Some commercial, weather and utility RTTY services send groups of
numbers separated by spaces. When receiving such non-amateur signals,
USOS should be OFF to prevent displaying LETTERS-shifted characters
when the originator may have intended the data to be FIGURES-shifted.
6.5.9 Operating at Commercial or VHF Wide RTTY Shifts
Most commercial stations found in the non amateur Short Wave bands
operate with a wide Frequency Shift keying of either 425 or 850 Hz
shift. To allow these stations to be received the WIDESHFT command
must be turned ON. If your license permits, you can also transmit to
these stations when WIDESHFT is ON.
6.5.10 The CODE Command for International RTTY Compatibility
The CODE command allows the PK-232 to receive (and sometimes send)
other RTTY character sets. Part 97.69 of the FCC rules specifies that
the International Telegraph Alphabet Number 2 (ITA #2) must be used by
U.S. stations when operating RTTY. This corresponds to the CODE 0
command (default), but you may want to see the CODE command for more
information on what your PK-232 is capable of.
6.5.11 Copying Encoded RTTY Transmissions
In the Short Wave bands many RTTY stations can be found that are not
transmitting in plain text. Most of these stations are using
sophisticated encryption techniques that make receiving them almost
impossible. There are a few stations however that use a relatively
simple bit-inversion technique to make them hard to copy. For these
stations, the PK-232 has included the BITINV command to allow the SWL
to decode these simple forms of encoded RTTY stations.
6.6 ASCII RTTY Operation
ASCII RTTY operation is almost identical to Baudot operation but there
are a few differences you must know. Because the ASCII code uses
seven bits to define a character (instead of the five bits used in the
Baudot/Murray code), the probability of receiving errors is somewhat
higher. For these reasons, ASCII is not used widely on the HF amateur
bands. However, some commercial and military HF stations do use ASCII.
6.6.1 Starting ASCII Operation
First you must enter the ASCII mode of the PK-232.
If you are using an AEA PAKRATT program, follow the instructions in
the program manual to enter the ASCII mode.
If you are using a terminal, simply type "ASCII" or "AS" from the
Command Mode followed by the <Enter> key to enter the ASCII mode.
The PK-232 responds by displaying the previous mode:
Opmode was BAudot
Opmode now AScii
Your PK-232's front panel will show the CMD and ASCII LEDs lit.
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