| |
PA2AGA > HDDIG 08.07.00 16:13l 219 Lines 7324 Bytes #-9406 (0) @ EU
BID : HD_2000_181A
Read: GUEST
Subj: HamDigitalDigest 2000/181A
Path: DB0AAB<DB0SL<DB0RGB<DB0MRW<DB0SON<DB0ERF<DB0BRI<DB0SM<PI8DAZ<PI8GCB<
PI8WNO<PI8HGL
Sent: 000708/1045Z @:PI8HGL.#ZH1.NLD.EU #:59750 [Den Haag] FBB $:HD_2000_181A
From: PA2AGA@PI8HGL.#ZH1.NLD.EU
To : HDDIG@EU
Date: Fri, 07 Jul 00 21:35:39 MET
Message-Id: <hd_2000_181A>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
Ham-Digital Digest Thu, 6 Jul 2000 Volume 2000 : Issue 181
Today's Topics:
BEWARE - 'Radioraft' Software (author is a pain in the neck)
CW versus hi speed digital etc. (12 msgs)
Digipan Software for PSK-31
Field day review (MixW rocks)
For Sale: MFJ-1278
FS: OptoTrakker Decoder
Mobile electronics at the best prices anywhere.
MP3 Player Competition 490
Tech question - AM/FM digital radio
Send Replies or notes for publication to: <Ham-Digital@UCSD.Edu>
Send subscription requests to: <Ham-Digital-REQUEST@UCSD.Edu>
Problems you can't solve otherwise to brian@ucsd.edu.
Archives of past issues of the Ham-Digital Digest are available
(by FTP only) from ftp.UCSD.Edu in directory "mailarchives/ham-digital".
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:2000/181
----------------------------------------------------------------------
Date: Wed, 5 Jul 2000 08:21:02 -0500
From: "BD" <bodu@pobox.com>
Subject: BEWARE - 'Radioraft' Software (author is a pain in the neck)
Yeah, but that's not the original shareware.. Some "80's era" people had the
idea that if programmers released fully-functioning software, that people
would be willing to pay after they'd used it for a few weeks. I guess it
turned out not to be as they expected tho.. I personally know of no one who
paid for most of the stuff they got as shareware.. Only a very few who paid
for any of it.
"Roger Halstead" <rdhalste@tm.net> wrote in message news:zUz85.3920>
> Generally there are share ware programs that won't do as much as the "for
> sale" version and sometimes it is difficult to tell the demo from the
> shareware version. <:-))
------------------------------
Date: Wed, 5 Jul 2000 06:37:58 -0500
From: "Peter O. Brackett" <ab4bc@ix.netcom.com>
Subject: CW versus hi speed digital etc.
Hamish:
If that is the postition you wish to take, then...
In modern digital transmission systems, HDSL transceivers use multiple level
PAM, ADSL transceivers use either CAP [A variant of multilevel QAM], or DMT
[Discrete Multi-tone] multiple QAM with up to 512 carriers of multilevel
QAM, VDSL uses QAM or DMT, etc.. etc...
Do you assert that these modern high speed digital techniques are digital or
analog communication systems?
Peter K1PO
"Hamish Moffatt VK3SB" <hamish@cloud.net.au> wrote in message
news:TyD85.980$I43.4778@news1.eburwd1.vic.optushome.com.au...
> Peter O. Brackett <ab4bc@ix.netcom.com> wrote:
> > Often the mode comparators, opportunistically take the "modes" apart in
> > their comparisons and compare a whole "mode" to a modulation. Say in
this
> > case comparing OOK to PacTor. OOK is just a modulation, while PacTor is
a
> > whole mode repleted with several stages of encoding, embedded modualtion
and
> > channel coding, etc...
>
> OK, but that's exactly what YOU are doing. When someone says CW uses
> on-off keying and is inefficient, you say CW could easily be applied to
> PSK or FSK instead. The fact is that Morse code is used with OOK
> 99.999% of the time.
>
> You say CW is digital because it is on-off keyed. We can represent
> any signal in a digital fashion, though -- that's simply called sampling.
> The EPROM repeater ID example just demonstrates that CW can be sampled
> like any other analogue signal.
>
>
> Hamish
> --
> Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Wed, 5 Jul 2000 06:49:47 -0500
From: "Peter O. Brackett" <ab4bc@ix.netcom.com>
Subject: CW versus hi speed digital etc.
Hamish:
FSK versus OOK.
Low peak to average ratio in the transmission of information is plainly
inefficient!
As Dr. Shannon pointed out so many years ago, the most efficient signalling
waveforms are those which emulate as closely as possible the characteristics
of Gaussian Noise.
Hamish, the peak to average ratio of Gaussian Noise [As measured by the
ratio of the mean to the standard deviation.] is certainly not unity, and it
is quite high approaching 12 dB or so...
And we see that in all of the most recent and modern digital communications
systems with high bandwidth efficiency, from the V.32/V.90 voice band modems
to the new ADSL DMT modems, they all use signalling waveforms with very high
peak to average ratios. Check it out...
The only thing that low peak to average ratio signals [constant envelope,
such as PSK or FSK] have going for them is that they can be efficiently
amplified by non-linear amplifiers. Their communications efficiency in
bps/Hz stinks! No modern high bandwidth efficiency systems use such simple
systems.
Hence OOK, is potentially much more efficient than FSK...
Hope this helps....
Peter ["The CW is digital guy"] K1PO
"Hamish Moffatt VK3SB" <hamish@cloud.net.au> wrote in message
news:wzD85.981$I43.4778@news1.eburwd1.vic.optushome.com.au...
> CAM <W6RCA@mindspring.com> wrote:
> > Hamish Moffatt VK3SB wrote:
> >> I don't see any advantage in OOK.
>
> > Do you see any advantage to FSK? For the same *average* power
> > output level, OOK and FSK have the same S/N performance.
>
> Doesn't the same average power require significantly higher peak power
> in the case of CW though?
>
>
> Hamish
> --
> Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Wed, 5 Jul 2000 06:42:14 -0500
From: "Peter O. Brackett" <ab4bc@ix.netcom.com>
Subject: CW versus hi speed digital etc.
Hamish:
With all due respect my friend, you are absolutely correct!
I admit that I have lost my perspective... heh, heh...
Well it seems now that you are "on to me"! The jig is up... I must admit
it....
Actually my only motivation in opening this thread was to try to get the CW
forever "controversy" going again over here on this nice digital NG!
I am truly sorry for my nefarious ways....
Peter K1PO
[snip]
> > CW has become far to much of an "emotional" issue for many, they have
lost
> > their sense of perspective.
>
> I respectfully submit that your comment applies mostly to you!
>
>
> Cheers
>
> Hamish
[snip]
------------------------------
Date: Wed, 05 Jul 2000 07:14:43 -0500
From: CAM <W6RCA@mindspring.com>
Subject: CW versus hi speed digital etc.
Hamish Moffatt VK3SB wrote:
> Doesn't the same average power require significantly higher peak power
> in the case of CW though?
Yep, or another way to say it is: Because of amplifier maximum dissipation
limitations, users of FSK are forced to reduce their power output level by
3dB below their maximum CW output level. When one says it that way, FSK
doesn't sound nearly as good, does it? :-)
--
http://www.mindspring.com/~w6rca
------------------------------
Date: Wed, 05 Jul 2000 07:24:38 -0500
From: CAM <W6RCA@mindspring.com>
Subject: CW versus hi speed digital etc.
To be continued in digest: hd_2000_181B
Read previous mail | Read next mail
| |
