Message-ID: <008601c965ba$cc55fe80$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <008c01c9652f$5e5d4950$0301a8c0@mal769a60aa920> <4951C1F1.3040101@telus.net>
Date: Wed, 24 Dec 2008 11:28:50 -0000
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Subject: Re: LF: wspr
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I did not ask a question about filtering !!!!!!!!!!!!!!!!!!
What I said was why use SSB mode which is 3 khz wide for a 6hz/200 hz wide 
signal when one could take advantage of the receiver narrow CW filter, and 
of course this is filtered further by manipulation of the soundcard by 
software. This is old hat technology and not new.
WSPR was engineered for VHF/UHF with plenty of frequency spectrum available 
and not MF/LF squeezed into a 3 khz slot along with other more robust modes
I am not opposed to any particular transmisson MODE but merely pointing out 
that the advantage claimed by some for WSPR is not justified in some cases 
and my recent observations indicate that I could have read the transmitted 
signal had it been ON/OFF CW, instead I had to wait ages for the signal to 
improve before text printed. This was the case last night with WE2XGR where 
the 2 minute interval trace was good enough to be read in on/off mode CW but 
not strong enough to print most of the time due to slow fade(QSB)
I might even research WSPR further for comparison purposes but I cannot 
imagine that I will get a print out first before I see a trace.


G3KEV

----- Original Message ----- 
From: "Scott Tilley" <sthed475@telus.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, December 24, 2008 5:00 AM
Subject: Re: LF: wspr


> If you could read you would do some research at K1JT's wonderful website:
> http://www.physics.princeton.edu/pulsar/K1JT/
>
> Joe has laboured for many a year on similar projects and has written
> much about his application of the art.  What you will find is that
> research into communication theory that started with CW has taken us 
> here...
>
> To answer your specific question the filtering is done in software. The
> DSP is done in your PC, thereby making filtering in the radio somewhat
> redundant unless you have strong neighbours in the passband.  So using a
> wide SSB filter and the radio in USB makes for easy math in ones head.
> Yes, we digital types use our heads from time to time.
>
> Often with modes like JT65 used on EME and now quite popular on HF one
> wants as much bandwidth as possible in the receiver so you can monitor
> up to the entire band in real time.  So lots of raw bandwidth into the
> computer is a good thing...
>
> All BS aside, you may find the technology very interesting to study and
> you may find that what you discover is that the spirit of the CW
> operator of old is alive and well just evolving with the times.
>
> CW will never die as it has a rich history but it shouldn't be allowed
> to impede the growth of new modes and technology.
>
> You should build yourself a Softrock SDR receiver or even a small
> transceiver kit and witness a true revolution in radio technology.  My
> little 40/30m rig allows me to watch the entire band of either in real
> time.  With some new software you can monitor all of the CW QSOs at
> once...  Pretty cool.
>
> Not to mention you can plug a key into the little box and do what you
> love most and work'm.
>
> 73 Scott
> VE7TIL
>
>
>
>
>
>
>
>
>
>
> mal hamilton wrote:
>> If recent published info is correct, this specifies a bandwidth of 6hz
>> why is USB with a bandwidth of 3 khz necessary to receive this
>> transmission.
>> Surely it would be obvious that CW mode was more appropriate where
>> one could use a narrow filter and dsp processor of a few hertz.
>> I have asked this question before but never got an answer.
>> g3kev
>>
>


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