I ordered from Inrad 6KHz AM filter.
I bought on ebay a Astron RS-35M Power Supply
I figure even if it has something wrong with it,
it will be easy to fix.
Thank you for all the help.
It's been mind bogglingly interesting.
Larry
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On 4/23/2014 10:47 PM, Walter Underwood wrote:
The usual approach is to choose a filter with steep skirts that is wider than
you need, so you can use the middle of the passband where the phase response is
not so bad. Then do additional filtering in DSP, where you can have good
amplitude and ph
On 4/23/2014 10:13 PM, Larry Lopez wrote:
Some of the wider filters in that paper are pretty good.
The narrowest filters are not so good.
The flat part of the passband has constant group delay.
The skirts are awful
Nothing at all surprising. In general, phase distortion (group delay)
goes alon
In analog filter design, you get to choose between good phase performance and
good amplitude performance. You can't have both. If you want a flat passband
and steep skirts, you'll get wonky phase. The Chebyshev filter is a good
example of controlling amplitude response. If you want good phase pe
Some of the wider filters in that paper are pretty good.
The narrowest filters are not so good.
The flat part of the passband has constant group delay.
The skirts are awful
For narrow filters it starts going weird.
Larry Lopez [via Elecraft] wrote:
> It turns out that the Elecraft 2.7 KHz 5 pole
And just for the record.
If you are going to optimize for bandpass shape
then you are going to have non constant group delay.
If you add more crystals you can have both and the
filters would be more expensive.
It's a compromise and we demand this compromise.
A phase linear filter looks bloody a
It turns out that the Elecraft 2.7 KHz 5 pole filter is the winner
according to:
http://www.qsl.net/gm3woj/k3filtertestssn2203.pdf
which makes me want to make my own filter.
Still, I'm going to keep the 400Hz 8 pole filter which
is coming with my S/N 27xx Elecraft Radio !!!
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> Joe is well aware of the issue. Hiss answer that the phase distortion
> issue trumps S/N ratio.
K1JT is correct as it relates to EME where one does not generally have
strong interfering signals. Remember the detection bandwidth in WSJT-X
is on the order of a few Hertz - not the 2.8 to 5 KHz a
I've already recanted on S/N ratio.
I was an idiot.
I kept skipping the part where the PC is also a DSP.
Sven's post on the other thread also brought my attention to it.
The only thing left is strong carriers overloading the receiver.
I'll go find WSJT and learn some more.
Thanks again Jim.
Larr
On 4/21/2014 1:59 PM, Larry Lopez wrote:
But what about:
very weak signals reducing the bandwidth increases the signal to noise
ratio.
very strong signals reducing the bandwidth can prevent the DSP chain from
desensitizing the receiver and/or saturating the a/d converter.
Joe is well aware of
This is wrong:
Even though a wide filter lets in a lot of noise
the DSP can get rid of it.
The WSJT software is a DSP.
It has it's own filters and the DSP on the K3
is not needed.
So the only job of the K3 is to produce a clean
wideband signal for the WSJT.
You would still have to prevent
Now with EME this isn't much of a problem I would think.
If no strong signals are present then the DSP wold be able
to shrink the bandwith just fine.
Even though a wide filter lets in a lot of noise
the DSP can get rid of it.
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Thank you Jim,
I read all your posts.
I'll quote your quote of K1JT again here:
K1JT says that it is best to run the radio broadband and let the WSJT
software provide the needed selectivity in its decoding algorithm. The
reason is simple -- phase shift can cause decoding errors, filte
On 4/21/2014 1:08 PM, Larry Lopez wrote:
I've been using the filters on my FT1000D
and I do notice the 250 Hz one doesn't
seem to help JT65HF as much I would
have expected.
Any ideas,
Read previous posts about this from W4TV and myself this morning.
73, Jim K9YC
_
I'm wondering if any digital filters exist for the K3.
I'm wondering which common filters work best on the K3.
I'm interested in JT65 and JT9
linear phase delay and constant group delay
means that the signal of different frequency
take the same time to go through the filter
so that the waveform i
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