I'm new to this forum and ardiuno programming, and also excited about
things that can be done using it.
I have an idea and I don't know if it's possible to make such thing.
I want to rotate an object to be pointed to a light source that is 1000 m away (line of sight is guarantied).
The object would have an enclosed photo sensor with hole that is perpendicular
to the plane which I want to be faced to light source. It would rotate until it detects
the light and then it would stop rotating.
Is it possible to do that over such a distance?
I don't want the sensor to turn to other sources like public lights, sun etc.
so the emitter should emit specific light and sensor should be sensitive only
to that specific light. Can it be done?
If not, can it be done with pulsing light source at known rate?
Thank you for any help or advice you can give me:)
You've started to consider the real problem - how do you distinguish a specific light source when there are other light sources?
An infrared remote control for your TV works in the presence of strong infrared light (sunlight). How does it do it? There are two parts to the solution. First, the LED transmitter only sends pulses at a frequency of 38kHz. The reciever is tuned to respond strongly to this frequency and not at all to other frequencies. Then that 38kHz "carrier" is modulated by turning it on and off in a specific pattern. The TV ignores the infrared codes intended for the DVD player. Once the TV has identified that it is getting a valid code from its own remote, then it can perform the action like changing the channel.
If you had a strong enough light source that could be modulated at 38kHz, then a remote control transmitter and receiver chipset can be used. A high-brightness LED might seem like a good idea but most of them use phosphors, which won't be able to switch at that high speed. You could use a lower frequency, but then you are going to have to build more of the circuits yourself instead of buying an off-the-shelf chip. Given then difficulty and expense of that, it would be worthwhile researching LEDs to find one bright enough and fast enough.
Then you could have the remote transmitter send a unique code, like your name, so you could be sure that the transmitter was yours.
How about using strong stroboscopic lamp as light source
and conventional photoresistor.
It would detect blinking light (dt between peaks would mean it's this source)
The only thing that is left is stop rotating when the amplitude is the highest
(when sensor is pointed directly to light source)
The prism to which you aim with theodolite must be faced to the instrument.
The problem is, when you move to the other point with the instrument,
all of the prisms must be turned and that means going there and turning it and
this is very time consuming.
When you move to other location with instrument, you would trigger all prisms to start
rotate and turn on the light where the instrument is. Prisms would rotate as long as they are
not faced to the instrument. Then the rotation would stop and they wait for new trigger signal.
What about sending a wireless message to the "prism" telling it to turn left or right.
However I don't know if it is easy to transmit wirelessly over 1km without complicated equipment. You could probably use a modulated laser beam - but it may be dangerous to people in the vicinity.
Just employ a helper or two ?
Why is technology always used to put people out of jobs?
I googled it a little and I saw that there are directional antennas, that
are used to determine the direction of the signal.
Is there a combination of radio emitter and antenna on the market to your knowledge
that are tuned together and can be used for direction determination?
Arduino + camera sensor could recognize bright spot and move a servo, as in this project: vimeo.com/44707148
Distance is not relevant, it's a matter of optical zoom you need to buy
jeeero:
I googled it a little and I saw that there are directional antennas, that
are used to determine the direction of the signal.
I don't think a directional antenna would be anything like sensitive enough.
I also feel that you are thinking about this problem from the wrong end.
As I understand it (and correct me if I am wrong) you will be at the location where your hypothetical bright light will be and you want it to be detected at a few distant locations so that the prisms at those locations can "aim themselves" at you. So far, you seem to be thinking that the intelligence for positioning the prism should be at the prism location.
I think it would make far more sense to have the intelligence in one location (where you are) and just have simple receivers at the prisms that take instructions - move left, move right. You could have a device with some buttons to select the appropriate prism and then a pair of left- and right-buttons to get it to point in the correct direction. I am assuming that you can tell when they are correctly oriented.
Would it be worth while setting up a high-powered wifi link (you can easily get powerful directional units) and that might allow all the action at the base station to take place on a tablet or phone. You could, perhaps, use ESP8266 devices at the prism locations (but keep in mind I don't know anything about their range).
What you need is a Paveway type gimballed "seeker head" commonly used to track objects that have been illuminated by a coded laser beam.
Precision engineering isn't cheap, what's your budget?
Perhaps you could adapt an astronomical telescope motorised mount to do the seeking.
Now i see that the problem is not very easy to crack.
I was thinking that there might be an easier solution, knowing
that laser scanners (LIDAR) can detect their own emited and reflected light
over 200 m away (reflected from non reflective surface like roof, road etc.)
I tought that active beacon would not be so hard to detect.
