RE: [Paparazzi-devel] Video transmitter

[Tom Apker]

Mohammad,

   If you have room in your airframe and can tolerate a fair amount of
directionality in either the telemetry or video signal, you can get
extra isolation by using different polarization for the two systems.
If you're using dipole antennas, have one vertical and one horizontal,
and then tilt your receivers to match.  The one that is vertical will
be omindirectional relative to the ground station, while the
horizontal one will have dead zones when the antenna points at or away
from the GCS.  You'll still want to place the antennas as far apart as
possible, and use minimum TX power on the less important one.

   Alternatively, if your video transmitter has an audio feed, you can
encode the telemetry data into that and save yourself weight and power
consumption aboard the aircraft.  That was a noisy, lossy way of doing
things with the old analog systems, but I haven't tried it with the
new digital video downlinks.  I think some of the new cameras even
have a way of sending data to them, mostly for commands like operating
a pan-tilt-zoom or adjusting the lighting settings, but I'm not sure
if you can tap into that line for ground-to-air communication.  At the
very least, you could operate the telemetry modem in RX-only mode,
which would reduce power consumption and avoid the interference issue.

Cheers,

Tom

On Mon, Mar 17, 2008 at 1:00 PM,  <address@hidden> wrote:
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>    1. Re: Assembled Tiny 2.11, IR boards,       and LEA-4P      modules
>       available for order (gwen hastings)
>    2. Re: Re: Paparazzi-devel Digest, Vol 48, Issue 10 (Pascal Brisset)
>    3. Video transmitter (Mohammad Ali Haji Pour)
>    4. RE: Video transmitter (Yves Touchette)
>
>
>  ----------------------------------------------------------------------
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>  Message: 1
>  Date: Sun, 16 Mar 2008 20:53:36 -0700
>  From: gwen hastings <address@hidden>
>  Subject: Re: [Paparazzi-devel] Assembled Tiny 2.11, IR boards,  and
>         LEA-4P  modules available for order
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>  Message: 2
>  Date: Mon, 17 Mar 2008 09:37:30 +0100
>  From: Pascal Brisset <address@hidden>
>  Subject: Re: [Paparazzi-devel] Re: Paparazzi-devel Digest, Vol 48,
>         Issue 10
>  To: address@hidden
>  Message-ID: <address@hidden>
>  Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>  Toby Seaman wrote:
>  >
>  > I've just tried minicom and chanegd to /dev/ttyUSB0 and hoped to get
>  > flashing lights showing TX, but got nothing.
>   Do you have the correct permissions on /dev/ttyUSB0, i.e. are you a
>  member of the dialout group ?
>   What configuration do you use in your airframe ?
>   "cat /dev/ttyUSB0" should display some chars on the terminal if
>  something is received (CTRL-C to stop, and "reset" to restore the terminal)
>
>  --Pascal
>
>
>
>
>  ------------------------------
>
>  Message: 3
>  Date: Mon, 17 Mar 2008 18:20:59 +0400
>  From: Mohammad Ali Haji Pour <address@hidden>
>  Subject: [Paparazzi-devel] Video transmitter
>  To: address@hidden
>  Message-ID: <address@hidden>
>  Content-Type: text/plain; charset=us-ascii
>
>  Dear all,
>
>  Can we use 900 MHz video transmitter? If we use 2.4 GHz what should we do to 
> avoid interference?
>
>  Regards,
>
>  Mohammad
>
>
>
>
>  ------------------------------
>
>  Message: 4
>  Date: Mon, 17 Mar 2008 11:41:30 -0400
>  From: Yves Touchette <address@hidden>
>  Subject: RE: [Paparazzi-devel] Video transmitter
>  To: <address@hidden>
>  Message-ID: <address@hidden>
>  Content-Type: text/plain; charset="iso-8859-1"
>
>  Hi,
>
>  You can 900Mhz for the video if you are not already using it for the 
> Datalink. Generally, we use 900mhz for the datalink and 2.4Ghz for the video, 
> but there is nothing wrong with doing the opposite if you can find equipment 
> with suitable range.
>
>  I'm not an expert with RF and dealing with interference, but here's a few 
> tips:
>  On board the aircraft, use the minimum TX power required for the range you 
> need.
>  Try to leave a maximum distance between the transmitting antennas (Video, 
> modem) and the receiving antenna (RC, GPS).
>
>  -yvest
>
>
>
>  > Date: Mon, 17 Mar 2008 18:20:59 +0400> From: address@hidden> To: 
> address@hidden> Subject: [Paparazzi-devel] Video transmitter> > Dear all,> > 
> Can we use 900 MHz video transmitter? If we use 2.4 GHz what should we do to 
> avoid interference?> > Regards,> > Mohammad> > > 
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