Hal Communications CWR6850, Instruction Manual

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CHAPTER 4 PAGE 28
length of the dots and dashes (usually caused by keying circuit shaping networks and RFI by-pass
capacitors). The distorted code can be particularly difficult to "copy". If the CTRL-S command is in-
voked, the dash length is increased by 33 %, giving a dot:dash ratio of 1:4 instead of the standard
1:3. Since the dash time is therefore increased, the net word-per minute rate is decreased for a
constant transmit speed setting. If the transmit speed is now increased (with the [ SPEED ] slide
control) to the former CW speed (when CTRL-D was not invoked), the net effect is that the DOT
time length in a character transmission is LESS; the "weight" has been decreased. It is recom-
mended that you use the CTRL-D command only when sending CW at higher speeds.
4.5 Special Considerations When Transmitting Baudot
Baudot RTTY code may be transmitted with the CWR6850 by pressing both the CW / RTTY and
ASCII / BAUDOT switch buttons IN. Baudot data rates are selected with the BAUD switches, 45
through 300 baud. Note that 110 baud and 300 baud data rates may be selected for Baudot use,
although these rates are not currently allowed for U.S. amateur applications. At present, only the
following Baudot data rates are authorized for U.S. amateur use by the FCC:
PANEL ACTUAL APPROXIMATE
LABEL BAUD RATE WPM RATE
45.5 45.45 60
50 50.00 66
57 56.88 75
75 74.20 100
Other data rates should not be used for on-the-air U.S. amateur Baudot transmissions but may be
used for local use, such as writing letters to the printer, etc.
The Baudot RTTY code uses 5 data bits to specify a given character. Since the 32 possible combi-
nations are insufficient to represent all 26 letters, 10 numbers, and punctuation plus control codes,
all 5 bit Baudot coded are used twice. Case shift characters are sent to the printer to signal
whether a following character will be a letter case (LTRS) or number/punctuation (FIGS). When us-
ing a manual Baudot RTTY machine, special keys are provided for these shift codes, LTRS and
FIGS; you must type these extra keys as they are required by the text. The CWR6850 automati-
cally keeps track of the Baudot case code required for a given character and inserts the proper
code in the transmitted data as required. Thus a standard typewriter keyboard arrangement is
used for Baudot and there is no difference in typing required between Morse, Baudot, or ASCII co-
des. However, the Baudot code itself does not distinguish between upper and lower case letters
and the same code is transmitted whether you type a capital or small letter. The LTRS and FIGS
may be manually transmitted if desired, using the CTRL O key combination for LTRS and CTRL N
key combination for FIGS.
The transmit features of the CWR6850 include non-overprint, word mode, and continuous mode.
The non-overprint feature automatically inserts the printer carriage control codes, two carriage re-
turns (CR), and a line feed (LF) at the end of each 72 character line. Also, the CR, CR, LF se-
quence is inserted if a space bar is typed after 58 or more characters are typed since the previous
CR, CR, LF operation. Thus, you need not be concerned with line lengths and insertion of the prop-
er printer controls - the CWR6850 does it for you! Just start typing! Even though the display
screen of the CWR6850 itself is only 32 characters long, your transmitted text will be formatted for
a standard 72 (or less) character line. If you wish to transmit shorter lines, such as in a table, etc.,
use the CR and LF keys.
The actual character transmission rate may be slowed down with the CTRL-U command. When
CTRL-U is used, the characters are transmitted at a slower rate than would normally correspond to