RCU Forums - View Single Post - Futaba, or just 2.4, problems at Joe Nall?
Old 05-17-2011, 10:23 AM
  #118  
hyperdyne
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Default RE: Futaba, or just 2.4, problems at Joe Nall?

Basically if there was more reflective materials than expected, the receiver could of seen increased fading/multipath which can cause rapid signal loss. And because futaba uses a single antenna at any given time. The best of their 2 antennas in the Rx is selected periodically and that one is electrically switched in. The cost function on which antenna to use is based on the correlation triangle "health" from their DSSS despreader (this is all in their patent). Problem is, the despreader is downstream and potentially the problem has gotten worse when the switch is finally determined. And then what if the other antenna is not much better? Signal lock is lost and Rx must do total reacquire. Add in lots of other signals that bring the noise floor up and aquisition (the achilles heel of any DSSS system) takes longer. Things can spiral from there.

You can read the "2.4GHz lockout today" thread, lots of good technical info. Point is, I will take a RAKE receiver any day of the week versus a single antenna-switching algorithm.

Anyway, YMMV.



ORIGINAL: readyturn


ORIGINAL: hyperdyne

If this was a case of multipath or fading loss then this corroborates Futaba's single antenna switching circuit is suboptimal, as would be expected on paper.


Would you please expand on this statement... seems to be all inclusive.

Thanks