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Re: LF: Re: Opera v qrs evaluation

To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: Opera v qrs evaluation
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
Date: Wed, 1 Feb 2012 17:43:47 -0000
Importance: Normal
In-reply-to: <004301cce0c8$ef41a700$0401a8c0@xphd97xgq27nyf>
References: <006201cce044$06c16f80$0401a8c0@xphd97xgq27nyf> <3A9A60CAE4EB4355A5B0A30CDA0F450A@JimPC> <AE79F5BD0B964D4CBF8E04AD01E73808@JimPC> <4F287B3F.1040109@talktalk.net> <001b01cce0c1$49ec88d0$0401a8c0@xphd97xgq27nyf> <4F290605.80706@talktalk.net> <004301cce0c8$ef41a700$0401a8c0@xphd97xgq27nyf>
Reply-to: rsgb_lf_group@blacksheep.org
Sender: owner-rsgb_lf_group@blacksheep.org
Talking of  digging holes , in this case ,   digging  in the noise , the 
OP32  mode  should provide the best s/n   with  decode possible with  over 
50/55% of the  data
Its  possible to  run this  on 500  , just  select  136  and set  the  dial 
frequency  as  500  , the  web -spots will  be showing  136  of  course , if 
your  not  cat  linked , but the  comparison  would  be  most valid at the 
lower end of  the  mode  s/n  ability .. or  on 136  where  there  is quite 
a  lot of  activity using  OP8 , which  is  giving quite  reliable  dx 
decodes . OP4  seems  to  be the  mode  of choice for  500 ,   options  of 
2/8 may  be better  suited as the  majority  of decodes  (Ed apart !)  are 
well  inside the  OP2 limits , with  OP8  perhaps  better suited to  dx ... 
one  for the  'to try list'  , though  development  did take place  with 
2/8  on 500.
Better  would  be a high  power  test  on 136 to  see  the  difference  of 
the  systems  at range, but to  date this  has yet to happen...
Mal is  right , its possible  to  have the  signal  showing on the  screen 
, but  no  decode , if over  50/55% of the  data  is lost then, no  decode 
is  possible, that  is  the  balance  on the  Tx time , too  short  and 
loose  s/n  . too  long  and qsb  might  remove  too  much  data  ..
Keeping a  eye  on the  longer  term  aim of a  'data mode'  the  beacon  is 
providing  useful test  data  and  reliable web linked   s/n  measurements, 
as well  as the seemingly  unlimited opportunity to  rake over the coals  of 
established 'technical facts' ,
Thanks to  Mal  for  running the  tests  , as perhaps,  not too 
unexpectedly  , follows the  usual pie  fight , which has produced some 
useful  analysis, as usual there's  madness  in the method on all  sides ..
Tie  braking  question :)

'you  cannot use  on/off  keying  for a  data  mode'  because ........

73 -G..

--------------------------------------------------
From: "mal hamilton" <g3kevmal@talktalk.net>
Sent: Wednesday, February 01, 2012 10:04 AM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: Opera v qrs evaluation

I would say your qrs on 500 was heard/seen but no one could be bothered to
report it.
I personally do not report QRS beacon acty on any band.
The majority of 500 Beacons are normal CW and I can hear the USA and Canada
frequently and strong enough for a QSO
I thought a PIC was an implement to dig a hole with !!


----- Original Message -----
From: "qrss" <qrss@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, February 01, 2012 9:29 AM
Subject: Re: LF: Re: Opera v qrs evaluation


Mal

Fact. Everyone including G3KEV has missed my QRS3 and QRS10 on 500kHz
every time I have had it on, using this same TX, in fact I removed the
PIC which sends the QRS and inserted OPERA, viola PA0's at 493km decode
me.
Please be technical not emotional about the subject it doesn't help.

73 Eddie


On 01/02/2012 09:10, mal hamilton wrote:
> QRSS does NOT get lost or missed  in the noise as you suggest and one
can
> always see at least part of the information trace, whereas Opera is all
or
> nothing and I have noticed at times a TRACE but NO DECODE.
> I wonder what your next distortion of the facts will be
> g3kev
>
> ----- Original Message -----
> From: "qrss"<qrss@talktalk.net>
> To:<rsgb_lf_group@blacksheep.org>
> Sent: Tuesday, January 31, 2012 11:37 PM
> Subject: Re: LF: Re: Opera v qrs evaluation
>
>
>> Dear Jim, Rik, Laurence
>>
>> Thanks for the information, it does seem from all tests that QRS3 and
>> OP4 are about equivalent.
>> QRS as we know takes a human to notice its there among noise and can
get
>> missed. With OPERA (and WSPR) if there is an RX on in range it's
de-coded.
>>
>> 73 Eddie G3ZJO
>>
>>
>> On 31/01/2012 22:51, James Moritz wrote:
>>> Dear Eddie, LF Group,
>>>
>>> I did a rough and ready comparative test on the "sensitivity" of >>> QRSS3
>>> and Op4 using your back-to-back transmissions. For 500kHz reception,
>>> broadband noise from the broadcast stations just east of here is >>> being
>>> nulled out using a loop oriented N-S. Rotating the loop out of the
>>> null position gives a convenient way of adjusting the SNR on Eddie's
>>> signal. So I increased the noise level until I judged Eddie's QRSS >>> was >>> just fully readable (using 0.3Hz FFT resolution), then left >>> everything
>>> in the same position for 4 transmissions, during which signal and
>>> noise levels stayed nearly constant (see the attachment). Opera
>>> reported an SNR of -31dB on Eddie's Op4 signal for all the
> transmissions.
>>> So, from what Graham said, Op4 may have a small margin in SNR with
>>> these conditions. You could argue about what constitutes "readable"
>>> QRSS, but there can't be more than a few dB difference between this
>>> signal and something indecipherable without prior knowledge. It takes
>>> 4 minutes to send a callsign using Op4; you could increase the dot
>>> length perhaps to 4s  and transmit most callsigns in 4 minutes, which
>>> would gain you about 1.2dB. But for practical purposes I think, in
>>> this test anyway, the two modes are approximately equivalent in their
>>> efficiency in sending callsigns.
>>>
>>> Cheers, Jim Moritz
>>> 73 de M0BMU
>>
>
>




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