©1999 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 4/29/04
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covered in detail later.
USING DTMF COMMANDS.
General.
Refer to your copy of the
computer-generated Repeater
Programming sheet we sent with your
repeater during the following
discussions. It will help to visualize
all the functions and what your codes
are.
The control parameters tell you
which functions are programmed to
default in the "on" condition when
power is turned on. The micro-
computer has variables in RAM mem-
ory which store these control parame-
ters. When the computer boots, the
default choices you make, which are
burned into the EPROM, are
transferred to RAM to be used during
operation. Cw speed, cw tone, beep
delay, tail time, and courtesy beep
type can be changed by touch tone
command, and the new settings are
used as long as power is applied to
RAM. All of the on/off functions can
also be operated by touch tone com-
mand. (Note that cwid interval and
transmit timeout period are fixed
constants which cannot be changed
by touch tone control.)
There are provisions for you to
supply an external 5V battery to
backup the RAM power source, or you
can provide uninterrupted dc power to
the entire repeater or no backup
power at all.
If there is no backup power and
power is lost to the RAM, then the
microcomputer will reload the original
default settings from EPROM when
power is restored. Any settings made
by touch tone to these five parameters
will be lost, and any features which
were turned on or off by touch tone
command will revert to your default
settings in EPROM according to the
questionnaire choices you made.
How to Enter Commands.
At present, there are 58 touch tone
commands which may be used to
operate the repeater remotely. These
are listed on computer-generated
Repeater Programming sheet.
Each command consists of four
digits. The first three digits may be
any combination of numbers or letters
on a 16-digit touch tone pad, but not
"*" or "#". The last digit must be a "*"
or "#".
The commands are usually in
pairs, with the first three digits
indicating the type of function, and
the fourth digit, a "*" or "#" specifying
one of two decisions: on or off, enable
or disable, higher or lower, or some
other such binary decision. No
function can be performed without
ending with either "*" or "#", which
acts as a sort of an "ENTER" key.
You have chosen the first three
digits of some of the commands to
make them unique. All commands
must have four digits, counting the "*"
or "#".
The TONES led indicates when a
valid touch tone signal is being
received and decoded. If someone
sends a touch tone command and the
TONES led does not illuminate, it may
be due to insufficient tone level,
distortion due to clipping or over
deviation in his transmitter, off-
frequency tone encoder, or excessive
twist (difference in level between high
and low tones).
When you transmit a touch tone
command to the repeater, the digits
are immediately stored in memory in
the microcomputer. Then, as soon as
the computer has time available, it
analyzes the digits you sent.
Note that the computer will not ac-
cept any new commands until it
finishes analyzing the previous one
you sent and finishes the rest of a
complete program cycle which
involves many other aspects of
repeater operation. This normally
takes 2 to 3 seconds. If you try to
send a command before then, the
computer will ignore it because the
input buffer is still loaded with the
prior command. If this happens,
simply wait a few seconds and resend
the command.
The computer automatically mutes
the audio from the main receiver
whenever it detects the presence of a
touch tone signal. Only a few
milliseconds of the first digit can be
heard on the repeater, and the
receiver remains muted until the
computer checks out the digits
received and clears its memory buffer.
This can sometimes give you an
audible clue as to when the computer
is ready for another command; since
the background noise may change
slightly when the receiver audio input
is unmuted at the end of the touch
tone command analysis.
This touch tone muting may be
defeated, however, either by manual
command of the owner or by the
default setting of the TT Mute feature
programmed into the eprom at the
factory.
Users should get in a habit of re-
leasing their push to talk switch
immediately after sending a touch
tone command. The repeater will
send a cw "R" (di-dah-dit) to
acknowledge (roger) a valid command,
and the user will hear the ac-
knowledgment only if his transceiver
is in receive mode at the time. It only
takes the computer about a second to
analyze a command and acknowledge;
so you won't hear the "R" if you hold
the mic button very long after the last
touch tone digit is sent.
What The Computer Does After
Each Command.
First, the computer stores the com-
mand in a four-digit buffer in
memory. If you send more than four
digits, it truncates (disregards) any
extra digits and accepts only the first
four. If you send fewer than four
digits, it does not process the
command unless there is a "*" or "#".
If the computer does not receive a
complete command within three
seconds, it clears the buffer and goes
on about its business doing other
things until another command is
received.
When the fourth digit of a series or
a "*" or "#" is recorded, the computer
decides that this may be a valid com-
mand; so it compares the digits in the
buffer with a look-up table to see if it
is a valid command and if the
command is allowed by the owner at
this time. This table is burned into
the EPROM from the codes you put on
the Questionnaire, and it appears in
the same order as on the
Questionnaire. (The reason for the
order used in the Questionnaire is
that frequently-used commands
appear first and therefore are found
quicker by the computer when it
checks each command.)
If the computer finds that the com-
mand matches one in the table, and
that command is currently allowed by
the owner, the repeater generates an
acknowledgment on the air in the
form of a cwid "R" (for "roger"). It then
performs whatever routine is pro-
grammed for that command,
depending on whether the last digit
was "*" or "#". If no matches are
found or the command is not
currently allowed by the owner, then
the computer simply clears the input
buffer and goes on about its business.