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[aprssig] Mobile Digi (TEMPn-N)

Robert Bruninga bruninga at usna.edu
Mon Jun 15 22:27:30 UTC 2009


Sorry to say, this wont work.
I tried it.

I tried it so that I could test HOP7-7 packets among a tabletop
of D700's, trying to get 7 of them to linearly digipeat a
packet.  It doesn't work.  Everyone of them always respond to
the FIRST packet.  Sure, they all wait DWAIT before
transmitting, but the decision to digipeat was made -instantly-
when the packet was received and placed in the buffer.  No
matter how long you wait, and no matter what it has heard in the
meantime, it is still going to transmit that packet when DWAIT
times out.

Good Luck.  Bob, Wb4APR 

> -----Original Message-----
> From: aprssig-bounces at tapr.org 
> [mailto:aprssig-bounces at tapr.org] On Behalf Of Tom Hayward
> Sent: Monday, June 15, 2009 1:53 PM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] Mobile Digi (TEMPn-N)
> 
> >> -at a fill-in or mobile digi, wait for 5-10 seconds to hear
another
> >>  digi to digipeat the packet, if it's not heard, then
digipeat
> >
> > <sarcasm> Did Kenwood OpenSource their D7, D700, and D710 
> control code so
> > that we could actually do something like this?
> 
> Well, this one is possible. Set DWAIT on your mobile digi to
70 (0.7
> seconds) or so. If the mobile doesn't hear the packet from
another
> digipeater within 0.7 seconds after the original transmission,
it's
> safe to say the packet needs some help along, from a mobile or
fixed
> digi. No need to wait a whole 5-10 seconds.
> 
> For this to work the conditions would have to be approaching
perfect.
> The mobile digi would have to be able to reliably decode the
fixed
> digi. And if the channel is congested, and the first packet
was missed
> due to QRM, digipeating it from another mobile will likely
just add to
> QRM.
> 
> There are times when mobile-digipeater and
everyone-is-a-digipeater
> can work, like during a search and rescue mission in the
backcountry
> where there is no existing infrastructure and you're
attempting your
> own mesh infrastructure by setting all the mobiles to
digipeat. Most
> of the time, a mobile digipeater is probably not helpful.
> 
> Tom KD7LXL
> 
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