Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma05.r1000.mx.aol.com (Internet Inbound) with ESMTP id D3DF438000090; Sun, 24 Mar 2013 17:18:25 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UJsIl-0007um-Gt for rs_out_1@blacksheep.org; Sun, 24 Mar 2013 21:18:03 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UJsIk-0007ud-Qj for rsgb_lf_group@blacksheep.org; Sun, 24 Mar 2013 21:18:02 +0000 Received: from smtpout4.wanadoo.co.uk ([80.12.242.68] helo=smtpout.wanadoo.co.uk) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1UJsIh-0001Rn-SN for rsgb_lf_group@blacksheep.org; Sun, 24 Mar 2013 21:18:01 +0000 Received: from AGB ([2.26.14.143]) by mwinf5d56 with ME id FZHe1l00W35BR0q03ZHebt; Sun, 24 Mar 2013 22:17:39 +0100 Message-ID: From: "Graham" To: Date: Sun, 24 Mar 2013 21:17:38 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: From: Graham Sent: Sunday, March 24, 2013 8:49 PM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: DJ8WX 8.97 kHz Ok Marcus That would be an interesting 'test' , the s/n levels seem to be a little varied , depending on the reference, I know when ros was first coded , Jose used fldigi as the comparison , but later changed to align with the path-sim propagation simulator , which then changed the base line , Op is also aligned with the same simulator http://www.moetronix.com/ae4jy/pathsim.htm [...] 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 [80.12.242.68 listed in list.dnswl.org] 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 32f0c002d258ce351b2c37fe18ccfa3a Subject: Fw: LF: DJ8WX 8.97 kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F7_01CE28D5.0342AF10" 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-sid: 3039ac1d600d514f6da14734 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_00F7_01CE28D5.0342AF10 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable From: Graham=20 Sent: Sunday, March 24, 2013 8:49 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: DJ8WX 8.97 kHz Ok Marcus=20 That would be an interesting 'test' , the s/n levels seem to be = a little varied , depending on the reference, I know when ros was = first coded , Jose used fldigi as the comparison , but later = changed to align with the path-sim propagation simulator , which = then changed the base line , Op is also aligned with the same = simulator http://www.moetronix.com/ae4jy/pathsim.htm The levels may not be inside the Opera decode range , I think -50 = was the best over short range tests , but those tests also showed = that the signal still left a trace on the qrss plot and its = possible , using you correlation process , detection at lower = levels may be possible as well ?=20 One thing that did seem to arise from the early pie fight's ( = eating , not 3.142) was testing over a real path and a static = simulation did provide differing results , assumedly based on the = 'decode profile' , a lot of tests may be in conflict with design = parameters , rather than providing an evaluation , say like comparing = slick and treaded tyres in the rain , especially in free running = data mode's , where , for example , interlacing would be based on = qsb profile (hf) and on MF are found to fail due to much longer = qsb -=20 I see a follow up from Uwe , may try other modes in a week or so = , if so , may be the Op monitors using mini-whips for 136 could = take a look for his signal as well for a day/night ? , if = there is to be a test , can post on the user group looking for = monitors, in case any one needs to re arrange things , tnx .=20 73 -G. From: Markus Vester=20 Sent: Saturday, March 23, 2013 6:14 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: DJ8WX 8.97 kHz Hi Graham, yes this is an interesting option. The correlation detector looks for spectral peaks in a long narrow FFT, = which integrates across the total duration of the Opera sequence (about = 2000s for Op 32). For a reliable detection, a phase-coherent central = peak needs to be at about 15 dB SNR in the corresponding bin width (0.5 = mHz). Taking a 100% duty cycle carrier for reference, at 50% duty cycle = we have 25% (-6 dB) energy in the central peak, and another 25% in both = AM sidebands together. Thus for Op-32, the threshold is around 21 dB = carrier-SNR in 0.5 mHz, scaling to -46 dB in 2.5 kHz (or -50 "dBOp" on = the Opera scale). The modulation energy will ideally also bring up a 15 = dB correlation peak, which is normally sufficient to ensure unambiguous = callsign identification. Extending the duration from 32 minutes to ~ 4 = hours would gain another 9 dB, arriving at a threshold of -55 dB in 2.5 = kHz (-59 dBOp). On my rather noisy VLF grabber, the carrier from DJ8WX reached about 9 = dB SNR today. Scaling the bandwidth from 1.5*0.48 mHz to 2.5 kHz, we get = -56.5 dB SNR (or -60.5 dBOp) - just 1.5 dB bit short of an Op-4H = detection. Of course other online VLF receivers (namely Paul Nicholson = and OK2BVG) do have significantly better receive conditions so Op-4H = correlation should be quite feasible there. For the standard Opera software decoder, Rik's measurements had = indicated a decoding threshold of -23 dB in 2.5 kHz for two-minute = Opera-2. This scales to -35 dB for Op-32 and -44 dB for Op-4H (-39 and = -48 dBOp respectively). Thus for Op-4H you'd want to see a carrier SNR = of 21.5 dB in a "qrss 6000" grabber window, which seems a fair challenge = at the distances we're interested in. For comparison, Stefan's famous LF reception at VK2DDI showed about 15 = dB SNR in an 11 mHz spectrogram, equivalent to -37 dB in 2.5 kHz (-41 = dBOp). Thus an "easy target" for Op-32 or even Op-8 correlation, but = still slightly below the edge of the classic Op-32 decoder. Best 73, Markus (DF6NM) From: Graham=20 Sent: Saturday, March 23, 2013 1:39 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: DJ8WX 8.97 kHz Marcu's / Uwe This would make a good test for the Op4H ( 4 hour) mode and = the correlation detector ? To date there have been no 'dx' test , with the addition of the = correlation ,then that should give three possible detections ? OP4H decode , qrss plot and Correlation ( and 50% saving on = power hihi)=20 OP4H has AFC as the shorter modes and is designed for normal sound = card use. with sound-card audio or CW-comport Tx keying , rx audio = is direct in from sound card , in short range tests -50 db s/n = has been reached , but that is a data decode , would the correlation = , take the level below the qrss plot ? 73-Graham G0NBD Markus (DF6NM) ------=_NextPart_000_00F7_01CE28D5.0342AF10 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
 

