5. Operation
By installing the ACC-513E or ACC-514E, the SD-170E can be used as a radio data-generating
device utilizing GMSK or FFSK type modulation. There is a micro-controller to control your
overall application, including the radio to handle data to transmit or receive. The radio is
controlled through the DB-15 connector and interfaces with a DTE by an interface cable.
In operation, the radio is placed into the transmit condition by receiving data from DTE.
If the radio receives data, the slave MCU of the ACC-513E/514E saves that data in its
memory and automatically creates a PTT signal at the same time to get the RF stage to
prepare for transmission. To avoid data loss in transition time of the RF stage, it is
important that there is a delay between activating the PTT signal and applying the data
to the RF stage. In these processes, there are many tunable parameters, which will be
explained in the next section, to provide maximum performance for user application.
This section describes the basic connection for data transmission or radio control and
then explains important parameters for data transmission.
5.1. Serial interface
In some systems, where data is required to be inputted to a SCADA system or simple
PC logger, the most useful receiver output will be the RS-232 serial stream. Any
system using serial data output will also require DTE(Data Terminal Equipment) such as
a PC, or workstation driver package, or PDA, to display the data and upload it into a
host process. So, To interface with these external equipment, the SD-170E contains a 15
pins D-sub female connector. The serial interface is configured as DCE with the pin out
shown in the table below.
D-
Type
Pin
No.
Function Description
Signal
Type
Input/
Output
1
Data modulation IN
(Tx Mod)
Signal is directly injected to MOD through data low pass
filter without pre-emphasis.
Analog signal
1KHz audio at 60% peak
system deviation
input level =
100 to 120mVrms
I/P
2
Data unfiltered OUT
(RX disc)
Discriminator audio from the SD-170E. This is the
unprocessed AF signal prior to tone filtering and de-
emphasis.
Analog signal
1KHz audio at 60% peak
system deviation produces
200 to 300mVrms
O/P
3 PTT
In
(Tx Key)
Signal from the ‘external device’ to key the SD-170
transmitter.
This line has an internal pull up resistor to +5V. Pulling the
line to 0V turns on the transmitter.
Note : If you installed option modem board, you can
select RS-232 signal level by Jumper (CON407,
r
) on
TTL level
0V = Tx
o/c = Rx
RS-232 level (option)
+12V = Tx
I/P
