Advantech INTRAC-305 - Manual (Page 86)

INSTALLATION INTRAC-305
Page 74 INTRAC-305 MANUAL - Issue 3.2 ©2011 Advantech Wireless
Selection of Southern or Northern Hemisphere within the
INTRAC is automatic based on a positive or negative input for
Latitude in System Setup - Station Co-ordinates.
TRACKING SIGNAL INPUT
The tracking signal may be provided as a dc voltage from an
external receiver or from the optional IBR-L internal receiver.
With IBR-L
The IBR-L requires a L-band beacon signal at a level within
the range -80dBm to -45dBm with a carrier to noise ratio
(C/No) of better than 40dBHz. To allow some margin for
exceptional propagation conditions we suggest that the
normal clear sky level when peaked on the satellite should be
in the range -70dBm to -50dBm. Severe signal fades will be
handled by the INTRAC algorithm entering Prediction mode
for the duration of the fade.
If the signal is greater than -50dBm attenuation must be
inserted and if it is lower than -80dBm a higher gain LNA/LNB
must be used.
An input level of -45dBm corresponds to a displayed level of
+25dB.
Note In some installations the LNA/LNB power is carried on the L-
band signal cable and special arrangements have to be made
to ensure continuity for the dc power when attenuation is
added in this cable.
Without IBR-L
The tracking signal, provided from an external receiver, needs
to be a dc voltage between -10v and +10v. This voltage
should vary proportionally (in dBs) with the received signal
strength.
The INTRAC can be adjusted for a fixed offset and a
proportionality constant between 0.1v/dB and 1.0v/dB in
either polarity.
Setting offset & gain Connect a switchable attenuator in the IF feed to the tracking
(beacon) receiver.
Connect the dc tracking signal to the INTRAC Signal Strength
Input BNC.
Remove the top cover to the INTRAC-305.
Link J31 and potentiometers R12 & R55 are used in the set-
up.
Link J31 can be changed for -ve or +ve polarity signals.
R12 adjusts the gain of the tracking signal buffer.
R55 adjusts the offset.
Set the switchable attenuator to 0 dB.
Adjust R55 so that the signal level displayed on the
INTRAC-305 is between -10dB and +20dB.
Adjust R12 so that 2dB attenuation of the receiver IF signal
causes the displayed signal to decrease by 2.0dB.