Hal Communications CWR6850, Инструкция по эксплуатации

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CHAPTER 5 PAGE 39
physically printed until an entire RECEIVED line is complete (as distinguished from a 32 character
display line). Some printers allow modification of the print format when some ASCII control codes
are received. All control codes to the printer except LF are normally suppressed to avoid print for-
mat changes on received text (or noise). The commands to the print can be enabled, however, by
typing "CTRL-C"; a second "CTRL-C" disables the commands.
5.6 Connection of an Audio Tape Recorder
An audio tape recorder may be connected to the AFSK OUT - TAPE and AF IN - TAPE connectors of
the CWR6850 for recording and playing back of messages. The AFSK OUT - TAPE connector fur-
nishes the CWR6850 transmit tones to the tape recorder input (microphone or auxiliary input). On
transmit, these tones are keyed by transmit data, such as that typed on the keyboard. Thus, you
can make-up long "brag-tapes" or messages on the CWR6850 screen and record them as you
"transmit" them. You may prevent the transmitter from turning on by temporarily disconnecting
the cable to the SW.OUT - REMOTE Jack (KOS to PTT connection). The TAPE OUT level may be ad-
justed with the AFSK GAIN rear panel control.
To transmit tape recorded text, select TAPE on the RX/TAPE switch (button in), type "CTRL-E", turn
the transmitter on with the SEND or AUTO switch position (use CTRL-A or CTRL-X as per discus-
sions in section 4.2), and start the tape in the playback mode. The recorded tones are now fed-
through the CWR6850 receive demodulator, filtered and detected, and then modulate the
CWR6850 transmit output tones (and TTL output). Thus, the tape data is reprocessed before
transmission, helping to eliminate some of the distortion otherwise caused by tape wear and
stretch. When the taped message stops, type CTRL-E again to end the echo-back feature.
The connection of the tape recorder to the CWR6850 is shown in Figure 5. Use shielded cables for
these connections; include RF and safety grounds to minimize any RF pickup in the tape recorder.
5.7 RTTY Tuning Oscilloscope Connections
In addition to all of the input/output (I/O) connections discussed above, you may also wish to use
an external monitor scope for a RTTY tuning indicator. The OSCILLO (SPACE and MARK) connec-
tors are provided for tuning indicator use. These output are the filtered signals present at the RTTY
demodulator discriminator circuits. The signals are approximately 8 V
PP
in amplitude and have an
internal impedance of approximately 200 kΩ. As shown in Figure 4, the standard convention is to
use an X-Y oscilloscope with the MARK signal connected to the horizontal scope input and the
SPACE to the vertical input. Since these signals have a relatively low output level, it is necessary to
use an oscilloscope with amplifier stages in both the vertical and horizontal sections. Use shielded
cable for these connections; be sure to include safety power as well as RF ground connections.
The display on the oscilloscope screen for correct receiver tuning will be of the crossed-ellipse
type. Correct tuning is indicated when the horizontal ellipse (mark signal) and the vertical ellipse
(space) have maximum amplitude (length of the ellipse) and are orthogonal. The 170 Hz shift ellip-
ses will be fairly wide and will not necessarily be at 90 degrees to each other - this is normal! The
ellipses for the wider shifts (425 and 850) will be noticeably narrower and closer to a full 90 de-
grees apart. With practice, the tuning scope provides the most accurate tuning indicator available.
Properly interpreted, the scope patterns tell which direction to tune the receiver and whether the
signal shift matches that of the selected demodulator shift.