[aprssig] Paths - Solution proposal

Chris Howard w0ep w0ep at w0ep.us
Sun Jul 13 12:55:31 CDT 2014


I ran a small digi in a fill-in location for a few years.

It was on a linux box running fedora/red-hat with soundmodem,
sound card, a homebrew radio interface and JavAPRSrvr software.
And I ran xastir as a local client.

There may be better ways to go these days, but at the time it was
cheap and reliable.


On 7/13/2014 12:31 PM, Jim Conrad wrote:
> Mark and the List;
> 
> Been reading the recent threads about the path issues and I'm a long time lurker and end user. I moved from Virginia to Rural North Carolina a few years ago and have APRS coverage issues where I live now. I want to put up a digi and an igate at my house. At present I have a 40 foot telephone pole to work with. Lots of available computers, familiarity with Linux and a bunch of old TNCs (Old PK-232s, not MPX, PK-900, MFJ 1278, KAM and a HAL DSP4100.
> 
> I'm looking for some advice as to how to proceed. My location is 35.39174, 78.94038 if you want to see what paths are already in place.
> 
> If anyone could suggest the most cost effective reuse of my existing equipment and the best software to implement my goal of an APRS digi and igate I would appreciate it. I've looked at Bob's page and the various wikis which are loaded with information but nothing consolidated that would make my learning curve less steep.
> 
> I would rather do it right the first time then cause problems for what is already here in my area as limited as that is.
> 
> Suggestions and comments are most welcome.
> 
> 73's
> Jim - N4WFP
> 
> 
> At 09:53 AM 7/13/2014, you wrote:
>> With the most common thread on the APRS sig over the last few months being paths I thought it time to remind everyone of why we have the current problem and what we should work together to first come up with a needs list and to secondly work to solve the issue.
>>
>> While I have brought this up on the list many years ago, there are many new users and it might be time for a reminder.
>>
>> The current system (Digi backbone) was built with the currently available (and surplus) old TNC's. Many at the time were TNC-2's or clones, as well as the then "modern" KPC-3 and 3+'s.
>>
>> The KPC-3+ have suffered from the delayed packet problem, and the TNC-2's have been implemented in many cases without UiDigi firmware.
>>
>> As a result we have been fighting for years to try and educate end users (the best of which are on this list) of what their path should be in many different operating environments and parts of the country.
>>
>> Solution:
>> Take "paths" and throw them out the window.
>> - (During the transition having a path will work with the "old" digi's)
>>
>> The number of times a packet is digipeated is network specific based upon the current load of the network.
>>
>> The Digipeater should decide whether to throw out the packet, delay it to see if it was heard by another digi, or digipeat it immediately.
>>
>> The digipeater will have to know:
>> It's location
>> It's PHG (coverage area)
>> How many hops it is to a reliable I-Gate
>> It's altitude (both average ground elevation for the area and antenna elevation above that terrain).
>> List of stations it has heard (MHeard)
>> - That list will also keep track of the packet location
>> Current channel loading
>>
>> We need the digi to decide!
>>
>> Examples:
>> If a digi hears a packet from one mile away (It knows it's location and the location of the packet), and it has not heard a packet from this station in X minutes the packet should be repeated!
>> (x is variable based upon the number of unique "direct" stations it has heard, and has the station moved more than Y distance).
>>
>> - If the station did not move (horizontally or vertically), and a packet was heard from the same station 10 seconds prior should the packet be digipeated?
>>         - Normally most of us would say "no", but if the channel loading is zero, then why not! (Private or test network)
>>
>> If a digi hears a packet from a station 100 miles away, should the packet be digipeated?
>> - Was it heard directly?
>> - Was it digipeated by another digi?
>> - What is the channel loading?
>> - Is the station moving or fixed?
>> - How long has it been since THIS digi repeated the packet?
>>
>> ----------------------------
>> With modern TNC's available there is no reason not to start working on a modern solution.
>> - Existing TNC's could be used if put into KISS mode and using small single board computers such as a Raspberry Pi.
>> - An ideal solution would be a dedicated solution (Tracker3, TNC-X, etc)
>>
>> The idea of this email was not to list "all" of the needs, but simply to point out that until (WE) begin to think of what is needed and begin to think of the algorithms needed, we will continue to have "path" problems.
>>
>> Respectfully,
>> Mark Cheavens
>> KC5EVE
>>
>> _______________________________________________
>> aprssig mailing list
>> aprssig at tapr.org
>> http://www.tapr.org/mailman/listinfo/aprssig
> 
> <:><:><:><:><:><:><:><:><:><:><:><:><:><:>
>         Jim Conrad - jjc at oceanviewcom.com
>           757-560-5970 - 757-512-5710 Fax
>            Amateur Radio Callsign N4WFP
>  CAGE 0UD60 - http://www.oceanviewcom.com
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> 


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