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<p>The simple answer is "It doesn't really buy us anything, and it
decreases the range of the transmission."<br>
The majority of on-air time for a TNC/Radio combination is taken
up waiting for the radio to key up and reach full transmit power.
This is the "txdelay" setting on your TNC, and is generally tuned
to your radio. It defines the time between when the hardware
closes the PTT button and begins to actually send modulated
audio. Typical values range from 150-400 milliseconds.
Regardless of the data rate, this txdelay is constant. The actual
data transmission is generally a fraction of the time we spend
just waiting for the radio to key up.</p>
<p>So, even though you;'re sending data ~4x faster, you're still
waiting for the radio to key up, and the channel is useless while
that's happening. If it takes 250ms to transmit at 1200bps, and
you've got 250ms of txdelay, you're tying up the channel for
~500ms. At 9600bps, you're on air for ~340ms. Also, bandwidth
and distance are roughly inverse: quadruple the data rate, cut
your transmission distance by 4x.<br>
<br>
In the end, it's generally not worth it.</p>
<p>John Gorkos<br>
AB0OO</p>
<div class="moz-cite-prefix">On 2/16/22 13:36, Jonathan Delaney
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:4d24c4c63dcd1.26f2bc081c8f@gmail.com">
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<div dir="auto" style="font-family: "Open Sans",
-apple-system, BlinkMacSystemFont, "Segoe UI",
"Helvetica Neue", Arial, sans-serif, "Apple
Color Emoji", "Segoe UI Emoji", "Segoe
UI Symbol"; font-size: 14px;">The <wbr>discussion <wbr>this <wbr>past <wbr>week <wbr>has <wbr>made <wbr>me <wbr>wonder <wbr>on <wbr>why <wbr>APRS <wbr>9600 <wbr>is <wbr>not <wbr>used. <wbr>To <wbr>my <wbr>knowledge <wbr>most <wbr>if <wbr>not <wbr>all <wbr>APRS <wbr>mobile/<wbr>handheld
enabled <wbr>radios <wbr>have <wbr>a <wbr>TNC <wbr>capable <wbr>of <wbr>9600 <wbr>bps <wbr>however <wbr>we <wbr>still <wbr>set <wbr>them <wbr>to <wbr>1200. <wbr>Is <wbr>this <wbr>because <wbr>most <wbr>of <wbr>the <wbr>digis <wbr>and <wbr>igates <wbr>still <wbr>use <wbr>1200? <wbr>What <wbr>would <wbr>it <wbr>take <wbr>to <wbr>get <wbr>everyone <wbr>to <wbr>change <wbr>to <wbr>9600?<wbr></div>
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UI Symbol"; font-size: 14px;"><br>
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