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Content preview: Mal, Main cause of decode fail with Opera is s/n , ie in qsb if more than 50% of the signal is lost, as in the s/n has dropped below the detector threshold , caused by signal fading or local 'noise' source being activated , then that cycle will fail, lowering the threshold , results in a increase of 'false decodes' [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [80.12.242.59 listed in list.dnswl.org] 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 860e51ceecdf98b32e8eba101d9d472d Subject: Re: LF: DX Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01CD627A.A2A24C90" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_NAME autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:433568576:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d60cb500297a4334a X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0018_01CD627A.A2A24C90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mal, Main cause of decode fail with Opera is s/n , ie in qsb if more = than 50% of the signal is lost, as in the s/n has dropped below = the detector threshold , caused by signal fading or local 'noise' = source being activated , then that cycle will fail, lowering the = threshold , results in a increase of 'false decodes'=20 Noise bursts are not a problem as the duration is very short = compared to the 'tx pulse length' , and where 'time hopping spread = spectrum' is used FEC , then noise burst's are not a problem..in = Operas case, the data encoding provides this function , as the = losses can be randomly or block distributed along the time line=20 Yes a trace on SL is the most simple method, but as you note, and = will catch the lifts in signal during the time period=20 But as yet , this has not produced a full call sign down under = , or reliably across the pond , ok there are data modes that = will layer / multi pass , psk gives another 6 db , but these all = require linear systems and at these power levels, that not = practical=20 73 -G.. From: mal hamilton=20 Sent: Sunday, July 15, 2012 8:13 AM To: rsgb=20 Subject: LF: DX Reference recent discussion about Opera es Wspr for long haul DX. Although these modes have some merit they would be more vunerable over = long distances to QSB and long bursts of QRN and therefore a decode = would be difficult.=20 QRSS es DFCW would be more suitable because part of the = callsign/information would be readable at some time during the = transmission.=20 I have noticed this on local data transmissions on 500 Khz, no decodes = because of QSB or QRN bursts but I can clearly see the trace and had it = been QRSS or DFCW I could easily have had an ID or parts of the = information. ie With data modes a DECODE or nothing, with QRSS/DFCW at least some = information. de mal/g3kev ------=_NextPart_000_0018_01CD627A.A2A24C90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Mal,
 
Main cause of decode fail  with  Opera is  s/n , ie = in=20 qsb  if  more than 50%  of the  signal  is = lost, as in=20 the  s/n  has dropped  below the  detector threshold = ,=20 caused  by  signal  fading  or  local =20 'noise'  source being  activated , then that  cycle = will =20 fail,  lowering the  threshold , results in a  increase = of =20 'false decodes'
 
Noise  bursts are not a problem as the  duration is  = very  short compared to the  'tx pulse length' , and = where  'time=20 hopping spread spectrum' is  used   FEC  , = then  noise=20 burst's are  not a  problem..in Operas  case, the =20 data  encoding  provides  this  function , as = the =20 losses can be  randomly or  block  distributed  = along the=20 time line
 
Yes  a  trace on SL is  the  most simple = method,=20 but  as  you note,  and will  catch  the  = lifts=20 in  signal  during  the  time  period
 
But as  yet  , this has not  produced  a =20 full  call  sign   down under , or  = reliably =20 across  the  pond , ok  there  are  data  = modes=20 that  will  layer / multi pass , psk  gives  another = 6=20 db  , but these all  require linear  systems  = and  at=20 these  power levels, that  not  practical
 
73 -G..
 
 
 

Sent: Sunday, July 15, 2012 8:13 AM
To: rsgb
Subject: LF: DX

    Reference recent discussion = about Opera=20 es Wspr for long haul DX.
Although these modes have some merit they would = be more=20 vunerable over long distances to QSB and long bursts of QRN and = therefore a=20 decode would be difficult.
QRSS es DFCW would be more suitable because part = of the=20 callsign/information would be readable at some time during the = transmission.=20
I have noticed this on local data = transmissions on=20 500 Khz, no decodes because of QSB or QRN bursts but I can clearly see = the trace=20 and had it been QRSS or DFCW I could easily have had an ID or = parts of=20 the information.
ie
With data modes a DECODE or nothing, with = QRSS/DFCW at=20 least some information.
 
de mal/g3kev
 
 
 
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