Vary sensetivity of IR Sensor

[vsmGuy]

What is the best way to vary the sensetivity of an IR Sensor pair using IR LED and TSOP1738 ?

First of all, I want to know what is the maximum practically achievable range using the above sensor pair.
A circuit which can reach this range will be great, alongwith code incase microcontroller is used.

Secondly, I want to know how I can reduce this range as I want.

For example, if IRLED + TSOP1738 can work till 1meters, I want to know how I can reduce this range to 5cm, 6cm and so on...

 

[vsmGuy]

Hmm... no one had any idea ?

Anywyas, I notices that TSOP1738 has a frequency response looking live a gaussian distribution.. so I thought that by changing the freqency I maybe able to vary it's sensitivity.. has no one tried this before ?

 

[yogi]

you have to change the frequency of the IR emitted and sometimes the intensity too........

 

[x_zoli]

Hi,

it's hard to determine the exact sensitivity because the TSOPs have an internal AGC circuit, helping them to achieve very good sensitivity under weak signal conditions.

 

[artem]

Have a look to this document :
**broken link removed**

to caluses linearity and sensitivity .

I suppose you have to measure environmental radiation and temperature for range correction . This seems to be unique for each photdiode led pair you are going to use .

Spectral sensitivity is just to find suitable opto pair , but things get more complicated after .

 

[KamalS]

The idea is definitely interesting, but I don't think that you will be able to use the TSOP range for this as it has an AGC which may interfere with this algorithm.

Using a normal IR Photodiode, you can vary frequency using PWM and intensity using Digital POT.

But still, for all practical purposes, it's better to use SONAR for ranging and IR for obstacle detection.

However, this is definitely a nice idea, a new concept which might work out well !

 

[dilraj.n]

hi,
you can reduce the range by increasing value of the current limiting resistor of ir led