[aprssig] TEMPn-N and or preemption was Re: Thinking Out Loud About... Digipeaters

[Peter Devanney]

I have been reading through the archives over the past couple days   
trying to understand which approach makes more sense - TEMPn-N or  
preemptive digipeating for use in  portable digi's used to make up an  
ad-hoc network. The summary below was one of the best comparisons I  
could find and is from where I am trying to extend my understanding.

My context for this is for use by SAR responders. Most of the time we  
will be in an area where we can often see the main network digi's and  
often cannot - if that makes any sense. The terrain is very hilly.

With the introduction of the D72 we now have the possibility that  
every team or selected teams can easily be a digi.

What happens in an area where there is no 144.39 "main" network  
coverage?

I understand that with TEMPn-N each tracker needs to re configured  
from normal day to day use (from WIDE 1-1,WIDE 2-1) to TEMP3-3 or  
similar. Not deal but can be done. I believe this would work well  
where there is no chance of accessing any of the 144.39  
infrastructure??? The ad hoc digi's provide all of the coverage and I  
do not lose a chance to benefit from even limited access to the main  
144.39 network with the TEMPn-N path in the tracker as I can't hit the  
main 144.39 network.

What happens in an area with some coverage from the main 144.39  
network but also lots of holes?

With a TEMPn-N path, I am unable to take advantage of the main  
network. I can only digi through the ad hoc portable digis? In  
practice this may be adequate.
With a WIDE1-1,WIDE2-1,SAR3-3 path do I get digipeated by the main  
network if within range and by the ad hoc SAR digi(s) if not within  
range of the main network digi's? This is assuming preemptive  
digipeating is not turned on?
With a WIDE1-1,WIDE2-1,SAR3-3 path and preemptive digipeating turned  
on do I only get digipeated by the ad hoc portable digi's running the  
SAR alias?

If my thinking is right, I have three configuration options, TEMPn-N  
and SARn-N with and without preemption turned on??

Is the WIDE1-1,WIDE2-1,SAR3-3 without preemption turned on is my best  
option? If within range of a main network digi I get digipeated. If  
not, the ad hoc portable digi will do it. I get the chance of using  
both infrastructures (main and ad hoc network) and I don't have to ask  
the tracker owners to change paths which is preferred as they will  
probably forget at 3am when its snowing heavily and fingers are  
frozen. Responding amateurs can use the main network enroute to and  
from the incident without any configuration change.

Is my logic sound or have I misunderstood the configuration options?

Any other suggestions on how to set this up? Again,  of the time we  
will be in an area where we can often see the main network digi's and  
often cannot - if that makes any sense. The terrain is very hilly.

thanks and 73
Peter VA3YOW
Ottawa, ON

On 23-Jul-09, at 2:18 PM, Tom Hayward wrote:

>> Plese consider using the TEMPn-N network for temporary systems.
>
> There are pros and cons to TEMPn-N vs WIDE1-1,WIDE2-1,SAR7-7.
>
> TEMPn-N facts:
> Any D700 can digipeat TEMPn-N.
> Every tracker will need to reconfigure his path to TEMP7-7 to  
> utilize TEMPn-N.
> While the tracker's path is set to TEMP7-7, it cannot utilize the
> standard APRS network.
>
> Preempt SARn-N facts:
> A D700 cannot preempt-digipeat SAR7-7.
> Every tracker can leave his path permanently set to  
> WIDE1-1,WIDE2-1,SAR7-7.
> Works simultaneously with the standard APRS network (WIDEn-N).
> Requires smart digipeater like Tracker2 or digi_ned
>
> The choice probably comes down to what equipment you have now. If your
> special event team owns mostly D700s, you may want to use TEMPn-N. If
> your team owns mostly Tracker2s, you can preempt and continue using
> WIDE1-1,WIDE2-1 while also utilizing a temporary network. If your
> teams need new hardware, the Tracker2 is the more inexpensive option,
> and more capable in this case.
>
> Tom KD7LXL
>
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