Kantronics KAM User manual

KAM
KPC-4
KPC-2400
KPC-2
KPC-1
Operations
Manual
Version 3.0 – Aug. 13, 1990
RF Data Communications Specialists
1202 E. 23r Street, Lawrence, Kansas 66046
Or er number [phone]
Service number [phone]
9 am - noon, 2 pm - 5 pm Central Time, Mon ay-Fri ay

The KAM, KPC-4, KPC-2400, KPC-2 an KPC-1 are Kantronics har ware an software esigns incor-
porating the AX.25 Version 2 Level 2 Packet protocol as a opte by the American Ra io Relay
League. This manual contains information from earlier KPC-1, KPC-2, KPC-2400, KPC-4 an KAM
manuals an a en ums, mo ifie as appropriate. In a ition, Kantronics acknowle ges the use
of material from the original Tucson Amateur Packet Ra io Corporation (TAPR) TNC-1 manual
grante by OEM agreement.
We have attempte to make this manual technically an typographically correct as of the ate of
the current printing. Pro uction changes to the TNC may a errata or a en um sheets. We solic-
it your comments an /or suggeste corrections. Please sen to Kantroncis Inc., 1202 E 23r
Street, Lawrence, KS 66046.
Printe in the U. S. A.
© Copyright 1989 by Kantronics Inc., 1202 E. 23r Street, Lawrence, KS 66046
All rights reserve .
Contents of this publication or the firmware escribe herein may not be repro uce in any form
without the written permission of the copyright owner.
NET/ROM is a registere tra emark of SOFTWARE 2000
Commo ore, C-64, C-128 an VIC-20 are tra emarks of Commo ore Business Machines, Inc.
TRS-80 Color Computer an TRS Mo el-100 are tra emarks of Ra io Shack, a ivision of Tan y
Corporation
Atari 850 is a tra emark of Atari Inc., a Warner Communications Company
IBMPCjr is a tra emark of International Business Machines Corporation
Apple an Macintosh are registere tra emarks of Apple Computer, Inc.

Operations Manual
Table of Contents
Page
Preface ..................................................................................................... 1
Some Abbreviations .......................................................................... 1
Intro/Getting tarted .............................................................................. 2
Asynchronous Comman s .................................................................. 3
Dual-Port Set-Up Comman s .............................................................. 4
Front Panels
KAM ................................................................................................. 6
KPC-4 ............................................................................................... 7
KPC-2 ............................................................................................... 8
KPC-2400 ......................................................................................... 9
KPC-1 ............................................................................................... 9
Packet Mode ............................................................................................. 10
Comman Mo e ................................................................................ 10
Connecte vs. Unproto ...................................................................... 10
Monitoring an Calling CQ ................................................................. 11
A Simple Connect .............................................................................. 11
Digipeating ....................................................................................... 12
Gateway ........................................................................................... 13
Multi-Connects .................................................................................. 13
Roun Table Discussions .................................................................... 13
Timing ............................................................................................. 14
Dwait vs. Persistence an Slottime ........................................... 14
Tx elay ................................................................................. 14
Frack ..................................................................................... 15
Retries AX.15 Level 2, Version 1 vs. Version 2 ..................................... 15
Flow Control ..................................................................................... 16
Software Flow Control ............................................................. 16
Har ware Flow Control ............................................................ 17
Converse Mo e vs. Transparent Mo e ................................................. 17
Getting Out of Transparent ................................................................ 18
HF Packet Operation .......................................................................... 18
PBB
General ............................................................................................ 19
Configuring your PBBS ....................................................................... 19
Using the PBBS ................................................................................. 19
Reverse forwar ing messages from your mailbox ................................. 21
KA-NODE
General ............................................................................................ 22
Configuring Your KA-NODE ................................................................ 22
Using a KA-NODE .............................................................................. 23
Local Acknowle gments, Higher Throughput ....................................... 24
Automatic Disconnect ........................................................................ 24
Using the XCONNECT Comman (KAM an KPC-4 only) ....................... 25
Determining Which Port You Have Connecte To ................................. 25
KA-NODE Comman s for Remote Use ................................................. 26

Kantronics Host Mode Operation ............................................................ 28
Communication Format
Host computer to TNC ............................................................ 28
KAM HF Mo es ....................................................................... 29
TNC to Host Computer ............................................................ 29
HF Mo e operation ............................................................................ 30
WEFAX Mode
General ............................................................................................ 31
Backgroun : HF WEFAX Transmission an Resolution ........................... 31
Fin ing WEFAX Broa casts ................................................................. 31
Tuning WEFAX Signals on HF ............................................................. 32
Receiving WEFAX Transmissions ......................................................... 32
The WEFAX Comman ....................................................................... 33
Suggestions for Writing a WEFAX Terminal Program ............................. 33
WEFAX Program Functions ................................................................. 33
KI Mode ................................................................................................ 35
RTTY and A CII Modes (KAM only)
RTTY Theory ..................................................................................... 38
RTTY an ASCII Operation ................................................................. 39
Miscellaneous Information ................................................................. 42
Summary of RTTY/ASCII Directives ..................................................... 43
AMTOR Mode (KAM only)
AMTOR Theory ................................................................................. 44
AMTOR Operation ............................................................................. 45
Tuning AMTOR .................................................................................. 46
Summary of AMTOR Directives ........................................................... 47
NAVTEX/AMTEX Mode (KAM only)
NAVTEX/AMTEX Theory ..................................................................... 48
NAVTEX/AMTEX Operation ................................................................. 49
CW Mode (KAM only)
Summary of CW Directives ................................................................. 50

