Our first system (see below) was the simplest and cheapest. We set it up at the institute where I worked and also at my apartment in Stockholm. The antenna on the roof of the institute gave a wide field of view while the home setup, with the antenna attached to balcony railing, was hemmed in tightly by nearby buildings. Two example images :

Image obtained with System 1 at the
physics institute with a wide field of view.

Image obtained with System 1 from apartment in city.

The institute images were sharper and longer (i.e. the longer the satellite is visible, the more of the image you can obtain). However, we also worked with this setup during the November-December period when the weather was bad and the days were short, so it was difficult to obtain an interesting image regardless.

Our first system

Our apartment was in the center of Stockholm. The antenna was mounted on our balcony and connected by a cable running through the window to a laptop running on our kitchen table!

Unfortunately, the "field of view" to the sky was very limited by the buildings surrounding our courtyard. Combined with the bad weather of winter and the short days, the images from home were dark and short (see one above).

However, this first setup was still a lot of fun, especially when I first managed to hear the 'tick-tock' sound of the NOAA satellite AM signal.

When the same system was set up at the institute with the antenna on top of the building we obtained much better pictures. (See example above.)

Setup: a basic system as show above consists of the following:

• Antenna - for the apartment we used a discone, which is useful for a wide range of signals but crossed dipole or QFH (quadrifilar helix) are normally recommended for APT reception. These cost as low as $50-100 range.
• Receiver - a typical consumer shortwave scanner will not work well for APT satellite reception. The IF (Intermediate Frequency) bandwidth is either too wide or too narrow. (Ideally, it is 42Khz.) So we purchased an Icom IC-PCR1000 [Update Nov.1.08: Icom now offers the PCR1500 in place of the PCR1000.] receiver that is controlled from a PC via a serial port connection. Its IF bandwidth can be set as desired from the control program.
• PC with sound card - the PC controls the receiver and uses the sound card to decode the image signal from the receiver's audio output.
• Software:
  • Radio control - the PCR1000 comes with a control program but we more often used RadioCom 3.0 (now available in version 5.0), which has many features useful for all kinds of shortwave scanning. (RadioCom screen image)
  • Image decoder - the audio from the receiver must be decoded to obtain the weather sat image. We used the freeware WXSAT progam in this setup. It can run directly from the sound card or from a WAV file. (WXSAT screen image)
  • Satellite tracker - the NOAA polar satellites crosses overhead about twice during the day. (Areas, like Sweden, near the poles can see them more often.) Currently two of the NOAA satellites are active (NOAA-14 & NOAA-15). So one must know when the pass will occur and how high in the sky it will be above the horizon. Therefore, a tracking program is needed. There are a number of such programs, both freeware and for purchase, with a varying range of features. Here we used the WinOrbit freeware program. .(WinOrbit screen image)

   

Procedure - the essential steps to get an image:

1. Track the satellites with WinOrbit to find when NOAA-14 or NOAA-15 would come into view and how high in elevation it would rise.
2. Tune the receiver with RadioCom to the right frequency (137.620MHz for NOAA-14, 137.500MHz for NOAA-15) in the FM mode and 50KHz IF.
3. Listen for the "tick-tock" sound of the satellite signal.
4. Record the audio to a WAV file with RadioCom, starting as soon as you first hear the satellite's signal. (The decoder can also work in real-time but its safer to record to a file and do the decoding later since I might want to try different settings.)
5. Decode the WAV file with WXSAT. Save the image to a bitmap file. (Note: we had to play with the parameter setup in WXSAT to decode the image successfully.)
6. Image processsing, e.g. cropping the visible or IR images, with a graphics program such as Photoshop.

As I continue to emphasize, the above components and procedures can be varied considerably from the approach given above. See the WeatherSat section of the top Space Radio page for links to other equipment and software options.