From: Graham
Sent: Sunday, March 24, 2013 8:49 PM
Subject: Re: LF: DJ8WX 8.97 kHz

Ok Marcus
 
That would be  an interesting  'test'  , = the   s/n=20 levels  seem  to  be a little  varied , = depending  on=20 the   reference, I know  when ros  was first = coded ,=20 Jose used  fldigi  as  the  comparison ,   = but  later  changed  to  align  with the =20 path-sim  propagation  simulator , which then  changed = the =20 base line , Op is also  aligned  = with   the =20 same  simulator http://www.moetronix.= com/ae4jy/pathsim.htm
 
The levels may  not be  inside the  Opera  = decode =20 range , I think  -50 was the  best  over  short = range=20 tests  , but  those tests  also  showed that  = the =20 signal  still  left  a  trace  on the  = qrss=20 plot  and its possible , using  you  correlation =20 process  , detection  at  lower  levels may be = possible=20 as  well ? 
 
 One thing that  did  = seem to =20 arise from the  early  pie fight's   ( eating , not=20 3.142)  was  testing  over  a  real path  = and=20 a  static simulation did  provide differing  results ,=20 assumedly  based on the  'decode  profile'  , a lot = of=20 tests  may be  in conflict  with  design parameters = ,=20 rather  than providing  an evaluation , say like = comparing  =20 slick and  treaded tyres in the  rain , especially =20 in   free  running  data  mode's , where , = for =20 example , interlacing would be  based on  qsb  = profile =20 (hf)  and  on MF are found to  fail  due to  = much=20 longer  qsb -
 
I see  a  follow  up from Uwe , may try  = other =20 modes  in a week  or  so  , if  so  , may = be=20 the  Op monitors  using  mini-whips  for  = 136 =20 could take a  look  for  his  signal  as =20 well  for  a  day/night ? , if  there  is = to  be=20 a  test , can post on the  user group looking  for =20 monitors, in case any one needs  to  re arrange things , = tnx=20 . 
 
