Kenwood TR-851A Instruction Manual page 24

4-7. DCL (Digital Channel Link} SYSTEM
4-7-1. DCL system description
(The optional MU-1 Modem unit is required for DCL
system operation).
The DCL system provides a convenient automatic
method of OSY'ing to an open simplex channel. The
system is microprocessor controlled for speed and
reliability,
and offers
several origina!
features not
previously available in amateur radio.
DCL System features
(a) The DCL system searches, on command, for an
open channel, remembers the frequency, returns
to the origianl operating frequency and transmits
control information to the receiving station that
switches both radios to the open channel. Micro-
processor contro! assures fast and _ reliable
Operation of the DCL system.
{b
The recall and reverse functions are provided to
ensure communications are not lost if the chan-
nel linkage operation fails for any reason.
(c) Digital code squelch operations are provided that
utilize a five digit access code, and may be used
in conjunction with the DCL feature. Five DCS
memory positions are provided. The transceiver
can use any or all of the code memories if
desired.
(d
Squelch will open only when the transmitting
station, and the receiving stations codes match.
(e) Automatic transmission and display of call sign
data. (Display of call sign data requires the use of
the CD-10 Call Sign Display). Up to 6 characters
can be input for automatic transmission when
the DCL system is turned on.
Notes:
1. The DCL system operates only when the op-
tional MU-1 Modem unit is attached. When the
system is operated without the MU-1, data
(Control signals} will not be exchanged with the
distant station although the keys on the system
operate.
2. The DCL system is intended for efficient com-
munication in the FM mode. Therefore, the
system does not operate in the USB, LSB, and
CW modes. When the FM mode is switched to
any other mode during a DCL system operation,
all DCL-related functions are deactivated.
4-7-2. Control signal
The DCL system operates by transmitting a control
signal that contains call sign data, digital access
code information, and open channel control informa-
tion.
24
This signal is transmitted under the following condi-
tions:
A. The PTT switch is pressed and released when
the DCL light is ON.
B. The OPEN channel data is sent to the distant sta-
tion during a channle linkage operations.
ir Code squelch contro! signal
{Without open channel data}
fo Channel linkage control signal
(With open channel data)
1. When the DCL system is operating:
[When the DCL switch is ON (DCL light ON), the
contro! signal is sent for about 0.2 seconds at
the beginning and end of each transmission.]
{a) Simplex mode
PTT ON PUT-GEE 2. Received about
0.2 seconds atter
'Control signal {about 0.2 seconds}
- > Transmit ION AIR ight ONE
+ Microphone is muted.
SS
iy
Don't start talking after a short delay to allow
the DCL/DCS control signal to be transmitted
without interference.
(b) OFFSET mode
PTT ON PTT OFF
' '
Y Yy
Tone iY 4 Tone Ly
_ fea
Z
he 7 = -
About Control sigeiat
1 second
Transmit (ON AIR ight ON) - HRecvive
When the OFFSET switch is ON, the control
signat is transmitted about 1 second after the
PTT switch is activated. This delay prevents
the control signal from being broken by the
slow response of some repeaters.
Notes: -
2. The 1750 Hz tone is modulated for the first se-
cond. (With the TR-851E/751E U.K. version).