IR Interference - Smart Phones & Plasma TVs

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tortugaranger

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IR Interference - Smart Phones & Plasma TVs
« on: 11 Feb 2022, 05:48 pm »
Hi All,

Once in a while a customer will report that their preamp is not responding properly, or at all, to command from the Apple remote that we use with all our preamps. If they send us their preamp to have us check it out, they invariably work normally when we test them here. Send them back to the customer and the problem reasserts itself. What's going on here?

#1 Smart Phones - Most smart phones today use infrared as a type of radar to determine if the user is holding the phone up to their face, presumably because they are talking into their phone. The phone sends out a constant IR stream, that stream hits and reflects off your face, and the phone detects the returning IR signal and uses it to calculate distance between face and phone. If the distance is small, the phone turns off its screen and disables the touchscreen so that your face doesn't randomly touch any buttons while talking. All fine and good. However, that smart phone IR radar stream represents a source of IR noise that can effectively block/corrupt IR commands coming from an IR remote. Pull your phone out of your pocket, put is down on the table face up  nearby, and suddenly your preamp stops responding to commands from your remote.

#2 Plasma TVs - Plasma TVs are notorious emitters of infrared noise that can interfere with command signals from IR remotes of all types and brands. This is not limited to Tortuga Audio products. Do an online search for "plasma TV IR interference" and you'll get a huge data dump of complaints.

More recently we have changed the IR receiver we use to a higher quality model that is more tolerant of infrared red noise but both smartphones and plasma TVs can still effectively block signals coming from our remotes. We have also refined our IR signal decoding logic to mitigate this problem but enough IR noise can always block any command coming from an IR remote.

Cheers,
Morten