Why Not Use ISM band?

[Mr-Shutter]

How come no one has thought of using ISM band radios at 2.4 Ghz. It provides a strong signal and ranges up to 3,000 feet. Radio problems seem to happen a lot at compition. Spektrum has come out with their "DSM" (Digital Spectrum Modulation) radios for rc cars and works awsome, also no easy to damage metal antenna.

"Because of the relatively low noise in the ISM band, and the noise immunity inherent in DSSM systems, Spektrum DSM is said to be free of "glitching" (momentary corrupted or missing signals which can cause erratic movement or loss of control). Additionally, the system "binds" each transmitter to its particular receiver, ensuring that no transmitter will interfere with other nearby Spektrum DSM systems."

also, i can see the radio being more compact and useing one of the I/O pins insted of a big heavy serial cable.

[ZZII 527]

I have a feeling we might see 2.4GHz radios in the new control system. For MIT's 2.007 competition, we switched over to ZigBee serial bridges this year. They're cheap, easy to use, have good range, and worked very well overall. But no radio can be entirely free of glitches: we found a slight increase in dropped packets in the presence of 802.11g wireless networks. The current 900Mhz radios probably don't have this problem.

[Greg Needel]

Originally Posted by Mr-Shutter

Radio problems seem to happen a lot at competition

Unfortunately this is a big misconception. In actuality the radios which are used on the robots and the field is one of the most stable parts of the control system. Most cases where people blame radio problems for robot malfunctions are actually other un-related issues, such as battery power, programming mistakes, and mechanical failures. I challenge everyone to actually look at their robots when a problem happens rather then just blaming it on the radios.

Specifically when dealing with the change over between autonomous and teleoperated modes make sure that your variables and states are set correctly.

[ahecht]

I'll second what Greg said. I wasn't that involved in FIRST in the 2007 season, but during the 2002-2006 seasons (which included 10 regionals that I competed in) I never encountered a radio problem that was caused by interference or signal issues. All the problems I encountered were caused by loose cables, bad code, scoring system problems, etc. I know the new 2007 radios had issues, but from what I understand those were mostly worked out.

[Al Skierkiewicz]

Everyone,
Your radio links are monitored during competition and if there is a radio issue you will be notified. Most often a lead inspector will carry the message and help you look for problems. I had far less radio issues this year then in the past once the new code was loaded into the radios. Most radio issues come from kinked or otherwise abused cabling, mounting of the radio deep inside the robot base or next to a motor, or battery issues.

[DonRotolo]

I agree, the radios used by FIRST are pretty bulletproof, and they do error detection so missing data is very rare. 900 MHz (which, by the way is also an ISM band) is a somewhat underutilized band these days, so it's a lot quieter than 2.4 GHz ISM.

Don

[Cuog]

I agree with those that said the radios we have are very robust. We had quite a few issues with lag in the controls or dropping signal pre ship date. But once we got to the regional and had the firmware on the radios and RC updates everything was flawless no more lag and I don't think we ever dropped the signal after that.

I think I'm beating a dead horse now but the radio modems we have now certainly seem to fit perfectly to most of our needs(yeah being able to send massive amounts of data back to the OI would be nice for stuff like video but its not needed and won't really be utilized by many i don't think)

[Mr-Shutter]

Do they have to be so big?

[petek]

The number one "radio problem" I saw at two regionals, the champs and two off-season events this year was forgetting to plug the serial cable into the RC. Somehow I don't think new radios are going to eliminate that problem...

Just the same, the smaller packages and more robust antennas used at 2.4 Ghz would be nice - especially compared to this year's radios.