User's Manual

Radio Activity S.r.l. 16 / 44
∞ Expansion connector - 6 pins. This connector holds the signals for GPS interfacing and for 1+1
assembly realizations. For further information about the use of these I/O see the related paragraph.
∞ Power supply – 2 pins. A 13,2Vdc @5A max should be applied to this connector. The polarity is
indicated in the panel.
Finally don’t forget to connect a ground cable to the GND Ø5MA nut to avoid lightning and rescue problems.
3.3.1 RX inputs specifications
KAIROS has got two RX inputs, one named “main” and the other named “diversity”. The contemporary use
of both receivers gives excellent performances over fading events. For further information, see the “ENB33 -
Soft diversity reception” document.
Both inputs have the following characteristics (typical):
Nominal impedance 50 Ohm
Operating maximum input -10 dBm
Maximum input without permanent damages +10 dBm
Received signal band 0..5000 Hz
Blocking level (>1MHz far from RX frequency)
-
32 dBm
RSSI measurement range -130 to -60 dBm
Synthesis step 50 Hz
Connector type SMA
In duplex applications an external duplexer filter is requested. Using standard European duplex spacing, this
filter must attenuate at least 75dB between TX and RX to avoid noise and TX/RX instability during transitions.
For lower duplex spacing or when an external power amplifier is used, increase the attenuation to assure the
maximum levels indicated in the KAIROS manual.
When KAIROS operates in simplex/half duplex mode, it is needed to mount the internal TX/RX RF switch as
indicated in the following figure. Note that this switch can’t be enabled/installed outside Factory. This feature
must be requested directly at order. In this case the TX connector assumes the role of Antenna connector
and the RX main is internally switched to the antenna when the TX isn’t active. The RX diversity in such
condition can be used regularly as diversity channel: