Re: PSK31 QRV #PSK31


Graham
 
Edited

Well , may be old ,

But, if you have 128  orthongonal  / close spaced psk carriers and a little supporting coding, you can send data at  6k or faster in a ssb channel .... its the basis for mt63,  (the first in) pactor 111 , ardop and now vara )

And the ultra low s/n  vlf  data mode also uses narrow psk modulation,  the reason Opera uses ask and not psk  , no one could send psk on the low bands back then......and still very few have linera amplification .

NB - The technical issues , where/are 

Audio  [1500 hz]  to  RF  on air  carrier  frequency translation ,   very few Tx/Rx where  able to  send on 500/477 KHz , , which prevented , the  use of conventional  data  modes ,  I used a  e-bay spacial,  Racal MA1723 exciter , which  covered [out of range] 500 K 
Now sets like the  IC7100   do function on  MF and provide on-frequency drive  out 

Amplification ,   There  was / is a  trend to  design MFET  'amplifiers'  using  a  dividing , logic drive ,  using the  same  channel  FET devices ,  this  required a  bi-stable  drive , which  in turn ,  at the  minimum  , divided the  drive  frequency  by '2' , requiring the  drive frequency to  be  x2 , but ,  then dividing   the  tone  spacing of any  mmfsk  data  mode by '2' , thus preventing  any of the  conventional  modes of the  time 
Using  P&N  channel devices , overcomes this issue , by  providing  on-frequency 'carrier power'  


73 Graham .. 

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