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PA2AGA > HDDIG 16.03.00 15:34l 199 Lines 7304 Bytes #-9546 (0) @ EU
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Subj: HamDigitalDigest 2000/73E
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From: pa2aga
To: hd_broadcast@pa2aga
Subject: HamDigitalDigest 2000/73E
X-BBS-Msg-Type: B
That would put the ssb Ebw ratio at 111. For the sake of this
discussion let's compromise and call the bandwidth 2.4Khz thus the Ebw
becomes 83. The Ebw for the Brit's mode would be 200/2.7 or 74 if I
did it right. Which, as far as I'm concerned makes the Ebw discussion
moot, they're even up for ham radio purposes.
>
The discussion now becomes how well would the subject standalone
digital voice mode perform under real operating condx? Will it dig
into the mud and crud in the noise as well as PSK31 and Pactor II do?
If yes it would be a huge improvement vs. ssb. What happens if two of
these digital stations are transmitting on say 500Hz centers at around
the same low signal strengths which is a very common occurance on HF
with all modes?
>
SSB is usable under these condx, NBFM is not as was demonstrated
decades ago thus NBFM was abandoned and HF ham radio moved to ssb. Any
HF digital mode will have to be able to survive the assorted
floggings on 75 & 20m phone and come out on top to go anywhere.
>
>CW is probably double that figure but, of course, CW requires many
>operators to equal the throughput of one SSB operator.
>
Let's limit the discussion to HF voice modes per your original post
else we get into the endless mindless phone/cw loop again. .
>
> But if you
>want to "extend the topic", we can factor power into the equation to
>talk about words per watt per kilohertz which starts to sound
>familiar, huh?
>
. . huh, yeah it sure does!
>
>Well, American hams don't have time to stop arguing about ham radio
>ceasing to exist on April 15 in order to invent anything.
>
That's my whole point. But fear not, they'll find something, anything
to drone on about after 15 April rather than burn and stuff some
boards and get a digital voice signal on the air.
>
>The German hams seem to be excelling in digital data modes
>
Went over my head - what have they cranked out?
>
>and the English hams
>seem to be leading the pack in digital voice.
>
Wasn't it a Brit who came up with PSK31 and some pretty decent
precursors to PSK31??
>--
>73, Cecil, W6RCA http://www.mindspring.com/~w6rca
>
w3rv
>.
------------------------------
Date: Sun, 12 Mar 2000 14:37:47 GMT
From: kelly@dvol.com (Brian Kelly)
Subject: May QEX digital voice article
On 12 Mar 2000 07:48:36 GMT, Hamish Moffatt <hamish@rising.com.au>
wrote:
>
>Have you listened around 14.060-080 lately?
>
Yes I have.
>
> We "digital types" would
>really do with some more bandwidth right now. In that band,
>we have PSK31, Hellschreiber, PACTOR, and some QRP CW, all fighting
>for a spot. PSK31 is confined to about 2 kHz of operation -- which you
>might think is plenty since it only requires 50Hz channel separation
>in theory -- until you actually try it and find that any strong station
>near where you're listening will completely wipe out a weak signal
>unless you have super-narrow IF filters because of AGC.
>
Then turn the agc off.
>
That's all perfectly normal HF band conditions and "issues". How much
HF cw and ssb have you used??
>
>And MT63 has no proper home at all.
>And at the same time, there's all of about 120 to 350 (minus a bit
>for SSTV) for SSB ragchewing/DXing. And not used very efficiently
>in comparison to the digital modes.
>
>So if you don't want any space set aside, OK but don't expect your
>daily net frequency to be clear and don't expect a digital mode operator
>to move.
>
Trust me, I'll "deal" with it . .
>
>I think a little more digital space would be ideal, especially
>so PSK31/Hell doesn't have to share with QRP CW and PACTOR, neither
>of which they are compatible with.
>
Harrish my good fellow I've been a cw dxer and contester for the best
part of a half century. Which is to say that for that past half
century I've shared the low ends of the bands with the digital
stations going back to the 1950s RTTY so I'm quite familiar with this
whole scene.
>
Which is also to say that for that half century I've been dealing with
weak signals and getting my brains kicked in by other stations while
I'm trying to beep somebody. It's no different on the phone bands.
That's completely normal and you bought into dealing with QRM when you
accepted your HF ham license. Quite whining and deal with it like the
rest of us deal with it.
>
w3rv
>.
------------------------------
Date: Sun, 12 Mar 2000 08:34:56 -0600
From: W6RCecilA <Cecil.A.Moore@IEEE.org>
Subject: May QEX digital voice article
Brian Kelly wrote:
> Which, as far as I'm concerned makes the Ebw discussion
> moot, they're even up for ham radio purposes.
Brian, are you against experimentation? Horses could outrun
the first automobile. Therefore, automobiles are moot? HF
digital voice is in its infancy. Don't perform an abortion
on it yet.
> >The German hams seem to be excelling in digital data modes
> >
> Went over my head - what have they cranked out?
IMO, PACTOR II is the absolute best HF ham digital mode. My SCS
PTC2e brings up PACTOR II mailboxes when I can't even hear the
incoming signal.
--
73, Cecil, W6RCA http://www.mindspring.com/~w6rca
>.
------------------------------
Date: Sun, 12 Mar 2000 15:42:12 GMT
From: kelly@dvol.com (Brian Kelly)
Subject: May QEX digital voice article
On Sun, 12 Mar 2000 08:34:56 -0600, W6RCecilA <Cecil.A.Moore@IEEE.org>
wrote:
>
>Brian Kelly wrote:
>> Which, as far as I'm concerned makes the Ebw discussion
>> moot, they're even up for ham radio purposes.
>
>Brian, are you against experimentation? Horses could outrun
>the first automobile. Therefore, automobiles are moot? HF
>digital voice is in its infancy. Don't perform an abortion
>on it yet.
>
Yo, of course I'm not opposed to experimentation. I've previously
stated that this new mode should be tried. I'll concede that my
mindset is such that I personally can't be bothered with
experimentation unless it has a basis in good physics and a visible
bottom line and leads to meeting some practical need. I don't have the
time or inclination to tinker just for the sake of tinkering, I don't
have much respect for aimless techo diddling, For better or worse
that's a pretty typical engineer's values
>
All I'm saying is that from the standpoint of rudimentary arithemetic
and some wobbly assumptions this new mode doesn't appear to be much
different from ssb wrt to spectral efficiency. Which is no biggie one
way or another. Maybe it has advantages and/or attractions in other
directions. Or weaknesses. Given that the obvious next step is to put
it on the air and wring out V1.0 in the real world. Which is also
standard engineer's "behavior". Bring it on, get it on the air, let's
see if it can cut the mustard, I don't have a problem with that.
>
Nor do I have a problem with HF digital tinkering vs. serious
development work as long as it doesn't screw up the band.
>
>> >The German hams seem to be excelling in digital data modes
To be continued in digest: hd_2000_73F
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