Preface
1
Preface
This manual will intro uce you to the various mo es of operation available with your new Kan-
tronics TNC. It assumes that you have rea the Installation Manual an have successful complete
connecting your TNC to your computer an ra ios.
First, we start with the mo es common to all Kantronics TNCs, inclu ing Packet, the Personal Mail-
box, KA-NODE, WEFAX an KISS Mo e. From here, we move into the mo es that are only avail-
able on the Kantronics All Mo e (KAM) communicator. These inclu e RTTY, ASCII, AMTOR an CW.
As you start, we must assume that you have your computer turne on an that you have starte
your terminal or communication software on your computer. Since there are many ifferent types
of computers an hun re s of terminal programs available, we will not attempt to tell you how to
accomplish these steps. If you have problems starting either your computer or your terminal pro-
gram, refer to the manuals that came with them.
ome Abbreviations
Ctrl-x = Ctrl is the control key an x represents any alpha character. This is a two key combination.
Press the Ctrl key while hol ing it own type the letter x (this can be capital or lower case, but will
shown as capital). Release both. If your computer keyboar has no key labele Ctrl, consult your
computer manual to etermine which key performs the control key function.
$ prece ing a number enotes a hex number (base 16)
<CR> = carriage return, $0D, ecimal 13, Ctrl-M, [↵]
<LF> = line fee , $0A, ecimal 10, Ctrl-J
I/O = Input/Output
Computer an terminal are use interchangeably to escribe whatever evice is attache to talk to
the TNC.

INTRO
2
Intro / Getting tarted
Now that you have your new Kantronics unit connecte to your ra io an computer, let's take a
moment to see what it is an how to make it un erstan what you want to o. A Terminal No e
Controller (TNC) is very similar to a telephone mo em because it receives igital signals from the
computer (Terminal) an converts them to tones suitable for transmission to istant location. The
TNC also receives tones from your ra io an converts them into the igital signals un erstoo by
your computer. A TNC, however, oes much more, because it controls the push-to-talk line of your
transmitter, keying the ra io whenever it nee s to sen ata. It also converts the ata into a
"packet", a ing the require a ressing, error checking an control information to insure the ata
gets from one No e to the next. The error checking implemente in your TNC must be the same
as the error checking use by any other station you want to talk to an this stan ar metho is
calle a protocol. The protocol use in Amateur Ra io Packet TNCs is calle AX.25. Different proto-
cols are use for other mo es of operation, such as AMTOR.
In or er for your TNC to o something, you must issue instructions to it, letting it know exactly
what you want one. In or er to accomplish this, the TNC must be in the Comman Mo e (expect-
ing you to give it instructions) an any time you want to change the way your TNC operates, you
must be in this mo e. The TNC tells you that it rea y for your comman s by sen ing you the
prompt cmd:.
When you first turn on your TNC out of the box (or after a har reset) you may see some garbage
characters on your screen. The TNC is performing an autobau routine. It is sen ing the same
massage over an over again at ifferent bau rates. When the TNC bau rate matches the bau
rate set in your terminal (communications) program, the isplay will rea :
PRESS (*) TO SET BAUD RATE
When these wor s are rea able press the asterisk, *, on your keyboar . This will set the bau rate
until the TNC is turne off; keep rea ing for how to avoi having to o this all the time. Then the
TNC will isplay the following:
ENTER YOUR CALLSIGN =>
At this point enter your amateur callsign. This callsign will be use by the TNC for many ifferent
things, inclu ing being in every packet you sen an eci ing if a packet it receives is specifically
for you. Now you shoul see the sign-on message an comman prompt on your screen, as:
KANTRONICS sign-on-message
cmd:
In some cases (notably Commo ore-64 users with the Kanterm program an some umb termi-
nals) the cmd: prompt may not appear. This is ue to the TNC sen ing lower case characters an
the terminal oesn't recognize them. In these cases, you will probably see only the colon (:). This
can usually be resolve by turning the LCOK comman OFF.
The cmd: prompt means the TNC is rea y to listen to you. Anything you type will be be inter-
prete as a comman . If the TNC oesn't un erstan , it will isplay:
EH?
To change a comman setting you type the comman , a space, the argument (a number or what-
ever is appropriate) an then the RETURN or ENTER [↵] key. If you turn the TNC off an back on

