XBEE 900HP S3B Range Test Problems

XBee & XBee Gateway
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1

I’m working on an outdoor project in farm fields. We’ve got clear LOS between modules, and the radio antenna are ~6ft and 8ft off the ground respectively.

Function Set: Xbee Pro900HP 10k
Firmware: 1067

One radio (home radio) is an Indirrect msg coordinator in transparent mode.
The other radios are set to be a Routers in api mode.

We’re getting very bad range on these things. Comms are unreliable past 300-400 ft. Increasing antenna height is an available option, HOWEVER, our range tests (as per xctu) say that we’re perfectly fine for over a mile. When performing the range test, we get 90%+ at that distance (with the same heights). This is far from the case when we try sending our usual signals.

Current theories:

  1. Range tests use direct transmissions and therefore are more reliable (as opposed to the broadcasts that we’re using).
  2. Something about the coordinator / router dynamic is screwing stuff up.
  3. Our range tests are reporting their success improperly.

So here’s a boiled down version of my question:
Why would a range test get a vastly different communications reliability than our normal setup?

and (if I may)

What options do I have to increase communications reliability (other than raising antennae)?

Other salient points on the system setup:
None of the system is on all the time due to battery restrictions. We cycle power to the coordinator, who then stays on while various routers come on and report their status.

2

The range test does unicast transmissions with up to RR attempts plus 1 to get the packet through where broadcast uses MT +1 time. Try increasing MT from the default of 3 to something more like 6 and see if that helps any.

3

First and foremost. Broadcasts DO NOT WORK as well as direct calls. Keep this in mind. Also you should understand that whenever you send out a broadcast, the xbee is ringing/sending that signal repeatedly for about 2 seconds. Any additional broadacast that you attempt at that time will actually interfere with the first transmission.

Lastly. I actually had rf intereference with my radios. We were next to a (cleverly disguised as a palm tree) cell tower that was impacting transmissions (i think).