Wireless Data Transfer

Thread Starter

opmee

Joined Dec 16, 2012
3
I'm just a newbie Electronics student so I'm still having troubles with basit circuits.

I have a homework which requires me to make RGB LED emit different lights for different 2-bit inputs. For example, blue for [10], red for [01]. The though point is it has to be wireless via Laser LED.

I'm supposed to generate signals with different duty cycles for 1 and 0. It seems like easier part to me. I plan to use capacitor, op-amp, diode to generate signals for 1 and 0. Then I will sum them according to my input and I will obtain different signals for each input.

But question is how can i make a receiver to calculate this signal and make RGB LED emit correct color of light.

WBahn

Joined Mar 31, 2012
28,186
You need to describe your assignment more fully. What, exactly, has to be wireless via a laser diode?

What level course is this?

Thread Starter

opmee

Joined Dec 16, 2012
3
there are two parts of this homework: transmitter, receiver. Laser diode has to transfer the signal produced in transmitter to receiver as light beams. A LDR will get those light beams. According to the signal, RGB in the receiver will emit different lights.

allowed components: any types of resistors, capacitors, inductors, diodes, LEDs, LDs, LDRs, and op-amps

Last edited:

WBahn

Joined Mar 31, 2012
28,186
So, have you given any thought as to your communications protocol. It's not as simple as sending 01 for red and 10 for blue. How do you send 01 and 10 with a single beam of light? There are many ways to do it, but it has to be carefully thought out and planned. What are some of your thoughts on how to do it?

Thread Starter

opmee

Joined Dec 16, 2012
3
I'm planning produce a square wave first, by a capacitor and op-amp. I will generate square waves with different duty cycles for 1 and 0. Then by using an op-amp as summing amplifier, according my input by buttons I will sum those square waves linearly.

And lased diode will work with respect to that final signal.

But I'm not still sure how to make LDR read that signal 50cm away.

sÃ¼lo3

Joined Dec 22, 2012
1
That's interesting. I have same project too.Can anyone help me to adjust duty cycle

WBahn

Joined Mar 31, 2012
28,186
Have you looked at what your combined signal will look like for all the possible input combinations? Is it easy for you to visually determine what the received value should be? If so, what features are you relying on to do it? In particular, if I put paper over everything but the current bit window (and hid the vertical scale), could you tell what the received value should be?

Have you considered using two-tone signals? Send one tone for one of the bits and a second tone for the other bit and then use filters to detect the presence of one or the other tones.