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Can I somehow use Vishay's TSOP series IR receivers and IR LEDs to measure the distance from an object? Has anyone done that before or has any idea how one could do it(clever programming or circuitry, maybe?)?

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    \$\begingroup\$ TSOP is a series of IR receivers by Vishay, here it doesn't mean "thin small outline package" or something like that. Right, gomek? \$\endgroup\$ – stevenvh Nov 27 '10 at 19:14
  • \$\begingroup\$ That's right stevenvh. \$\endgroup\$ – gomek Nov 28 '10 at 5:26
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    \$\begingroup\$ Please do not use the TSOP acronym as a general purpose noun for infrared receivers. TSOP is far more commonly used to refer to a specific type of IC package, and it makes the question very confusing. \$\endgroup\$ – Connor Wolf Nov 28 '10 at 13:31
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    \$\begingroup\$ Have you considered using an Ultrasonic Sensor for distance measurement? There are a few that are out there and being used in the industry to do the same. Or is that you have to/want to use IR Receivers? \$\endgroup\$ – IntelliChick Nov 28 '10 at 22:43
  • \$\begingroup\$ Why do people suggest different things when people want to do one thing? \$\endgroup\$ – abdullah kahraman Oct 3 '12 at 10:13
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I doubt you could do better than just detect the obstacle this way. What you need is a device like Sharp GP2D12, which measures distance between 10cm and 80cm. About USD 10, IIRC.

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  • \$\begingroup\$ I just discussed a method but I agree with Stevenvh, if there is a device to do it you are much better off. +1 \$\endgroup\$ – Kortuk Nov 27 '10 at 19:08
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Sure, see paragraph 4 about Vishay's fixed-gain receivers:

Many other applications require a reflective sensor that detects not only presence but also proximity by measuring the strength or weakness of the reflected signal. Instead of a fixed detection threshold, analog information from the sensor is needed. This is possible with the TSOP4038, TSOP58038, and TSOP58P38 IR proximity sensors. The length of the sensor’s output pulse in response to the emitter signal varies in proportion to the amount of light reflected from the object being detected. For near objects, the output pulse approaches 100 % of the emitted pulse, for far objects the output pulse becomes shorter.

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You will need to have to approach it one of a different ways. one method would be to sweep what power you are radiating with the LED (something like a digital potentiometer to control the current) so that different range of objects will be detected.

It is very important that you recognize different materials will reflect IR differently making it very hard to get accurate results unless you know what materials will exist. The Receivers also have automatic gain control that will remove a continuous signal at the frequency and can remove yours if you send it continuously.

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You can get some effective LED power control by adjusting the mark/space ratio of the 37khz carrier. However it isn't a good way to get any sort of repeatable distance info - could be useful for object detection and approach/retreat discrimination . Elmos's Halios can do IR ranging by comparing reflected light with a local reference signal, but unless you're designing high volumes there are cheaper and simpler ways.

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