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ZL3AI > APRDIG 31.03.07 00:33l 117 Lines 4011 Bytes #999 (0) @ WW
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To : APRDIG@WW
Message: 14
Date: Tue, 27 Mar 2007 09:02:44 -0500
From: "Michael Huslig" <mhuslig_at_kantronics.com>
Subject: Re: [aprssig] SCS Tracker
Jack,
How does the GPS connect?
Mike
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Message: 15
Date: Tue, 27 Mar 2007 10:53:43 EDT
From: WB4GQK_at_aol.com
Subject: Re: [aprssig] APRS -- Chicago to Mackinac Island sailboat race
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Message: 16
Date: Tue, 27 Mar 2007 11:16:44 -0400
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] APRS -- Chicago to Mackinac Island sailboat race
>...I have raced our sailboat in five open ocean...races.
>I set up WinAPRS to transmit our position once an hour....
You are welcome to transmit a moving position report more often when
underway, so that a lost packet does not have as much of an impact. At the
Naval Academy, we used 10 minutes per boat, but we had our own frequency.
I woiuld think the APRS 10 MHz freq could handle 30 minutes per boat while
underway easily. entire race. At any time my wife wants to check on how we
are
>Now a couple of times a plot was not received due to poor
>propagation... So my XYL simply selected NEW Message...
>And queried "How are things going?"..[when] I was not
>available to answer BUT she got a reply that gave her our
>position at that instant.
I think that would be the APRS "directed Query" that would trigger the
position update. Or does WinAPRS have the ability to trigger a posit in
response to a message too? Just trying to clarify how that worked.
Thanks
Bob
WB4APR
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Message: 17
Date: Tue, 27 Mar 2007 11:54:08 -0400
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] APRS -- Chicago to Mackinac Island sailboat race
>You are welcome to transmit a moving position report more often
>when underway, so that a lost packet does not have as much of an
>impact. At the Naval Academy, we used 10 minutes per boat, but
>we had our own frequency.
Oh, and TX power from the battery is completely insignificant even at the
10 minute rate. The SEA2222 SSB transcievers we were using drew about 1
amp just on receive. The TX power was insignificant in comparison even
though it was 20 amps for 2 seconds every 10 minutes. That is only 33 mA
AVERAGE TX power compared to 1000 mA continuous for the receiver. So TX
power was only 3% of the radio system power.
Bottom line, APRS TX power is usually completely insignificant to RX power.
Unfortunately, when I convinced the skippers how insignificant the TX power
was, it also convinced them how significant the RX power was, so they often
ended up turning off the Transceiver completely, so they could justify
keeping their boom-boxes blaring all day instead... They said they would
turn it on now-and-then.. But having a human in the loop almost guarantees
unreliabilty.
Oh well. Human nature must be included in all designs. Plan on it... But
don't save power on TX. It is insignificant... And MAX TX power is always
better!
Bob, WB4APR
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Message: 18
Date: Tue, 27 Mar 2007 09:31:05 -0700
From: "'Scott Miller'" <scott_at_opentrac.org>
Subject: RE: [aprssig] APRS -- Chicago to Mackinac Island sailboat race
>Unfortunately, when I convinced the skippers how insignificant
>the TX power was, it also convinced them how significant the RX
>power was, so they often ended up turning off the Transceiver
>completely, so they could justify keeping their boom-boxes
If you don't need RX for anything, use a tracker with a power control
output. The OpenTracker 1m (the one in the metal case) will switch more
than 20 amps with the optional on-board high-side switch. And any
OpenTracker or TT3 could be used with an external relay.
Scott
N1VG
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End of aprssig Digest, Vol 33, Issue 27
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