Of course the K3 has already done most of this, and then thrown Q away
at the last minute. The upconvert is, of course, done by the transmitter.
Alan Bloom wrote:
The other way to get the I/Q signals is with an I/Q modulator.
Basically you run the baseband audio signal into two mixers whose
Several weeks ago, I believe that Wayne posted a message asking what
kind of different uses people were coming up with for their K3. One
thing I've been playing with lately is feeding the signals from two
horizontally polarized antennas at different heights on my tower into
the Main and Sub
Spectrum Laboratory by DL4YHF http://www.qsl.net/dl4yhf/spectra1.html
may be able to do this already.
If the K3's 15 KHz IF output were available from the main and sub
receivers, Spectrum Laboratory could use those to generate the automatic
phase display using the direction finding feature.
What if I fed
the output from two VERTICAL antennas into the K3 receivers in diversity
mode, fed the audio output of both receivers into the A and B channels
of the computer sound card, and used an application that introduced an
adjustable delay in one audio channel before summing the two
David Gilbert wrote:
Playing around with this stuff got me thinking, though. What if I fed
the output from two VERTICAL antennas into the K3 receivers in diversity
mode, fed the audio output of both receivers into the A and B channels
of the computer sound card, and used an
There is another VERY important thing that is being missed by this
discussion. A VERY large component of fading is due to multipath -- that is,
the arrival of more two or more wavefronts that travel different paths, and
thus have slightly different travel times. This produces a phase shift
Thanks for the reply, Alan.
That's interesting. I didn't realize that the two receivers in the K3
had a random phase difference between them even when locked. I noticed
differences in phase delay when I changed frequencies during my tests
with the two horizontal antennas on the tower, but I
Yes, that should work, just switch the sub receiver antenna over to the
main receiver to calibrate the phase. I think you'd get the best
accuracy by looking for a null and then subtracting 180 degrees.
By the way, I think rather than an adjustable delay between the two
channels you need an
On Sep 16, 2010, at 9/169:59 AM, Jim Brown wrote:
A VERY large component of fading is due to multipath -- that is,
the arrival of more two or more wavefronts that travel different
paths, and
thus have slightly different travel times.
Selective fading does not require multipath. The
Hi, Bill.
All true, but I thought that implementing it at audio might have some
advantages ... assuming at least that someone already had the sub receiver:
a. Cheaper. The DXE unit is $500 ... considerably more than that if
you buy the active antennas as well.
b. More versatile. Since the
If you plot the fade statistics for HF signals, however, you find many
times that the result looks much more like Rician fading than Rayleigh.
Jack K8ZOA
On 9/16/2010 2:11 PM, Kok Chen wrote:
On Sep 16, 2010, at 9/169:59 AM, Jim Brown wrote:
A VERY large component of fading is due
Well, I was thinking mostly in terms of CW so I think delay and phase in
the context of a single frequency are essentially the same. I did give
a bit of thought to what it would take to make it work for SSB, though,
and while I am the last person on earth you'd ever want to consult on
math,
Alan has verified your point about relative phase of the two receivers
changing with frequency, so that indeed would have to be accounted for.
A possible mod would be to feed the main synth to both receivers. This
would then only be good for diversity operation, but there would be no
Hi, Lyle.
Thanks for the comment. If nothing else, I'm learning from this discussion.
Actually, until Alan pointed out that they were different, I thought
that the two receivers WERE driven by the same main synth in diversity
mode. If it were possible to have that option when in diversity
On Thu, 2010-09-16 at 11:29 -0700, David Gilbert wrote:
Well, I was thinking mostly in terms of CW so I think delay and phase in
the context of a single frequency are essentially the same. I did give
a bit of thought to what it would take to make it work for SSB, though,
and while I am
Hi Dave,
For some reason I got several copies of your message. I'll go ahead and
post my reply to the reflector since it may be of wider interest.
Yes, another way to get a constant phase shift at all frequencies is to
convert to an I/Q (in-phase/quadrature) signal. One way to do that is
to
That sounds very good, Alan. As I say, I'm not very knowledgeable on
signal processing so all of this is very interesting to me. I guess
whether any of it ultimately turns out to be useful to anyone remains to
be seen.
Regarding the multiple posts ... my ISP has been acting very flaky this
I just rummaged around in Google and found a different paper that
Watterson wrote related to HF propagation and digital modes (almost 10
years after his HF channel model paper):
http://www.its.bldrdoc.gov/pub/ntia-rpt/79-29/79-29.pdf
His conclusion definitely advocates the use of diversity
On Sep 16, 2010, at 1:55 PM, Alan Bloom wrote:
I think there are some free filter design programs on the web that can design
an all-pass network. It may need to be a big filter (i.e. lots of
coefficients) to get good amplitude and phase accuracy over a 10:1 frequency
range (300 Hz to 3
On Thu, 16 Sep 2010 12:06:23 -0700, David Gilbert wrote:
I thought
that the two receivers WERE driven by the same main synth in diversity
mode. If it were possible to have that option when in diversity mode,
that would seem to greatly simplify what I was suggesting.
YES!
Jim K9YC
20 matches
Mail list logo
