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Re: LF: 477 VK5CV de VK2XGJ Op8 690 mi -17 dB F:8% in Dapto, Austealia w

To: <[email protected]>
Subject: Re: LF: 477 VK5CV de VK2XGJ Op8 690 mi -17 dB F:8% in Dapto, Austealia with 25w
From: "Graham" <[email protected]>
Date: Fri, 22 May 2015 19:57:09 +0100
Importance: Normal
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
 
Hi Markus
 
The  communal  sever is  running  the  decision  making  part  of the  dynamic  system , along  with  distributing  the  call signs  for the  list , the  call  signs  are  also  vetted  before  distribution  to  prevent  'random'  events 
 
The web linking  transports from the  Rx's  call  / s/n  / % fade / time    or   call  / s/n / time  [ no % fade  for  dynamic ] , there  is  no  DSP   shared and  as  such  cannot  influence  the    decision  of each Rx station
 
The  satellite   Rx's   provide the  time  stamp  , and  as can  be  observed ,  [ if  the  windows  software is  used .. ]  the  spots  from the   dynamic  detectors  are  transferred   to  the  server , then  after a  finite  delay .  are  distributed to the  Opera  users . with  the  ''??'' stamp   'single'  or  'false' or  no  '??' then  validated .
 
The  Opera  system  functions  , with  or  without  web linking .  in a  stand  alone ,  dynamic  detection  , the  s/n  provides  the  confidence  level , other  than  that , If  the  TX is  web-linked , the  psk-map  data  base  holds  the  TX beacon  .. without  this , then  its difficult  to  evaluate ,  unless  there  exists  a  string of  decodes / detections ,  from which  a  profile  may be  established or  other  Rx stations  have  decoded/detected  the  station
 
There  being  no  master  clock ,  the system  runs  as simultaneous unique  individual decodes/detection's , the  only  not allowed  condition  , would  be  a  random  detection , occurring  within  the time  validation  window  of a  genuine Tx ..But  that  event  would  need  to share the  call  sign  with a  actual  event  to  be  of  importance 
 
In this ,   three   Dynamic  Rx stations  share the  same  time  stamp , and  are  validated [ green]  two  would  of  also  validated  each other.

18:38 477 VK3ELV de VK5FQ Op8 Deep Search 437 mi -36 dB in

18:38 477 VK3ELV de VK2XGJ Op8 Deep Search 290 mi -36 dB

18:38 477 VK3ELV de VK5CV Op8 Deep Search 431 mi -36 dB

A local  off  air  decode ,  simply  provides  a  live input to  the  server ,  which  in turn  evaluates  the situation  and  is  suggested  for  remote or  QRP  TX sites.

Dynamic  is  only  provided  for   477K and  136 K  , all  other  bands  are  single mode

73-Graham

G0NBD

 


 

Sent: Friday, May 22, 2015 6:52 PM
Subject: Re: LF: 477 VK5CV de VK2XGJ Op8 690 mi -17 dB F:8% in Dapto, Austealia with 25w

Hi Graham,
 
> ... note  Phil is also  running  RX  and may  provide  shortly  a secondary , off-air  decode to  provide a  time  stamp.
 
maybe this is not such a good idea. When the timestamp from a local decode is propagated over the Opera web link, all other active decoders immediately get this info. A sceptic (are we?) could suspect that this might be used by the detectors to correlate their last-received noise against the known message and timeframe, using an arbitrarily low detection threshold - a la "You've heard it too, haven't you? You surely have...". This could make false positives very likely, but no one can tell them from a real one. The Opera program then has four minutes (one on MF) to output such a hit as a delayed dynamic deep search decode. afterwards, the matching timestamps would be used to falsely "verify" a false detection, which had really been provoked by exactly that timestamp.
 
In my opinion, it would enhance credibility to not propagate local decodes, but let the transmitter only keep a "secret" log of their emissions. This could then be used in an a posteriori comparison against correlation results, which have been created independently without a priori knowledge of transmit times. 
 
All the best,
Markus
 

From: Graham
Sent: Friday, May 22, 2015 3:19 PM
Subject: LF: 477 VK5CV de VK2XGJ Op8 690 mi -17 dB F:8% in Dapto, Austealia with 25w

 
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