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PA2AGA > HDDIG 19.07.00 17:51l 163 Lines 6083 Bytes #-9311 (0) @ EU
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Subj: HamDigitalDigest 2000/193A
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To : HDDIG@EU
Date: Wed, 19 Jul 00 14:26:25 MET
Message-Id: <hd_2000_193A>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
Ham-Digital Digest Tue, 18 Jul 2000 Volume 2000 : Issue 193
Today's Topics:
12 Khz digital IF filter
CW versus hi speed digital etc. (2 msgs)
Forget HF & CW - Think Digital (3 msgs)
FS: Hamcom/JVFAX Demodulator with Software
Guide to the rec.radio Newsgroups
New Online Auction Site With Radio Category
psk31 and vox
SCMS how to get around
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We trust that readers are intelligent enough to realize that all text
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policies or positions of any party. Your mileage may vary. So there.
Loop-Detect: Ham-Digital:2000/193
----------------------------------------------------------------------
Date: Tue, 18 Jul 2000 10:53:30 GMT
From: sdeyoreo@my-deja.com
Subject: 12 Khz digital IF filter
In article <20000716165723.19859.00000119@ng-bk1.aol.com>,
chramade@aol.com (ChRAMADE) wrote:
> What yo ask for can be done by some specific (and free) components. If
this is
> what you are really looking for, just tell me and I will tell you the
address
> where to download them. You can also make a search with "TSound"
>
What I want to do is in real time, bandpass filter this 12Khz input
signal to the soundcard and send it back out the soundcard. I'ld need a
bunch of samples to work on, while the next bunch is loading up.
I was hoping to use VisualBasic. I'm just a beginner in C/C++, but this
might be a project to learn alot about C/C++, so I'ld be willing to try.
I'm an analog, DC to light guy, with some programming background.
Ultimately, I want to make a PC shortwave radio where as much processing
as possible is done in the PC.
I searched on Tsound, but not much, I'll look again.
Appreciate your help and anything new I can learn from you.
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
Date: Mon, 17 Jul 2000 18:08:02 -0400
From: "Ed Hare, W1RFI" <w1rfi@arrl.net>
Subject: CW versus hi speed digital etc.
Klein Gilhousen <kleing@NOSPAMqualcomm.com> wrote:
> In any case, for an optimal implementation, OOK is worse the PSK but
> not all that much.
Unfortunately, most amateur OOK CW is not optimal. Try coming up on
frequency 100 Hz away from a CW QSO in progress and tell me the result. :-)
73,
Ed Hare, W1RFI
------------------------------
Date: Mon, 17 Jul 2000 18:14:21 -0400
From: "Ed Hare, W1RFI" <w1rfi@arrl.net>
Subject: CW versus hi speed digital etc.
Klein Gilhousen <kleing@NOSPAMqualcomm.com> wrote:
> Right. In my case, when I listen to a weak CW signal, I don't see
> much difference between the 2K filter and the 500 Hz filter in the
> absense of interference. But then, I am not one of those "skilled
> operators." I think the human ear and brain probably has the ability
> to do a certain amount of band pass filtering.
Yes, the mental DSP is pretty well known. Under some circumstances, I can
copy a weak CW signal byt ear better in a 2kHz bandwidth than I can in a
narrow bandwidth. Most OOK CW signals in the amateur service have pretty
sharp rise and fall times so the keying sidebands do extend up and down the
band a bit. Keeping them in the passband does add to intelligibility.
Narrowing up the bandwidth eliminates some of the keying sidebands, and thus
eliminates the keying "presence" to me. My mental DSP is able to select the
desired audio tone and by anticipating the rhythm, I think I am able to
mentally differentiate between the keying sidebands and noise and/or QRM in
the wider bandwidth.
Other than the dB lost vs more robust digital modes, there are operator
factors that affect the aural decoding of OOK CW in the other direction --
mental fatigue. I can copy a CW signal right down to the noise, but it sure
isn't pleasant. Most CW QSOs have a signal/noise ratio that is MUCH greater
than it needs to be.
All in all, a very enjoyable, and usually inefficient, mode. :-)
73,
Ed Hare, W1RFI
------------------------------
Date: Mon, 17 Jul 2000 22:02:31 GMT
From: Rich@iwantnospam.org (Rich)
Subject: Forget HF & CW - Think Digital
On Sun, 16 Jul 2000 20:05:12 -0500, CAM <CAM2338@bigfoot.com> wrote:
>Rich wrote:
>> Pray tell - how does one generate CW using only a spark gap transmitter?
>> The last time I looked, they generated damped waves - certainly NOT CW.
>
>I thought so too, Rich, but I was corrected. The later spark gap transmitters
>used a sustained arc and were perfectly capable of CW.
Sure - the ones that were based on the Alexanderson ( and I know
I've really messed up the name... ) alternators, and related
spark-era equipment, but the device specified by the original poster
wasn't in that catagory - and the alternator certainly would be
a major home-brew project, as opposed to a simple interruptor-style
transmitter.
- Rich
------------------------------
Date: Mon, 17 Jul 2000 18:41:29 -0600
From: kenny@kacweb.com (Kenny A. Chaffin)
Subject: Forget HF & CW - Think Digital
In article <nGlc5.1718$Mt6.5234@newsfeed.slurp.net>, rlewis@staffnet.com
says...
> > How much "real" information is in that 1 MB file?
> >
>
> Every byte is "real" information, Peter. If you get one byte wrong the
> program may not run at all.
>
> > My point was about "efficiency" and its' "simplicity".
> >
>
> I guess I missed your point. The previous poster commented on how we
> depend on the work of others (example: ICs) to build a modern digital
To be continued in digest: hd_2000_193B
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