need urgent help

[p.gholap93]

I am using SHARP GP2Y3A003K0F sensor for obstacle detection i.e. if an obstacle comes in some range of GP2,a buzzer will sound. As I know I analogue o/p of GP2 changes with distance and I am interpreting the same using 8 bit ADC of ATMEGA 16.
In datasheet it is given that phase shifted pulses have to be given to the LEDs. But the problem is when I give such pulses my ADC readings don't follow the expected trend (i.e. decreasing as obstacle moves away from the sensor.)The ADC readings are quite abrupt.
But if I keep only one LED CONTINUOUSLY ON then the ADC readings decrease as the obstacle moves away from the sensor.They detect obstacle perfectly.
So I what could be the use of those 5 LEDs ? Or how should they be operated?
please repl

 

[ronv]

I think (but not sure) the leds have a slightly different angle towards the target. This may let you determine direction as well as distance. From the timing diagram you need to give the output time to settle before you can sample it. If you are interested only in distance 1 led is fine or the data sheet says no more than 2 on at the same time.

 

[p.gholap93]

well i have tried it also but there is no specific angle as such for a particular LED. For ANY ONE LED continuously ON readings are of the same nature irrespective of the direction of target.I think the 5 LEDs are to increase its range of detection but it is not happening so.

 

[ronv]

Maybe to increase the field of view (angle).