Danish Interpretation Systems DCS 6000 User Manual

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Danish Interpretation Systems DCS 6000 User Manual Manual pdf 21 page image

DIS User ManualUser Manual DCS 6000 Digital IR System rev H.docx 21Black spots3.6.5The receiver picks-up IR signals from tworadiators which cancel out each other. Themultipath effect can be identified by theobservation that the bad reception only occursalong a specific line and/or when good receptionreturns when the receiver is rotated to anotherdirection.This can be confirmed by keeping the receiver inthe position and direction with the bad receptionand then either shading-off the radiation fromone radiator with your hand or switching off oneradiator. If this improves the reception quality,then the multipath effect is causing the problem.Note that IR radiation that is reflected from asurface with a high reflectabiliy can also causemultipath problems.Black spots can occur in case a transmitter islocated in the same room as the radiators. In thatcase, disable the mini IR radiator of thetransmitter with the configuration menu (seesection 2.5.16).Check that the signal delay compensationswitches on the radiators are set to the correctvalue and that a switch is not accidentallypositioned between two numbers. Re-check yoursystem design. When necessary, reduce thedistance between the two radiators that causethe problem and/or add an extra radiator. Notethat due to the physical characteristics of thesignal distribution, it is not always possible tocompletely avoid multi path effects.Interference from IR systems3.6.6IR assistive hearing systems and IR microphonesoperating at frequencies above 2 MHz candisturb the reception at the lowest carriers. Ifsuch is the case, disable the lowest two carriers(see section 4.5.11) and re-check the reception.