IR Laser for Comm

[Fish4Fun]

I have the most complex residential water system in history, won't go into details, but I would like to monitor some facets of it. The "water shed" is ~75ft from where I would like to monitor it. The obvious/simple answer is to run a wire, but what fun would that be? The next obvious answer would be RF, and that is a consideration, but perhaps a bit more than I want to byte off.

I have played with IR remotes for quite some time, and they are brilliantly simple, but prone to problems in full sun, and of course somewhat bandwidth constricted, but as the volume of data is small, and the time between packets is not critical, I am thinking it might be a good choice, and the project would give me a chance to see how far I can "push" IR comm (hopefully 75+ft!).

My thoughts were to start with "directional shielding" of the detector(s) (don't know if two-way comm is really requisite, so perhaps just "detector"), this being a fancy way of saying, "put a piece of pipe pointing toward the emitter over the detector". This should considerably limit the amount of noise the detector receives. What I am unsure of is how to amplify the IR signal enough to make sure the detector receives a signal. I could certainly use a large number of IR LEDs and "hope for the best", but I was thinking an IR Laser might be a cool thing to try.

I have ZERO experience with IR lasers and was hoping for some thoughts on the viability for this purpose. I have NOT investigated IR laser diodes beyond simple searches to verify they exist and get some inkling of cost/power. It appears a simple IR laser diode in the < 50mW range can be fairly cheap, but I don't know anything about the associate drive requirements. Regular IR LEDs are dirt cheap // easy to drive (plus I have TONS on hand), and I could easily configure an array of them, but the notion of using a low power laser intrigues me.

So, looking for thoughts on IR laser diodes....

Fish

 

[(*steve*)]

I would practice with a normal red laser. They have the obvious advantage in being simple to point in the correct direction. Also you can't accidentally stare into them.

Placing a tube over the detector is a good idea to eliminate stray light With a laser it can bu quite long (it is helpful if it is black and flocked) but beware of insects making their home inside!

Start with something in the range of 1 to 5 mW. With care you can get very good range out of that.

The important issue is modulating your signal. If your signal is carried on (say) a 1kHz carrier, it is a simple matter to filter out lower frequency signals. Most sources of interference are going to be way slower than that.