Re:how many 3-ch sensors connect to rfxcom

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Re:how many 3-ch sensors connect to rfxcom

Post by skyewright » Wed Apr 22, 2009 11:24 pm

wfpost wrote:How many 3 channel sensors can I connect to my new rfxcom gadget? 3?
I have 6!

The only problem is that as there are only 3 channels you'll find that periodically any pair of sensors that are assigned to the same channel will want to transmit at the same moment and will conflict (depending on relative locations and signal strengths the sensors may block each other, or one may be strong enough to obscure the other).

The conflicts happen because the time between transmitions for each sensor is almost but not exactly the same as for the other sensors, so overtime the moment of transmission for any pair gradually drifts together, coincides (for a few hours), then drifts apart. The behaviour is quite regular.

What I've done is to give the sensor that I most want to report in full time (a temp in a jar solar / black body night time cloud sensor) a channel to itself (so it is never blocked), two others share another channel, and three others share the third channel. For something like a soil temp I don't mind too much if the signal is lost now and then.

If the type of sensor you want is available with more channels, you might prefer to avoid the problem by making use of the extra channels.

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Re:how many 3-ch sensors connect to rfxcom

Post by Acki » Mon May 04, 2009 8:47 pm

I´m using 14 (!) i.e. 7x thr 128 and 7x thgr 122nx.
And it works fine.
Being no coward, I´ve ordered 4 thc 238-sensors now :unsure:
I will report as soon as possible


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