AMTOR (Amateur Teleprinting Over Radio) is a
error-correcting data communication mode.
It is derived directly from the commercial mode known as
SITOR, (Simplex Telex Over Radio)
which has been used by maritime radiostations for many
It was adapted for amateur radio use by G3PLX, Peter
Martinez who is also the maker of PSK31.
What equipment is needed ?
Now a days (in 2004) cheap priced modems can be found on
the 2nd hand market.
Modems like ICS AMT-1/AMT-2, AEA PK-232, PK-900, KAM
Plus, MFJ-1287 are good units.
The German PTC modems also handles Amtor, but they are
They all connect to the tranceiver AF in/out/PTT and a
seriealport on the computer.
You also need a software/terminalprogram. There are many
to be found on the Internet.
Which one to use, depends on the modem brand. See the
software section for more info.
There are to different modes used in Amtor - FEC and ARQ.
FEC (Forward Error Correction) - Also called Mode B - Listen to Amtor FEC
This mode is used when calling CQ, QRZ or if you are in a
QSO with several stations.
In FEC every character is transmitted twice, compared and
accepted or rejected.
Accepted character is sent to the screen, rejected
character is presented as a dash
or an underscore on the screen.
ARQ (Automatic Repeat Query) - Also called Mode A - Listen to Amtor ARQ
This mode is the primary Amtor mode, and is used for QSOs
It can only be used between two stations at the time.
The station sending information (text) sends this in
blocks of 3 and 3 characters.
The receiving station checks each block and sends a
single charcter back to confirm reception
The sending station retransmit the block if checksum
Text will only apear on receivers screen when checksum
has passed at the other end.
Likewise characters will only be presented as echoed text
at sender when received
checksum has been accepted.
Where are Amtor stations found ?
In Europe the busiest frequency has been 7037,0 kHz.
Tuesday evenings (UTC) is Amtor night from 3585 and up to 3600.
All frequencies are "Mark" frequencies.
MARK frequency minus Mark tone = Dial frequency. (USB mode)
Example: 7037 and MARK tone of 1400 Hz = Dial 7035,6 kHz.
Active Amtor stations
The following stations are known to be active on Amtor:
G3MUL, Colin (Silent Key June 2009)
For updates, send an e-mail to: firstname.lastname@example.org