Radios at Rutgers

Hey,
I was wondering if any of the other regionals have had problems with the radios? During several matches at Rutgers, the Red Alliance lost data signals from the radios, but nothing was done about it. One such match cost our alliance with team 550 major QP becuase with 30 seconds left, both our robots lost signals and we couldnt drive. The match ended with both of our robots sitting in the middle of the field not moving, and the score was tied at 38-38. Since the other alliance had two goals they were given the win, and the 114 QP. During that 30 seconds both of our robots could have made it back to the home zone and given us a score of 58, but that didnt happen. When we contested the match they told us there was nothign they could do, and then they brough the matter to the InnovationFIRST representative, who proceeded to tell us that our batteries caused the problem. However our battery was running at a constant 12.8 volts, and isn’t it a bit much of a stretch to say that a battery problem beset two teams at the same exact moment in time? This was not the only match that radios seemed to be screwy, yet nothing was done about it. Anything like this happen at any othe regionals?

YES!!

Our stuff went dead, into standby mode, and that costed us like 110 pts!!! We had to settle for 20, and they said our programming was bad. We where fine Thurs, Fri, but on our last Qualifying match, it screwed us!! Lets say i was a little mad…:mad:

I also heard about the radio problems at Rutgers. We were fine all day Thursday, but kept cutting out in our first two matches on Friday. (We still won the second match by resetting the robot like crazy and getting a push from our ally… :slight_smile: ) We thought that the radio was the problem but later found out that the light shorted to the frame of the bot. After fixing the wiring, we never cut out again. While your situation sounds a bit different from ours, you might want to double check the wiring before your ship to Florida, if you have time.

Sorry, but i didn’t realise Rutgers was a nother place for competition. Our stuff cut out at GLR, they said that it was their fault, than said our programming sucked. They even had a person to come over and inspect the wiring/programming, and nothing was bad!!!:mad:

same thing happened to us. Match started and we didn’t move after checking everything in the pits and finding out it was fine we were very heated at the officials!

We at Team 25 also had problems with the radios several times during qualification matches.

Also we belive that during one finals matches, we had 3 goals in our zone when the radio cutout!!!

Seems like one year there were radio problems that were caused by two way walkie talkies(frs?) being used in the room.

I know this is a sore point for teams who have failures with control systems, but…
In the scheme of things, FIRST has instituted the rule of no rematches and tied it with the throwing out of the lowest score in oder to keep the competition moving. If you have been to a regional, you will note that no matter how well planned the event is, somewhere between 9:00AM and 9:01AM things start to go awry and backup. It is something we all live with and it is the only rule thus far that is consistent and expected.
As to radio cutout, there have been RF monitors at FIRST events to check for interference to insure that teams are not interacting with other teams. Some people do forget and power up in the pits without the tether.(Big mistake and very dangerous!) When both teams at a player station cutout at the same time and the rotating lights extinguish at the same time, the first place to look is at the player competition ports at that station. However, it is not impossible for both robots on a team to reach low battery at the same time and reset their respective robot controllers. It does appear that short dips in the power supply can scramble the robot interface without a full reset occurring. Sorry you guys got skunked.
Good Luck To All

I know that last year, FIRST said that in the event of failure of the competition equipment, they would offer a rematch to the team that was affected. I know this because at one of our regionals last year, the competition controller for our station failed and our robot went on and off for several cycles. We were offered a rematch, but declined, sinc the final score was decent, and wouldn’t change much after a rematch.

It’s possible that the rules have changed since then, but that’s what happened last year, and is what I am basing my information on.

*Originally posted by Chief’sDad *
**Seems like one year there were radio problems that were caused by two way walkie talkies(frs?) being used in the room. **

That should not occur since the output is so low around 100mW and the frequency is in the 440mhz area while the radio controlers are around 900mhz unless one of he FRS channels are a harmonic of the frequency that the controlers run on but it is not likely.

Many FRS (Family Radio Service ?) radios do operate in the 900 MHz band. This is an unlicensed band when the radios are low power output. Some cell phones, and wireless phones also operate in this band. Hence the insistance by FIRST that no radios or cell phones be used on or near the playing field.

FRS is in the 400Mhz band, it is on the same set as the GMRS here is more detail:

1… 462.5625
2… 462.5875
3… 462.6125
4… 462.6375
5… 462.6625
6… 462.6875
7… 462.7125
8… 467.5625
9… 467.5875
10… 467.6125
11… 467.6375
12… 467.6625
13… 467.6875
14… 467.7125

they should not be a problem

They shouldn’t be, but the 1st harmonic of all of these frequencies falls in the 900 MHz band. Still, it is highly unlikely that a 1/2 watt FRS signal’s harmonic (which is very weak) would happen to be near enough one of the robot’s channels to interfere with it.

Are the IF radio modems FM? If they are, their signal probably cancels out most interference, unless the interference is very strong.

I’m guessing that most people’s interference problems are coming from other robots, bad antenna positioning, or maybe cell phones, but even that seems unlikely to me.

Last year at the Western Michigan we had radio problems for three matches. It was found out later that teams were operating their robot in the pits WITHOUT using the tether. Once they started using the tethers, we had no more problems.
At the Buckeye I found at least three teams not using tethers and I made them aware what could happen. They were very gracious about using them from then on…

Wayne Doenges

Come to think of it we might of have our signal broken at Rutgers a few times. In our last match during the finals I was driving the robot and then the controls wouldn’t respond. I don’t know if it was the signal that was inturrupted or if it was the motors locking up from getting hot.

I used the term FRS to indicate that unlicensed 2way radios are available in the 900 MHZ band. There are a variety of services that are also allocated for that band. The frequencies of interest for the radio modems are 902-904 and 926-928 MHz. The FCC allocation tables (www.fcc.gov) have fixed, mobile, broadcasting, radio location, amatuer radio and television, personal communications, ISM (?) and fixed microwave. Television stations also have a variety of products available in this band for point to point communications and data.
Without getting to techie (I can if you want!) the second harmonic of a 450 MHz radio can end up on frequency in the 900 MHz band very easily. But so can a variety of other things mixing together such as an FM transmitter mixing with a the second harmonic of a radio at 415 MHz. There can be mixing taking place right on your robot if you have loose metal in close proximity to the radio modem.
The bottom line here is most radio modem problems are easily solved by checking for bad cables, correct placement of the radio on the robot and keeping all teams from using radios in the pits. If you have done this in the past and think it’s OK to operate with the modem in the pits, please stop, it’s potentially dangerous for other teams in the pits and is bad for the competition.
Good Luck All