E.F. Johnson Company 7780 Series, Preliminary Service Manual, Page: 22 / 116

TRANSCEIVER OPERATION
2-8
November 1999
Part No. 001-7780-500
ation). Monitoring before transmitting may not occur
automatically in this mode, so the channel may have to
be manually monitored before transmitting (see
Section 2.4.3). Selecting a conventional channel
selects a transmit and receive frequency and other
parameters such as Call Guard squelch coding.
SMARTNET/SmartZone Operation
This is a trunked operating mode that uses ID
codes to select which mobiles are being called and
which calls are received. Monitoring is performed
automatically and special messages and tones indicate
busy and out-of-range conditions. Enhanced features
include roaming (SmartZone only), telephone, private,
and emergency calls, Call Alert, and messaging. Oper-
ating features unique to SMARTNET/SmartZone
channels are described in Section 2.5.
This radio supports only the SMARTNET II
trunking protocol. It does not support the SMARTNET
I (also referred to as Type I) protocol. When a
SMARTNET or SmartZone channel is selected or the
radio is powered up on a SMARTNET/SmartZone
channel, it searches for a control channel and attempts
to register on the radio system. Once a control channel
is found, the alias (name) of the selected channel is
displayed. If a control channel could not be found
(because of an out of range condition or the system ID
is not correct, for example), “NO SYS” is displayed
and the radio continues to search for a control channel.
The control channel transmits and receives
system information to and from all radios registered on
the system. Therefore, once a control channel is found,
it is continuously monitored for incoming call infor-
mation and is used to make call requests. The radio
automatically changes to a traffic channel to place and
receive calls and then returns to the control channel
when the call is complete.
2.4 CONVENTIONAL FEATURES
2.4.1 INTRODUCTION
The following information describes features
unique to the conventional operating mode (described
briefly in Section 2.1.2). Refer to Section 2.3 for infor-
mation on features common to all operating modes,
and to Section 2.5 for information on features unique
to the SMARTNET/SmartZone mode.
2.4.2 DISPLAY MODE SELECTION
If the Displayed Information option switch is
programmed, the display mode used to indicate
conventional channels can be user selected. Pressing
this switch cycles between the following modes. The
selected mode does not change when power is turned
off. If the Displayed Information option switch is not
programmed, the Alias mode is always used.
Alias - The preprogrammed alphanumeric tag for the
channel is displayed.
Number - The channel number from 1-16 is
displayed.
Frequency - The receive frequency of the selected
channel is displayed in megahertz.
2.4.3 MONITORING BEFORE TRANSMITTING
With conventional operation, channels are moni-
tored automatically or manually as follows:
Automatic Channel Monitoring
If the selected channel is programmed for the
Busy Channel Lockout feature, monitoring is
performed automatically. Refer to the description of
this feature in Section 2.4.5 for more information.
Manual Channel Monitoring
The automatic monitoring just described may not
be programmed or it may occasionally disable the
transmitter even if the channel is not in use. In this
case, the channel must be monitored manually as
follows:
Rx Indicator - With scanning disabled, note if the
green RX indicator on the top panel is on. If it is not,
the channel is not being used and the call can be
transmitted. If it is on, a carrier is being detected, so
the channel may be busy (see next paragraph).
Monitor Mode - There may be times when the busy
indication is displayed even though no one is using
the channel. Monitoring should then be performed
by disabling Call Guard squelch using the Normal/
Selective option switch as described in Section
2.4.6 or the monitor mode described next.