Introduction

TRANSPONDER

FREQUENCY AND NUMBER

DOWN LINK

 

 

 

 

TRANSPONDER

FREQUENCY

 

 

 

 

 

NUMBER

11.729GHz

11.788GHz

11.847GHz

11.906GHz

11.965GHz

12.024GHz

12.083GHz

12.142GHz

1

2

3

4

5

6

7

8

9 11 13 15

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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11.7585GHz 11.8175GHz 11.8765GHz 11.9355GHz 11.9945GHz 12.0535GHz 12.1125GHz 12.1715GHz

HORIZONTAL

VERTICAL

POLARIZATION

POLARIZATION

Figure 1-7: Transponder assignments for a typical Ku-Band, 16-transponder satellite that employs alternate polarization (Not all Ku-Band satellites conform to these frequencies and/or this polarization scheme)

Finding The Correct Transponder

Once the satellite has been found it will be necessary to find the proper trans- ponder and determine if it is available. With the 1705A frequency readout offset correctly set up, it is possible to directly zero in on the correct transponder. Figure 1-8 is a computer simulation of the 1705A Spectrum Monitor display in FULL SPAN/DIVISION. Each division corresponds to 100 MHz. If the satellite previously discussed is being looked at and the brightup is on the first marker, then the first signal is transponder number 1 and the antenna feed horn is horizontally polarized. Further, it is possible to determine that transponders 5, 7, 9, 13, and 15 are currently in use. Rotating the feed horn polarity 90˚ would bring up a display of the vertically polarized transponder down links.

Optimize Signal Strength Once the correct satellite has been identified, minor adjustment to the antenna position will optimize the link. The antenna azimuth and elevation can be fine tuned for maximum signal strength and the opposite polarization carefully nulled while observing the spectrum monitor crt screen.

1705A Spectrum Monitor

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Image 34
Tektronix 1705A instruction manual Horizontal Vertical Polarization, Frequency and Number Down Link Transponder