WXSAT-L-------
FAQ--------
FAQ--------
NOAA 14
USIR-WEFAX
-----EXPLORES! Direct Readout
----------------------GVAR-USIR
----------------------GVAR-USIR
-----EXPLORES! Direct
Readout
----------------------GVAR-USVIS
----------------------GVAR-USVIS
-----EXPLORES! Direct Readout
----------------------GVAR-FDIR
----------------------GVAR-FDIR
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15) What type of antenna
system do I need?
APT signals are circularly polarized so a crossed dipole is the simplest reliable antenna design. The optimum design is a quadrifilar antenna but this antenna is very complex and therefore significantly more expensive. (Contact Satellite Data Systems or Spectrum International for details on quadrifilar antennas or see http://www.pilotltd.u-net.com/qha.htm.) The APT data is a video signal; noise is not tolerated as easily as it might be in audio data. Less than optimum antennas produce images with high noise levels.
GOES signals, in addition to the approximately 35,000 km signal path, are affected by weather and operational considerations on the spacecraft. While it is possible to receive a usable signal with a yagi or helix antenna, there signal budget leaves very little room for additional signal reduction. Any signal reduction produces an excessively high noise level. For these reasons, the additional gain possible with a dish makes the dish antenna the most desirable antenna. See Taggart for one antenna and feedhorn design.
APT signals are circularly polarized so a crossed dipole is the simplest reliable antenna design. The optimum design is a quadrifilar antenna but this antenna is very complex and therefore significantly more expensive. (Contact Satellite Data Systems or Spectrum International for details on quadrifilar antennas or see http://www.pilotltd.u-net.com/qha.htm.) The APT data is a video signal; noise is not tolerated as easily as it might be in audio data. Less than optimum antennas produce images with high noise levels.
GOES signals, in addition to the approximately 35,000 km signal path, are affected by weather and operational considerations on the spacecraft. While it is possible to receive a usable signal with a yagi or helix antenna, there signal budget leaves very little room for additional signal reduction. Any signal reduction produces an excessively high noise level. For these reasons, the additional gain possible with a dish makes the dish antenna the most desirable antenna. See Taggart for one antenna and feedhorn design.