Receiving Weather Satellite Images With Your Macintosh

NOAA-12 Pass (2123z July 29, 2000)
This pass stretches all the way from down in the Caribbean to Hudson Bay, Canada.
It was received on an Icom R-7000 receiver with too narrow of a bandwidth. Also, you can see some interference from an unknown terrestrial source, I am trying to locate the offender!

Russian RESURS Pass (1620z July 30, 2000)
This pass stretches all the way from the southern part of the Hudson Bay, Canada, down to the tip of the Yucatan.
It was received on an Icom R-7000 receiver with too narrow of a bandwidth, causing distortion of bright (white) areas.

Russian MET 3/5 Pass (1750z July 30, 2000)
It was received on an Icom R-7000 receiver with too narrow of a bandwidth, causing distortion of bright (white) areas.

NOAA-14 Pass (2116z July 29, 2000)
This pass stretches all the way from the tip of the Yucatan to Hudson Bay, Canada.

How to receive weather satellite images
How to receive weather fax over shortwave radio

How to receive weather satellite images

The easiest way to receive weather satellite images is to check the schedules for the HF stations, and find when they're re-transmitting satellite images.

But, if you want to recieve the images directly from the satellites, here's what you'll need:

VHF Receiver. It must be able to tune the 137 MHz satellite band in FM mode. While at first this sounds easy, most any scanner will do this, there is a problem. Satellites transmit using FM with a deviation of about 30 kHz, wider than used by police and fire transmissions, and more narrow than that used by FM radio stations. So chances are, the audio coming out of your radio will be either distorted (if you use FM narrow) or noisy (if you use FM wide)

Antenna. It must be either a directional antenna with a rotor to track the antenna, or a suitable non-directional antenna. I recently built a quadrifilar helix antenna, and have had excellent results.
Software to decode the weather satellite images. Again, MultiMode comes to the rescue.
Software to track the satellites to indicate when they will be overhead, and optionally track them by driving the rotor. It's also necessary to adjust the receive frequency to account for doppler shift. An excellent program is MacDopplerPro from Dog Park Software.

Other than the above items, receiving the images is similar to receiving HF weather fax transmissions, except that you have to continuously re-tune the radio, or have it controlled by your computer! Also, a given satellite usually only makes one or two passes overhead each morning and evening. Each pass usually lasts 10 to 15 minutes at the most.

MultiMode - Decodes weather fax and satellite images on your Macintosh, without the need for extra hardware.

Return to Black Cat Systems

cps@blackcatsystems.com

Chris Smolinski