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I am interested in using an IR receiver (as opposed to a standalone PIN photodiode or phototransistor) to measure distance/range. I thought I had found an appropriate match in Vishay's TSSP4P38 mid-range proximity sensor, which varies its pulse width with reflected signal strength. These, however, seem to only detect changes in distance as stated in p.3 of this document from Vishay; also, it's reflective and I want to be able to detect the distance (and possibly bearing using an array of IR detectors) from an IR emitter as depicted in the image below.

image


After my search, I have found only Vishay offers an IR receiver capable of outputting "analogue" information; is there an alternative IR receiver capable of measuring absolute distance I have overlooked? I would like to exhaust my IR receiver options first, before I look into using a photodiode/phototransistor which will require extra circuitry, such as amplification, filtering and demodulation.

Additional information: Range of ~2m to 3m and not too sure of accuracy and resolution at this stage, but possibly within ~10cm @ 3m.

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  • \$\begingroup\$ Do you specifications of range of operation, resolution, accuracy and whether you can connect Tx/RX with an electrical signal (like a reference signal - for demodulation) adding these will help people provide answers. \$\endgroup\$ – placeholder May 13 '13 at 2:44
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You can't use light like that to measure distance. Think about how long it would take light to travel 10cm, and then you'll see what you can't use that to measure distance.

All IR receivers give you 'relative' distance because they can only measure relative distance as a function of relative change in received light intensity, which makes your measurements dependent on a number of environmental factors.

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  • \$\begingroup\$ Could you please point me to these IR receivers which provide relative distance? I think I may have caused confusion by stating "absolute distance". I need to find the distance/range between an emitter and detector - this is certainly feasible through calibration which generates a relationship between the received signal strength and distance. \$\endgroup\$ – Igor May 13 '13 at 6:29
  • \$\begingroup\$ That Vishay part you referenced in your post can provide you with that info. The width of the output pulse is proportional to distance given the same emitter, reflector and conditions. \$\endgroup\$ – EEToronto May 13 '13 at 21:08
  • \$\begingroup\$ Many companies make IR distance sensors that use structured light instead of time of flight or differences in intensity. Google "laser displacement sensor" for the industrial versions. Here is a link to some small ones from Sharp: 198.186.240.116/optoelectronics/sensors/… \$\endgroup\$ – user3624 May 18 '13 at 5:17
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For anyone who stumbles upon this thread in the future and is disappointed by the prior lackluster response:

ams creates light-to-voltage converters which contain a photodiode and transimpedance amplifier on a single monolithic IC whose output voltage is directly proportional to the received light intensity. Unfortunately the angular displacement doesn't quite meet my requirements, but hopefully it is of use to others.

I am now investigating the use of PSoC (Programmable System-on-Chip) by Cypress Semiconductor which allows for the extra circuitry associated with IR photodiodes, including the Transimpedance Amplifier, Programmable Gain Amplifier, Band-pass Filter, Peak-detector, all to be implemented in the one IC.

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  • \$\begingroup\$ Cypress AN2042 is worth a look. There is also example source code available, I have it but couldn't find a download link, I think I might have just e-mailed them and asked for it. \$\endgroup\$ – PeterJ May 18 '13 at 0:15

protected by W5VO May 13 '13 at 3:05

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