INTRO
3
again, the changes will not be remembere unless you have use the PERM comman , or using a
Battery Backup or SmartWatch.
All comman s are liste alphabetically in the Comman s Manual an many are iscusse by mo e
in this Operations Manual. The Comman Manual also has an intro uction that goes into more e-
tail on the structure of comman s.
Asynchronous Commands
Asynchronous comman s are comman s that allow your TNC an computer to talk the same lan-
guage. These comman s in the TNC will have their counterparts in your computer program,
although some programs may limit what you can set. Following is a list of TNC efaults an their
correspon ing computer setting. then we will explain the comman s using both the computer an
the TNC terminology.
TNC Computer
ABAUD 0 The TNC runs an autobau routine to allow it to match the
spee set in your computer when the TNC receives an asterisk
8BITCONV ON Data Bits or Wor Length 8
PARITY 4 Parity no or none
ECHO ON Full Duplex
XFLOW ON Software Flow Control
Baud Rate is how fast the computer an TNC will talk to each other. This is set in the TNC with
the ABAUD comman . The settings allowe by the TNC are 0, 300, 600, 1200, 1800, 2400, 4800
an 9600. (KPC-1 only allows 0, 300, 1200 an 9600.) When set to 0, the autobau routine will
run at power-up – requiring you to press the asterisk whenever you turn on the TNC.
Word Length an Data Bits are often use interchangeably to refer to how many bits are use
to recognize a character. Each character is ma e up of smaller parts calle bits (analogous to a it
or ah in Morse co e). These bits are seen as high or low voltages on the cable between the TNC
an computer to make the esire combination for a character. A stan ar by the name of ASCII
allows 8 bits for each character, although all the stan ar alphanumeric characters an punctua-
tion can be recognize with only 7 bits. The TNC will talk to the computer using either 7 or 8 bits
epen ing on setting of the comman 8BITCONV. As efault 8BITCONV ON means 8 bits. Set
8BITCONV OFF to strip the 8th bit an use only 7 bits.
Parity etermines what the 8th bit will be an is an ol form of error etection which few mo -
ern- ay programs check. PARITY 4 is the efault in the TNC which means the 8th bit will be seen
as part of the character. O or Even Parity will change the 8th bit epen ing on whether there is
an o or even number of high voltages in the 7-bit character. Mark an Space Parity will hol the
8th bit either high or low. In the TNC, setting PARITY 0 is o parity; Parity 1 is even parity;
PARITY 2 is mark parity; PARITY 3 is space parity an PARITY 4 is no parity. 8BITCONV must be
ON before the TNC will look at the 8th bit (the TNC always sen s the 8th bit in TRANSPARENT
Mo e).
top Bits. The TNC always uses 1 stop bit.
Full Duplex or Half Duplex. (Some programs use the term Echo for Half Duplex.) When using
Full Duplex the computer expects the attache evice to sen back (echo) what was sent to it. A
setting of Half Duplex will tell the program that it must o the isplaying to the screen for what
you type. The TNCs efault is ECHO ON, which tells the TNC to sen back what it receives. This

INTRO
4
correspon s to a setting of Full Duplex for the computer. If you set your computer for Half Duplex,
you will nee to turn ECHO OFF or you will see two of everything you type. When using a split
screen program, you may want to set ECHO OFF in the TNC because the program will be han ling
what you type in the buffere keyboar screen.
Flow Control. Often times one evice may talk to another evice faster than it can han le the in-
formation. When this happens, the excess information is store in a buffer until it can be pro-
cesse . This buffer is only so large. If the ata were to over-flow the buffer, it woul be lost. Flow
Control is the terminology use for how the evices inform each other to stop or start sen ing a-
ta. There are two ways to accomplish this: software an har ware. The TNCs efault XFLOW ON
allows the TNC to implement software flow control (har ware flow control is always recognize by
the TNC).
Software Flow Control is implemente by the program or TNC looking at the ata an watching for
two certain characters. One of these characters (normally Ctrl-S) tells the evice to stop sen ing
ata an the other (normally Ctrl-Q) tells the evice to re-start sen ing ata. The TNC comman s
XOFF an XON tells the TNC which characters to sen to the computer to stop an start ata flow.
The comman s STOP an START efine which characters the TNC expects from the computer.
These comman s all come efaulte for normal software flow control.
Har ware Flow Control is implemente by the evice watching the voltages on the RTS an CTS
pins of the RS-232 port. The TNC will always monitor these pins, so only connect them if you are
going to use them. If you use har ware flow control, you shoul turn XFLOW OFF. See the Con-
necting your Computer section of the Installation Manual for how to wire your RS-232 cable for
har ware flow control.
Perm. If you woul like to customize the efaults in the TNC for your situation, all you have to o
is type PERM at the cmd: prompt (followe by a RETURN or ENTER key). This comman will write
your customize efaults to the EEPROM. Now, if you turn the TNC off an back on again, your e-
faults will be use . This comman can be use at least 1000 times, so as you experiment with
your parameters an fin ones you woul like to have ifferent than factory efault, just use this
comman . If for any reason you ever want to go back to the factory efault, a Har Reset can be
performe (see the Har Reset section of the Installation Manual), or use the RESTORE D com-
man as escribe in the Comman s Manual.
Dual-Port et-Up Commands
PORT. The KAM an KPC-4 both have two ra io ports. When turne on, the KAM will be a ress-
ing the VHF port an the KPC-4 will a ress Port 1. If you wish, this may be change so that the
other port will be a resse when the unit is turne on. For the KAM, you coul type PORT HF at
the cmd: prompt, an for the KPC-4 you woul type PORT 2. This comman woul then nee to
be PERMe (if not using Battery Backup or SmartWatch). This only affects what port the TNC will
a ress when it is turne on after the next soft reset. In or er to change ports uring Packet oper-
ations see Multi-Connects in the Packet section or the STREAMSW comman in the Comman s
Manual. When using non-packet mo es on the KAM the HF port is automatically selecte . In or er
to enter a non-packet mo e, the MAXUSERS comman must be set to allow HF operation.
MAXU ER . This comman causes the TNC to allocate the memory require for the maximum
number of simultaneous connections you wish to allow. The KAM an KPC-4 will allow a setting of
0. If MAXUSERS is set to 0/0, these TNCs will accept only one connect at a time from either port of
the TNC. This special con ition will be highlighte by being isplaye simply as MAXUSERS 0. This
makes it feasible to use the KAM/KPC-4 with MBL or RLI BBS programs on two frequencies. Setting
MAXUSERS to 0/n or n/0 will isable the port esignate for 0.

INTRO
5
PMODE (KAM only). When set to NONE as efault, the KAM will be in the Packet Mo e. This com-
man allows you to have your KAM come on in the mo e you select. Optional parameters are:
ASCII, AMTOR, CW, FEC, RTTY, NAVTEX an NONE (Packet). Starting the KAM in the Kiss or Host
Mo e is accomplishe with the INTFACE comman (INTFACE will overri e PMODE). As with all
comman s this must be PERMe for the KAM to remember it after being turne off (if not using
the Battery Backup or SmartWatch.

