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Date: Thu, 5 Jan 2012 22:13:32 +0000
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From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Dual OPERA Beacon 500K OP2+OP15
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Morally, sort of, and certainly for technical and self training reasions,
I think we should only be using modes we know the innards of.
Thei should apply to amateur radio generally - there is no excuse for
authors keeping schemes to themselves (except perhaps financial,
patent and IP reasons -lilke D-STAR -  but that would be a case of
commercial systems being used anyway)

However, having taken a cursory look at the coding trying a variety of
callsigns (like ANON, ANOB, ANOC, BNON etc)
it doesn't look that complicated, and appears to have a simple
systematic part to it.

The callsign appears to take up the first 33 bits, which seems about
right for a simple uncompressed letter + character encoding (unlike
WSJT's systematic and more-rigourous scheme for getting teh callsign
into 28 bits)     There doesn't seem to be interleaving.   The coding
seems the same for each speed setting, with around 230 bit periods per
transmission. And  I'm a bit more convinced its something like
Manchester coding, in which case that means only 130 active bits,
although the Manchester like coding, if soft-decision decoded
sensibly, could add something to the error correction process.

But any proper code-breaking would take ages unless its possible to
turn the output tones into '1's and '0'  for software analysis so
don't hold your breath !

Andy
www.g4jnt.com


On 5 January 2012 21:29, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:
> Gary,
>
> is=A0there=A0any=A0documentation=A0about the Opera coding ?
> If=A0not=A0this mode=A0would=A0be=A0illegal=A0for=A0radioamateurs, at=A0l=
east in Belgium.
>
> 73, Rik=A0=A0ON7YD - OR7T
>
> ________________________________
> Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.o=
rg]
> namens Gary G4WGT [g4wgt@tiscali.co.uk]
> Verzonden: donderdag 5 januari 2012 22:18
> Aan: rsgb_lf_group@blacksheep.org
> Onderwerp: RE: LF: Dual OPERA Beacon 500K OP2+OP15
>
> Hi Minto,
>
> Sorry that you seem to be experiencing a problem from the Opera beacons.
>
> There should be no QRM from Opera as the Tx sub-band is 501.300 to
> 501.700kHz & would not interfere with your CW QSO's on 502.000 & 502.500k=
Hz.
>
> Also the Opera software will not Tx on an occupied freqency due to it's
> agile frequency feature, it will automatically QSY to a clear frequency
> within it's sub-band before Txing.
>
> I am monitoring the frequency & I have not seen any Opera signal outside =
the
> limits which I have mentioned above in this email.
>
> 73, Gary - G4WGT.
>
>
>> From: minto.witteveen@gmail.com
>> To: rsgb_lf_group@blacksheep.org
>> Date: Thu, 5 Jan 2012 21:47:02 +0100
>> Subject: Re: LF: Dual OPERA Beacon 500K OP2+OP15
>>
>> I am not convinced that this Opera beaconing (experiment??) is a good
>> thing,
>> that is to say not as it is currently conducted on 500.
>> For some reason the frequencies that are used are smack in the middle of
>> the
>> =91normal=92 CW part of 500. Why not go to the (upper) band edge like WS=
PR?
>> Already I have experienced some annoying interference, after calling CQ =
on
>> 502 and/or 502.5 I heard more than one Opera sig on 502.0 and 502.2 =96
>> right
>> through my CQ. Probably no operator listening or Opera not checking the
>> QRG?
>> Just now I heard PA3CW calling CQ on 502.00. Halfway through his CQ an
>> Opera
>> beacon started ON EXACT THE SAME FREQUENCY. Dick PA3CW did respond (with
>> ...--..) to the CW-like Opera beacon but to no avail..
>>
>> So please let=92s agree on the band edges for these types of beacons. Th=
ey
>> have their use and are fun to work/play with, but as I understand it the=
y
>> do
>> not need much bandwidth so moving to a confined area the band edge(s)
>> should
>> not be a problem.
>> And select one. I see (hear) an Italian beacon day and night somewhere
>> above
>> 501. Another 500 Hz of the 3 KHz allocated lost for CW.
>>
>> Regards, Minto pa3bca
>>
>>
>> ------------------------------------------------------------------------=
--
>> Ceterum censeo Carthaginem delendam esse
>>
>> From: Graham
>> Sent: Thursday, January 05, 2012 18:35
>> To: rsgb_lf_group@blacksheep.org
>> Subject: LF: Dual OPERA Beacon 500K OP2+OP15
>>
>> All
>>
>> Running dual beacon OP 2 and OP15
>>
>> on 500K usb dial set
>>
>> 5 watts carrier power per mode/carrier to 40 ft top loaded vertical
>> erp ? anyone guess ?
>>
>> Reports welcome
>>
>> 73 -Graham
>> G0NBD
>>
>>
>>