Message-ID: <CC0B693B69CE4020ACA680ADBAD07B99@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <000701c962f1$b79b04c0$4201a8c0@home> <016901c963c8$1c543720$8d01a8c0@JAYDELL> <494EE0A8.5040607@telus.net> <004501c963cf$24a20db0$8d01a8c0@JAYDELL> <000701c96492$04944b00$4201a8c0@home> <002201c96495$a77afe10$8d01a8c0@JAYDELL> <000b01c9649c$6066dec0$4201a8c0@home> <000501c96533$75ad5100$4201a8c0@home> <00a201c96539$eed9c440$0301a8c0@mal769a60aa920> <fc7eccec0812231419p13a4ee36x5456c10c5ed1a04c@mail.gmail.com>
In-Reply-To: <fc7eccec0812231419p13a4ee36x5456c10c5ed1a04c@mail.gmail.com>
Date: Tue, 23 Dec 2008 22:37:43 -0000
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Subject: Re: LF: Re: Re: WSPR
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Andy,

I would say that's not quite the case .. I found on top band a while ago 
that 'a lot' of cw inside the 200 hz search band would prevent decodes of a 
relatively strong wspr signal , ie showing well on the display and on 
speclab  .. ok it was during a cw contest but all the same , the cw signals 
did not cross  the wspt trace.....

I had some odd  decodes 4 mtrs  70.030 and after posting a note in a few 
groups a lot of reply's spoke of false decodes which, till then I had not 
associated with the wspr system.. I'm still not totally convinced, but 
without knowing the full depth of the 'best fit' routines its not 
immediately obvious.

I noted in the decodes from the usa ,  (BadMsg)    appears , is this a tx 
code or rx de code error message ?

G ..

--------------------------------------------------
From: "Andy Talbot" <andy.g4jnt@googlemail.com>
Sent: Tuesday, December 23, 2008 10:19 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: Re: WSPR

>
> No,
> the receiver can demodulate all the 6Hz-wide signals that may be
> present within the 200Hz Rx search bandwidth.
>
> The operational Rx bandwidth for receiving purposes is 6Hz, generated
> by the DSP filtering, so interfering signals within the 200Hz
> bandwidth will not corrupt the wanted signal unless it actually
> overlaps it, and places enough jamming energy into the 6Hz passband.
>
> Andy  G4JNT
> www.g4jnt.com
>
>
>
> 2008/12/23 mal hamilton <g3kevmal@talktalk.net>:
>> Tnx Jim for the info but in actual fact 200 hz is required and not only 6 
>> hz
>> as some have specified, in other words if there was other acty within the
>> 200 hz bandwidth it would corrupt the target signal.
>> mal/g3kev
>>
>> ----- Original Message ----- From: "James Moritz"
>> <james.moritz@btopenworld.com>
>> To: <rsgb_lf_group@blacksheep.org>
>> Sent: Tuesday, December 23, 2008 7:19 PM
>> Subject: LF: Re: WSPR
>>
>>
>>> Dear Mal, LF Group,
>>>
>>> The transmited WSPR signal has a bandwidth of about 6Hz.
>>>
>>> SSB mode is used for transmission in order to translate the soundcard
>>> audio
>>> to the appropriate RF frequency. But the signal bandwidth remains 6Hz
>>>
>>> At the receiver, a 200Hz bandwidth is extracted from the receive audio 
>>> by
>>> the DSP routines in the PC. This allows the transceiver to switch from 
>>> TX
>>> to
>>> RX without changing modes.  (In my case, I have configured the rig to 
>>> use
>>> the 250Hz CW filter as the "narrow SSB" filter, so the RX bandwidth is
>>> only
>>> 250Hz anyway).
>>>
>>> This 200Hz of bandwidth is then sub-divided into numerous narrow 6Hz
>>> sub-channels, that can be simultaneously processed to receive lots of 
>>> WSPR
>>> beacons operating simultaneously on slightly offset frequencies within 
>>> the
>>> overall 200Hz range. That's the beauty of DSP.
>>>
>>> Overall, this means one transceiver can alternately transmit a WSPR 
>>> beacon
>>> signal and then receive many different WSPR signals within a 200Hz 
>>> range,
>>> during different 2 minute time slots.
>>>
>>> Cheers, Jim Moritz
>>> 73 de M0BMU
>>>
>>>
>>
>>
>> --------------------------------------------------------------------------------
>>
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - http://www.avg.com
>> Version: 8.0.176 / Virus Database: 270.10.0/1861 - Release Date: 
>> 12/22/2008
>> 11:23 AM
>>
>>
>>
>
>



>
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> Checked by AVG - http://www.avg.com
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> 12/23/2008 12:08
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