FRONT PANELS
6
Front Panels
KAM
The front panel has two switches, eight LEDs an a ten segment LED bargraph. There are seven
LEDs use as operating status in icators. The front panel is ivi e into two sections. The left
three LEDs are the in icators associate with HF operation, an the four right LEDs are the in ica-
tors associate with VHF operation. The two segments are ivi e by a white color bar. Each LED
has the functions in icate below:
HF ection:
XMIT – This LED will illuminate when the KAM is keying the PTT line on your HF ra io OR when
HF packets are being receive .
CON/LOCK – This LED will illuminate when you have an HF Packet connection OR an AMTOR lock
con ition.
TA/VAL – This LED will illuminate when you have unacknowle ge HF packets OR vali AMTOR
ata.
VHF ection:
XMIT – This LED will illuminate when the KAM is keying the PTT line on your VHF ra io.
RCV – This LED will illuminate when you are receiving a VHF packet.
CON – This LED will illuminate when you have a VHF Packet connection. In a ition, when operat-
ing non-Packet HF mo es, this LED will blink ON/OFF for approximately 10 secon s if KAM receives
a VHF Packet connect request.
TA – This LED will illuminate when you have unacknowle ge VHF packets. Also, if the CON light
is OFF, the STA light is use to in icate PBBS status – ON stea y in icates someone is connecte
to the PBBS an blinking in icates mail in the Kantronics TNC for you.
POWER INDICATOR
POWER - The single LED on the right en of the front panel illuminates when power is applie .
witches
ON/OFF – Provi es power control of the KAM.
AM/FM – Switches the limiters in or out of the emo ulator circuits. This switch shoul be set to
AM for CW operation an FM for RTTY/ASCII/AMTOR. For Packet operation, either AM or FM can
be selecte . Use the setting you prefer.

FRONT PANELS
7
Ten egment LED Bargraph
The bargraph provi es a visual in ication of the receive HF signal. The en segments, labele
MARK an SPACE, blink alternately on a properly tune RTTY/ASCII/AMTOR or Packet signal. In
CW Mo e the left en (MARK) of the bargraph illuminates when no signal is present an the right
en (SPACE) lights when a signal is etecte . In a ition, when your PTT line is being keye to
transmit on the HF port, the LED bargraph will be blanke out. The bargraph may be use to tune
WEFAX if the au io from the WEFAX signal is connecte to the HF ra io port as well as the VHF
port. Between picture transmissions, most WEFAX stations transmit a SPACE signal.
KPC-4
The front panel has a power switch an nine LEDs. There are eight LEDs use as operating status
in icators an one for power. The front panel is ivi e into four sections, each section containing
two operating status LEDs. Each section is separate by a white color bar. Each LED has the func-
tion in icate below:
PORT 1
XMIT – This LED will illuminate when the KPC-4 is keying the PTT line of your ra io attache to
ra io Port 1.
RCV – This LED will illuminate when you are receiving ata from your ra io attache to ra io
Port 1.
TREAM
CON – This LED will illuminate when you have a Packet connection on the current stream. The
current stream is the stream to which the I/O is irecte . (See STREAMSW in the Comman s Man-
ual.)
TA – This LED will illuminate when you have unacknowle ge packets on the current stream.
PORT 2
XMIT – This LED will illuminate when the KPC-4 is keying the PTT line of your ra io attache to
ra io Port 2.
RCV – This LED will illuminate when you are receiving ata from your ra io attache to ra io
Port 2.

FRONT PANELS
8
MONITOR
MAIL – This LED will illuminate when there is a station connecte to your PBBS. In a ition,
whenever the PBBS is hol ing mail a resse to you an no connection to the PBBS exists, this
LED will blink continuously.
RPT – This LED will illuminate whenever the KPC-4 gateway or igipeat functions are actively in
use an will stay on for several secon s after each use.
Power Indicator
POWER – The single LED on the right en of the front panel will illuminate when power is ap-
plie .
witch
ON/OFF – Provi es power control for the KPC-4.
KPC-2
The front panel has five LED in icators which provi e information as follows:
POWER – This LED illuminates when power is applie . The power ON/OFF switch is locate on
the rear panel.
XMIT – This LED illuminates when the TNC keys the PTT line of your ra io to sen ata.
RCV – This LED illuminates when the TNC etects a signal on the ra io frequency.
CON – This LED illuminates when you have a Packet connection on the current stream. The cur-
rent stream is the stream to which the I/O is irecte . (See STREAMSW in the Comman s Man-
ual.)
TA – This LED illuminates when the TNC has outgoing packets which have not been acknow-
le ge on the current stream. Also, if the CON light is OFF, the STA light is use to in icate PBBS
status – ON stea y in icates someone is connecte to the PBBS an blinking in icates mail in the
Kantronics TNC for you.

FRONT PANELS
9
KPC-2400
The front panel has five LED in icators which provi e information as follows:
POWER – This LED illuminates when power is applie . The power ON/OFF switch is locate on
the rear panel.
XMIT – This LED illuminates when the TNC keys the PTT line of your ra io to sen ata.
RCV – This LED illuminates when the TNC etects a signal on the ra io frequency.
CON – This LED illuminates when you have a Packet connection on the current stream. The cur-
rent stream is the stream to which the I/O is irecte . (See STREAMSW in the Comman s Man-
ual.)
TA – This LED illuminates when the TNC has outgoing packets which have not been acknow-
le ge on the current stream. Also, if the CON light is OFF, the STA light is use to in icate PBBS
status – ON stea y in icates someone is connecte to the PBBS an blinking in icates mail in the
Kantronics TNC for you.
KPC-1
The front panel has three LEDs which provi e information as follows:
POWER – This LED illuminates when power is applie . The power ON/OFF switch is locate on
the rear panel.
XMIT – This LED illuminates when the TNC keys the PTT line of your ra io to sen ata.
RCV – This LED illuminates when the TNC etects a signal on the ra io frequency.

