[aprssig] APRS-IS Database :: Query for static dataset

[Pete Loveall AE5PL Lists]

There are some servers which have history ports configured for user-defined filtering.  All ports on a server that are publicly available are listed on their status page, as Stephen stated.  Each server is run by individuals so they can configure their server as they see fit, offering certain ports and not offering others, usually based on available bandwidth.

It is also important to note 2 things: the history port does not contain duplicate packets if those packets were dropped during normal processing (history queue is distinct from the duplicate processing table); history ports are read-only (do not accept packets) to keep people from reinjecting minutes old packets into APRS-IS (yes, that was prevalent in the early days of APRS-IS).

As Steve stated, the duplicate processing is done on an individual server basis and results vary depending on the interconnection and feed points to each server.  What doesn't vary is only one packet getting through a server and duplicates are ignored/discarded during the duplicate window for each packet (which, in the case of javAPRSSrvr, is a sliding window to reduce RF induced loops).  There is significant information on server operation at www.aprs-is.net

Hope this helps.

73,

Pete Loveall AE5PL
pete at ae5pl dot net

> -----Original Message-----
> From: Stephen H. Smith via aprssig
> Sent: Monday, July 20, 2015 12:54 PM
> 
> On 7/20/2015 10:32 AM, Nagi Punyamurthula via aprssig wrote:
> > Steve,
> > This is great information about the availability of the 30min dump - I see
> that as a nice golden nugget of a resource .
> >
> > Adding to Lynn's, would be good to know if this data source supports
> filtering and if the standard APRS-IS server filter format would work.
> >
> No, these older ports don't support filtering.  The whole point was that until
> port 14580 arrived, all APRS server ports were predefined and fixed.  You just
> logged into a specific port number and took what was offered.
> 
> Port 14580 was a major innovation in that for the first time, the user could
> customize the feed.
> 
> You can see what ports are offered by any given server by going to
> servername:14501     which loads the status page for that server.  For
> example:
> 
> http://second.aprs.net:14501      or    http://socal.aprs2.net:14501