increasing infra red range for uart communication

[arnab913]

Hello,
my project is to communicate with microcontroller by uart protocol through ir.I succeed in it quite nicely.But the distance is very small,like 6 inches.
So how can I increase the distance.I am using 16f73 for remot (tx) & 16f877a for Rx.I am also confused about selecting perfect boud rate,currently using 9600.I am sending characters,i.e. 'x','y',.....& working with it.
Oh... using ir led & receiver of two pin by a comparator.
thanks in advance.

 

[chuckey]

For maximum range you need :- max power in required direction ( LED input power, focusing optics). For reception, you need max receiver sensitivity and focusing optics + using the minimum bandwidth required, this is to minimise the noise, which is proportional to bandwidth. So with your present baud rate (if satisfactory for your needs), fit a low pass filter to reduce the receiver's bandwidth to a minimum, subject to the bit rate error you can tolerate.
Frank

 

[rfredel]

Hello arnab913,

To increase the distance of IR-diodes you need higher pulse current through the diodes or a reflector.

Look for the datasheet of the diode to find the right current or give the type of the diode and your circuit.

Regards

Rainer

 

[arnab913]

Thanks Rainer nd Frank.
IR emitter/receiver(2 pin) Datasheet that we find in net is common one to all.Can you suggest me datasheet of any specific IR of my required current rating?
I'm facing problem with TSOP as it receives only specific frequency's pulse(38 kHz).I don't know at all pulse of what Hz my circuit giving....
2-3 meter range will be satisfactory for me now.I'll work with RF module next.
Using opamp lm324 for receiving....
So,what should I do now:roll:

 

[Pjdd]

There are many factors that determine the range of IR reception. Others have mentioned some of those factors. Another one is the IR LED itself. Different types have different output intensities for the same drive current. Vishay TSAL6200 is a good one and has a combination of a strong output and a fairly wide transmission angle. A TSAL6100 has twice the radiation intensity but a narrower angle.

I have used the TSAL6100 in a number of projects and can get reliable reception to 20m in sunlight, using a common SM0038 as the receiver.