RESEARCH CONCEPTS RC2000C Manual page 38

32 RC2000C Polar Tracking Antenna Controller
If the AGC has POSITIVE polarity and the signal strength is too low, turn the OFFSET pot counter-
clockwise. If the AGC has POSITIVE polarity and the signal strength is too high (or is '***'), turn the
OFFSET pot clockwise.
If the AGC has NEGATIVE polarity and the signal strength is too low, turn the GAIN pot counter-
clockwise. If the AGC has NEGATIVE polarity and the signal strength is too high (or is '***'), turn the
GAIN pot clockwise.
8. While still in MANUAL mode, position the antenna 'on satellite' and adjust the GAIN pot (for
POSITIVE polarity receivers) or the OFFSET pot (for NEGATIVE polarity receivers) so that the signal
strength value is about 650.
If the AGC has POSITIVE polarity and the signal strength is too low, adjust the GAIN pot clockwise.
If the AGC has POSITIVE polarity and the signal strength value is too high (or is '***'), adjust the
GAIN pot counter-clockwise.
If the AGC has NEGATIVE polarity and the signal strength is too low, adjust the OFFSET pot
clockwise. If the AGC has NEGATIVE polarity and the signal strength value is too high (or is '***'),
adjust the OFFSET pot counter-clockwise.
9. Position the antenna 'off satellite'. If the signal strength is between 50 and 100, proceed to step 10.
If the signal strength is less than 50 or greater than 100 perform steps 7 and 8 again.
10. Position the antenna 'on satellite'. Jog the antenna off of the satellite until the picture is just barely
watchable. Note the signal strength value. Go to CONFIG mode and use the SCROLL keys to bring
up either the AGC C Band Threshold item or the AGC K/L Band Threshold item, whichever is
appropriate for the frequency band that the user has chosen to operate at (and has adjusted the pots
at). Key in the signal strength value noted above. Terminate the entry with the ENTER key.
Single Receiver - Dual Frequency Band Inclined Orbit Satellite AGC Setup
The setup procedure described above was for the case where a single satellite receiver is connected to
the controller, and the user is interested in tracking only satellites of a single frequency band (either C or
Ku). A slight increase in complexity occurs if the user must be able to track both C and Ku band inclined
orbit satellites. This is because the same AGC channel is used for both frequency bands, and therefore
the OFFSET and GAIN pot adjustments for that channel must be made so as to accommodate both
frequency bands. At the heart of the problem is the fact that the signal strength (as seen by the receiver's
AGC circuits) will vary with the frequency band selected due to differences in antenna gain, LNB gain,
and the differences in output power between C, Ku, and L band satellites.
The adjustment procedure for the dual band case is very similar to the single band case described above.
The following paragraphs describe the modifications required to adapt the single receiver - single band
procedure, to the single receiver - dual band case.
1. The procedure is similar to step 1 above except that the user should align the antenna with a strong
C band and a strong Ku (or L) band satellite. The voltages for each frequency band should be
recorded.
2. Similar to step 2 above except that both C and Ku (or L) band AGC voltages are obtained when the
antenna is looking at nothing.
3. Similar to step 3 above. The only modification is that the user should select the frequency band
whose 'on satellite' and 'off satellite' receiver AGC voltage difference is the greatest to make the
determination of which AGC channel to use.
4-5. No changes from steps 4 and 5 which are outlined above.
6. As outlined above, in the next few steps the user will adjust the GAIN and OFFSET pots of the AGC
channel which is connected to the receiver. The difference is that in steps 7 through 9 the term 'on
satellite' must be replaced with 'on satellite, strong band' and the term 'off satellite' must be replaced
with 'off satellite, weak band'. These terms are described below.
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Chapter 4 Inclined Orbit Satellite