Steve,

Your experience is typical with the current AMSATs in orbit, which are all in a low-earth orbit, resulting in a high velocity pass, relative to your ground station. In addition, the higher the frequency, the greater the doppler shift.

Most regular satellite operators use PC-based software to control the doppler shift tuning. Keplarian elements are published, which can be used to predict the orbit and pass times, allowing for prediction of the doppler shift.

I'm guessing most "modern" all-mode VHF/UHF rigs support computer-control. If you want to work the sats, you really need a rig that does full duplex, so you can hear yourself (which is sometimes the only thing you'll hear on some of the linear transponder sats, unfortunately!). A high-gain directional antenna also helps....

73,

Dave NøTGD

On 1/6/07, Steve Raas sraas@optonline.net wrote:

Hello Everyone . I just received the Oscar-58 beacon on 437.4650 and have a question. I have read abt dopler shift and how It can affect radio signals especially with the sats. This being only the 3rd time ive ever even herd a sat I was shocked to note that the frequency drift was a few Hz lower on every cw note ( the beacon ). It reminded me of an old heathkit HF radio that drifted .. but never settled down. Is this about the normal expected Doppler Shift in a cw/ssb signal on the amsats? I was constantly turning the VFO ever so slightly. Or is this more on par for this particular Sat?