Introduction to Packet Radio, covering keyboard to keyboard QSOs, unproto mode, nodes, routing, digipeaters, packet via the ISS, APRS and WinLink. Covers hardware TNCs as well as software soundmodems like UZ7HO and Direwolf

1. Intro to Packet Radio
April 2022
Kevin Hooke KK6DCT
River City Amateur Radio Comms Society

2. Agenda
 This is an intro, will cover a range of topics at high level
 What is Packet?
 What do you need to operate packet?
 What are some things you can do with packet?
 Keyboard to keyboard QSOs
 Mailboxes, BBS
 APRS: position tracking, messaging
 Winlink email

3. Demo: Send me an APRS message!
 Message me: KK6DCT-7
 Running a Mobilinkd TNC with Wouxun HT, Ed Fong 2m
antenna
 Will come back and look at this more detail later

4. What is Packet Radio
 Digital Mode, mainly for text message communication
 Transmit speeds 300bps HF, 1200bps to 9600bps on VHF/UHF
 Slow even compared to dialup modem speeds, 28.8kbps, 56.6kbps
 Used to support other modes
 APRS – Automatic Packet Reporting System http://www.aprs.org/
 Winlink – email over Amateur Radio https://www.winlink.org/
 AX.25 - network links between computers over radio

5. Packet Radio history
 1978 First packet over radio – Montreal
 1979 first all-in-one packet device - Vancouver Amateur Digital
Communications Group
 Early 80s Tucson Amateur Packet Radio – first Terminal Node
Controller (TNC)
 1983 TAPR TNC-1 kit $350
 1983 TAPR-2 TNC-2 kit $250
From: Terrestrial Amateur Radio Packet Network
http://tarpn.net/t/faq/faq_packet_radio_changes.html

6. Packet Radio History (2)
 TAPR allowed their TNC design to be produced for profit by other
companies:
 AEA and Heathkit sold TNCs based on the TNC-1 design $350 kit,
$400 assembled
 Kantronics KPC was a smaller version of the TNC-1 design
 Later others old TNCs based on the TNC-2 design:
 AEA, MFJ, DRSI, PacComm – approx $130 in 1990

7. Is packet still used?
 Sacramento Valley packet activity :
 Sunday 8pm Packet net on 145.050MHz - approx 10 – 20 checkins each
week
 Many packet nodes in area, e.g. Berryessa Peak – one hop
coverage to Bay Area
 BERRY/KBERR on 145.050MHz
 BERR37 on 144.037MHz
 Frequent activity on 145.050, some activity on 144.037
 Constant APRS activity on 144.390MHz

8. Hardware or Software TNC?
 Hardware TNCs – been around for years (still work fine)
 Used can be pricey on eBay > $100
 Shop around to get one cheaper
 Software TNCs
 Easy to setup:
 UZ7HO
 SV2AGW AGW Packet Engine Pro
 Slightly more involved:
 Direwolf

9. Hardware TNC examples
 AEA PK232 multi mode comms controller
 Timewave PK232SC (currently available $599) ouch!
 Kamtronics KPC-3 (currently available $249)
 MFJ-1270X, TNC-X $179

10. Hardware APRS trackers
 Byonics https://www.byonics.com/tinytrak4
 Sell multiple models
 TinyTrak 4 $85
 Also self contained models: Tx, tracker and GPS
 Balloon tracking etc

11. Easiest hardware option?
 Mobilinkd http://www.mobilinkd.com/ TNC3
$125
 Bare boards were available cheaper earlier
 Now sold in a case
 Connects with cable to radio – options available
for common HTs and data ports
 Bluetooth to a phone or table
 Use with software like APRSDroid on Android

12. Software Soundmodems
 Software Soundmodems – most are free!
 Easy to install, very little configuration:
 UZ7HO Sound modem – Windows only : http://uz7.ho.ua/packetradio.htm
 More configuration reqiured, but more flexible?
 Direwolf – Windows/Linux/MacOS : https://github.com/wb2osz/direwolf
 Software $
 SV2AGW AGW Packet Engine Pro 30 days shareware, $49

13. What do you need to use a
Soundmodem for Packet?
 HF or
VHF/UHF
 Radio
 Soundcard
interface, e.g.
 Signalink or
Rigblaster
 Phone, Table,
Laptop or
desktop
computer

14. Easiest/Quickest Getting Started with
Packet Radio – UZ7HO Soundmodem
http://uz7.ho.ua/packetradio.ht
1. Download and unzip
soundmodem111.zip
2. Download and unzip
easyterm49.zip

