so i finally decided to give satellite operation a shot after watching a few videos and reading about it for like two years. got my 2m/70cm setup working pretty well for terrestrial stuff and figured how hard can it be right. very hard apparently.

im using a yaesu ft-818 with a cheap arrow antenna, tracking with gpredict on my laptop. the pass looked good on paper, AO-91 coming overhead at about 73 degrees max elevation. i could hear the downlink fine at the start, nice clear signal, got excited. but then i tried to work anyone and just... nothing. nobody could hear me. i was transmitting on the uplink frequency but i think i was off because of doppler and just not compensating right.

so my question is do you manually tune while the pass is happening or is there software that handles this automatically somehow. i saw something about CAT control but i dont really understand how that works with gpredict. also does the arrow antenna need to be cross polarized or does that only matter for certain satellites. feel like im missing something obvious

yeah the doppler thing trips everyone up the first time or two. the key thing to understand is that for something like AO-91 which is FM not linear, you really only need to correct the uplink frequency because the repeater on the satellite handles the downlink shift automatically. so if you hear yourself coming back through the bird you're on frequency. if you dont hear yourself, tune the uplink up a bit at AOS and work it down toward the published frequency as it passes overhead, then below as it goes away from you. rough numbers for 70cm uplink you're looking at maybe plus or minus 10kHz across a full pass.

for linear transponders like FO-29 or AO-73 it gets more complicated because you have to compensate both sides simultaneously. thats where CAT control through gpredict actually earns its keep. but start with the FM birds first, get comfortable with the mechanics of tracking and tuning, then tackle linear later. also the arrow doesnt need to be cross pol for most LEO work, circular helps but plenty of people work satellites with a standard linear yagi just fine.

ive been doing this about a year and honestly AO-91 was my learning satellite too. one thing that helped me way more than i expected was just listening to a full pass without even trying to transmit. just track it, keep the signal peaked, get used to how fast things move. because when youre new you're trying to physically aim the antenna AND tune AND talk AND not panic and its too much at once. the pass is over before you figure out whats wrong.

also 73 degrees is a pretty high elevation pass which sounds great but it moves across the sky really fast near the peak, like surprisingly fast. some people actually find lower passes easier to work when youre starting out because theres more time. anyway keep at it, took me four or five attempts before i actually made a contact