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From: P.Schuman on 5 Apr 2008 11:55
Adam Chapman wrote:
> Thanks to all of you, I replied to this particular post because it had
> the most questions for me to answer.
> I do hope that Im not appearing to be lazy here, I've never had to
> work in wireless systems as I am an aerodynamisist recently turned
> image processing geek. I was expecting my question to have an easy
> answer but as usual here wasn't so sorry and thank you for taking your
> own time to help me.
>
> On Apr 2, 11:54 pm, Jeff Liebermann <je...(a)cruzio.com> wrote:
>> On Wed, 2 Apr 2008 08:00:06 -0700 (PDT), Adam Chapman
>>
>> <adam.chap...(a)student.manchester.ac.uk> wrote:
>>> I've ordered a wireless webcam that will be out onboard an
>>> autonomous aircraft for a university project.
>>
>> I've done that. You're about to have a battery problem.
>>
>>> The camera has a "2dBi Diversity Antenna" and transmits video over
>>> an IP protocol in the 2.4-2.4835 GHz range.
>>
>> Duz this camera have a manufacturer and a model number? A URL with
>> the specifications would be nice.
>>
>
> The camera is a Trendnet IP-TV301W model, specification at
> http://trendnet.com/products/proddetail.asp?prod=110_TV-IP301W&cat=48.
> I don't physically have the camera yet because the university is still
> processing the account, which in my experience can take a very long
> time. If it is possible to estimate transmission ranges with certain
> equipment, I would have an easier job justifying the expense to my
> department.
>
>> 2dBi is a simple monopole antenna. It has a radiation pattern that
>> looks like a donut. There's a big null when in line with the
>> antenna, such as when the aircraft is flying directly overhead.
>>
>
> The 2dBi antenna can be replaced, if there is a better type then I am
> happy to use it. I would prefer an antenna that emits as spherical a
> pattern as possible, otherwise we will have to limit aircraft
> maneuevres.
>
>
>
>>> Now the aircraft needs to operate in a 500x500m area, although I
>>> expect that my ground station computer will be placed some distance
>>> away from the operating area.
>>
>> I have this thing about numbers. How far is "some distance"? How
>> high does the air thing have to fly? What's the MAXIMUM distance you
>> expect to see an image?
>>
>
> I have just recieved more information from the competition organisers,
> who tell me that all flying will be within 500m of the launch site and
> flying is not permitted above 400ft (121.92 m) This gives the max.
> Euclidean distance as 514.65m, although i expect we will be measuring
> that distance on the aircraft with GPS, and with the civilian accuracy
> limitations on GPS (~ +- 12m), I would suggest a target transmission
> distance of 550m.
>
> Due to safety rules we will never lose sight of the aircraft so we can
> expect no obstacles between transmitter and reciever.
>
> I've been slowly writing this reply all day, and thinking a lot as i
> do so. A helical antenna looks the best as it is the most isotropic,
> although it is also pretty big for our aircraft. However even that has
> +-45 degree 3dB lobe, so i might have to have the aircraft bank more
> when closer to the centre of its circular mission area.
>
> The link calculator link from LR told me that if i put an antenna with
> a 7dBi gain (like the one at _) on the UAV and at the ground station,
> i will have a range of over 7km with a 100mW transmitter, which I
> assume can be achieved using an in-line amplifier. Does this
> calculator use the range in the direction of the strongest energy
> emisiion from the antenna?
>
> I guess that more than on antenna on the same aircraft with different
> orientations would interfere with each others signals?
>

how big is the plane ?
do you have a UK link for the project, or photos ?


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