SATELLINE-3AS
User Guide, Version 2.3
23
3.2.1 RSSI-signal
RSSI-signal (R
Received S
Signal S
Strength IIndicator) (pin 5 of the D-type connector) gives an
indication of the strength of the received radio signal. This signal can be used to determine the
approximate signal level. The curve on the following diagram describes a typical relationship
between the received signal strength and the voltage at pin 5. Please note that only the RSSI
signal of the right side receiver of SATELLINE-3AS Epic is connected to the pin 5.
RSSI value of the last received message can also be requested locally by using a SL command
(SL@R?, see chapter 9.3.3). The RSSI value is available 7s after the reception of the message.
After that the value is returned to zero. SATELLINE-3AS Epic responds by the stronger RSSI value
of the two receivers.
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
OFF
-120
-118
-116
-110
-100
-90
-80
-70
-60
-50
-40
-30
3.3 Priority RX/TX
SATELLINE-3AS offers a
Priority
setting, which selects the priority between reception and
transmission. The setting can be changed in
Programming Mode
. By default, transmission has
higher priority than reception i.e. the default value is Priority TX.
Priority TX
means, that a terminal device attached to a radio modem decides the timing of the
transmission. The transmitter is immediately switched on when the terminal device starts to
output data. Should reception be in progress, the radio modem will stop it and change to a
transmit state. There is no need to use any handshaking for the control of timing.
Priority RX
means, that a radio modem tries to receive all data currently being transmitted. If a
terminal outputs data to be transmitted (or an SL command), it will buffered. The radio modem
will wait until the reception has stopped before transmitting the buffered data. This will result in
timing slacks to the system, but decreases the number of collisions on the air, this is particularly
useful in systems based on multiple random access.
RSSI-pin voltage level / V
Signal level / dBm