73 -G.
 
 
 
 

From: Markus Vester
Sent: Saturday, March 23, 2013 6:14 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: Re: LF: DJ8WX 8.97 kHz

Hi Graham,
 
yes this is an interesting = option.
 
The correlation detector looks for = spectral=20 peaks in a long narrow FFT, which integrates across = the total=20 duration of the Opera sequence (about 2000s for Op 32). For a = reliable=20 detection, a phase-coherent central peak needs to be at = about 15=20 dB SNR in the corresponding bin width (0.5 mHz). Taking a 100% duty = cycle=20 carrier for reference, at 50% duty cycle we have 25% (-6 dB)=20 energy in the central peak, and another 25% in both AM sidebands = together.=20 Thus for Op-32, = the threshold is around=20 21 dB carrier-SNR in 0.5 mHz, scaling to -46 dB in 2.5 kHz (or -50 = "dBOp" on the=20 Opera scale). The modulation energy will ideally also bring up a 15 = dB=20 correlation peak, which is normally sufficient = to ensure unambiguous=20 callsign identification. Extending = the=20 duration from 32 minutes to ~ 4 hours would gain another 9=20 dB, arriving at a threshold of -55 dB in 2.5 kHz (-59=20 dBOp).
 
On my rather noisy VLF grabber, the carrier from = DJ8WX reached=20 about 9 dB SNR today. Scaling the bandwidth from 1.5*0.48 mHz = to 2.5=20 kHz, we get -56.5 dB SNR (or -60.5 dBOp) - just 1.5 = dB bit=20 short of an Op-4H detection. Of course other online VLF receivers = (namely=20 Paul Nicholson and OK2BVG) do have significantly better receive = conditions=20 so Op-4H correlation should be quite feasible there.
 
For the standard Opera software = decoder, Rik's=20 measurements had indicated a decoding threshold of -23 dB in 2.5 kHz for = two-minute Opera-2. This scales to -35 dB for Op-32 and -44 dB = for=20 Op-4H (-39 and -48 dBOp respectively). Thus for Op-4H=20 you'd want to see a carrier SNR of 21.5 dB in a "qrss = 6000"=20 grabber window, which seems a fair challenge at the distances we're = interested=20 in.
 
For comparison, Stefan's famous LF reception at VK2DDI showed about = 15 dB=20 SNR in an 11 mHz spectrogram, equivalent to -37 dB in 2.5 kHz = (-41=20 dBOp). Thus an "easy target" for Op-32 or even Op-8 correlation, = but still=20 slightly below the edge of the classic Op-32 decoder.
 
Best 73,
Markus (DF6NM)
 
From: Graham
Sent: Saturday, March 23, 2013 1:39 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: Re: LF: DJ8WX 8.97 kHz

Marcu's / Uwe
 
This would  make a  good  test  for = the  =20 Op4H  ( 4 hour)  mode  and  the =20 correlation   detector ?
 
To date  there  have been  no  'dx' test , with = the  addition  of  the  correlation  = ,then =20 that  should give  three   possible detections  = ?
 
OP4H decode ,  qrss plot  and =  Correlation   =20 ( and  50%  saving on power hihi)
 
OP4H has AFC  as the  shorter  modes and  = is =20 designed for  normal sound card  use. with  = sound-card =20 audio or  CW-comport Tx keying , rx  audio is  = direct  in=20 from  sound  card  , in short range  tests  -50 = db=20 s/n  has been reached , but  that  is a data  decode = , would=20 the  correlation , take the  level  below the  = qrss =20 plot ?
 
73-Graham
G0NBD
 
 
 

Markus=20 (DF6NM)
 
------=_NextPart_000_00F7_01CE28D5.0342AF10--