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eHam Forums => APRS => Topic started by: N4SRN on January 28, 2019, 03:31:53 PM



Title: EZ Guide to Understanding APRS Raw Packets?
Post by: N4SRN on January 28, 2019, 03:31:53 PM
I’m looking for an EZ Guide to understanding APRS Raw Packets such as seen on APRS.FI raw display options. “EZ” as a write up addressing such a topic rather than referring me to the specification. A Primer, so to speak, for the less technical folks not inclined to get a EE/ComSci double major.  ;-)

Bret/N4SRN


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: W4KYR on January 29, 2019, 05:30:44 AM
I’m looking for an EZ Guide to understanding APRS Raw Packets such as seen on APRS.FI raw display options. “EZ” as a write up addressing such a topic rather than referring me to the specification. A Primer, so to speak, for the less technical folks not inclined to get a EE/ComSci double major.  ;-)

Bret/N4SRN

Let me add another question to go with your question. Is it possible use "Wireshark" to analyze APRS and Packet Radio Packets? If so, how?


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: VE7KNL on January 29, 2019, 05:37:50 AM
This might help
http://www.aprs.net/vm/DOS/PROTOCOL.HTM


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: WD9EWK on January 29, 2019, 08:47:37 AM
This might help
http://www.aprs.net/vm/DOS/PROTOCOL.HTM

In addition to this, the aprs.fi site provides a way to decode the raw packets. When you are looking at the raw packets for a station, you will see a drop-down menu that should have "Normal". Change that to "Decoded", and then you see both the raw packet and a breakdown of most of the data in the packet. Here's an example showing position packets and a message...

(https://www.qsl.net/wd9ewk/pics/Decoded_packets.jpg)

73!


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: N4SRN on January 29, 2019, 09:38:14 AM
Excellent stuff y’all - thanks!


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: KB3VWG on January 30, 2019, 07:09:09 AM
Let me add another question to go with your question. Is it possible use "Wireshark" to analyze APRS and Packet Radio Packets? If so, how?

Yes!

I simply ran Wireshark on the interface that was speaking AX.25. You can also collect pcap files via tcpdump to be read in Wireshark.

Also, a guide on the raw packets: https://www.tapr.org/pub_ax25.html - that is the specification of the protocol.


73,

KB3VWG


Title: RE: EZ Guide to Understanding APRS Raw Packets?
Post by: W4KYR on January 30, 2019, 08:01:36 AM
Let me add another question to go with your question. Is it possible use "Wireshark" to analyze APRS and Packet Radio Packets? If so, how?

Yes!

I simply ran Wireshark on the interface that was speaking AX.25. You can also collect pcap files via tcpdump to be read in Wireshark.

Also, a guide on the raw packets: https://www.tapr.org/pub_ax25.html - that is the specification of the protocol.


73,

KB3VWG

Thanks