References: <006201cce044$06c16f80$0401a8c0@xphd97xgq27nyf> <3A9A60CAE4EB4355A5B0A30CDA0F450A@JimPC> <AE79F5BD0B964D4CBF8E04AD01E73808@JimPC> <4F287B3F.1040109@talktalk.net> <001b01cce0c1$49ec88d0$0401a8c0@xphd97xgq27nyf> <4F290605.80706@talktalk.net>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
In-Reply-To: <4F290605.80706@talktalk.net>
Message-Id: <B2CE2EB7-7B23-403F-AD0E-47C713FCEFB0@gmail.com>
Date: Wed, 1 Feb 2012 15:52:32 +0000
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Re: Opera v qrs evaluation
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Hi Eddie et al,

There is no doubt that the greatest value of modes like WSPR and OPERA (in a=
ddition to their ability to work with very weak signals) is that monitoring a=
nd reporting is automated and via the Internet. Some may think this is cheat=
ing, but if the aim is to see how signals propagate and what the effect of a=
ntenna or rig changes are, then surely pinging reports via an Internet datab=
ase is perfectly valid. WSPR helped me this way a lot.=20

Good luck with your ongoing tests. There ARE people here who are interested i=
n the results based on good experiments and careful measurements. Sadly Mal i=
s only worried about the size of his kit.=20

73s
Roger G3XBM

-- Via my iPod Touch 4g --

On 1 Feb 2012, at 09:29, qrss <qrss@talktalk.net> wrote:

> Mal
>=20
> Fact. Everyone including G3KEV has missed my QRS3 and QRS10 on 500kHz ever=
y 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.
>=20
> Please be technical not emotional about the subject it doesn't help.
>=20
> 73 Eddie
>=20
>=20
> 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 o=
r
>> nothing and I have noticed at times a TRACE but NO DECODE.
>> I wonder what your next distortion of the facts will be
>> g3kev
>>=20
>> ----- 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
>>=20
>>=20
>>> Dear Jim, Rik, Laurence
>>>=20
>>> 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-code=
d.
>>>=20
>>> 73 Eddie G3ZJO
>>>=20
>>>=20
>>> On 31/01/2012 22:51, James Moritz wrote:
>>>> Dear Eddie, LF Group,
>>>>=20
>>>> 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.
>>>>=20
>>>> Cheers, Jim Moritz
>>>> 73 de M0BMU
>>>=20
>>=20
>>=20
>=20
>=20