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<DIV><FONT face=Arial size=2>"Da problem" with operating above the GPS
consellation is that its antenna clusters are pointed the wrong way,
towards the ground. As with any antenna, however, there is a potion of the
pattern behind the antennae that exists at a weak level. There have even
been studies of using "weak signal" GPS on the moon rather than establishing a
new constellation there.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The software in receivers operating above the
constellation would have to know to discard any solution that is below the
constellation, just as receivers now discard any solutions that are
above the constellation. </FONT></DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=wes@kd4rdb.com href="mailto:wes@kd4rdb.com">Wes johnston</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=vk4tec@tech-software.net
href="mailto:vk4tec@tech-software.net">vk4tec@tech-software.net</A> ; <A
title=aprssig@lists.tapr.org href="mailto:aprssig@lists.tapr.org">TAPR APRS
Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, April 23, 2006 6:42
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [aprssig] Does GPS work in
space ?</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>Yes and no.... </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Yes, with the proper GPS receiver. "Da
Rules" say that a gps unit can give position reports if it is >18Km (I
forget the exact number) as long as it is not moving faster than 500m/s.
You can do one or the other, but not too high and not too fast at the same
time. So since it impossible to go into orbit at less than 17,000mph,
when your garden variety GPS gets to 18Km altitude, it will stop reporting
positions. Note that most GPS manufacturers read the rules as EITHER
18km or 500m/s, hence there are MANY MANY gps units that won't go higher than
18k/m... the GPS18 from garmin interprets the rules correctly thrus is good
for balloon use over 18km up.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>PCSat has a GPS on board and for a while did
report it's position because it had an exempted GPS receiver. Even
though it's in orbit, it's in a lower orbit than the GPS satellites, so they
are still overhead relative to PCSAT. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Anyone know if these rules apply to the new
european gps system?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Does anyone know if the GPS system will work when
a receiver it higher than the GPS satellites? Seems like it should from
a purely mathematical standpoint.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Wes</FONT></DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=vk4tec@tech-software.net
href="mailto:vk4tec@tech-software.net">Andrew Rich</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=aprssig@lists.tapr.org
href="mailto:aprssig@lists.tapr.org">TAPR List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, April 23, 2006 5:44
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [aprssig] Does GPS work in
space ?</DIV>
<DIV><BR></DIV>
<DIV> </DIV>
<P><FONT face=Arial
size=2>-----------------------------------------<BR>Andrew Rich<BR>Amateur
radio callsign VK4TEC<BR>email: </FONT><A
href="mailto:vk4tec@tech-software.net"><FONT face=Arial
size=2>vk4tec@tech-software.net</FONT></A><BR><FONT face=Arial size=2>web:
<A
href="http://www.tech-software.net">http://www.tech-software.net</A><BR>Brisbane
AUSTRALIA </FONT></P>
<DIV> </DIV>
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