Re: Einstein Field issues Handled correctly?
 

While this problem has been brought to light by the Einstein matches I do not think it is new. At MSC 33 died in the semis about 3 seconds into teleop. In the finals 67 had similar looking drop outs although I cannot confirm that it was in fact an identical problem. 1114 also seemed to have issues although those could be on the robot side (Both 67 and 1114 were connection issues.) Perhaps we, as a community, should begin documenting all of these failures throughout the season in order to identify patterns and the actual quantity of failures. It is easier to accept there is a problem when you have data to back it up and with many examples of failure to look through it would hopefully make identifing the problem that much easier.

Regards, Bryan

Re: Einstein Field issues Handled correctly?
 

Weather radar uses microwave radio pulses that would not have any effect on other wireless signals. Otherwise your internet would drop every time the radar makes a rotation (radars run at all times, not just when there is a storm)

Re: Einstein Field issues Handled correctly?
 

There are several channels / frequency bands.
E.g. 36, 40, 44 (5180, 5200, 5220 mhz). If they use the middle channels (unlikely, but you never know), the radios are required to listen for radar and switch channels (called Dynamic Frequency Selection).

Re: Einstein Field issues Handled correctly?
 

Does the cell phone noise hypothesis hold any water? I feel like these things happen when there are a lot of people near a field, such as during elimination matches (see 1717 on Newton for similar problems). A lot of phones including mine have WiFi capabilities and may have interfered with the routers on the field.

Re: Einstein Field issues Handled correctly?
 

I was at the event where 118 was having issues (CT) and it was traced back to their robot.

Whatever this was really cost the championship for every alliance. They all were strong and each could have taken it if they were running on full power. 987's alliance was extremely close in the last match the High Rollers only needed to score a few more but they were motionless.

Re: Einstein Field issues Handled correctly?
 

For complete thoroughness, specs on NOAA's NEXRAD radars say they use 2.7Ghz to 3.0Ghz. NOAA also says they're constantly emitting high energy pulses. Short high energy pulses. Something like 1000 pulses per second, but the transmitter is still only active about 7 seconds out of every hour. So it seems unlikely that that's the culprit.

Re: Einstein Field issues Handled correctly?
 

Am I correct in thinking that the radios use spread-spectrum techniques? It has been quite a few years since I have worked with such radios.

Re: Einstein Field issues Handled correctly?
 

Okay, somethings wrong here. In the last 4+ hours since championships have been over, there have been 14 posts in the 'congrats 16, 26 and 180' thread. There have been hundreds complaining about the field issues. Whether you like it or not, they are the FIRST World Champions. It isnt their faults that there was a problem with the field. Their achievements are just as important as field issues. I suggest that everyone heads over to the thread to congratulate them.

http://www.chiefdelphi.com/forums/sh...hreadid=106040

Re: Einstein Field issues Handled correctly?
 

Holy crap. I didn't know about that.... I think that's part of the source of the problems.

I'm pretty sure FMS sticks each robot on a different 5GHz channel, and actively manages them, in a way that *may* not be compatible with DFS.

If the consumer grade d-link detects 5GHz radar stuff in its channel, and decides to try to jump onto another channel and FMS doesn't play nice on that decision guess what? boom, robot dead.

Would also explain why Red 2 in particular was having issues. Guessing the closest radar antenna was on the frequency that Red 2 was arbitrarily assigned by FMS.

Re: Einstein Field issues Handled correctly?
 

I have witnessed competitions as a FRC competitor and as a scorekeeper at a regional.
I have spent some time thinking about what they could do to fix/prevent the problems occurring. First, they should have used an electronics system from a field that has been through regionals and has proven to work in a competition.
Then, they should have tested robot connections before matches, possibly going as far as to run a match with the robots sitting on their carts, not on the field, and the sounds turned off so the audience doesn't hear.

If they didn't get solved with the earlier ideas, they should have started changing the field electronics out incrementally starting with the portions that interface with the robot, and prepping a second server to try as a complete overhaul and start the electronics from scratch. Then they should have tested connections during awards and speeches.

Replaying the first two matches was the right thing to do, but when problems persisted, they should have tried to do more, if for no other reason - because this is EINSTEIN.

Re: Einstein Field issues Handled correctly?
 

This was what I was thinking of:
http://en.wikipedia.org/wiki/U-NII
Where radar avoidance is mentioned several times.

Re: Einstein Field issues Handled correctly?
 

This is what sums up my feelings. You could tell that what happened on the field set the tone for the arena, the announcers weren't the same, Dean, Woodie, etc weren't the same and we were just seeing them via a webcast. The fact that nothing was done to remedy the problem is flabbergasting when you are in the most important matches of the season.

118 might be a seperate issue, but you don't have robots just start to lose comms in matches all at once. I could see 1114's issues come back but have robots that performed 100% in their division elims hit Einstein and all but three experience issues you have a MAJOR problem on your hands.

Re: Einstein Field issues Handled correctly?
 

Pretty sure our radios operate in the 5.15-5.25GHz range. From D-Link's website:
As a result, per U-NII our radios are not subject to DFS.

Re: Einstein Field issues Handled correctly?
 

In the future, it may be advantageous to operate in that band, specifically because most consumer grade wifi does not.

Re: Einstein Field issues Handled correctly?
 

Blaming TCP or IP should be completely out of the question. First of all, these are two of the most (really, THE most) used networking protocols in existence today. They are used by every single device (that's billions of devices) that connects to the internet.

Furthermore, one of TCP's advantages over other transport-layer protocols (such as UDP, commonly used for tasks such as video streaming) is it's reliability.

Which brings me to...
Though I don't know for sure, I'm assuming that the FTA was telling you that the application only sends the signal once for auto/teleop, constantly for disabled. Even though the application layer only sends one message down to the lower layers (TCP, IP, etc), TCP will keep sending the packet over and over again until it receives an acknowledgement. If that packet is dropped, it will be resent.

I very highly doubt that. I also doubt that never having used the Einstein field before would be to blame for any issues. The hardware and software are identical to that used on every other field.


Are there kinks that need to be worked out? Yes.
Do I think it is the FMS or field hardware's fault. Not really.
Do I think it is the robots' fault? Not really, though I have seen enough robots to believe that robots with various electrical or programming issues are just confuddling this problem more.