Replies to This Discussion

Permalink Reply by Mike Lombardi on August 17, 2010 at 5:37pm

I just order all the items you listed. Thanks for doing the research Keegan. I ended up going with this camera instead because if you spend over $200 at bevrc, you get free shipping (which would have been $25).

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Permalink Reply by Cronselaar on August 22, 2010 at 2:45am

Hi, keep in mind that 1.2 is in the gps range... The best I have used was a 1.5watt 1.5GHz setup which cost $80. From the same place I bought a chinese "webbie" to record on the plane in HD and pal to my screen on the ground. No more vidz with the bad signal on it.. Anyway, with the 1.5 I've never flown out of range, scared my radio will go after 3km.. Just my 2c

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Permalink Reply by Guillaume Helle on August 27, 2010 at 5:51am

> The best I have used was a 1.5watt 1.5GHz setup which cost $80.

What model is it and where you bought it?

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Permalink Reply by Joseph Reynolds on August 28, 2010 at 10:39am

Question about this... Is it true that the higher the frequency the faster it drains the battery? for example I will keep the numbers small for easy math:

Given a 1000Mah battery

and

900Mhz @ 100Mw power = A hours battery life
1.2Ghz @ 100Mw power = B hours battery life
2.4Ghz @ 100Mw power = C hours battery life
3.4Ghz @ 100Mw power = D hours battery life
5.8Ghz @ 100Mw power = E hours battery life

or will they all be the same because thy are all outputting the same "100Mw" power raiting? How do these transmitters work?

thanks for your responses in advance :)

Joey

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ModeratorPermalink Reply by Nathaniel Caner on August 28, 2010 at 6:47pm

Joey,

Your second assumption is the correct one. "Power" is the measure of energy output, 100 milli watts or .1 watts will draw the same current regardless of the transmitter frequency. The diference is in how far the RF wave will travel on that same 100 milli watts. The higher the frequency the shorter the distance you will travel with the same amount of power.

Regards,

Nathaniel

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Permalink Reply by Joseph Reynolds on August 29, 2010 at 6:10am

Thank you so much for answering my question.

I have another question, is it generally true that the lower the frequency the larger/heavier the transmitter?

and another question concerning these transmitters in particular, how do voltage requirements fluctuate from low frequency transmitters to high frequency transmitters? In my research I am finding that they all operate in the same general voltage range, but I know that if I increase my voltage to my Tx then the mili-amp-hour draw will be less. Do I understand correctly, how does this balancing act work?

it might help you to answer this if you know why I am asking. I am looking into the Hydogen fuel cell to power my onboard electronics and LiPo batteries for my electric motor. The fuel cell provides Tons of mAh at very low voltage while the LiPo provides both, the whole system is augmented with solar panels to assist power requirements druing daylight operations. My fear is that I will have to power my video Tx off of my LiPo which will decrease my overall flight time (not something I can do).

What are your thoughts?

--Thanks
Joey

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Permalink Reply by Max on August 28, 2010 at 6:52pm

What about a UHF radio or 72mhz?
This will free up the 2.4 band for semi-legal video... at least it would be on the right band ;)
10mw 2.4 works quite good too IMO...

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Permalink Reply by Joseph Reynolds on August 29, 2010 at 6:20am

Well I do know that the lower the freq. the lower the data rate. Would Keegan still be able to send his video over the 72mhz freq? I thought that's why everyone used the 1Ghz+ range for video and the lower 900Mhz and below for remote control/navigation.

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Permalink Reply by Max on August 29, 2010 at 8:38pm

No no no, 72mhz is ONLY for RC control, it works very well and no reason not to use it.
It will give you back 2.4ghz for the video and 900mhz for data - this is what I use (36mhz for Australia) and it works fantastic.

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Permalink Reply by Joseph Reynolds on August 29, 2010 at 9:31pm

oh I see ok thank you

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