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[aprssig] D72 TXD delay TX test

Wes Johnston, AI4PX wes at ai4px.com
Tue Dec 7 22:30:47 UTC 2010


Mark, I was trying to say that if the digis were as mal-adjusted as the
appliance operator's tracker, the cumulative delay would be 8 seconds.  In
truth, i can live with 5ms extra time on a given digi... it starts to hurt
when we get to 200 to 300ms.

Wes
---
God help those who do not help themselves.


On Tue, Dec 7, 2010 at 17:27, Mark Cheavens <mcheavens at usa.net> wrote:

>  The "extra" tx delay is not cumulative unless the TX delay is on each
> station.
> Example(Yours) has an extra 300ms, but each of the digi's only have 5ms,
> the 27 hops are (27 x 5) + 300
>
> BUT,
> I do believe long term if we did "compressed bunching" we could save a LOT
> of time!!!!!
>
> Couple this with digi's that only transmit based upon DISTANCE / change in
> information and available bandwidth, and then "bunch/compress" all the
> output into one burst would be much more efficient..
>
> Mark Cheavens
> KC5EVE
>
>
> At 04:19 PM 12/7/2010, you wrote:
>
> Hallelujah!!!
>
> 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.
>
> Wes
> ---
> 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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