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.

As it turns out, everything. You see, grammar and spelling are important. As smart as computhief might be (and upon decoding his posts, it turns out there is some valuable information in there), I have a conflicting signal (wut, u) that his post isn't worth reading. So you see, one signal says, "Intelligent statement, pay attention," while another says, "Nothing important here, ignore".

You see, conflict.

Grammar and spelling are formalized ways of formating a wide variety of information. By using proper grammar and spelling you reduce the chance that your message will be misunderstood or ignored as noise. You also come across as at least as educated and intelligent as you really are, rather than as an ignoramus who could not communciate a simple thought even if by chance he should have one.

While this is a bit off topic for this thread, the attempt is being made to correct the behavior of somebody whose valid inputs are often ignored because they are hard to decipher. It is appropriate for a gentle rebuke to occur here where the error occured. Some of us who follow this thread are expressing our desire that communication in it remain clear to those of us who are accustomed to speaking and writing standard American English. It seems to me that computhief263 is merely trying to save on keystrokes at the expense of clarity. This is a disservice to his readers and causes us to lower our opinion of his educational attainments.

Now that at least three of us have made our objections known, we can drop the subject and return to weightier matters...

I hope that sounds really stuffy, I was trying.

I agree. From an English major, grammar, spelling, and punctuation are indeed important.

This can be further debated in a different thread, as this is obviously non-technical, and it has been brought up several times before... This is a dead horse that has been beaten one too many times and leads everyone nowhere. We'll just go on the basis of - please spell as correctly as you are able and rememeber that 'ur' and 'n', etc., are not words. You make it easier on the Chief Delphi community when you make your posts clear, concise, to the point, and complying with the English language.

With that said, everyone, you are now returned to your regularly scheduled technical forum.

2 electrical students, 2 software/electrical kids

Our team has around 19 students...

From what I saw of the setup at Nationals, all radio chanels are predefined on a per-station basis, and are tested regularly for proper communication. Each station's Arena Controller was labeled with a specific designated channel (set in dip switches I believe) such that when the OI is plugged in, it's pre-set to a constant channel for that station. All that remains is the activation of the Robot Controller, which scans all frequencies for it's team number, and auto-switches itself to the proper channel it recieves.

There were 5 fields, with 8 stations per field, yielding 40 channels. However, 8 were not in use during qualifications (from Einstein).

I believe they mapped out ahead of time which fields use which channels for which stations (A1, B1, C1, D1, A2, B2, C2, D2).

hmm... Jason, good job on asking that question. Never thought of the whole channel issue in terms of nat's, and your question brought out some of the cool behind-the-scenes work that goes into the controllers. I think its been pretty much answered in depth, but kudos for asking.

Although I do wish people would have read your full post before replying with stuff that you made clear you knew in your origional post.

Thanks for all the info everyone! I really appreciate it. I wonder if we can get FIRST and IFI to release some sort of documentation about behind the scenes tech that goes on at compitions for those of us who are interested . FIRST is all about science and technology, right? Well, teaching kids about the setup behind the fields and all the technology that goes into make everything run smoothly can only help this goal along... As for replying about other stuff, its ok. I confused some people (I have a bad habit of that :rolleyes: ) so they thought I wanted information on the competition port.....

From what i understand the reason that IFI hasn't been more forthcoming with information about the specifics of the competition port and the way they run competitions is because one of the ways that they are able to recoup some costs is by renting out the Competition Controllers (Arena Controllers) to off season competitions.

That is why alot of people were surprised when they released the documentation for the competition port this year, as they have always been protective of that information.


But yes it would be cool if they did release full documentation on the whole system.

IFI released information about the kill and channel selection options early on - Dr Joe's Yellow Dongle paper was out not long after First started using the new controller. You can have off season comps, and test your robot with this info.

The info about the auton_mode and the way to use it for testing iwhile required for testing programming, is new this year, so has not been released until this year.

IFI releases info to allow you to do things you must do to get ready for the contest, but the rest is proprietary, For instance, the standards for the communications between OI and arena controller are still clouded in secrecy, and no one is talking about pin 1 ....

<whisked away by IFI operatives before he could ...... oops, they're bac.......>:D

As we stated before, there was evidence at regionals that a team setting up for the next match and had plugged in their controller were likely to interfere with the teams currently playing on the field. Since this was more apt to happen during practice sessions, the interference was observed more during those matches. We had evidence on several occasions where robots stopped functioning due to corrupt data packets. We concluded that should enough bad data packets be received, the controller would default to a shutdown condition. A power cycle or reset would restore the original program loop and the controller would then search, acquire, and function normally if the offending interference were no longer present.
This is why it is so important for teams to only use tether in the pits. In confined areas during regionals, teams using radio links in the pits can have an effect on robots in competition.
Now, my two cents on the abbreviation issue. As a ham radio operator using Morse code, abbreviations are able to get your message through in a shorter time. The transfer rate, though, is in the 5-13 words per minute range. In a medium where the transfer is faster than the spoken word, please make full use of the language and make yourself heard and understood.
P.S. Spell check is a blessing too.

for most ISM frequency ranges, 3 channels apart are enough to prevent interference, so if you have a phone on channel one, set your wifi base station on channel 5, whatever else you have on channel 9, etc