Introduction to Packet Radio - Part 3
by Larry Kenney, WB9LOZ
In Part 2 I talked about how to get on the air and make your first QSO.
Now let's take a look at some of the commands that are available in your
TNC or packet software to help improve your station operation.
The TNC (Terminal Node Controller) has more than 100 different
commands available for you to use. You're able to customize your packet
operating with these commands and turn on and off various features as you
wish. Not all TNCs are exactly alike, but all have pretty much the same
set of commands. I'll be using the command set in the TNC2 and clones in
my examples. You might want to check the command list in your TNC manual
to see if your TNC uses the commands as indicate here.
For those of you who are using the packet software and modem instead
of a TNC, you'll find a list of the commands in your help documentation.
You will find that some of the commands cannot be modified while the
software is running. Some have to be changed with the program's
configuration file.Check the help document for instructions on how to
change these commands in your particular software.
We covered a few of the commands previously: CONTROL C for entering
command mode, MYCALL, MONITOR, ECHO, CONNECT, and DICONNECT. (Refer to
Part 2 if you need information on these commands.) Now let's discuss a few
that will affect the way your station functions on the air. CONV (converse
mode): Your TNC will automatically switch to this mode when you connect
with someone, but you can also switch to this mode by entering CONV (CR)
at the Cmd: prompt. When you're in converse mode and are NOT connected to
another station, anything you type will be transmitted via the path you
set with the UNPROTO command.(See the next paragraph for UNPROTO.) Packets
sent via UNPROTO are sent only once and are not acknowledged, so there is
no guarantee that they'll get through. This mode is used frequently for
sending CQ's.
UNPROTO: Designates the path used when you send BEACONS or when you're
In converse mode and NOT connected to another station. The default is CQ,
but you can enter a series of digipeaters if you wish, or specific group
or club name. Some examples: CQ v WB6SDS-2,W6SG-1,AJ7L SFARC
vW6PW-1,W6PW-4 If you include digipeaters in your UNPROTO path, you will
have to change the information for each frequency you use. (BEACONS will
be discussed in a later part of this series.)
FRACK: Determines how long your TNC will wait for an acknowledgment
before resending a packet. It should be set too low, or you'll simply
clutter up the frequency, yet it shouldn't be to high, or you'll spend too
much time waiting. I use FRACK set to 7, and have found that to be a good
overall value.
DWAIT: Used to avoid collisions, DWAIT is the number of times units the
TNC will wait after hearing data on the channel before it transmit. I have
DWAIT set to 16, and have found that to work, well.
PACLEN: Indicates the number of characters in the packets you transmit,
ranging from 0 to 255. ( A value of 0 equals 256.) The more characters
you send per packet, the longer it takes to transmit the information and
the greater your chances are of noise, interference or another station
wiping it out. I've found a PALEON. of 80, which is the length of one
line, to be a good value. When working a station nearby, PALEON. can be
increased. When working a distant station, it should be decreased.
RETRY: Your NC will retransmit a packet if it doesn't receive an
acknowledgment from the station you're working. RETRY indivates the number
of times the TNC will try to get the packet through before giving up and
disconnecting. This can be set from 0 to 15, but I've found 8 to 10 to
work well. Less than that causes an necessary disconnect if the channel
happens to be busy, but more than that clutters up the channel. Do NOT set
RETRY to 0. That means infinite retries, and serves no useful purpose. It
simply clutters up the frequency needlessly.
The following commands affect "monitoring", which is what you see on
your screen from stations you're NOT connected to.
MONITOR: This must be ON for you to monitor anything. When ON, you see
packets from other stations on the frequency you're tuned to. What packets
you see is determined by other commands from the list below. If MONITOR is
OFF, you only see the packets that are sent to you while you're connected
to another station. Note: On some TNCs, such as AEA PK -232, monitoring
functions are connected by a number after the MONITOR command, such as
MONITOR 3 or M 3. Refer to your TNC operating manual for details.
MALL: If MALL is ON, you receive packets from stations that are
connected to other stations, as well as packets sent in unproto
(unconnected) mode. This should be ON for "reading the mail". If MALL is
OFF, you receive only packets sent in unproto made by other stations.
MCOM: If ON, you see connect[c or sabm], disconnect[d], acknowledge
[ua] and busy [dm] frames in addition to information packets. If OFF, only
information packets are seen.
MCON: If ON, you see packets from other stations while you're connected
to someone else. This can get very confusing, but is useful when your
path is bad and you want to see your packets are being digipeated okay.
OFF, the monitoring of other stations is stopped when you're connected
to another station.
MRPT: If ON, you see a display of all the stations used as digipeaters
along with the station originating the packet and the destination station.
If OFF, you see only the originating and destination stations. For
example, if you have MRPT ON, you might see a transmission such as this:
K9AT>WB6QVU,W6PW-5*: I'll be leaving for the meeting at about 7:30. If
MRPT was OFF, the same transmission would look like this: K9AT>WB6QVU:
I'll be leaving for the meeting at about 7:30. In the first case, you can
see that the W6PW-5 digipeater was being used. The asterisk indicates
which station you were hearing the packet from. In the second case you
have no idea if digipeaters are being used or what station you were
receiving.
HEADERLN: If you have turned ON, the header of each packet is printed
on a separate line from the text. If OFF, both the header and packet are
printed on the same line.
MSTAMP: the date and time the monitored packets are received is
indicated if the MSTAMP command is ON. If it's OFF, the date/time stamp is
not shown. NOTE: The date and time must be entered into your TNC memory
using DAYTIME command before the MSTAMP command will function. I run my
station with all of these commands except MCON, turned ON so that I can
really see what's happening on the frequency I'm monitoring. Try various
combinations of these commands and then decide on the combination you like
best for your station.
MORE COMMANDS- The commands discussed here are a few of the basic TNC
commands. I'll discuss many of the other commands available to you later
on in this series.
Courtesy of N0KFQ
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Newsletter "SMARCalling" March 1998
