The UPC-28 consists of IRC-28 emitter panel, IRP-20 DC power pack and mounting brackets. The IRC-28 is UL listed for compliance with IEC 60065 audio/video and similar electronic apparatus.<br><br>The IRC-28 transmits two channels of audio over infrared. Channel A is transmitted at 2.3MHz. Channel B is transmitted at 2.8MHz. Both carriers are frequency modulated. Channel A is normally used to carry the hearing impaired audio, while channel B is normally used to carry the visually impaired - narrative audio.<br><br>The UPC series assistive listening devices are part of an infrared system, designed to fill a lifetime void with intelligible, clear sound for the thousands of hearing impaired individuals. IR headphone receivers will work in any auditorium, but play audio only from that auditorium. There is no possibility of receiving soundtrack from another auditorium.