APRS Network - Page 1
Forum section: electronics / rf-microwave

author: metrologist
author_rank: Super Contributor
timestamp: December 13, 2016, 05:41:50 pm
content: I'm curious about the general function of the APRS network (not so much the RF side). Is there a centralized server and who owns it? Could such a system function without a centralized server/database? When I access aprs.fi, where does the telemetry data come from since it is historical?

author: AlphaBob
author_rank: Newbie
timestamp: December 13, 2016, 08:06:34 pm
content: The ARPS system is made up of distributed "gateways" that repeat position and other information received at a particular location onto the internet. APRS.fi as well as other websites monitor that data flow constantly and provide real time position mapping. Note that APRS can also be used for sending small telemetry packets and short messages. There are many hundreds/thousands of APRS nodes globally.So there is no centralized server -- its a distributed network.APRS.fi's server keeps a history of messages that they have obtained off the internet.

author: metrologist
author_rank: Super Contributor
timestamp: December 13, 2016, 08:31:54 pm
content: So the aprs.fi server retains a copy of all transmitted data? There must be a physical server somewhere for the data. Is it using Google's servers for the mapping feature with all of the telemetry (and msg) data?Is the OpenAPRS server just another redundant server retaining APRS data?How are these servers able to capture the data from all nodes? If aprs.fi and openaprs.net were not online, how could I set up a computer to log all global aprs data?

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 14, 2016, 10:29:55 am
content: i see you think more than an IT Engineer than some Radio guy!The most Amateur Radio Hobbyst here dont realy care about APRS Messages.

author: LaserSteve
author_rank: Super Contributor
timestamp: December 15, 2016, 05:55:24 pm
content: APRS transmitters are typically tethered to a GPS or other sensor. Certainly not to Google maps... A user might choose to display his/her data as a KMS file on Google...'APRS rides on Packet Radio, the concept being low/ no cost to use, shared nodes in a distributed system. If I want to set up a packet node, I agree to pass or repeat all packets that are from a user with a amateur radio license, are not spam and have a valid checksum when I'm not broadcasting my own messages. My modem inside my Digipeater or Terminal Node Controller hooks to a Ham Radio rig and translates data to audio tones for transmission. I may or may not archive the message, that is my preference.If your a networking person, the term for the net style is "Modified Aloha Networking" or AX.25 Packet Networking. AKA Forward and Store networking.Yes, there can be optional routing and internet back-bones... Just no real need for anything like DNS or Google....The simplest network is two TNCs and two radios...http://wiki.complete.org/PacketRadioUsers have to accept the fact that not every packet sent may make it anywhere, let alone around the world. If your data burst is not in range of a radio receiver nothing happens.I'm curious why you would like to record every APRS message in the world? Are you an NSA contractor that is seriously bored?Steve

author: metrologist
author_rank: Super Contributor
timestamp: December 15, 2016, 07:32:49 pm
content: I'm not asking so much specifically about APRS, but rather the basic concept (and not on the RF side). I am interested in the APRS-IS side, after the data is received specifically by an iGate station.A person has to run and pay to operate an iGate station and that station could act as a server for anyone to access the data. I think this is similar to the aprs.fi site where they are also using a Google map widget. But I am not sure if aprs.fi is a standalone server (that a fanatic individual is paying out of pocket to operate) or if Google is offering a service that allows aprs data to be mapped on their mapping servers. I have seen member maps set up on Google map servers and those are using a google domain, so aprs.fi and other aprs-is servers must therefore be standalone servers set up by fanatics.I'm interested in how to access all of the aprs internet data because I just want to know how it is done, how does aprs.fi receive all the data, and then explore ways to use that technique to create another service.So I was reading the aprs-is site and I think there is enough info there to tell me how to set-up my own server to collect this data.I will look into those other keywords, aloha networking and forward and store.

author: metrologist
author_rank: Super Contributor
timestamp: December 15, 2016, 07:34:29 pm
content: What are examples of forward and store networking on the internet or other services?

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 15, 2016, 08:03:13 pm
content: Here is a presentation by Heikki Hannikainen who developed, owns and operates aprs.fiIt is my primary source of information about aprs.fi Recommended....https://youtu.be/L1sMe0ANbQ8

author: AG6QR
author_rank: Frequent Contributor
timestamp: December 20, 2016, 05:03:13 pm
content: There IS a central place on the Internet. It is aprs-is. It is described here:http://www.aprs-is.net/Specification.aspxIgates receive packets over the air and send their info to aprs-is. If they are bidirectional igates, they monitor aprs-is and send appropriate packets out over the air.The popular aprs.fi site is a client of aprs-is -- it takes the aprs-is data and presents it graphically on a map.