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ZL3AI > APRDIG 16.03.07 07:04l 83 Lines 3155 Bytes #999 (0) @ WW
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From: ZL3AI@ZL2BAU.#79.NZL.OC
To : APRDIG@WW
Message: 5
Date: Sun, 4 Mar 2007 19:41:11 -0800
From: "'Scott Miller'" <scott_at_opentrac.org>
Subject: RE: [aprssig] APRS Multi-Mode Tracker
>JPG is only intended for continuous-tone images; i.e. photos. It applies
>image compression by looking for gradual gradients of brightness and color
>from groups of adjacent pixels.
Actually, it generally transforms the image to a YCbCr color space, applies
chroma subsampling, then performs a discrete cosine transform on each 8x8
pixel block in each channel, quantizes the resulting coefficients, and uses
entropy coding to store them with run-length encoding and Huffman
compression. But yeah, it makes straight lines and edges look fuzzy. =]
>2) What you are striving for is not a "multimode tracker" but a
>full-function APRS station that happens to be mobile. The commonly-accepted
>usage of the term "Tracker" is for a dumb (or should I actually say deaf")
>transmit-only mobile that spews out posits periodically and can't receive
>anything.
The Tracker2 does pretty well for mixed PC and standalone operation. I
haven't implemented a GPS pass-through yet, but I could.
Scott
N1VG
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Message: 6
Date: Mon, 5 Mar 2007 06:06:25 -0800 (PST)
From: "Curt, WE7U" <archer_at_eskimo.com>
Subject: Re: [aprssig] APRS Multi-Mode Tracker
On Sun, 4 Mar 2007, Scott Drumm wrote:
>Alternatively, I just read a writeup about the
>PacComm<http://www.paccomm.com/>dual-port PicoPacket...
>
>It looks like the PicoPacket will do all of the above, w/o the need for a
>second TNC or strange cabling, yes?
I'd steer clear of this one. I have one of these and have had nothing but
problems with it. Admittedly it's an early model so perhaps they
eventually fixed the design flaws. Mine tends to lose it's configs all the
time even with a fresh lithium battery in it. Seems to be a design problem
in the battery backup system.
I plan to use a Tracker2 for my mobile, but they're not in production yet.
I have some beta-test models. With this unit I can run it standalone or
hook it up to a PC when I wish. As far as the GPS I should be able to snag
the GPS data out of the TNC via an APRS program. If I wished to run a
separate non-APRS mapping program I could wire the GPS data out over to a
separate serial port on the laptop or else run two GPS'es.
The Tracker2 will let me run Base-91 compressed packets which have higher
precision than standard APRS packets yet the packets are still quite short.
Of course SmartBeaconing(tm) is nice as well. You can't get this stuff with
the Kenwoods.
Other almost-as-good possibilities:
TinyTrak4 (also in beta-test)
uTNC+ (in production)
--
Curt, WE7U. APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto: A tax on people who are bad at math." -- unknown
"Windows: Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me: I picked the coordinate system!"
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