Ross SRG-4400, User Manual

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SRG-4400 User Manual (Iss. 06) GPS Option • 14–7
Connection with a Line Amplifier
The SRG-4400 can be used with an external Line Amplifier when a long cable run is required.
Because of the internal LNA, the overall gain (including signal losses past the external Line
Amplifier) should not exceed 35dB. Levels higher than that can affect the jamming detection
capability of the SRG-4400.
The external Line Amplifier should have a noise figure better than 1dB. This will give an overall
system noise figure of around 2dB. The external Line Amplifier, if having no pre-select filter,
needs to be able to handle other signals other than the GPS/GLONASS signal. These signals are
typically at much higher levels. The amplifier needs to stay in the linear region when presented
with these other signals. Again, the system designer needs to determine all of the unintended
signals and their possible levels that can be presented and make sure the external Line Amplifier
will not be driven into compression. If this were to happen, the GPS/GLONASS signal itself
would start to be attenuated and the GPS/GLONASS performance would suffer.
The external Line Amplifier needs a source of power. It may get this from the 5 volt DC voltage
on the antenna cable or an external PSU.
Figure 14.7 GPS-4400-200M — Connection with an External Line Amplifier
GPI/RS232
100-BaseT
GPS 1Hz 10MHz IN 10MHz WK/TTL1 WK/TTL2 6Hz/TTL3 DARS AES 1 AES 2
SDI 2 BLACK
BALANCED AUDIO/AES/LTC
COMPOSITE BLACK 1 REF LOOP TRI/BLACK 2 TRI/BLACK 3 TRI/BLACK 4 SDI 1 SDI 1 BLACK SDI 2
Coaxial Cable
(656ft / 200m)
SRG-4400
Coaxial Cable (26ft / 8m)
FME Plug
FME Jack
GPS Antenna
TNC Plug
Adapter Cable (5in / 130mm)
TNC Jack
SMB Jack
GPS
LINE AMPLIFIER