Re: IR detector system, biasing of photo diode

On a sunny day (Sun, 27 Oct 2024 21:16:11 +0000) it happened
liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
<1r23uzl.g0c7e315xtehyN%liz@poppyrecords.invalid.invalid>:

john larkin <JL@gct.com> wrote:
>

On Sun, 27 Oct 2024 09:03:20 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
 

On a sunny day (Sun, 27 Oct 2024 02:19:14 +0200) it happened Klaus
Vestergaard Kragelund <klauskvik@hotmail.com> wrote in
<vfk0u0$3u9en$1@dont-email.me>:
>

Hi
>
I am working on an IR detector that will guide a robot into a docking
station.
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A IR transmitter on the docking station transmits a beam, and 2 IR
detectors on the robot detects the beam and lets the robot navigate
towards the target. The working distance is a couple of meters.
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I need it to be insensitive to ambient light/sunlight.

>
>
I use a cheap camera module to track a light source in H and V direction,
and just a simple Microchip PIC : for processing It can, with some added
code, track object forms too, like a cross or maybe a big character.
panteltje.nl/pub/horizontal_IR_target_tracking_4686.avi those camara
modulea are IR sensitive to some extend, sometimes you can remove the IR
filter from such modules. It may be a bit of overkill for your
application, but OTOH it can do a lot more. Mainly designed to detect and
follow jet exhaust.. You could uee utrasonics too, maybe even simpler, no
sun problem, like a bat. Cheap electret mikes? or modify some ebay 1
dolalr distance sensors... can be used for anti-collision too.
>
 

 
Right. A sonic scheme could measure the phase between two mikes to
determine the direction of the source with high resolution. That could
be an analog multiplier or a bit of code. The amplitudes would be
useful too.
 
One could compute direction, distance, and velocity almost for free.
 
No problem with sunlight!

>
Terrible problems with acoustic reflections.

Could be a problem, depends on the situation
I once build a 44 kHz Doppler radar that would even detect if I blinked an eye..
 https://panteltje.nl/pub/experiment_with_44kHz_doppler_from_philips_remote_control_IXIMG_0758.JPG
I also have so RF Doppler motion sensors in use... Tsting:
 https://panteltje.nl/pub/wrapped_RF_doppler_motion_sensor_IXIMG_0797.JPG
  those are REALLY sensitive.
Thats is the type of sensor that opens the doors in the shop for you if you want to enter / leave.
Also just a few dollar on ebay, and very small.

And you can combine sensors...