Hi all!
I did some RSSI range testing yesterday with 2 motes and did not even get near the specifications. On campus, with line of sight, I got about 250 meters (accross a football field!). And on a highway (that is under construction, so no traffic, pure open space) I got to about 1.3 km. That is very far from the 5.95 km stated in the spec sheet.

I have 802.15.4 waspmotes with XBee Pro modules and 5dBi antenna and UFL connector. I was using scannedBrothers functions with power level maxed out (4). One person at one end with the mote connected via USB to a laptop, holing the antenna up in the air. The other person walking away with the other mote and the antenna up in the air. We had line of sight all the time.

1- Is there an obvious reason why I am not able to get more read range?
2- Can I use higher gain antennas with my waspmote?

Thanks!!
Mag

Hum guys, just an extra observation that might explain everything.
I just noticed that from the XBee manual :

XBee-PRO
• Indoor/Urban: up to 300’ (90 m), 200' (60 m) for
International variant
• Outdoor line-of-sight: up to 1 mile (1600 m), 2500'
(750 m) for International variant
• Transmit Power: 63mW (18dBm), 10mW (10dBm)
for International variant
• Receiver Sensitivity: -100 dBm

So if the max outdoor line of sight of the XBee module is 1.6km, how is it possible that your waspmote have a range of 7km????

You can use higher gain antenna's I guess... I remember that we did a range test here, similar to the hidden station problem with three and four devices, with 3dBi antennas on a soccer field... with lowest power level of zero and sometimes we had a maximum transmission range of 90 meters, sometimes around 135 meters. It depended on the weather plus the exact orientation of the antenna, since every antenna behaves differently when it comes to transmission characteristics.
Ah and we used normal XBee 802.15.4 modules, didn't test the pro modules...

In total I guess that the maximum range values from the Libelium test in the Monegros desert seem to be either really optimistic since nobody could confirm their results up to now. But I guess that the specifics of the test environment "improved" the range... it seems for example strange that RSSI values from different devices and frequencies for 356m and 639m LOS are the same. (http://www.libelium.com/libelium-downloads/EWSN2010PosterFinal.pdf). I guess the specific Fresnel zone of the testing area helped here... but I cannot prove it due to the lack of proper testing ground.

Thanks for your reply Michael!
I agree that the desert must play a big part in this test... Thanks for the link!
Here in Nova Scotia it is relatively humid, with a hilly terrain. This week-end, we found a stretch of highway about 2km long with line of sight, we were able to get signal, but it was very low. We added a ground plane under the antennas (I bet that's why Libelium tested theirs on top of cars!) And it helped, roughly got 10 dB more with it.
But like anything, we need to experiment in our own environment to get what we need out of it :-)
Cheers!

Wow I didn't thought that the use of ground planes would make such a difference... 10dB is a lot!

Did you have the chance to try higher gain antennas? Would be interesting to see, how the Waspmote works with them... I remember reading at the Freaklabs Blog that the antenna socket and the antenna must be "matched" to get the full antenna gain... so any practical comparing test with another antenna then just the plain 3dBi and 5dBi antennas would be interesting.

Greets
Michael

Hi Michael!
I didn't try another antenna yet. I'll see what I can find in the lab next week. The problem with higher gain antennas (from what I understand) is that they have a narrower beam. It's like if instead of having "more power" they just concentrate their power by focusing the beam. Anyways, I think it's still worth a try, but maybe not a practical solution :-| And yep, they gotta be matched at 50 ohms...
Will update as soon as I find something to test with!
Cheers!
Mag