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PA2AGA > HDDIG 17.06.00 21:47l 217 Lines 7150 Bytes #-9440 (0) @ EU
BID : HD_2000_166D
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Subj: HamDigitalDigest 2000/166D
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Sent: 000617/1540Z @:PI8HGL.#ZH1.NLD.EU #:52154 [Den Haag] FBB $:HD_2000_166D
From: PA2AGA@PI8HGL.#ZH1.NLD.EU
To : HDDIG@EU
Date: Sat, 17 Jun 00 14:34:37 MET
Message-Id: <hd_2000_166D>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
>
> >> But I still prefer Pactor 1 with its ERROR FREE copy. (I even prefer
AMTOR
> >> over PSK31 with its almost error free copy)
> >>
> >> Rob
> >
> >Rob, you're not making any sense. PSK31 is a minimum bandwidth mode
> >(more power per BW/Hz). AMTOR and PACTOR are not even in the same
> >class. They are ultra-wide shift FSK (in comparison).
>
> And that's often a good thing when faced with skywave multipath. A wider
> shift would be even better, which is why the best designed HF protocols
> use wide shifts. It offers frequency diversity when the proper sort of
demodulator
> is used. That can sharply improve performance in the presence of skywave
> multipath. PSK31's very narrow shift offers virtually no frequency
diversity
> gain.
>
> The thing about HF signals is not that they're very weak, hell you can
hear
> most of them with your ears, and a matched filter is just as effective for
> separating a wide shift signal from the noise as it is for separating a
narrow
> signal (it is the baud that ultimately determines the Eb/No you'll have).
> The extreme example of that is spread spectrum.
>
> The key thing about HF signals is skywave multipath. To get good solid
> copy, you need a mode that's very resistant to it (or lots of brute force
> power to punch through regardless). Three ways to do that are wide shift,
> which gives frequency diversity, multiple transmission symbols per bit,
> which makes the signal more immune to multipath and interference, and
> a strong FEC, which recovers damaged symbols.
>
> PSK31 is a nice RTTY replacement for casual chatting between amateurs,
> but it isn't the best choice for getting the message through under harsh
> conditions. As Rob notes, under some conditions AMTOR or a Hell mode
> are better (but wider multitone methods employing strong FEC are better
> still, see Clover II, PACTOR II, or especially MT63 for current amateur
> examples, or check out the work done by KA9Q and N4HY for less well
> known but even better methods).
>
> The big advantages of PSK31 are that it is very cheap to implement (free
> for most of us), and that the programs which do it are very user friendly.
> Those are the primary reasons it has become popular. The fact that it
> also coexists well with other modes has allowed it to gain ready
acceptance
> by the users of other modes. That's a factor that can't be ignored on HF
> with the current mix of modes.
>
> PSK31 is becoming the CW equivalent for the new age. It is not the best
> when a message has got to get through correctly under harsh conditions,
> but it is adequate for lots of things that amateurs want to do.
>
> Gary
> Gary Coffman KE4ZV | You make it |mail to ke4zv@bellsouth.net
> 534 Shannon Way | We break it |
> Lawrenceville, GA | Guaranteed |
------------------------------
Date: Wed, 14 Jun 2000 23:27:44 GMT
From: "Hank Oredson" <horedson@att.net>
Subject: PacComm Pactor I Controller. Opinions?
"Gary Coffman" <ke4zv@bellsouth.net> wrote in message
news:ddafkssh4la1h9qs4d71l9b1ov9qj5849v@4ax.com...
> On Wed, 14 Jun 2000 06:56:36 -0500, "Steve Sampson" <ssampson@usa-site.net>
wrote:
> The key thing about HF signals is skywave multipath. To get good solid
> copy, you need a mode that's very resistant to it (or lots of brute force
> power to punch through regardless). Three ways to do that are wide shift,
> which gives frequency diversity, multiple transmission symbols per bit,
> which makes the signal more immune to multipath and interference, and
> a strong FEC, which recovers damaged symbols.
Hi Gary,
Same situation on VHF / UHF, where the multipath comes from
other propagation issues (like mountains and buildings).
Use more power, use smaller beamwidth, use wider bandwidth.
--
... Hank
http://horedson.home.att.net
------------------------------
Date: Thu, 15 Jun 2000 13:00:47 +1000
From: "David Findlay" <nedz@bigpond.com>
Subject: Packet Radio
I am about to try and get my HAM liscence. I am interested in getting into
packet radio. What sort of transmission speeds are currently obtainable? Can
you get 10Mb/sec? I want to set up a small network of automated weather
stations that will report to a central location. Could I use small FM
transmitters, that don't require a liscence to operate?
David Findlay
------------------------------
Date: Thu, 15 Jun 2000 05:42:54 -0500
From: "Scott Schultz" <n0iu@arrl.net>
Subject: Packet Radio
The "standard" on VHF-FM Packet for many years was 1200 baud, but now 9600
is very common. Be sure to get a radio that has a 9600 baud data port on it
Good luck with getting your ticket!
73,
de Scott N0IU
"David Findlay" <nedz@bigpond.com> wrote in message
news:2dY15.7$c5.136@newsfeeds.bigpond.com...
> I am about to try and get my HAM liscence. I am interested in getting into
> packet radio. What sort of transmission speeds are currently obtainable?
Can
> you get 10Mb/sec? I want to set up a small network of automated weather
> stations that will report to a central location. Could I use small FM
> transmitters, that don't require a liscence to operate?
>
> David Findlay
>
>
------------------------------
Date: Wed, 14 Jun 2000 10:04:36 -0400
From: Darryl Wagoner <darryl@shecora.com>
Subject: Skysweeper software
Hi,
I just looked at their web site and they didn't tell much about the
product. Like does it work with SSB or is it just data & CW?
Tero Laitinen wrote:
>
> I have tested for some time the brand new skysweeper software
> (www.skysweep.com).
> It seems to work fine atleast with CW, RTTY, PSK31/QPSK. I had to test it
> with .WAV files (only signal input from file
> is allowed in demo mode)
> Have anybody tested the registered version? How it does perform in real-time
> environment?
>
> -Tero
--
Darryl Wagoner DE WA1GON
603-598-6500 x929
------------------------------
Date: Wed, 14 Jun 2000 14:20:27 GMT
From: kh2d@my-deja.com (Jim)
Subject: Skysweeper software
I don't think you'll need a $200 program to do SSB, Darryl.
Most people using SSB manage it with just a microphone.
73, Jim KH2D
On Wed, 14 Jun 2000 10:04:36 -0400, Darryl Wagoner
<darryl@shecora.com> wrote:
>Hi,
>
>I just looked at their web site and they didn't tell much about the
>product. Like does it work with SSB or is it just data & CW?
>
>Tero Laitinen wrote:
>>
>> I have tested for some time the brand new skysweeper software
>> (www.skysweep.com).
>> It seems to work fine atleast with CW, RTTY, PSK31/QPSK. I had to test it
>> with .WAV files (only signal input from file
>> is allowed in demo mode)
>> Have anybody tested the registered version? How it does perform in real-
time
>> environment?
>>
>> -Tero
>
>--
>Darryl Wagoner DE WA1GON
>603-598-6500 x929
------------------------------
End of Ham-Digital Digest V2000 #166
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