[aprssig] D72 TXD delay TX test

Wes Johnston, AI4PX wes at ai4px.com
Tue Dec 7 16:19:42 CST 2010


It's bad enough that the average appliance operator never set's his TXD, but
the digi owners sure should. Think about it this way.... I tx a packet with
a bad TXD.  Let's say it costs an extra 300ms.  Now my packet goes out 3
hops, potentially hitting 27 digipeaters (yeah, it's a worst/best case).
300ms x 27 is 8.1 seconds of on air time wasted just with the digipeaters.
It may not sound like much, but think how many times your local digipeater
TX's every day.

Is it time to start talking about queueing packets for 10 or 20 seconds
again??? <ducking>  Seriously, it can be done with a simple timer on the
ext-CD input.  You just hold that input active for 10/20 seconds and let it
drop for one second.  Rinse Lather Repeat.  The digi then uses ONE txdelay
to transmit several packets.  It's a good time saver if we can live with the
bunching effect.

God help those who do not help themselves.

On Tue, Dec 7, 2010 at 16:43, Robert Bruninga <bruninga at usna.edu> wrote:

> >> I'm interested to know how much of the capacity
> >> of the 9k6 is taken up with message content
> >> and how much with TxDelay's?
> On a tangential item, the new TH-D72 HT defaults to 200ms at
> 1200 baud and Kenwood did not recommend going shorter.  It has
> settings for 150 and 100 ms..  Lemme do a test.  Hold on.
> Here is what I got Transmitting from D72 to an old D700 with
> external KPC-9612:
> 1200 baud to KPC-9612 *not* 100% at 150 ms and below
> 1200 baud to D700 internal  100% at 100ms
> 9600 baud to KPC-9612 got   100% at 100 ms
> 9600 baud to D700 internal  100% at 100ms
> Test was HT in basement on 0.05 watts through industrial
> building to sat antenna on roof.   More testing with other
> combinatinos would be warranted, including how fast the D72 can
> receive.
> TOO MANY APRS DIGIS have absurd 300 and 500 ms delays!
> Bob, Wb4APR
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