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Re: [Paparazzi-devel] Range testing for Xbee modems (2.4GHz)


From: Roman Krashanitsa
Subject: Re: [Paparazzi-devel] Range testing for Xbee modems (2.4GHz)
Date: Mon, 23 Aug 2010 12:03:05 -0700

Hey Bao,
 
We did a pretty much same test about two years ago in the University of Arizona, right in the middle of our campus. The ground station was located on elevation about 10m from the ground (2nd floor of the student union), and the othe modem was been slowly walked on a straight line away from the ground station. We maintained a direct LOS all the time and pretty much 100% of Freshnel zone due to elevation, at least up to the point of signal loss. Again, some palm trees were around and of course lots of wifi.
 
We had a video test, then data test, both on 2.4Ghz. The data test showed lots of dropped packets starting at about 600m. Could not get much longer than that. Video required amplifier and a filter - up to about 1300m. As far as I remember, we used 3dbi patch antennas.
 
Hey Martin, long time no see! I think xbee also has something about frequency hopping in its settings. We haven't used it, but I think it is still there.
 
Sincerely,
Roman Krashanitsa

2010/8/22 Martin Mueller <address@hidden>
Hi Bao,

the difference between XBee (at least XBee "Series 1") and a 2.4GHz RC is that some RC systems change its operating frequency if one is occupied or even jump with the frequency all the time whereas XBee stays at a fixed (user changeable) frequency. If that frequency is in use by Wifi, Bluetooth, analog video or even a microwave oven, the XBee will loose data or stop completely.

The XBee range varies a lot with the noise level you have. It could be > 16km in a "calm" alpine scenario or just 100m in a noisy urban environment.

Martin

----- original Nachricht --------

Betreff: [Paparazzi-devel] Range testing for Xbee modems (2.4GHz)
Gesendet: Mo, 23. Aug 2010
Von: BX Guan

Hey guys, this is a relatively simply question, but first a bit of background: My plane is controlled with a 2.4GHz system as well. Tried to do some simple range testing (as in, another group member walking around with it) yesterday on my uni ground so it is full of trees and probably lots wireless/bluetooth around as well. Now the question: of the several trials, my modems loses connection with each other at a very short range, somewhere within the range of ~100m to ~300m. I was testing the range of the RC system at the same time and it responds properly for about 1km, despite growing gradually slower and weaker towards the end. I was just wondering what exactly went wrong, as the modems themselves should have a range of at least the same if not more than the RC system. I had a 9dB gain antenna plugged into my ground modem.  And if anyone's wondering, got the modems as part of the bundle from PPZUAV. Any feedback/ideas would be greatly appreciated. Thanks. Bao

--- original Nachricht Ende ----

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