PACKET
10
Packet Mode
Packet-Ra io is the communication of igital ata via ra io. A packet is a group of characters with
a flag an hea er at the beginning an a checksum an flag at the en . A flag is a specific charac-
ter use to signify the beginning an en ing of a packet. The hea er is information concerning
who the packet is from, who it is to, any relay stations nee e to get to the estination an some
control information. A checksum is a complicate mathematical formula that pro uces a number
that is unique to the combination of characters that are in the packet. This unique number is fig-
ure by every station that han les the packet an if it oes not match the number that is in the
packet, the packet is thrown away, thus error-free communications. A packet is also calle a
frame. The Terminal No e Controller (TNC) is the workhorse of Packet-Ra io. As a listening evice
it hears an au io signal from the ra io, changes the ata to igital form, etermines if it is a goo
packet an sen s it to whatever evice is attache , usually a computer. As a relay evice it also
checks the packets it receives an etermines if the packets nee to be resent, then oes so if ap-
propriate. As a sen ing evice it receives igital ata from the computer, packetizes it an changes
it into au io tones which are sent out to the ra io. The rules the TNC uses to o all of this is calle
a protocol.
The most use protocol in amateur Packet-Ra io is AX.25 Level 2 an the nitty gritty etails of the
inner workings can be foun in a book name AX.25 Amateur Packet-Ra io Link-Layer Protocol
available from the ARRL. Most of you are not going to want to go that eep, the TNC takes care of
the nitty gritty for you, although there are parameters you can set that etermine how efficiently
some of that work is one. In this section of the book we will iscussing the fun amentals of how
to get on the air an how parameters interrelate. The efault parameters will get most everyone
on the air, but by using this information, you can change your parameters to be most efficient in
whatever situation you fin yourself.
Command Mode
In or er to change parameters, or give any other instructions to the TNC, you must be in Com-
man Mo e. This is the mo e you will be in when you turn on the TNC (unless you have change
the PMODE parameter in the KAM). Once you have left Commen Mo e for any reason, there is a
parameter calle COMMAND that etermines what special character you will use to return to Com-
man Mo e. This comes efaulte as a Ctrl-C. (While hol ing own the control key press c, then
release both.) All parameters are escribe in alphabetical or er in the Comman s Manual. When-
ever you enter Comman Mo e, the TNC will sen a prompt to your screen that looks like this:
cmd:
Connected vs. Unproto
There are two ways to sen ata in Packet-Ra io, connecte or unproto (unconnecte ). In the
Comman Mo e you first establish a connection. Then your TNC will sen packets to that specific
station an expects acknowle gments in return. If an acknowle gment is not receive , the TNC
will resen the ata ( epen ing on the setting of AX25L2V2 it may sen a poll first). The RETRY
parameter will etermine how many times this is one before the connection is lost ue to ba
con itions. If the acknowle gment is receive , the TNC is happy an will sen more ata, when
available. Therefore the Connecte Mo e, barring impossible con itions, assures that the station
you are connecte to, will receive everything you say an in the or er you say it.
In the Unproto Mo e your TNC sen s a packet. As far as the TNC is concerne , the packet is not
irecte to a specific station, therefore no acknowle gment is expecte an no retrys are at-
tempte . This mo e is often use for calling CQ an informal roun table chit chats.

PACKET
11
Monitoring and Calling CQ
If you turn the MONITOR comman ON, you will begin to see other people's packets on your
screen. You will notice two callsigns at the beginning of each packet separate by a >. The first
callsign is the station the packet is from. An the secon callsign is the station the packet is to. An
Unproto packet may have a name or CQ for the secon callsign.
To set what what will be seen as the "to" callsign of an Unproto packet, you use the the UNPROTO
comman . This comes efault as CQ, but if you wante to put in your name instea , you woul be
sure you are in Comman Mo e an issue a comman similar to this:
u name <CR>
where u is short for unproto, name is your name an <CR> is the return or enter key on your
computer keyboar . In or er to call CQ you must get into the Convers Mo e, so that what you are
typing to the TNC will be interprete as ata to be sent out on the air an not as comman s. To
o this, type:
k<CR>
or, if you have a version earlier than 2.84, this shortcut is not available an you must type:
conv<CR>
Now anything you will be packetize an sent out on the air. Remember to get back to Comman
Mo e you enter a Ctrl-C ( efault) by hol ing own the control key while pressing c. You will be
going between Comman an Convers Mo e epen ing on if you want to talk to the TNC or have
the TNC packetize what you type to go out on the air.
A imple Connect
Once you see a station you woul like to connect to, be sure you are in Comman Mo e, an issue
a connect request, example:
c callsign <CR>
where c is short for connect an callsign is the callsign of the station you wish to connect to. If for
any reason the connection fails, the TNC will sen the following message to your screen:
*** RETRY COUNT EXCEEDED
*** DISCONNECTED
When your TNC oes receive an acknowle gment for a connect packet it will isplay a message on
your screen like:
*** CONNECTED TO callsign
an your TNC will change to the Converse Mo e ( epen ent on setting of NOMODE an
CONMODE). Now what you type will be interprete by the TNC as ata to be sent to the other sta-
tion an not comman s to the TNC. The MCON parameter comes efaulte to OFF. Therefore once
you are connecte all you will see is what you type an what the other person sen s you. Any
packets sent by other people will not be monitore .
Two things etermine when the ata will be packetize . One is the parameter SENDPAC. This is
efaulte as the return or enter key you are telling the TNC to make a new packet. A secon pa-
rameter, PACLEN, etermines the maximum length of any packet. If you enter ata longer than
this length, a packet will be ma e even though you have not presse the return or enter key.

