Message-ID: <13C0C25482A94912AB3B3AE52A745B86@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <580A925A.9000603@lineone.net> <163F863FB932436E8D8DBC12AF91F375@AGB> <580B3D5F.4010501@lineone.net>
In-Reply-To: <580B3D5F.4010501@lineone.net>
Date: Sat, 22 Oct 2016 16:37:46 +0100
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Subject: Re: LF: Simultaneous decoding of WSPR on LF
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Status: O

Hugh ,

By 'time'  I was more  concerned  with the  synchronisation , along the 
time  line ,  ' clock jitter '  in  computer speak .. if sections  of the 
time  line are displaced due to  IRQ  action or similar , you  could reduce 
the  system's ability to reach  maximum  - s/n

Opera requires  ~ min of  40%  capture of the  Tx signal ,  along the  time 
line ,  either  randomly , blocks or 40/60 split , using manchester coding , 
each data 'bit'  is  self-sync , so it impossible to  'loose' lock.. where 
as a conventional system would need to  establish  sync at the start ,...... 
as long as 40% of the opera recovered [or sent !] plays ball ,  it  will 
decode ,  [ or detect for  dynamic, has the  same 40% requirement]

 or in wspr  case , sync is  provided  externally If the  time line is  then 
jumped , the  system will  no  be  able to recover the  data  , and  as in 
the   2 pass  wspr , unless  the  two  signals  are  exactly  the  same  in 
time  and  coherent phase , the  expected  +3 dB gain cannot be  realised .

73-G,

--------------------------------------------------
From: "LineOne" <dhchurch@lineone.net>
Sent: Saturday, October 22, 2016 11:20 AM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Simultaneous decoding of WSPR on LF

> I checked the PC time and it seems that the Realtek software stops "net 
> time" from loading on occasions so, for another reason as well, I 
> eventually found some older Realtek software that doesn't do this. The 
> software supplied with the motherboard will not share the "line out" with 
> any software if it's used for, as I do, a small speaker amplifier. It has 
> to have the Realtek drivers loaded otherwise no audio at all.
>
> 73,  Hugh
>
> On 21/10/2016 23:27, Graham wrote:
>> May be  down to  time  Hugh ,
>>
>> Opera  is  free running, so absolute time  reference has no effect on the 
>> system  performance ..
>>
>> Stephan   should have the  solution, his night  garden uses similar 
>> things .
>>
>> The other is  cpu loading ?
>>
>> 73-G,
>>
>> --------------------------------------------------
>> From: "LineOne" <dhchurch@lineone.net>
>> Sent: Friday, October 21, 2016 11:10 PM
>> To: <rsgb_lf_group@blacksheep.org>
>> Subject: LF: Simultaneous decoding of WSPR on LF
>>
>>> So far I've been decoding Opera32, WSPR2 and WSPR15 simultaneously on an 
>>> old IBM "Thinkpad" in the shack. This weekend I've managed a wireless 
>>> connection to a desktop PC in the house so only a receiver is running in 
>>> the shack leaving nice, clean signals.
>>>
>>> Decoding Opera 32 is going well (3000km best so far this evening) but 
>>> the PC, with the same operating system and radio software, will not 
>>> decode any WSPR at the same time. I haven't yet tried running just 
>>> WSPR-X (for WSPR2) on it's own but it does show a good signal on the 
>>> waterfall if I arrange a 1.5kHz heterodyne in the shack. Why would a 
>>> supposedly superior computer refuse to cooperate, I suspect the Realtek 
>>> on-board sound card and software is  not actually up to the job?
>>>
>>> 73, Hugh, M0DSZ
>>>
>>>
>>>
>>
>>
>
>