[aprssig] APRS buoy - transmit power and antenna?
scott at opentrac.org
Tue Sep 11 00:19:19 CDT 2007
Assuming you're in the open ocean and only care about hitting a
satellite, is the J-pole going to give you a suitable radiation pattern?
Or would a 1/4 wave be better?
R. Simmons wrote:
> You folks should consider wave height also... in calm seas, not a problem,
> but heavy swells in a storm can easily render a buoy obscure ( in a trough )
> and therefore "intermittant".
> ----- Original Message -----
> From: "Steve Noskowicz" <noskosteve at yahoo.com>
> To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
> Sent: Monday, September 10, 2007 9:07 PM
> Subject: Re: [aprssig] APRS buoy - transmit power and antenna?
>> Oh, We noticed.
>> The attached "Line-of-Sight" spreadsheet agrees
>> pretty close to the URL you posted. It is not clear
>> if that one has any diffraction correction. I made
>> this sheet in response to questions about UHF
>> controlled UAVs my son is designing.
>> Looks like about 9-10 miles for a bouy to a 30'
>> station...ignoring any ducting of course. Would make
>> an interesting experiment, though. You might hit a
>> satellite at times, but 300mw. sounds pretty thin.
>> 73, Steve, K9DCI--- "Jan T. Pharo" <la2bba at jpharo.net>
>>> "Richard Amirault" <ramirault at verizon.net>, Mon, 10
>>> Sep 2007 15:23:06
>>>> No one seems to have noticed my comment on limited
>>> distance of line of sight
>>>> due to curvature of the earth.[...snip...]
>>> In eyeheight from a small craft (where you stand
>>> with the feet approximately at sea level) we learnt
>> in my boating course that I'd have the horizon about 3
>> nautical miles away (and the web site mentioned above
>> tell me the same). It might be a good idea to build
>> the buoy so the antenna is as high above the water
>>> as possible, in order to increase the distance to
>> the horizon (and possibly reach a digipeater on a
>> tower ashore)
>>> 73 de Jan, LA2BBA
>>> Hvaler, Norway
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>>> aprssig at lists.tapr.org
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