15. Start up uz7ho
 From File menu, make sure
soundcard is your device
(Rigblaster, Signalink etc)

16. Start up easyterm
 Start up EasyTerm,
Settings
 Set your callsign
 Optionally a beacon and
path

17. Connecting to a Node
C
KBERR
EasyTer
m:
UZ7HO
Soundmodem:

18. Calllsigns on Packet -SSIDs
 -0 Your primary station usually fixed and message
capable
 -1 generic additional station, digi, mobile, wx, etc
 -2 generic additional station, digi, mobile, wx, etc
 -3 generic additional station, digi, mobile, wx, etc
 -4 generic additional station, digi, mobile, wx, etc
 -5 Other networks (Dstar, Iphones, Androids,
Blackberry's etc)
 -6 Special activity, Satellite ops, camping or 6
meters, etc
 -7 walkie talkies, HT's or other human portable
-8 boats, sailboats, RV's or second main mobile
-9 Primary Mobile (usually message capable)
-10 internet, Igates, echolink, winlink, AVRS,
APRN, etc
-11 balloons, aircraft, spacecraft, etc
-12 APRStt, DTMF, RFID, devices, one-way
trackers*, etc
-13 Weather stations
-14 Truckers or generally full time drivers
-15 generic additional station, digi, mobile, wx,
etc
http://www.aprs.org/aprs11/SSIDs.txt
SSID = Secondary Station Identifier, suffix on callsign indicates the type of
station, e.g.KK6DCT-1 = my primary station

19. Packet Modes
 Connected Mode
 Packets exchanged between 2 connected stations (C callsign)
 Packets are acknowledged or with retries for reliable delivery
 Everything typed is sent as a packet to other station
 (On h/w TNCs) To exit: Ctrl-C, then D (disconnect)
 Unproto
 Packets are unacknowledged
 Used for Beacons, ID, broadcast transmissions e.g. for a packet net

20. H/w TNCs: CONVerse mode vs
Command mode
 On most TNCs’s Ctrl-C puts you in command mode to enter config
commands for your TNC
 Ctrl-C to exit
 Cmd:> CONVerse
 Enters Converse mode
 Everything typed after this point is sent as a packet
 If you have an UNPROTO path set, unacknowledge packets will be sent via
this path
 Ctrl-C to exit

21. Monitoring: beacons
 Line1: audio level and tuning info
 Line 2:
 KF6DQU-10: originating station
 > BEACON : this is a beacon packet
 Text message: Winlink 2000 RMS Packet Server
What do received packets look
like?
e.g. With Direwolf:

22. Monitoring: Digipeated beacons
 Line 1: Digipeater KBERR: this packet was digipeated by KBERR
 Line 2:
 W6OAK : originating packet – we didn’t hear it direct from W6OAK, we only heard it via the
Digipeater KBERR
 > BEACON : beacon packet
 KLPRC3,KBERR*,KJOHN,KBETH,KBERR,ROSE
 This is a route path indicating the path between digipeaters that the originating station wants this
packet to go
 * : indicates we heard this packet from this station: KBERR*
 Note that we didn’t hear it from any of the other nodes

23. Why is Packet popular on Raspberry Pi?
 It’s cheap $35 Pi 3B – although all models currently backordered)
 It runs Linux
 Linux has built-in ax25 network stack that supports packet apps
 Axcall
 Beacon
 Node
 More steps involved to get running but not that hard if you follow the steps
 Many how-to guides online
 Including my own at https://www.kevinhooke.com?q=packet

24. Packet uses
 Station to station (keyboard to keyboard) text chat
 Personal Mailboxes (leave, read messages)
 Bulletin Boards
 Digipeaters
 Beacons
 Packet via International Space Station
 APRS
 Winlink: email via radio

25. Station to Station Connect (QSO)
 C stationid
 Enables stations to text chat (keyboard to keyboard)
 Once connected, all text you type is sent addressed to the
other station, until you disconnect

26. Personal Mailbox
 Most hardware TNCs support a Personal Mailbox
 Software options too
 Most seem to not be checked?
 Anyone can connect and post/read messages
 Typical commands:
 L = list messages
 LM = list messages to me

27. Nodes
 Allow you to connect to other nodes heard by that node
 Extend your coverage by hopping between nodes
 Example:
 Connect directly to KBERR node:
 C KBERR
 While connected to KBERR, now connect to WOODY
 C WOODY

28. Digipeaters
 Retransmit packets for extended range
 C [stationId] via [node1, nodeX]
 e.g.
 c ag6qo-1 via berr37
 I can’t reach ag6qo-1 in Winters directly, but I can via BERR37
(digipeater on Berryessa Peak)

29. Nodes in California 145.050
 From David Ranch’s
website KN6ZTD
 http://www.trinityos.com
 Lots of good Packet on
Linux info, including
Rasberry Pi setup and
config

