Timewave DSP-232, Руководство по эксплуатации

Страница: 155 / 271

Chapter 8 ASCII and Baudot Operation
The
RECEIVE
command allows you to insert a character in your typed text that will cause the DSP to (
RETURN
)
to receive after all the text has been transmitted.
RFRame ON
|
OFF
Default: OFF
Mode: Baudot and ASCII RTTY Host: RG
OFF Print received Baudot and ASCII characters regardless of errors.
ON
Check received Baudot and ASCII characters for framing errors.
With
RFRAME OFF
, Baudot and ASCII modes operate as always, that is, characters are copied based on the
presence of the DCD signal.
With
RFRAME ON
, the DSP checks received Baudot and ASCII characters for framing errors. A framing error on
a character in an asynchronous mode (such as Baudot and ASCII) occurs when the bit in the stop position is
detected to be the wrong polarity (the polarity of the start bit is supposed to be “space” or 0, while the stop bit is
supposed to be “mark” or 1.) The unit stops copying characters when 4 out of the last 12 characters have framing
errors. Copy resumes when the most recent 12 characters are error-free. This significantly reduces the copying of
“garbage” characters when no signals are present.
RXRev ON | OFF Default: OFF
Mode: Baudot and ASCII RTTY/AMTOR Host: RX
OFF Received data polarity is normal.
ON
Received data polarity is reversed (mark-space reversal).
Use
RXREV
to invert the polarity of the data demodulated from the received mark and space tones. So, instead of
“space” equalling zero, it’d be one; “mark” would equal zero instead of one.
In some cases, you may be trying to copy a station that’s transmitting “upside down” although it’s receiving your
signals correctly. This is especially true when listening to signals in the shortwave bands. Set
RXREV ON
to
reverse the data sense of received signals.
RXREV
operates only at
RBAUD
and
ABAUD
speeds up to 150 baud.
TXdelay
n Default: 30 (300 mS)
Mode: packet, Baudot and ASCII Host: TD
“n” 0 to 120 specifies 10 mS increments.
TXDELAY
tells your DSP how long to wait before sending packet frame data after keying your transmitter’s PTT
line.
All transmitters experience a certain length of time from the instant the PTT line is keyed to when the signal is
actually transmitted. The default value of 300 mS should work with almost all transceivers. In fact, many of the
newer transceivers can use smaller
TXDELAY values. (Crystal-controlled transceivers can often use smaller values
as well.) On the other hand, tube-type transceivers and amplifiers can require a longer time to switch and may
require
TXDELAY to be increased. Experiment with the value to determine the shortest setting you can use in
reliably in packet.
Baudot and ASCII use
TXDELAY to set the timespan between PTT ON and the start of transmitted data.
September, 05 8-17