Satellite montitoring on the cheap:

I glanced up at the satellite tracking screen in front of me. It was clear that the MIR space station was emerging over my horizon. I checked the downlink frequency display on the receiver, adjusted for Doppler Shift and backed off the squelch. The steady beat of a Morse Code beacon crackled from the speaker of a second satellite receiver. Switching to another tracking screen, I realized that the footprint from an amateur radio satellite was also in the neighborhood. Suddenly the FM hiss from the first receiver disappeared as a clear Russian voice came through, tinged with excitement. It was a cosmonaut aboard MIR and there was trouble (again).

This is not an opening paragraph of some cheesy sci-fi novel, it's an actual depiction of how you can turn your desktop into a sophisticated satellite monitoring station with very little investment. Let's roll the tape back for a replay. The "satellite tracking screen" was actually my computer which was set up on NASA's J-Track website for kids. Here you can check out the current position of 500 of the 9,000 currently operating satellites whizzing around us overhead. They've made it really easy by allowing you to toggle between screens showing MIR/Space shuttle, amateur radio sats and NOAA weather satellites, among others.

The "downlink frequency display" was the LCD screen on my police scanner tuned to one of the frequencies on which MIR operates for voice communications back to Earth. "Adjusting for Doppler Shift" was simply tuning the receiver so that the tone remains constant as MIR passes by. "The squelch" is the circuit which mutes the "FM hiss" found on a frequency where there's no signal present. Normally, you want the squelch engaged, but satellite signals are weak and may not be able to open the squelch on their own. The "second satellite receiver" was actually a shortwave radio tuned to the 10 meter band where several amateur radio satellites have a downlink beacon which is simply a playback chip continuously identifying the spacecraft on a particular frequency as it makes its way around the globe.

When Russia's first Sputnik surprised the world over 40 years ago with its little beep beep beep, it took very sophisticated receiving equipment and a lot of complicated math to figure out where it was in the sky. Radios capable of tuning in the beeps were not widely available. Today, the miracle of the microchip has changed all of that. Off-the-shelf radios and access to the Internet is all you need to tap into the fascinating world of satellite communications. In fact, recent developments in computer-based radio receivers has made it possible to receive data directly from orbiting weather satellites using only a computer. The radio's inside!

It's easy to get started in satellite monitoring, but you'll have to understand a few basics. First, the satellites used for TV and those whole Earth views from space are in what's called geosynchronous orbit (or "GEO") at a distance of about 23,000 miles. This means that they are rotating around the Earth at the same speed the planet is revolving so they appear to be stationary. The low flying spacecraft, such as NOAA weather sats, the Space Shuttle, MIR and the whole array of new telephone sats, operate in a "near Earth" orbit at a distance of about 200 to 800 miles. They're moving fast (about 17,000 miles per hour), so they come and go quickly from view. Even though these satellites are relatively small and hundreds of miles away, you can actually see them if you know when to look and how!

Receiving GEO satellites requires a dish-type antenna, but receiving the lower orbiting satellites (LEO) can be done with little more than the stubby rubber antenna attached to a scanner or the telescoping whip of a shortwave radio. However, huge improvements can be gained by using an external antenna. Radio Shack has a nice small UHF/VHF antenna (RS# 20-176) for US$20 which, when attached to your scanner, will dramatically improve reception. It will also help if the antenna is placed outside or in the attic. The higher up the antenna is, the better your reception will be. You'll also need a length of cable to connect the antenna to your scanner. Radio Shack also has these cables, complete with connectors, in lengths from 2-50 feet, at prices ranging from $5 to $35.

The Sangean ATS-818, a great shortwave radio available for under $150.
Street Tech's Le Grande Fromage Gareth Branwyn owns one of these.

If you have a shortwave radio which is capable of tuning the 10 meter band (the 28-30 MHz range), you can hear ground-based amateur radio operators from different parts of the world contacting each other by voice or Morse Code using a number of satellites. Your shortwave radio needs to have a BFO (Beat Frequency Oscillator) knob or some other device which allows reception of sideband and Morse Code signals. Many of the really cheap shortwave radio don't have this. Again, reception will be greatly improved by adding a wire antenna in the attic.

So, where do you tune in? The easiest place to start is with one of the amateur radio sats because they're almost always in constant operation. Everything you need to know about amateur radio satellites, including links to some interesting websites, can be found at AMSAT. If you're a licensed amateur radio operator, you can transmit on the amateur satellites and actually contact MIR and the Space Shuttle! Here are a few satellites and their frequencies to try on your shortwave receiver:

• (Russian Sputnik) RS-12/13: 29.410-29.450 MHz
• (Russian Sputnik) RS-15: 29.354-29.394 MHz

The next easiest listening target is the MIR space station, or if it's on a mission, the Space Shuttle. Try these frequencies on your scanner, but remember, cosmonauts have work to do, and they sleep once in a while too, so don't expect to hear something every time the spacecraft passes by:

• MIR to ground: 143.625 MHz (This channel was very active during the various MIR emergencies)
• MIR amateur radio: 145.985 MHz (More often you'll hear 1200 Baud AFSK (Audio Frequency Shift Keying) packet transmissions which can be copied using a widely available program for your computer and a packet modem.)
• Space Shuttle: 145.55 MHz (This frequency is used for both voice and packet).

The world's polar orbiting weather satellites may also be heard on your scanner by tuning in the 137 MHz range. Several countries operate their own weather sats that are available to us merely by tuning in. International agreements have established frequencies and protocols for transmission and reception. The result is that, even with modest home equipment, you can play The Weather Channel on your desktop. All you need is a computer loaded with a simple weather facsimile (WEFAX) program, a receiver capable of tuning narrowband FM transmissions, a high gain antenna and a modem to connect the receiver to the computer. NOAA operates its satellites on 137.5000; the European Space Agency (ESA) uses 137.0800 for its METEOSAT series sats; Russia uses 137.4000 for its Cosmos and Meteor series APT (Automatic Picture Taking) satellites which include earth resource imaging.

If you guessed that there are spy satellites to tune into as well, you're right. But these frequencies are well-guarded and you aren't likely to find any information on tracking such satellites. However, the 135.5-138 MHz band is home to all kinds of low-flying government satellite communications. You'll need a more sophisticated receiver and an impressive antenna installation to snag these transmissions. If the satellite monitoring bug bites hard, you might consider the ultimate computer-controlled radio which is made by WiNRADiO. Capable of tuning up to 1500 MHz, this is an amazing receiver. With the addition of their "Digital Suite" software you'll be able to decode WEFAX and much more with sophisticated features such as audio spectrum analysis built-in.

After crawling the Web for awhile you'll come across all kinds of interesting sites for satellite imagery enthusiasts. There are also a few small circulation offline magazines which have information on this subject. The best by far *was* Satellite Times which was published by Grove Enterprises. It stopped publishing as of the Sept. '98 issue, but there may be copies of back issue available. They regularly published hard-to-find frequencies of all manner of satellite communications.

Here are a few other websites related to weather satellite imagery hardware and software:
Quorum Communications
Paccom Packet Radio Systems
Time Satellite Systems
VANGUARD Satellite Remote Imaging Systems
Satellite Related Software Page