I'm currently having a prototype which involve using an IR sensor for obstacles detection. But the results required a comparison of the range result I obtained from the prototype to compare it to a real life application. I have been surfing the Internet but none of the information was useful. I hope someone could help me to sort this up. Thanks and have a great day.

  • \$\begingroup\$ There's no obvious reason why a soundly engineered prototype would necessarily differ from a product. You're going to need to be more specific about your system, results, and expectations. Do you used pulsed IR to reject other sources? \$\endgroup\$ – Chris Stratton Oct 5 '20 at 13:46
  • \$\begingroup\$ Well, why would it be different? \$\endgroup\$ – user253751 Oct 5 '20 at 14:43

Just like Friis Loss in RF calculations , the same applies to optical power.

Therefore the half beam width HBW of both emitter detector and bandwidth BW of Tx, Rx path loss and gain, noise threshold of Rx and interference come to play.

Often these rated in kbps-meter products. thus if using DC only, filtering and integration for changes make garage door sensors very sensitive to 10m and Remote controllers good for perhaps 10 to 50m , more or less depending on emitter current (mA) pulse and emitter HBW for transmission with ceiling reflection. Here the carrier was in the 30kHz region with AGC and 3kHz BW in the Rx with a Q=10 BPF integrated in Rx. (Sharp/Vishay)

But without these design choices, the range might only be cm or m . Laser diode emitters obviously give more range. Object reflection depends on reflectivity and scattering, while Object path sensitive depends on beam width. I have used 100mA 10 deg emitter pulses and using IrDA2 detectors with binary codes to get error free detection in recessed apertures to 1deg to detect a resistor wire crossing a 1m path. You cannot do this with reflection.

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    \$\begingroup\$ Thank you so much for helping with such detailed information. Much appreciated and sorry for the late reply. \$\endgroup\$ – littleamateur888 Oct 10 '20 at 16:10
  • \$\begingroup\$ Any questions? Understand this yet? \$\endgroup\$ – Tony Stewart EE75 Oct 10 '20 at 16:50
  • \$\begingroup\$ Don’t forget to upvote or improve your question \$\endgroup\$ – Tony Stewart EE75 Oct 10 '20 at 18:36
  • \$\begingroup\$ upvoted. Thanks and have a nice day. \$\endgroup\$ – littleamateur888 Oct 10 '20 at 20:03
  • \$\begingroup\$ I guess you need credits to vote \$\endgroup\$ – Tony Stewart EE75 Oct 10 '20 at 23:25

Back in university, a friend examined various optical distance detection methods.

Importantly, he found DUAL sensors (one LED, two photodiodes/transistors) with an OFFSET DISTANCE between the 2 sensors, allowed a more robust detection system.

In later years, I modified the sensor interfaces, using regular diodes to post-process the photodiode currents into LOGARITHMS of the photon flux.

By taking the LOG, thus compressing the dynamic range, we would get a uniform change in output (differential) voltage, regardless of the target reflectivity.

We experimented with 8" by 8" washcloths, from off_white to dark_blue; quite useful results for distance detection.

  • \$\begingroup\$ I had actually generated the analog result which obtained by using an arduino. The problem that im dealing with now is that my so called lecturer wanted a scaling factor of the distance of the sensor compare to the real life application. But anyways thank you so much for helping. Much appreciated. \$\endgroup\$ – littleamateur888 Oct 10 '20 at 16:13

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