ProfitPress Mega CDROM2 …eeware (MSDOS)(1992)(Eng)/ProfitPress-MegaCDROM2.B6I/MISC/NETWORK/PKGOL624.ZIP/DOCFILES.EXE/HF.DOC

Text File | 1992-02-27 | 5.6 KB | 141 lines

                         Notes on HF operation
                         ---------------------

Operating HF is more challenging than VHF for several reasons. There are
more "Hidden" stations, those you cannot hear, yet both you and these
hidden stations are QRMing each other in the eyes of a 3rd station.

Also, background noise may cause your system to think the channel is busy,
and the Carrier Detect (CD) shows "true" or "on" when in fact only noise
is present.  On the PK-232, the threshold adjustment is CRITICAL. To decode
Baudot, Morse, and Packet, the DCD should be lit when receiving signals.

Sometimes, the DCD light will flicker, and for HF Packet operation, this
may cause the packet to be rejected, even though received without error.
To fix this, set UBIT 0 OFF (user bit) if your TNC supports the UBIT
command, or use CUSTOM $0A14 to accomplish setting bit 0 of the "user bit"
set to OFF. The default is ON, which causes the TNC to "Discard Packets
too weak for DCD."  This means that any fluctuation in receive audio
that causes the DCD led to blink or fail to light will cause the packet
to be discarded, EVEN IF IT WAS DECODED PROPERLY.  Many people have
considered giving up on HF packet, or selling the PK-232s because of this
one bit setting. They can hear packets, see them moving the TUNE indicator
LEDs, but not decoding anything because of the fluctuations in the
DCD led.

With UBIT 0 OFF, or CUSTOM $0A14, your TNC will still use DCD to
determine when to transmit, but it will decode many more packets than
it would otherwise. For successful HF packet operation, set your TNC
as suggested.


Setting HF Receiver:

1.  Operate in Lower Sideband, LSB unless you have an FSK capable radio.

2.  If your radio has Receiver IF Shift (Intermediate Frequency Shift)
    set it to favor higher pitched tones. SSB Voice will sound awful
    and seem to have more "hiss" due to the passing of higher frequencies,
    but the TNC will work much better if the lower tones are removed, and
    the higher ones favored.

3.  Turn OFF your RIT (Receiver Incremental Tuning) unless you have some
    good reason, based on experience, to leave it on. It is helpful to
    other stations to have QSOs using just a small spectrum space, that
    is, transmitting on the same frequency, rather than station A on
    one frequency, and station B on another, tying up two areas of the band.

Setting the HF transmitter:

1.  Enter the direct terminal mode using [Alt-F3] and use the built-in
    CALIBRATE command as follows:

    cmd:CALIBRATE
    (you will see numbers appearing here)

    Use the following Keys to "Toggle" the settings:

    K      Toggle between On/Off (Key/Unkey)
    Space  Toggle between Mark/Space (Low,High)
    H      Toggle between Wide/Narrow pair.
    D      Toggle between Dual/Single tone
    Q      Quit to cmd: prompt

2.  Use the Dual tone to adjust your SSB transmitter. Do not use
    an audio processor, or push the transmitter to the point where
    the ALC (Automatic Limiting) must take over. Chances are,
    you want to run your system well below the maximum power to
    avoid "cooking" your finals.

3.  Use the AFSK output control (on the PK232, it's on the back, on
    the PK88, it's inside) to produce audio levels that are in a
    range that can be controlled by the "mic" gain control of your
    transmitter. Too much audio input to the mic jack makes it
    difficult to set your audio. Too little may introduce noise
    from the audio amplifier in your transmitter as you turn up the
    mic gain trying to get some reasonable output signal.

PACKET MODE:

1.  When you operate on HF Packet, set VHF OFF (PK232) or TONE 1 (PK88) to
    select the 200 Hz shift version of Packet.

2.  Also set HBAUD 300 (the over the air packet Baud rate).

Hint: On PK232, You may have to "toggle" the WIDE parameter from ON to OFF
before the narrow filters are selected by the PK232 (a "feature" of some
earlier AEA ROMS).

Non-PACKET MODES:

1.  Be sure EAS is ON. (Echo as Sent). THIS IS VERY IMPORTANT.

2.  Use [F8] to set the shift to NARROW for amateur bands.

3.  Set the RXREV and TXREV to OFF, or use the [F4] key to change to OFF.

4.  Tune the receiver until the Tuning LEDs seem to span the range from
    Mark to Space (Left to Right).

5.  Use SIAM mode if necessary [Alt-F5] to help determine what signal
    is being decoded. You will soon be able to recognize the signals
    by ear.

6.  Once in non-Packet modes, you will find the following mode change
    keys to be very useful:

    [Ctrl-F2]   Enter BAUDOT mode. Receive BAUDOT if DCD is lit and
                baud rate properly set.

    [Ctrl-F4]   Enter AMTOR Standby mode. Receives FEC transmissions.

    [Ctrl-F6]   Enter ARQ LISTEN (ALIST) to decode ARQ (Chirp chirp)
                transmissions.

    ALIST Note: Short ARQ Chirps are ACKs, and don't print anything
                Longer Chirps contain data, that appears on your screen.



To Transmit in Non-Packet modes:
--------------------------------

The [ESC] key is your "Push to Type" key TOGGLE.


Mode              [ESC] key result
--------------    -----------------------------
AMTOR Standby     Key and enter FEC mode

                  Queue up an Unkey, enter AMTOR Standby when no more
                  characters are echoed back.

BAUDOT            Key, send whatever is in the buffer or what is being typed

                  Queue up an Unkey
                  Unkey when no more characters are being echoed

MORSE             Same as BAUDOT