home | news | reception | shareware | msg | shop | links | join | about us

last issue
RIG 76 is now out

useful links


An introduction to receiving imagery.

Polar APT

Most members start by receiving images from the `Polar orbiting satellites', which transmit Automatic Picture Transmission (APT) signals in the 137MHz band. Current satellites include the American NOAA series and Russian Meteor or Sich series. These tend to be sun-synchronous, with two orbits passing at or near overhead at the same times each day, 12 hours apart. APT resolution is about 4km per pixel and two channels are usually transmitted, Visible and Infra Red.

The 137MHz band is a fairly easy band in which to build your own equipment and is relatively inexpensive as a band to start with. Provided you own a PC then it is possible to get started receiving APT signals for a little as Receiver and antenna, by using shareware to decode the signal and using the power of your computer sound card.

High Resolution Picture Transmissions (HRPT and CHRPT)

For the really keen and requiring either more experience in construction or a bit more savings, there are the highest resolution images available, namely HRPT or CHRPT. These transmission are from the Polar Orbitting satellites, about 1.7 GHz, and comprise either 5 (HRPT) or 10 channels (Chinese HRPT) of spectral information, giving resolution down to 1.1km pixels. It is necessary to track the satellite with your antenna and image files can be as large as 120MB.

The equipment is more specialised and due to the high frequencies and data rates involved, HRPT is more for the experienced amateur.


Meteosat second Generation (MSG)

Meteosat Second Generation (MSG) consists of a series of four geostationary meteorological satellites, along with ground-based infrastructure, that will operate consecutively until 2020. The MSG satellites carry an impressive pair of instruments, the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), which has the capacity to observe the Earth in 12 spectral channels and provide image data which is core to operational forecasting needs, and the Geostationary Earth Radiation Budget (GERB) instrument supporting climate studies.

Eumetsat is relaying the signal via Hotbird and this can be received using a receiver card. This is a digital satellite TV 'free to air' satellite receiver that is installed inside your computer.
Please see the article on the MSG page for more details.