracy of reception from a "too hot" remote control IR emitter.
Award for Community Excellence 2019 Achiever* *The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.