Re: Whats new in VARA 4 ? #VARA #qrp

Andrew O'Brien

For those of us that have previously paid for earlier versions of VARA, is this new version simply a continuation or do we have to pay again ?

Andy K3UK

On Sun, Jul 5, 2020 at 4:17 PM Graham <g0nbd@...> wrote:

[Edited Message Follows]

Whats new in VARA 4 , live as from  1 July 

Faster high rate  transfer and lower 
s/n weak signal performance 

Completely re-worked protocol 

 2.3 KHz b/w : 16  speed levels

New 500 Hz B/W mode : 13 speed levels

Mixed  B/W  connections  possible -winlink - bpq

Unlicensed  access remain at MFSK  2.3 K  175   /  500 Hz 88 Net rate 

 V4 deploys  a all new re configured, non backward compatible
protocol ,providing a  faster  and streamlined  Data /Ack  sequence 
with  new symbol rates / carrier  configurations , supporting , 
higher transfer rates and  enhanced weak  signal  performance to
that  expected of  conventional chat-mode's  

Level 16 , of the  2.3K mode, provides  a net rate  of 7050  BPS
with  49 on air  carriers , running at symbol rate  of  42 Baud 
the  49 carrier  modem is  engaged at level 10  with  2011 BPS 
in keeping with  HF channel compatibility , none of the  speed
levels  deploy symbol rates  over  94 B,  round ''50   being the  norm

The new 500 B/W mode  reaches a  maximum  throughput of 1534 BPs
with 11 carriers , 42  baud symbol  rate, making  for a  very  robust connection .
primarily provided to  allow  use in the  narrowband  mail  box  areas , in association
with  email/file  transfer . 

Interestingly  level  1 , 2.3 K and level 1  500 Hz b/w   is set  at  18 BPs
at the  same  s/n  ratio, for  each  mode ...In discussions round s/n  ,
the  new  low  sensitivity levels/data  rate is felt to 
exceed  that  offered by the  OLIVIA data  mode , which, in terms
of  payload delivery  , offers a very high level 
of  'link completion' under  adverse conditions,  

CHAT users, are  provide  , only with  access  to the  2.3 K b/w mode , winlink 
or BPS is required to access  the  500  version , however,  the  2.3  modem now
provides close or  if not  below the  noise  live  qso  and file  transfer . this coupled with
the off air  'monitor option' , gives reasonable round table  performance, fast arq , providing
error free conversation at  amtor  rates , at weak signal levels, without the detection  and 
lock time  delays of conventional 'robust'  'chat' modes , 

QRP  , Unregistered the  modem  is limited to  phase continuous  MFSK,
  providing  compatibility with  non lienera TX , eg class C, E/D  , OFDM require's
linear path . providing an alternative  to  Olivia dx qso's ,  noting  [Olivia has a  phase  component to
the modulation  waveform and requires a  Linera  TX path]   .....Noting  of course,  Vara 
requires a full linear Tx&Rx  path , once the  speed  ranges , engauge the  OFDM modem
registered or  not,  the  QRP aspect remains  available  

MF/MF-Ecomm's  The  500Hz  Bw  meets data B/W  requirement's **  for the  MF band , and could provide E-COMM's 
making  use of the  enhanced weak  signal  aspect , MFSK  2.3 K  175   /  500 Hz 88 Net rate 
its unusual for  High power MF Tx to  be  linear , but , if  so, then  full  use could be  made .
noting,  there  is no facility to  change the  TX tone mid band , perhaps not  so much of a issues these  days 

** May change  region to region, 

   Modem  rate / level  chart 

Mixed mode connection, accessed  via  option  choices  in the  
modem set up , where possible, gateway connection at  2.3 K
is advised , to  minimise access time . 

The 500<->2300 gateway compatibility option can be used by Sysops to 
monitor  both,  2300 and 500  simultaneously. the modem will detect 
and configure to the  calling  station 


The modem  requires a  minimum  Dwell  time  of  4 seconds  , when  using the  TRI-Mode  

VARA is  now  included in the  Forwarding  facility 

VARA  FM , VARA  9600 , VARA SAT  all  remain as  was 

73 -Graham


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