nats: stoping conflicting robot signals?
 

How does FIRST make sure that robot signals don't interfere with each other? Correct me if I'm wrong, but I believe they have 4 wireless channels available to use, one for each robot. For regionals this seems fine as there is never more than 4 robots operating in a match at the same time. However, at nationals they have 4 divisions equaling the potential of 16 (4*4) robots running at the same time! Does FIRST unlock extra channels for nationals, are the fields far enough away that they don't interfere, or is it something else entirely :confused: ?

I guess I'm interested in the technical administration aspect of running a FIRST competition, especially nationals due to the high volume of teams, but finding it hard satisfy my curiosity! So, as a side note, does anyone have any info on this, or know where
I can get some? I would really appreciate it....... Thanks!:

Re: nats: stoping conflicting robot signals?
 

Actually, the IFI system is capable of 40 channels. However, only 5 channels are available without the OI being connected to an Arena Controller.

Even with 40 channels, setting up the Championship must have been a challenge, as typically adjacent channels can't be used at the same field without them interfereing with each other.

Jason,

You may want to do a search for 'Competition dongle' or 'yellow dongle' or 'competition port pin out' here on CD and you should find several threads explaining how the competition port works and how innovation FIRST unlocks the channels and how you can get access to them.

I'm aware that there are 40 channels availible, but doing somre research (including the modem manufactor's website, http://www.electrowave.com/. did you know they make a special modem only for FIRST?) seems to suggest only 5 channels are used. Channel 40 is the default channel, it is the only one you can use without a competition port pluged in. With the port, there are 4 addition channels unlocked. According to the modem manual "While the modem is capable of using 40 channels, only 5 channels are available to the user in the standard modems" The comp port wiring diagram agrees, they give you 5 channels to use (if you manualy select them). If IF does enable all 40 channels for comp, doesn't that mean the mobile modem has to scan through 40 channels looking for a signal <i>every</i/> time as it doesn't know if the extra channels are enabled ahead of time?

Shorting that pin on the Competition Port enables an additional 4 channels as you have mentioned. However, when hooked to the Arena Controller, there is some other method that IFI uses to enable all 40 channels. I don't know how, but I'm assuming it's done with the serial link that exists between the OI and the arena controller. If you look at the arena controllers (they're located in a column that sits underneath the shelf that you put your controls on and look very similar to an OI) when you're at a competition, each one has it's assigned channel number shown on the 7 segment displays. At all the regionals where I've taken the time to look at them, they have not used any of the 5 channels that are available to everyone by using the competition port dongle, presumably to avoid interference from the team s that inevitably run their robots in the pits without the tether. So in answer to your question, yes the robot controller does indeed scan through all 40 channels each time it's powered up or loses signal.

Additionally, the radio modems themselves lock out access to all but 5 channels in the default mode. There is a special command that must be sent to the modems to unlock the other 35 channels.

This year IFI had a new tool they used at the competitions that monitored all 40 channels to watch error rates as well as to watch for people powering up in the pits. If you ever looked at the scoring table, there was a laptop connected to two radio modems. The display said something to the effect of "Innovation First Scanner" and it showed all channels that were actively being used. The 5 "user accessible" channels were highlighed in a different color to indicate that someone was using them in the pit area.

IFI released a paper earlier this year about the competition port pinout, hopefully this will be a good starting point for you.


Official Competition Port Pinout Guide

wut ever u do just make sure that u know what/how ur hooking something up to the compition port.
b/c if u mess something up its not that hard to fry the OI.

i did it earlier this year to the 2002 OI as i mentioned in a previous post.

if u hav no clue wut u are doing, then DONT DO IT!

And if you have no clue how to write a proper English sentence, maybe you should learn...

Dave is absolutely correct, i volunteered at Nat's and from what i got out of the IFI guys when i talked with them is the normal setup was to have 1 channel on each range(0-9, 10-19, 20-29, 30-40) on the field with no other field repeating any channels and they left out the 5 that the modems could access in the pits. So no channels had multiple uses at once, this year the channel scanner program IFI used was very helpful for when a communication problem occurred you could tell if it was a teams fault or if it was an actual problem that needed to be fixed.

~Mike

P.S. check the white paper DJ posted to the pin diagrams and more in depth info.

Dude, go easy on him, some people are just like that. Not everyone's perfect.

Oh btw, you shouldn't start a sentence with "And".

hehe sry jeff
but i was jus pointing that out from expierience that if u fry ur OI its a pain to to try andexplain how u did it, and even more of a pain to try and get IFI to fix it 4 u

That isn't necessarily true, but I am not here to start a grammar war and neither should you...

Follow your instructions carefully and it will work, my electrical team built one this year that worked just fine...just do the obvious and check your wiring.

You guys had an electrical team? How big was your team?

Don't most teams have an electrical subteam? We have four programmers and two electrical gurus that make up ours (and two of the three girls on the team are part of this subteam! :)). They are responsible for programming and wiring the robot, dealing with the pneumatics and building the controls.

Anyway, back on topic ...

- Katie

Can we get this thread back on topic? I mean come on folks, what do grammar arguments have to do with stopping conflicting signals, or technical discussion.. and Start a new thread if you wanna discuss electrical sub teams.

Sorry if this is coming acrossed as being a jerk.