IR sensor blues

A project log for Standing desk remote control

Control multiple desks over wifi

lion-mclionheadlion mclionhead 09/21/2022 at 07:240 Comments

So the TSOP3238 seems to have a washout filter in addition to bandpass filtering.  Go out of range & it no longer generates any pulses until you either stop transmitting for a while or go right in next to it.  It's as if the ambient level is constantly recalculated based on all the rejected pulses.  The problem manifests itself as unrecoverable losses of signal when using it at long range or when the sensor is partially obstructed.  There's no way to stand in the middle of the room, sending all the desks the same code by just turning the dial & aiming the control.

Normal users already know they have to stop transmitting & press the button again on standard remote controls which only send the code once.  This makes the washout filter a non issue.  For a control which always rebroadcasts the code & is expected to resume a connection on its own, the washout filter is problematic.

The obvious solution is to constantly power cycle the IR sensor when it's not receiving anything, like a thermal camera.  This would wipe out all the benefits that the washout filter is giving.  Maybe a slower bit rate would make it more immune to rejected pulses.  There could be a more omnidirectional transmitter.  It's not a showstopper.  The mane idea is to not waste any time chasing a firmware bug.

The other problem is the optical sensors getting bumped into & bent.  The receivers need an enclosure or the optical parts at minimum need a support.