Radio Location - please help!

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Posted by Janna at 2/18/2001 4:19 PM EST


Student on team #349, The RoBahamas, from International Academy and Ford Motor Company and Robert Bosch GmbH.



Hey everyone,

We've been having problems with a *very* intermittent radio signal (i.e. the radios don't work unless held within arms length of each other). Has anyone else had this problem? If hypothetically it wasn't a problem with the radio itself and instead had to do with location of the radio...where would a good place to put the radio be, considering our base is small and we have a big rotating arm? (Anyone from Chief Delphi in particular have advice to offer?) Thanks in advance,

Janna

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Posted by Lloyd Burns at 2/18/2001 8:59 PM EST


Engineer on team #188, Woburn Robotics, from Woburn Collegiate and TorDistSchoolBrd, ScotiaBank. OntPwrGen, Enbridge.


In Reply to: Radio Location - please help!
Posted by Janna on 2/18/2001 4:19 PM EST:



: Hey everyone,

: We've been having problems with a *very* intermittent radio signal (i.e. the radios don't work unless held within arms length of each other). Has anyone else had this problem? If hypothetically it wasn't a problem with the radio itself and instead had to do with location of the radio...where would a good place to put the radio be, considering our base is small and we have a big rotating arm? (Anyone from Chief Delphi in particular have advice to offer?) Thanks in advance,

: Janna

We have ours velcro'd to the top of the RC, in a horizontal position, close to the aluminum structure. They work at the full length of the arena. Perhaps you are keeping them so close they overload. Perhaps you should try different cables to/from your radios.

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Posted by Al Skierkiewicz at 2/19/2001 1:34 PM EST


Engineer on team #111, Wildstang, from Wheeling High & Rolling Meadows High and Motorola.


In Reply to: Radio Location - please help!
Posted by Janna on 2/18/2001 4:19 PM EST:



If you hold the modem outside of the robot, do you still have a problem? If not than you are either shielding the energy or pulling the antenna off frequency. It seems like this a problem teams run into every year. The rubber flexible antenna on the end of the radio modem at the robot side, is sensitive to metal objects being placed near it. Worst case is for the very end to be touching a metal object. Steel is worse than aluminum. What takes place is that the object pulls the resonant frequency of the antenna to a much lower frequency. The antenna becomes very inefficient and the modem stops handshaking. Watch the lights on the side of the modem and experiment with moving it around.
Many teams try to bury the modem inside the robot and then surround it with metal covers and structural steel. All of those things reduce the efficiency.
Please note that the antenna is closer to one side of the modem than the other. When mounting the modem, take advantage of this and mount the antenna as far away from a metal object as you can. For a few years now, we have tiewrapped the modem directly to a 1" aluminum box tube and had no problems.
If all else fails, and you suspect that the modem has been abused, then the rubber antenna may be broke. It is flexible, but not indestructable.
al

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Posted by Tim Gates at 2/19/2001 10:00 PM EST


Engineer on team #288, RoboDawgs, from Grandville High School and X-Rite/Delphi.


In Reply to: Radio Location - please help!
Posted by Janna on 2/18/2001 4:19 PM EST:



make sure that both antennas (OI and RC) are parallel to each other. Both vertical.

Tim Gates

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Posted by James at 2/20/2001 7:03 PM EST


Coach on team #21, ComBBAT, from Brevard Community College and Boeing.


In Reply to: Radio Location - please help!
Posted by Janna on 2/18/2001 4:19 PM EST:



Are they both this/last years control system. Mixing last with this years causes intermitent operation unless you are on the teather, or the raidos are really close. We had a simular problem. Also cellular and cordless phones interfear with the communication of the modems.

James R.