IR Remote Interference

[Stillen]

the problem with IR, is that the further you get back from the intended target (our robots) the wider the spectrum band is. The year we were introduced to IR during a FIRST competition they suggested that we use a bic pen to focus the ir signal to the ball drop pedestals. This worked, only because we were seeking out the same signal. This year where we will be transmitting multiple signals at the same time, it won't matter how we focus/defuse/ or "up" our signal. We will still be intefering by having multiple signals at thesame time..

[keen101]

Originally Posted by Andy Goetz

Couldn't a team just use a protective hood on IR Sensor? The robot could us a compass or a gyroscope combined with a turret to keep the sensor pointing at the RoboCoach area.

That is a very cool idea.

[Gdeaver]

The IR interference is going to be a problem. Dave did point out that sound and light are also options. If key is for a team to use a fequency that no other team would think to use.

[Daniel Bathgate]

If only for this reason, lets not use our remotes as joysticks in another tele-operated period! If your design calls for buttons to be held down, you may want to rethink it to give your alliance partners a chance to send commands to their robots.

If alliances split robocoaches between the stations, use tubes to make their remotes directional, and treat the signals as commands and not a direct controller (such as "investigate that rock" and not "drive forward while I hold this button down"), IR should work. Pretend your robot is like Dave's, and on Mars. Another tele-operated period is not the intent of the hybrid period!

Having "start moving forward" and "stop" buttons would work better for everyone than moving forward while the button is held down, with the same effect. Let's practice gracious professionalism with our hybrid control designs!

That said, other mediums for command transmission would be great fun and potentially less prone to interference. Let's see the light and ultrasonic stimuli! (We might have to ask people to please not use flashlights or jingle keys near our robot )

[Mr. Freeman]

Originally Posted by Stillen

i just tired this at home. It appears this WILL be a problem..... If two infrared commands are issued at overlapping times, even if they are different frequencies they cancel each other out...

I have also tested this and found the same thing. Summary of my tests can be found in this thread: http://www.chiefdelphi.com/forums/sh...737#post670737

[mneary]

The robot could us a compass or a gyroscope combined with a turret to keep the sensor pointing at the RoboCoach area.

But the interfering remotes will also be in the RoboCoach area.

[JHSmentor]

So - the really big question is has ANYONE figured out how to avoid the IR interference from other remotes? I'm not looking for a theoretical answer but one that has been tested and proven to work. This has to be possible if they are included it in part of the game - I'm assuming someone has figured it out.

[Gdeaver]

The key to reliable Hybrid comunications is to use a fquency band that no other team is using. We have sound, visible light and IR.

[ida_noeman]

Lol you could also use a huge elliptical dish!

[Glooper]

Just wondering, do the remotes have to be pointed at the same robot to recieve interference?

[steve d]

We're going to make a remote and use our own code. We'll use a BasicStamp and an IR transmitter to blast out our own "secret" code.

[robotrobot2]

The problem is that multiple IR signals give constructive or destructive interference. Even if the two receivers are set to different frequencies, the second frequency will be slightly changed by the first, an vice versa. The only way to really fix this is by using using an absurdly high frequency, (almost actual red) and increasing the window at which the receiver will respond.

[wireties]

>This could well be a problem. But, it probably could be solved by "boosting" the >signal from your remote. Ie. wiring more IR LED's in series. (or is it in parallel?)
>
>anyway, once more IR LED's are soldered on your remote, it will effectively >double or triple the range of your remote.

I don't think it works that way (but could be wrong). To get a greater range, you'll need higher intensity. The light from multiple LEDs won't add constructively unless the wavefronts are perfectly aligned (quite hard to do). You can increase the intensity by increasing the current through the LED (up to a point, check the data sheeet) or using a different LED. But this may or may not be allowed as it can become unsafe at some point.

HTH,
Keith

[JHSmentor]

one way of looking at the interference factor is that it forces the teams to be cooperative. The robocoach area will only have members of your direct alliance. this will require some coordination from these members to make sure only one transmits at a time. Eliminating the noise from the other alliance is easy enough by having a directional cone pointed only at the robocoach area.

of course, without a turret to point the cone, this will only work up to the first turn in the course - by then, maybe it does not matter.

other than that, I have not seen any discussion in other threads of a more robust solution. Of course, this does not take into account other types of communication (light and sound).