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Date: Mon, 17 Jul 00 18:07:10 MET
Message-Id: <hd_2000_192A>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
Ham-Digital Digest Mon, 17 Jul 2000 Volume 2000 : Issue 192
Today's Topics:
12 Khz digital IF filter
Argh! Need help calibrating MFJ TNC
CW versus hi speed digital etc.
Forget HF & CW - Think Digital (21 msgs)
LPFM Application Info...
psk31 and vox
PSK31 in french (soon in english)
Send Replies or notes for publication to: <Ham-Digital@UCSD.Edu>
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Archives of past issues of the Ham-Digital Digest are available
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We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party. Your mileage may vary. So there.
Loop-Detect: Ham-Digital:2000/192
----------------------------------------------------------------------
Date: 16 Jul 2000 20:57:23 GMT
From: chramade@aol.com (ChRAMADE)
Subject: 12 Khz digital IF filter
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"
------------------------------
Date: Sun, 16 Jul 2000 21:01:53 GMT
From: ken.hoover@yale.edu (Ken Hoover)
Subject: Argh! Need help calibrating MFJ TNC
This is driving me nuts. I have a MFJ 1276 TNC (basically a 1270C with
PACTOR capability - it uses the same manual) that I'm trying to use for plain
old 1200 baud 2 meter packet. When I got it a while back (from ebay) it would
receive fine but I couldn't connect to everything. Figuring that it was
probably in need of calibration, I started in on the process listed in the
book.
Without elaborating too much on the details, I was able to get the HF and
VHF
modulators aligned fine (using the software-based calibration procedure since
I
don't have an oscilloscope) but the demodulators just are not behaving the way
that the book says they should even though I'm following the process exactly.
If anyone has done this type of calibration on one of these monsters, PLEASE
email me directly. (And no, my ham budget won't accomodate replacing the TNC
so please don't suggest that.)
Thanks in advance for any help you can give!
- 73 Ken KE1LR
------------------------------
Date: Mon, 17 Jul 2000 00:12:55 GMT
From: kleing@NOSPAMqualcomm.com (Klein Gilhousen)
Subject: CW versus hi speed digital etc.
On Sat, 15 Jul 2000 20:47:13 -0500, "Peter O. Brackett"
<ab4bc@ix.netcom.com> wrote:
[...]
>So I say CW channel coding is ternary, not binary.
Peter,
Here's a little more on the binary/ternary issue.
Consider that Morse can be defined in binary this way without mixing
up the definition of modulation and code:
Signaling elements: a unit (dot) length pulse and a unit length
silence. Let's define the pulse as a 1 and silence as 0.
The code:
A: 10111000
B: 111010101000
C: 11101011101000
D: 1110101000
E: 1000
F: 101011101000
G: 111011101000
H: 1010101000
I: 101000
etc.
Looked at this way, Morse has some interesting properties. Notice
that every character starts with a 1 and ends with 3 zeroes.
Hmmmm....kinda like TTY. In fact, you could take this code and
modulate using binary FSK instead of OOK. Or use binary PSK. Not
saying you ought to, just that you could.
This is just as much a binary code as ASCII, just a different one.
So, my conclusion is that you can certainly define Morse as a binary
code if you want to. I suppose you can also define it as ternary (or
whateverary) if you want to. (I'm just not quite sure why.)
On the matched filter issue: wouldn't a matched filter for 20 wpm
Morse have a bandwidth of just 33 Hz? Well, at least that's the
frequency of the dot clock in the keyer so that is the baud interval.
My FT1000D's 250 Hz filter doesn't come close to being matched for
that.
But all this is dangerous thinking. Next, it may lead to someone
designing a really good software decoder for Morse for all the new
5wpm Extras. ;-) ;-) (Lord knows I need one.)
Klein, WT6G
------------------------------
Date: Sun, 16 Jul 2000 09:05:05 -0400
From: "Bob Lewis" <rlewis@staffnet.com>
Subject: Forget HF & CW - Think Digital
> Young lady, making a simple spark gap and a crystal radio
> receiver to send and transmit CW ....
That assumes that you consider a spark gap and a crystal radio "modern
digital communications" - I don't. I enjoy CW but most of the time
it's not the most efficient means to transfer data. How long do you
think it would take to send a 1 MB binary file at 20 WPM CW and what
are the odds of it being received "error free"?
------------------------------
Date: Sun, 16 Jul 2000 09:24:12 -0500
From: "Peter O. Brackett" <ab4bc@ix.netcom.com>
Subject: Forget HF & CW - Think Digital
Bob:
Heh, heh...
How much "real" information is in that 1 MB file?
Sorry...
My point really wasn't about that issue. My point was about "efficiency"
and its' "simplicity".
Boy scout, survival mode kind of issues, minimalist requirements for
communications, etc...
Most modern up to date technologists wouldn't know how to put together a
workable communications system on a life raft, mountain pass, desert island,
or whatever... without 10 million transistors and 100 MB of code... A
really knowledgeable person who understands how things work at a basic lever
could do that with a few pieces of readily available junk. Lifeboat hand
cranked radios...
So what's your point?
Peter K1PO
"Bob Lewis" <rlewis@staffnet.com> wrote in message
news:0jic5.1580$Mt6.4084@newsfeed.slurp.net...
> > Young lady, making a simple spark gap and a crystal radio
> > receiver to send and transmit CW ....
>
> That assumes that you consider a spark gap and a crystal radio "modern
> digital communications" - I don't. I enjoy CW but most of the time
To be continued in digest: hd_2000_192B
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