17
the modem option board by the completion of the RF stabilization. The model contains
tunable value for this period of time, which the user can adjust these timings into their
system within the limited range. Especially,
“
Tx On delay
”
and
“
Tx Off delay
”
which are
important timing parameters in the transmitter. (see Figure 5.3.)
Tx On delay : The period of time for transmitter
’
s stabilization before the data is
processed for modulation.
Tx OFF delay : The period of time for avoidance for cutting off the tail end of the
data bit stream.
Data
(into SD-160)
P.T.T
Data
(into RF Stage)
Tx Delay Time1
(Dump mode : Unavailable)
Auto mode : Created by Slave MCU
Dump mode : Inputted by External Equipment
Tx On Delay
Tx Off Delay
Inputted Data
Modulated Data
Squelch (Mute) Open
Squelch
Data path open
Recoverd data
Rx On Delay
Recovered Data
TRANSMITTER
RECEIVER
Figure 5.3. Timing parameters in data transmission
5.2.2. Data Reception (Rx)
If the Slave MCU receives a Rx_ready signal from the Master MCU, the Slave MCU on
the modem option board will get the Modem IC to prepare to receive data, at the same
time, the Master MCU releases a Busy detecting signal through the DB-15 Connector.
Before receiving data, the Modem IC or receiver should be synchronized by a
