VARA HF “Tactical, Level 17” can transfer up to 8489 bps: That is the maximum physical-level transfer rate. Expect no more than perhaps 25% of that on the logical level and definitely not with somehow standard ham radio means!
Using the VarAC data transfer mechanism I have seen peaks of around 1000 bps. OK, VarAC uses VARA with 500 Hz of …
VARA HF “Tactical, Level 17” can transfer up to 8489 bps: That is the maximum physical-level transfer rate. Expect no more than perhaps 25% of that on the logical level and definitely not with somehow standard ham radio means!
Using the VarAC data transfer mechanism I have seen peaks of around 1000 bps. OK, VarAC uses VARA with 500 Hz of bandwidth. But transferring 5 kB lasts several minutes due to phases with much lower transfer rates, repetition etc.
You also cannot do this with standard ham radio equipment because of the crest factor of digital transmissions: Within minutes your TX and possibly power supply overheats! When chatting with VarAC my PA heats to perhaps 15 K above surrounding air temperature. But If I try to transmit two sentences in JS8, my PA turns off within 3 min at 60°C. For the next sentence my PA needs 5 min to cool down.
For my purposes, a better fan might suffice. But transferring 1 MB over shortwave needs lots of radiated power and a lot less CMEs than we presently have - another limitation of any shortwave application.
VARA HF “Tactical, Level 17” can transfer up to 8489 bps: That is the maximum physical-level transfer rate. Expect no more than perhaps 25% of that on the logical level and definitely not with somehow standard ham radio means!
Using the VarAC data transfer mechanism I have seen peaks of around 1000 bps. OK, VarAC uses VARA with 500 Hz of bandwidth. But transferring 5 kB lasts several minutes due to phases with much lower transfer rates, repetition etc.
You also cannot do this with standard ham radio equipment because of the crest factor of digital transmissions: Within minutes your TX and possibly power supply overheats! When chatting with VarAC my PA heats to perhaps 15 K above surrounding air temperature. But If I try to transmit two sentences in JS8, my PA turns off within 3 min at 60°C. For the next sentence my PA needs 5 min to cool down.
For my purposes, a better fan might suffice. But transferring 1 MB over shortwave needs lots of radiated power and a lot less CMEs than we presently have - another limitation of any shortwave application.
Alexander - I'll defer to your hands-on experience. It did sound a bit too good to be true... but it was a fun thought experiment.