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" <[email protected]>
To: <[email protected]>
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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