Orbital Weather Satellite APT Image Reception
Posted: Mon Oct 09, 2017 7:49 am
Key Words: Weather Satellite, NOAA, WEFAX
Weather Satellite Reception 1 of 3
This is a 3 part post due to the limitations for loading images into this bulletin board.
APT weather satellite image reception is very straight forward and easy to do from almost anywhere on Earth. Currently, as of 2017, there are still a handful of orbital weather satellites transmitting the APT or Automatic Picture Transmission format. As a minimum, you will need an antenna, a radio receiver capable of receiving FM frequencies from 137.1 to 137.9125 MHz having a bandwidth of 30kHz to 50kHz, such as the RSP2, a personal computer with a reasonably fast microprocessor, and image decoding software. To gain a much better range for receiving images, an 18dB low noise preamplifier is required. Without the 18dB preamplifier, you can get good APT reception for about 40 to 60 degrees of an overhead satellite pass when applying the antenna below and the RSP2. With the preamplifier, you can potentially receive images within a few degrees of horizon-to-horizon. With the configuration described below using a backfire quadrifilar helix antenna and applying an 18dB 0.6dB noise figure or better low noise preamplifier mounted at the antenna, you can use the RSP2 to obtain some very nice APT weather satellite images, such as those shown in the following examples:
ANTENNA CONSTRUCTION
A very effective antenna for receiving the right hand circular polarized APT signal from orbital weather satellites is the backfire quadrifilar helix.
What you will need:
1) 25ft (7.62 m) of 6 awg bare copper wire. This can usually be found at a reasonable cost in the electrical wiring section of many hardware stores. It is important that it is coiled, but not tightly, in its packaging and that it is without kinks that cannot be easily straightened. If it comes in a coiled form, this is helpful in forming the antenna elements.
2) Long clear acrylic tube 1 inch (2.54 cm) diameter by 1 m or approximately 3 ft long (the length does not have to be exact as long as it at least 30 inches (76.2 cm). The diameter is critical as the antenna center tube will additionally be used to form the balun. The wall thickness of the tube should be 0.125 inches (0.3175 cm).
3) Short clear acrylic tube 0.625 inch (1.5875 cm) diameter having a length of at least three inches. This smaller tube will be cut to form an internal washer/support in the larger tube. Alternatively a thick plastic washer of some type can be applied as long as it fits snugly inside the larger tube described in 2) above and is around 0.25 inch (0.635 cm) thick. Ensure that the washer is not metallic or made of any substance that can interfere with RF.
4) 5 ft (1.524 m) of 18 awg enamel coated magnet wire.
5) 3.5 ft (1.0668 m) of RG-8x or RG 58U coaxial cable.
6) Chair leg end cap to fit a 1 inch or 2.54 cm diameter tube. These are typically available from hardware stores.
7) Soldering iron or propane torch and solder capable of soldering 6 awg copper wire.
8) Heavy duty industrial glue, such as 3M Scotch-Weld™ DP-420.
9) Two part 5-minute epoxy.
10) Permanent marker.
11) Measuring tape.
12) Pliers for bending the 6 awg copper wire into the required element form.
13) Saw for cutting the acrylic tubing.
14) Good quality, non-metallic, outdoor enamel paint.
Continued in Weather Satellite Reception 2 of 3.
Weather Satellite Reception 1 of 3
This is a 3 part post due to the limitations for loading images into this bulletin board.
APT weather satellite image reception is very straight forward and easy to do from almost anywhere on Earth. Currently, as of 2017, there are still a handful of orbital weather satellites transmitting the APT or Automatic Picture Transmission format. As a minimum, you will need an antenna, a radio receiver capable of receiving FM frequencies from 137.1 to 137.9125 MHz having a bandwidth of 30kHz to 50kHz, such as the RSP2, a personal computer with a reasonably fast microprocessor, and image decoding software. To gain a much better range for receiving images, an 18dB low noise preamplifier is required. Without the 18dB preamplifier, you can get good APT reception for about 40 to 60 degrees of an overhead satellite pass when applying the antenna below and the RSP2. With the preamplifier, you can potentially receive images within a few degrees of horizon-to-horizon. With the configuration described below using a backfire quadrifilar helix antenna and applying an 18dB 0.6dB noise figure or better low noise preamplifier mounted at the antenna, you can use the RSP2 to obtain some very nice APT weather satellite images, such as those shown in the following examples:
ANTENNA CONSTRUCTION
A very effective antenna for receiving the right hand circular polarized APT signal from orbital weather satellites is the backfire quadrifilar helix.
What you will need:
1) 25ft (7.62 m) of 6 awg bare copper wire. This can usually be found at a reasonable cost in the electrical wiring section of many hardware stores. It is important that it is coiled, but not tightly, in its packaging and that it is without kinks that cannot be easily straightened. If it comes in a coiled form, this is helpful in forming the antenna elements.
2) Long clear acrylic tube 1 inch (2.54 cm) diameter by 1 m or approximately 3 ft long (the length does not have to be exact as long as it at least 30 inches (76.2 cm). The diameter is critical as the antenna center tube will additionally be used to form the balun. The wall thickness of the tube should be 0.125 inches (0.3175 cm).
3) Short clear acrylic tube 0.625 inch (1.5875 cm) diameter having a length of at least three inches. This smaller tube will be cut to form an internal washer/support in the larger tube. Alternatively a thick plastic washer of some type can be applied as long as it fits snugly inside the larger tube described in 2) above and is around 0.25 inch (0.635 cm) thick. Ensure that the washer is not metallic or made of any substance that can interfere with RF.
4) 5 ft (1.524 m) of 18 awg enamel coated magnet wire.
5) 3.5 ft (1.0668 m) of RG-8x or RG 58U coaxial cable.
6) Chair leg end cap to fit a 1 inch or 2.54 cm diameter tube. These are typically available from hardware stores.
7) Soldering iron or propane torch and solder capable of soldering 6 awg copper wire.
8) Heavy duty industrial glue, such as 3M Scotch-Weld™ DP-420.
9) Two part 5-minute epoxy.
10) Permanent marker.
11) Measuring tape.
12) Pliers for bending the 6 awg copper wire into the required element form.
13) Saw for cutting the acrylic tubing.
14) Good quality, non-metallic, outdoor enamel paint.
Continued in Weather Satellite Reception 2 of 3.