Re: VARA vs. Pactor-III Speed Comparison Plots

Graham
 
Edited

James . 

One thing that's  missed ,is,  vara maintains  on air presence as  an ofdm  modem,  and remains so, for all  transfer speeds , that is actually  a  design milestone , whereas   other  systems , revert to mmfsk  in an attempt to  maintain throughput in adverse conditions, [ofdm uses  multiple  psk  carriers , mmfsk  is  single  tone] But sacrifice the robustness of the  ofdm  modem,  a real test  is to have  in band  jamming  at the  same  time , 

The low  on air  rate  of  30 baud  per carrier of  vara and  being adaptive to 'channel  dely' , actually is able to facilitate  reliable  multi-hop long range communications at  maximum speed , only  thing that missing are  the  odd  sun-spot's ..Im not sure , what the  distance  record  stands at now, the  system  is  widely deployed , EU<>USA on 7 MHz has been achieved at good  rates  from a  maritime  mobile  station ..point to point  I don't know ?

I think you  find it  works quite  well ,  you can  deploy the  HF version  over  VHF using fm or ssb , may well  give extended range  and  speed , the  fm  version provides  higher maximum  speed , but not the  very low s/n  of the  HF version ..may be worth looking  at  

A more challenging  test  would be  Vara and  P4  

73-Graham
g0nbd


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