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From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <201204261339.q3QDd0QR027303@vivaldi19.register.it>
In-Reply-To: <201204261339.q3QDd0QR027303@vivaldi19.register.it>
Date: Thu, 26 Apr 2012 15:28:39 +0100
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Subject: Re: LF: info about better digital mode in 2200m band
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Ok Andrea,

Op simply (ish)  uses  time  to  determine  the  s/n  level , by virtue of 
the  power / time .. the time's  in data  terms  are  very  long , but  as 
compared to  existing  systems is a  improvement ..

For  each  X2 time,  there is a  3 dB advantage , OP2  = -26 dB   OP4  -29dB 
OP8  -32dB  etc
wspr  minimum  decode  -32  / -34 dB .. so  that's  -8 or -6 db   correction 
factor.

Interestingly  this  puts the OP4H  8Khz  mode  past -50 dB  decode level if 
you  comparer to the  higher 'standard'

Remembering  wspr  may  be peak  reading and  Op  average , its also 
possible  Op will  decode below the  stated level's, due to the  average s/n 
measurement.

One of  the main   thing are , stations are  getting  good results  with the 
minimum of hardware, overall frequency  stability requirements  for  OP32 
is  approx  +/- 2 Hz  over the  32  min  period , widening  as  the  time 
reduces. ( I think its a linear ratio ..but  will  check, that  makes  OP4 
(500Khz)  +/-  16 Hz)

Q what Ae and  power  is used ?

Good luck , G..

--------------------------------------------------
From: "DP engineering" <a.dellimmagine@dp-engineering.it>
Sent: Thursday, April 26, 2012 2:39 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: info about better digital mode in 2200m band

>
> I know for sure that lentus and K1JT's modes are comparable.
> They both use the "stadard" definition:  signal power/noise power over 
> 2500Hz band/signal
>
> In my mind roughly : Opera2=WSPR, Opera8=WSPR-6db, Opera32=WSPR-12db
> Do you think it's correct?
>
> Opera2=WSPR states that Opera il less efficient (same period for less 
> information). But Opera don't require any kind of syncronization.
>
> LENTUS = WSPR - 7db  For me it's reasonable (same information, more time 
> to trasmit it,  no pseudo-random sequence for syncronization, less "code 
> gain" but more "symbol" gain)
>
> OK, making comparisons is not so easy... maybe also my conclusions are 
> discutable
>
> I5ZPO / IW5BHY Andrea
>
>
>>----- Original Message -----
>>From: g8fzk@g8fzk.fsnet.co.uk
>>To: rsgb_lf_group@blacksheep.org
>>Data: Thu, 26 Apr 2012 13:49:32 +0100
>>Subject: Re: LF: info about better digital mode in 2200m band
>
>>Just one or two  thing's to  check
>>
>>The  S/N  readings  produced  by  Opera are  referenced to the  SIM - PATH
>>software , so  s/n  levels  shown are  calibrated to a different  standard
>>
>>The  original  system was  calibrated to be  similar  to fldigi / wspr , 
>>but
>>after a  series of  tests   by  members of the  yahoo digital  group, 
>>Jose
>>, felt  these  levels  where  not  realistic and  re calibrated  , giving 
>>a
>>lesser reading. Im not  sure  as  what Patrick  has  referenced his  modes
>>to, but if lentus  system is  similar to  jt65 etc  , then you  will  need
>>to add a conversion factor.
>>
>>As a yard  stick  ,  OP2 @  -26dB  S/N   is  similar to  WSPR,
>>
>>Also   note the  Op  s/n  levels  are  all  indicated  as  Average , over
>>the  time  line , so  if  you  only  decode  50% of the  transmission
>>(sufficient for  decode) then the  s/n  level  will show  as  -3dB 
>>compared
>>to 100% decode
>>
>>The  Opera  system  has  also a  QSO  mode  using  the  same  coding
>>system, but  is set to  120 second  TX period  for  15 characters
>>and  operates  round  the  -20 dB s/n  level
>>
>>Set Op to  500 Khz  for  access to the  qso  mode  if wanting to try, but
>>you do need -20 dB s/n for  decode,
>>
>>ROS-MF7&2   mode  is  available ,multi tone, 99Hz  b/w at  2 baud , this
>>operates at  the  same  S/N   of  WSPR  , but  needs  AUDIO/SDR   Tx
>>facility.  however it is  a  live rtty mode  with no  'time frame' or 
>>'time
>>locking' MF-7 is  6 / 7  dB less, but  has a  chr rate  similar to
>>psk31....
>>
>>73 -G..
>>
>>
>>>>>The  OP system  is  still  under  development , so  if users  have  any
>>>>>requirements  etc , pls  write in<<<
>>
>>
>>--------------------------------------------------
>>From: "DP engineering" <a.dellimmagine@dp-engineering.it>
>>Sent: Thursday, April 26, 2012 1:10 PM
>>To: <rsgb_lf_group@blacksheep.org>
>>Subject: Re: LF: info about better digital mode in 2200m band
>>
>>> Hi Mauro,
>>> At the present, I think Opera is the most widely used.
>>> WSPR reaches -27db, not enough for covering long distances on LF. So, 
>>> it's
>>> rarely used.
>>> Opera and lentus perform better:
>>> Lentus reaches -34db for  5 minutes trasmission, Opera8 and Opera32 
>>> (8/32
>>> minutes trasmission)  reach -32db and -38db respectively.
>>> In my opinion, technically speaking, Lentus is the best (it is also very
>>> good for making QSO). Lentus requires a very good syncronization among
>>> station. In addition, if you use a SDR, you may have some problems due 
>>> to
>>> the latency of the SDR.
>>> Instead, Opera is very simple and very close to the "regular" QRSS.
>>>
>>> So, my conclusions are:
>>>
>>> For medium distance beacons : Opera8 or Lentus
>>> Foe long distance beacons : Opera32
>>> For QSO : Lentus
>>>
>>> best 73's'
>>> I5ZPO Gino (operated by IW5BHY Andrea)
>>>
>>>
>>>>----- Original Message -----
>>>>From: ik1wvq@stmb.it
>>>>To: rsgb_lf_group@blacksheep.org
>>>>Data: Thu, 26 Apr 2012 12:27:27 +0200
>>>>Subject: LF: info about better digital mode in 2200m band
>>>
>>>>Hi,
>>>>
>>>>what is the better digital mode for starting listening 137 KHz
>>>>band  as "reverse beacon" (no TX)??
>>>>("better" = greater number of active stations in Europe)
>>>>
>>>>WSPR ?? LENTUS ?? OPERA ??
>>>>
>>>>what frequency is utilized for those modes ???
>>>>
>>>>thanks in advance to all ..
>>>>
>>>>73 de Mauro IK1WVQ
>>>>
>>>>P.S.: my RX station is : PA0RDT 8 meters over the roof, RACALL 1792
>>>>.. not great station at all ..
>>>>in QRSS mode the only station what I can receive is the "broadcast
>>>>(HI!)" beacon of Stefan DK7FC .. NO OTHER ...
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>