Quote:
Originally Posted by Al Skierkiewicz
Esqaured,
The modems operate in the 918MHz FRC band. So most cell phone interference is from cell phones operating just under 900 MHz and obvious FRC radios and Ham operators in the adjacent band. I suspect you might find that interference is not as big a problem as the AGC overload caused by nearby signals forcing the input gain down.
Please check for EMI as well, I think it will prove to be useful data.
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I should have been more specific in my previous post, the medium power amplifier I will try out has a spec'd frequency range of 1-8GHz, but continues to exhibit reasonable gain and output power specs for another 2-300MHz below it. The 5V/m is my best guess at effective radiated power at these "unspecced" frequency ranges.
You've got an excellent point about AGC (Automatic Gain Correction, which in RF systems is intended to avoid saturating your receiver, which leads to data that all looks like the same, far too high level). To test this, I'd have to crack the case on the modem, and somehow I doubt our team leader will go for this
Anyone void their warranty and see how they implemented this year's radio?
Another possibility: I've seen front-end bandpass filters that had poorer than expected rolloff outside the band, resulting in a susceptible front-end. Since the hardware repair to the first team's radio was relatively quick, replacement of a poor quality filter would fit into this category. Additionally, it may not be an issue with all filters, so some teams could be operating just fine.
In the end, I expect this to be similar to last year's 8.2V problem where some teams had it, some didn't. Very similar in that both resulted in non-responsive or potentially destructive robots!