10ghz artemis1 astronomy astrophotography ATA ccsds ce5 contests digital modes doppler dslwp dsp eshail2 fec freedv frequency gmat gnss gnuradio gomx hermeslite hf jt kits lilacsat limesdr linrad lte microwaves mods noise ofdm orbital dynamics outernet polarization radar radioastronomy radiosonde rf amplifiers satellites sdr signal generators tianwen vhf & uhf vlbi