PACKET
12
When you have finishe your conversation you nee to en the connection. To o this, you go into
the Comman Mo e an type a d for Disconnect. Remember to press the return or enter key after
any comman to the TNC. Once your station has receive the acknowle gment for the the iscon-
nect packet the TNC will sen this message to your screen:
*** DISCONNECTED
Either station can issue the isconnect comman , no matter which station originate the connect.
Digipeating
Everything we have one so far will only be hear by those within range to hear your signal. With
Packet-Ra io it is possible to get further than that. The DIGIPEAT parameter in the TNC comes e-
faulte ON. This makes you a possible relay station, or igital repeater – igipeater, or just igi for
short. In many VHF communities one, or more, of these is put up in a goo , high location an re-
ferre to as a e icate igi. The TNC an ra io is all that is nee e for the igital repeater to o
its job. A computer woul be nee e if you wante to change a parameter, but it woul not nee
to stay there for the igi to work. The higher the antenna, the more effective a igi will be, but re-
member, every TNC has the capability of being a igipeater.
If we turn the MRPT comman ON, we will begin to see more than just the "from" an "to" sta-
tions of the monitore packets. We will also see the callsigns of those stations that have been use
as igipeaters. (If you turn HEADERLN ON the hea ers will en with a return an be on a separate
line from the packet ata.) This list of stations is often calle a path. Here is an example of what
you might see:
WK5M>KA5ZTX,IAH*,LAG,AUS:
Hi there
In this example WK5M is talking to KA5ZTX using the igipeaters IAH, LAG an AUS. The asterisk
besi e IAH tells you that you are hearing that igipeater. You will notice that IAH, LAG an AUS
are not real callsigns. The TNC provi es parameters (MYALIAS an ALIAS) to set up an alias,
which is often easier to remember than a callsign. To make this connection WK5M woul have
type the following comman to his TNC:
c ka5ztx v iah,lag,aus
v is short for via an up to 8 igis may be use . You must specify igis in the or er they will be
encountere along the path from your station to the station you wish to connect to. A space must
be type after the c an on both si es of the v, but igis are separate by commas an no
spaces. A path can also be use with the Unproto comman :
u cq v nom,lch,sli,bix
Unproto sets up the path for anything that is subsequently type in the Convers Mo e where no
connect exists. Connect issues a connect request to the specifie station, via the specifie path.
Then an error-free conversation can take place between them.
When igipeating the packet goes all the way from the first station, through all relay stations, then
to the estination station. Then the response also has to take this same path in reverse. Chances
for collisions, therefore retries, are multiplie with every igi use . This is often calle en -to-en
acknowle gment. Another way to get from one place to another is to connect a "no e". A no e
will take care of the acknowle gment between it an the next no e or en user. See the KA-NODE
section for more information. Ask your local packeteers about other kin of no es which may be in
your area, such as TheNet an NET/ROM.

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13
Gateway
In the KAM an KPC-4 a Gateway is also available. This is similar to igipeating except that the re-
transmission of the packets takes place on the other ra io port of the TNC from where it was re-
ceive . In other wor s, if you are on VHF an sen a packet via a Gateway callsign of a KAM your
packet woul be retransmitte on HF, on whatever frequency the ra io connecte to the KAM is
set for. When you use one of these gateways remember that on HF the bau rate is slower so you
may want to lengthen some of your timing parameters. See the KA-NODE section for another way
to accomplish this with a more reliable connection.
The TNC has some parameters that nee to be set before this feature can be use . The MYGATE
parameter nee s a callsign that is ifferent than any other callsign parameter an GATEWAY nee s
to be turne ON. Also keep in min that gateway operation is not permitte by FCC rules an regu-
lations in an unatten e station.
Multi-Connects
The TNC makes it possible for you to talk to more than one person at the same time, if you want
to. A stream (or channel) is use for each conversation. The comman MAXUSERS etermines
how many streams may be use at one time. An the comman USERS etermines how many
people can connect to you. An incoming connect uses the next available stream. If the number of
streams set by USERS is full, then that station will get a busy message instea of a connect. How-
ever, if MAXUSERS is set larger than USERS, you can still issue outgoing connects on the a itional
streams.
The character specifie in the STREAMSW parameter is use to change from one stream to anoth-
er. The streams are lettere A – Z. So in or er to change streams you type the STREAMSW charac-
ter an then the letter esignator for the stream you want (no return or enter in this case). This
can be one in Comman or Convers Mo es an the CON an STA lights on the front panel of the
TNC will change appropriately for the stream you choose.
For an example, let's assume I'm using a KAM an have my HF streamswitch set to the " \ " an
the VHF streamswitch set to " | ". Now if I want to transmit on HF packet, I simply enter \a to
cause my current I/O stream to be the A stream on the HF port. To change back to VHF, I woul
enter |a to go to the A stream of VHF. The current I/O stream when the TNC is first turne on will
be the A stream of the port specifie by the PORT comman for ual-port units.
The STATUS comman allows you to see who is on which stream, or the status of the stream, i.e.
waiting acknowle gment, connect in progress, isconnecte . Turning STATSHORT ON will cause
the STATUS comman to list only the current Input/Output stream an any connecte streams.
If you are connecte an have MONITOR an /or MCON OFF, the normal hea ers containing the
"to" an "from" callsigns will not be shown. The setting of STREAMEV will then etermine how
often you see the stream esignator. This parameter comes efaulte OFF, so the stream esigna-
tors are only shown when a change in streams occurs. Turning this comman ON will make the
stream esignators show on every packet. Turning STREAMCA ON will also a the callsign of the
"from" station besi e the stream esignator.
Round Table Discussions
Several people talking together present a ifficult situation for Packet-Ra io since the protocol re-
quires two stations to connect in or er to make sure they receive each others packets. If you
wante to be absolutely sure that everyone got everything you sai , you woul have to connect to
each person an retype everything to each person. That coul get a bit cumbersome, so most

