Packet Radio
For
Hamradio
1st
A Little History
ALOHAnet
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A class project at the University of Hawaii
The Professor was a ham
70 cm was the band
The year was 1971
Successfully demonstrated the world’s 1st
random access network and mailbox
Evolution
• ALOHAnet moved from radio to wires.
• There were several iterations for improved
performance
• 1973 – Bob Metcalf at Xerox invents ethernet
• Bob Metcalf opens 3Com and the rest is
network history.
What’s important about this?
• Hamradio was first to demo an important
capability
• Dial-up networking was starting up to allow
access to E/N connected networks
• Modems were being maufactured that
allowed inexpensive home opertions
• Dial-up BBS’s were becoming “common”
• Hams’ curiosity was again piqued.
So what did the hams do?
• A handful started to experiment with
telephone dial-up modems at about 300 Baud
• A few invented their own modems using the
XR series chips
• The wired protocol, X.25, was adopted for
early packet radio
• X.25 was extended to AX.25 to handle
addressing issues.
II
• Early BBS’s were patterned on the dial-ups
• By the Mid 1980 networks of networks were
incorporated into amateur packet radio.
• Phil Kairn, KA9Q, puts TCP/IP on top of AX.25 to
extend network capabilities
• TAPR created the TAPR-2 TNC.
• AEA, MFJ, Kantronics, and others started to make and
sell affordable TNCs based on TAPR-2
• And now we are up to date.
The Neo Situation
• AX.25 has been accepted by the ITU as RX.25
It’s the same thing, just the name was changed to fit ITU standards
. 1200 Baud has become a defacto standard
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RX.25 is now standard with a few TCP/IP BBS’s
From it’s peak in the 80’s to early 90’s,
amateur packet mainly supports EMCOM and
APRS
PART II
• FSK, 170 Hz. shift is used for 1200B
• Some TNC’s use 200 Hz. shift
• Sound cards have begun to replace hardware
TNC’s
• There are no backbones left in the area.
• Connecting through digis is common
• Packet radio and the Inet have merged
So, you really want to do it?
How to do it and what you’ll need
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You will need:
2 meter radio
Computer running a terminal application
Either a TNC or sound card. (I recommend a TNC)
The usual 2 meter antenna
Cables to hook up everything
Time to play and a BBS in line-of-sight
What a BBS Needs
• 2 meter radio
• Computer
• Either a TNC or sound card (I recommend a TNC)
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BBS Software
The usual 2 meter antenna
Cables to hook up everything
Looks just like a home station, however there will be
a need for more storage if there is a lot of traffic.
Some basic things to know
• Almost all TNC’s today can act as a simple BBS.
• Any station can digipeat if that capability is
turned on
• TNC based BBS’s can not route
• All packet networks work on a carrier sense,
multiple access (CSMA) basis same as
ethernet
• Packet radio uses error correction, APRS does
not
part II
• There are a number of different BBS types; ie,
FBB, NET/ROM, RLI, MBL, etc.
• There is a general commonality in the
commands
• HF packet is painful, but you can try it on
14.104 MHz.
The Club’s situation and BBS
• Everything was smoked in a lightning strike
• AARC was running a Phil Kairns based BBS accepting
RX.25 and TCP/IP, JNOS.
• Digipeating was turned on for range extension
• AARC could do static routing via radio or ethernet and
had at least 5 Gbs of data storage.
• TCP/IP apps FTP, SMTP, and Telnet were acceptable.
• Everything should be replaced due to age or lightning.
Recommendations
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Kantronics KPC-3 - $230.
Astron RS-20 - $140.
Kenwood TM-281A - $150.
A cheap netbook - $200.
Assorted cables - $50. (est)
• Total Est. - $770.
A Serial Port Interface
Simple Computer Audio Interfaces