30. Bulletin Boards
 Messages/News – software can mirror messages between
bulletin board instances across internet
 Chat
 Other interactive apps, text based games
 Local example: AG6QO-1 in Winters, reachable via BERR37

31. Beacons
 Announce presence of your station, advertising Mailbox,
Bulletin Board, upcoming events (nets, swap meets etc)
 Most TNCs have settings for a beacon
 With ax25apps on Linux (e.g. Raspberry Pi) you can do:
 beacon -c KK6DCT-6 1 "Hello from KK6DCT-6 node!"
 Defaults to beacon every 30 mins

32. Unproto packets
 Sunday Packet Net uses unproto (unacknowledged) packets
 Packets are broadcast, not sent to a specific station
 U cq v KBERR, KBETH, WOODY
 Test message! ← all text entered after this point is sent as unproto
packets

33. Unproto – with Hardware TNCs
 Terminal apps like EasyTerm don’t support unproto
 Terminal comms app to a hardware TNC
 U cq v kberr, kbeth, woody
 Sets Unproto mode path
 CONV
 Puts into converse mode, text typed will be transmitted as unproto frames
 Ctrl-C
 Get back to command mode

34. Unproto – software TNCs and apps
 EasyTerm doesn’t support unproto
 Some do: LinPac
 UISS – easy app to use, only sends unproto frames via
connected software TNC https://www.qsl.net/on6mu/uiss.htm
 Intended for use for unproto packets via International Space Station
 Can be used to send unproto frames for any use
 I use this for checking in on the Sunday Packet Net

35. Packet via the International Space
Station (ARISS)
 2m digipeater on 145.825MHz
 Unproto to ARISS
 Packets digipeated from RS0ISS
 Stations receving packets on 145.825 report packets received
back to displayed here http://ariss.net/

36. UISS
My CQ to
ARISS
Packet
digipeated
back from
RS0ISS
CQ via
ARISS

37. Map of last heard packets via ISS
 http://ariss.net/

38. QSL Card for Packets via ISS
My most favorite QSL
card!

39. Requesting an ISS QSL
 Instructions: https://www.ariss.org/qsl-cards.html

40. APRS - Automatic Packet Reporting
System
 Probably most common current use for Packet today (and probably
most broad topic)
 GPS position tracking and other info/status packets and messaging
 Packets retransmitted via Digipeaters to extend range
 Digipeaters cover local RF for up to 3 hops
 I-GATE bridge gaps over internet
 APRS messages can be sent to any active station worldwide
 RF → I-GATE → Internet → I-GATE → RF

41. Digipeaters and WIDE
 WIDEn-N = n= how many hops, N=how many hops remaining
 WIDE1-1 – packet is retransmitted 1 hop only
 WIDE2-2 – packet is retransmitted 2 hops, then ends
 Each hop decrements a count

42. WIDE2-2 example
 Station 1 sends: WIDE2-2 hello!
 Digipeater1 hears packet and retransmits: WIDE2-1 hello!
 Digipeater2 hears packet hears retransmission and transmits:
 WIDE2 hello!
 Orginal packet is re-transmitted (digipeated) 2 times only

43. Why WIDEn-N?
 Limits number of retransmissions
 Avoids unnecessary noise by excessive digipeating of packets

44. Typical APRS usage - tracking
 GPS position
reporting – station
locations and
tracks plotted on
https://aprs.fi

45. APRS Services / bots
 SMSGTE: APRS to SMS text message:
 To: SMSGTE@phonenumber
 Text message is sent out to phonenumber
 If recepient replies, reply is sent back out to APRS to originating station
 WXBOT/WXYO Weather forecast via APRS message
 Send message to WXBot and it will reply with weather for your location
 Examples:
 To: WXBOT, Msg: Davis, CA
 To: WXBOT, Msg: tomorrow
 Email via APRS
 Send email via APRS
 To: EMAIL, Msg: email@address message

46. APRS Services / Bots (2)

47. APRS apps: Xastir

48. APRS apps: YAAC
 YAAC – Yet Another APRS Client
https://www.ka2ddo.org/ka2ddo/YAAC.html

49. Connecting YAAC across your network
 Direwolf running on a
Raspberry Pi connected to my
2m radio upstairs
 YAAC running on my laptop
elsewhere in the house using
an AGWPE connection over
WiFi

50. Connecting YAAC to APRS-IS
 Connection
to APRS-IS
interet
network

51. APRS to WXXBot

52. APRS to email
 To: EMAIL, Msg:
email@address text message

53. APRS nearest repeater query

54. Winlink – email over Packet

55. KN6HTD doing some Winlink