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people use the Unproto Mo e an are aware that a collision may occur once in a while. You can
usually tell by the conversation if something was misse ; if you on't get an answer to a question
it's probably not that he is ignoring you, but either the question or the answer got colli e with.
With MONITOR ON, the BUDLIST an BUDCALLS comman s can help in setting up your monitor-
ing to see only those you want to see. List up to 10 calls in BUDCALLS an set BUDLIST to BOTH.
Now you will only see packets "to" an "from" those calls. If you like, you may each want to con-
nect to one person, then you know at least that one got what was sai , but be sure MCON an
MALL are ON.
Timing
Dwait vs. Persistence and lottime
When the TNC acts as a igipeater, packets that nee to be relaye are retransmitte as soon as
the frequency is clear. Because of the en -to-en acknowle gment of these kin s of packets it is
best for an originating station to avoi colli ing with igipeate packets. The TNC provi es two
ways to accomplish this elay. These two metho s are the stan ar DWAIT metho or the newer
PERSISTENCE/SLOTTIME algorithm. During a connect using no igis, this elay also gives the re-
ceiving station time to switch from transmit to receive.
Using the DWAIT metho , once the TNC etects a clear frequency, it will wait DWAIT (times 10
millisecon s) time before beginning to keyup the ra io to transmit a packet. This is a packet origi-
nate by you not a igipeate packet.
The algorithm use with the PERSIST an SLOTTIME parameters helps avoi collisions by ran om-
izing the wait time before transmitting. The more ran om the timing the less chance of two TNCs
transmitting at the same time an colli ing. Once the TNC etects a clear frequency it will wait
SLOTTIME (times 10 millisecon s). Then it will generate a ran om number. If this number is smal–
ler than the setting of PERSIST the TNC will transmit. If it is larger, it will wait another SLOTTIME
an generate another ran om number an again eci e whether to transmit or not. When using
PERSIST an SLOTTIME you shoul set DWAIT to 0, since both will be use if specifie .
As an example, let's assume that PERSIST is set to 63 an SLOTTIME is set to 10. This value of
SLOTTIME results in a ran om number being generate every 100 millisecon s. When the TNC
sees that the channel is clear, it waits 100 ms, then generates a ran om number between 0 an
255 (inclusive). In our example, the number was 83, then the TNC woul not start the keyup of
the transmitter since 83 is greater than the 63 PERSIST value. Instea , it woul wait an a itional
100 ms, an if the channel is still clear, generate a new ran om number. This time, let's say it
comes up with the number 27. Since this is less than the PERSIST value, we now start the keyup
of the transmitter to sen the packet.
Txdelay
TXDELAY shoul be a juste to allow your ra io sufficient time to switch from the receive mo e to
transmit an evelop full power output. If the TNC sen s the packet before the ra io is at full
power, the beginning of the packet will be lost an no one will be able to eco e it. It is a goo
i ea to allow a little extra time for this parameter to allow the station you are talking to sufficient
time to switch from his transmit mo e back to receive. This is not usually necessary if you are con-
necte through a igipeater, but if you are connecte irect, this coul make the ifference be-
tween successful communications an no communications. The TNC sen s flags uring this perio ,
so if someone has this set extra long you will hear a repetitive soun at the beginning of the
packet.

