Steve Wolf, W8IZ@W8IZ

(This text from the W8IZ packet radio bulletin

board. It's formatted to fit a 80 character screen.)

Imagine yourself during the evening drive-time talking

to a friend on a popular two meter repeater. Every time

you or your friend drops the mike, everyone listening

announces they are there and says, "Beacon!". That would

be enough to drive you to simplex.

That is essentially what a beacon does, it robs time

from other users of the channel. Like a two meter repeater

a packet channel is not multi-tasking. Never has been

and never will be! Two stations, one of which is

transmitting, are using the frequency at any one time.

A beacon can do nothing but hold up that flow of


A good example of a beacon's result can be seen on

145.01 or 223.7, the two forwarding frequencies used in

our area. Listen on a Friday evening, during the summer,

when the band is wide open.


Aloha! Neat word but death to packet radio. Aloha

happens when there is too much activity on a channel and

nothing can get through. A TNC waits until the frequency

is clear to transmit its information. However, it can

not wait forever. When the timers time-out, it goes

ahead and send its information on top of whatever is on

the band. The channel can only support so much activity.

With a couple of nodes forwarding traffic, a person

or two using a PBBS and two or three LANs hearing each

other, the frequency will be constantly buzzing with

packets. Add a beacon and pow, a TNC times out and

transmits over another packet. The frequency is still

active. The two TNCs that had collided now time out over

another TNC or two. Timers again time out and this time

the frequency goes quiet. All have collided and Aloha

exists. All you hear are beacons.


Can you hear REP, the Republic, Ohio, node. How

about AKR? And MTG? Probably not. You can hear CLE

though, can't you? Well, CLE hears REP, MTG, AKR and

a ton of other nodes. CLE hears you. When it is time

for your beacon to be sent, you will patiently await a

clear frequency and then send. You will send right over

REP talking to CLE. CLE looses the packet, ignores

REP and REP must wait for a timeout to resend the packet.

Aloha begins.


Much of the same on the channel you are listening on.

However, there are five other ports that may also be

listening. It is not at all unusual on the NCARC PBBS

to have two users on 145.09 while the board is forwarding

mail on 223.7. Maybe someone is using the K Node, too.

Every incoming packet must be decoded and attended

to. A beacon must be received, decoded and discarded.

Even for a very fast machine, a busy channel will slow

it down noticeably. Even on a non-busy frequency, the

PBBS might be working its little processor off on other



Take out an ad in QST. Ask a newsletter editor to

publish you information. Put a message on a PBBS. Tell

your friends on VHF.


Why they beacon every ten minutes, I don't know.

The NCARC PBBS beacons at intervals of a little over 24

hours. Software exists that can be set up to monitor

PBBS beacons. With PBBS beacons, there is a mail call.

This software looks at the mail call and if it recognizes

the call of the owner, it will call the board and retrieve

the mail.

If the software were designed to call the board

and retrieve the mail, it would eliminate beaconing

all together.

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