|Subject:||Re: [Paparazzi-devel] New Telemetry Hardware - Digi 9XTend|
|Date:||Fri, 15 Nov 2013 09:25:16 +0200|
|User-agent:||Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.0|
Not at all, even with 2.4 ghz they are a luxury but when you start using frequencies like 900mhz for telemetry and 1280 for video they are needed.
Also sometimes they are needed to reduce interference of the 900-1.3ghz video tx (not modem) with the GPS.
This also means that GPS units with antenna band pass filters are better for smaller UAVs.
Your biggest friend is spatial separation of the antennas and using different polarization for the video, telemetry and/or GPS.
In bigger UAVs with video rf power > 10w they use an rf switch (or two video tx units) and two 180-240 degree radiation antennas each mounted on the wing tip and activated according to the position of the UAV in respect to the home station thus avoiding radiating directly the UAV's fuselage.
Btw i found this and i am tempted to try it with a normal 2w bidirectional amplifier:
From the specs i see that i can tolerate the 100ms latency (provided that the specs correspond to reality) since we are not actually doing any fpv flying and it's size looks very small.
If anyone has used it or something similar let us know...
I am also using this for experimenting but not at full power, 5w are more than enough and cooling is easy when mounted near the propeller:
On 11/15/2013 08:44 AM, alonso acuña wrote:
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