PACKET
15
Frack
Frame acknowle gment time. If the TNC expects an acknowle gment of a packet it has sent, it
will wait FRACK secon s for the acknowle gment. If the acknowle gment is not receive it will
either sen a poll or retransmit the packet, epen ing on the setting of AX25L2V2. When igis are
use , extra time is allowe for each transmission using the following equation:
FRACK × ((2 × n )+ 1) secon s
where n is the number of igipeaters. The lower the bau rate (HBAUD) the longer this parameter
shoul be set, because everything is slower. The length of the transmission ( etermine by
PACLEN an MAXFRAME) also nee s to be taken into account when eci ing how to set FRACK.
Longer packets (an more of them) require more time to be transmitte , more time to be re-
peate by the igipeater an so on own the line. The FRACK timer begins when PTT is release
(the packet has been sent) an is suspen e when ata carrier from the ra io is present or when
your station is transmitting.
Retries AX.25 Level 2, Version 1 vs. Version 2
The way retries are accomplishe epen s on AX25L2V2 being OFF or ON. To explain this we will
follow a conversation through its path. First lets assume station "A" is connecte to station "B"
with Version 1 protocol (AX25L2V2 OFF). When station A sen s a packet to station B, he expects
to receive an acknowle ge back in icating that station B has receive the information. In or er to
verify that the proper packet (or frame) has been acknowle ge , each frame has a number. This
number is sent as a part of the frame so the receiving station knows where this packet belongs in
the conversation. The frame numbers range from 0 – 7 an because of this, we are limite to a
MAXFRAME of 7 (we o not want the same frame number reuse in the same transmission). This
is also true for Version 2. If the first acknowle ge is receive , there is really no ifference between
the two versions, practically speaking. The ifference shows up with retries, so let's assume that
the packet i not get through on the first attempt.
Let's now assume that station a sen s frame number 3 to station B. Station B oes not receive the
frame an therefore no acknowle ge is receive by station A. With version 1, the entire packet is
retransmitte (with the same frame number) again to station B an this continues until station A
receives an acknowle ge from station B. This acknowle ge can two basic forms. The first time sta-
tion B receives frame 3, he will sen an acknowle ge of the form "rea y to receive frame 4"
<rr4>. If this acknowle ge is sent an station A i not receive it, station A will again sen frame
3. Since station B alrea y receive frame 3, he woul acknowle ge it with the from "I've alrea y
got frame number 3" <rej4>. This is also known as Reject Frame sent. This process woul contin-
ue until the retry count is excee e when, un er version 1, the sen ing TNC will initiate a iscon-
nect an ump the packet into the air UNPROTO. (The monitoring of the comman s in < > e-
pen s on the settings of MRESP an MCON.)
Now let's look at the same con itions un er version 2 (AX25L2C2 ON). Station B oes not receive
the frame an therefore no acknowle ge is receive by station A. This time, station A sen s a
POLL or question to station B saying, in effect, " i you receive my frame number 3?" <<RR3>>.
Since station B i not receive the frame, he woul respon with "no I i not" <<rr3>>. This
really says "I am rea y to receive frame 3". At this point, station A, upon receiving the rr3 woul
imme iately resen the entire frame. If station B ha alrea y receive frame 3 once but the ac-
knowle ge never got to station A, the question from station A for the retry woul be the same.
Station B's response however, woul be ifferent. He woul respon with "rea y to receive frame
4" <<rr4>>. If station A oes not receive station B's reply this POL/REPLY sequence woul con-
tinue for the number of retries set in the sen ing TNC an if no response was receive , the TNC at
station A woul then begin to issue connect requests to station B since there is still an outstan ing

PACKET
16
packet of information. This is the major ifference between version 1 an version 2. The connect
attempts woul then continue for the number of retries set in the TNC an if no response was re-
ceive from station B after all of the above, station A woul isconnect an ump the packet UN-
PROTO. The parameter RELINK can be turne OFF to avoi the reconnect attempt.
In either version 1 or version 2 another interesting feature of packet is the ability to automatically
reestablish a connection. For instance, station A is connecte to station B an has one frame out-
stan ing. Station B isconnects without station A knowing it (perhaps a power failure, ouble is-
connect or even a timeout (retry count excee e )). The first time station B receives the outstan -
ing packet from station a he will sen a isconnect message to station A. When station A receives
this, station A automatically issues a connect request to station B an the connection is re-estab-
lishe to pass the outstan ing traffic.
Flow Control
The flow control comman s insure that the TNC gets everything that is sent to it by the computer
an that the computer gets everything the TNC sen s it. When the computer sen s the TNC ata,
the TNC stores this ata in a buffer until it can packetize it, sen it an get acknowle gment.
When the TNC sen s the computer ata, it also stores in a buffer until it can be processe , store
to isk, sent to printer, or whatever. This buffer area is only so big, if more ata is sent than will fit
in the buffer, it is lost. To avoi this, the two evices can tell each other to start an stop sen ing
ata. This is calle Flow Control an can be accomplishe in two ways: software an har ware.
Which way you implement, this epen s on the capabilities of your computer communications pro-
gram an personal preference. The cable between your computer an TNC must also be wire ap-
propriately.
oftware Flow Control
Software flow control sen s special characters on the TXD an RXD lines of the RS-232 cable.
These are the same lines use for sen ing regular ata between the TNC an computer – Soft-
ware flow control normally sen a Ctrl-S to stop ata an a Ctrl-Q to restart ata. When a buffer
gets close to full the evice will sen a Ctrl-S an expect the other evice to stop. When the buffer
gets emptier, it will sen a Ctrl-Q to tell the other evice to sen more ata. How full or empty a
buffer is when the special characters are sent, is etermine by the program. But, since the regu-
lar ata lines are being use a Ctrl-S sent from the keyboar will also stop ata. An likewise, if
there is a Ctrl-S in a file being sent, ata flow will stop until a Ctrl-Q is receive .
XFLOW nee s to be turne ON for the TNC to use software flow control. XOFF etermines the
character sent by the TNC to stop the flow of ata from the computer, an the XON character re-
starts the flow. The TNC expects the computer to sen the STOP character to stop ata an the
START character to restart ata. To use software flow control these comman s woul be set as fol-
lows: XFLOW ON, XOFF $13, START $11.
In the Transparent Mo e two more comman s are provi e that make it possible to sen or re-
ceive these special characters an still use software flow control. TXFLOW controls flow control
sent by the TNC to the computer an TRFLOW controls what the TNC expects from the computer.
In both these comman s are ON (an the above comman s are set as state ), then software flow
control will take place in both irections to an from the TNC an computer. But if you are in
Transparent Mo e sen ing a file, the computer is not going to be telling the TNC to stop an start
since you are sen ing the file. But if there is a Ctrl-S in the file, the TNC will think the computer is
telling the TNC to stop an will not sen any ata to your computer until it receives a Ctrl-Q (even
if you have complete sen ing the file). To solve this problem, you can turn TRFLOW OFF an
sen all characters an turn TXFLOW ON, so the TNC will still tell the computer when to stop an
restart. On the other han , if receiving a file, set TRFLOW ON an TXFLOW OFF.