Jee Labs Talk

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1. charlie
   

   Hello,

   Concerning the power consumption I was thinking retransmission is not always the best option. In my case the central node was switched of after "an evening playing with jeenodes" while the temperature probe was still outside measuring the freezing cold -9°C.

   Due to the fact that the central node stopped ack-ing, the temperature probe kept on re-transmitting, which ultimately had the batteries running on empty by the morning...

   Ok, my batteries are not of that quality and were probably not fully charged, and I have no clue how NiMH batteries behave at -9°C, but nevertheless it captured my mind today...

   Anyhow,
   jcw, have you ever considered (adding) FEC to make the transmission more reliable iso re-transmitting (or a combination).

   Regards,

   Charlie

   Posted 19/12/2009 18:16:53

2. jcw
   

   FEC as in forward error correction? Not sure that will help much - radio waves at these power levels are finicky. There will always be periods when nothing gets through at all. I sometimes see my weather station on the roof drop out for up to an hour - presumably it's at the limit of the range, but still...

   I would expect to get more effect by making the code a bit smarter - instead of staying in high-power mode until the final ack is received, the node should really go to sleep in between as well. Then that last remaining large current drain period would be reduced from seconds to milliseconds.

   This definitely needs to be addressed. I'm seeing similar behavior for some new nodes here as well - there's a lot of reinforced concrete in the house, range is extremely variable.

   Posted 19/12/2009 20:18:54