- Original Message -
From: Leigh L Klotz, Jr.
To: digitalradio@yahoogroups.com
Sent: Friday, December 01, 2006 5:38 AM
Subject: Re: [digitalradio] USA: No Advanced Digital HF Data Comms
From what I can gather, the code is just an ECC'd data block and the
contents
L Klotz, Jr.
To: digitalradio@yahoogroups.com
Sent: Friday, December 01, 2006 5:38 AM
Subject: Re: [digitalradio] USA: No Advanced Digital HF Data Comms
From what I can gather, the code is just an ECC'd data block and the
contents of the data aren't that important; it is the decodability
I personally can not support any modes wider than a standard SSB width.
I don't even support the use of wide band AM primarily because if you
let one mode use such a wide mode, then it is very difficult to suggest
that no other mode should use an equivalent space.
It might be acceptable to use
, 2006 9:58 AM
Subject: Re: [digitalradio] USA: No Advanced Digital HF Data Comms
I personally can not support any modes wider than a standard SSB width.
what is learned here.
Walt/K5YFW
-Original Message-
From: digitalradio@yahoogroups.com
[mailto:[EMAIL PROTECTED] Behalf Of Danny Douglas
Sent: Thursday, November 30, 2006 9:41 AM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] USA: No Advanced Digital HF Data Comms
I am
, and
then was there a need for nation wide emergency communications?
Joe
W4JSI
- Original Message -
From: DuBose Walt Civ AETC CONS/LGCA
To: digitalradio@yahoogroups.com
Sent: Thursday, November 30, 2006 11:22 AM
Subject: RE: [digitalradio] USA: No Advanced Digital HF Data Comms
KV9U wrote:
We need to continue to advance our technological abilities and narrow
modes do this best. We already have the modes that operate about as
fast as they can for a given bandwidth and robustness. What we don't
have are modes that can adaptively change with the conditions
Walt,
I think there is no doubt that this is true. The question I have
been struggling with is how much is enough/too much. I guess what I
am looking for is a curve showing bandwidth vs. throughput for
parallel tone modems, or maybe more precisely where is the point of
diminishing returns?
Mark Miller wrote:
What my question
boils down to is generally, what is the accepted maximum bandwidth of
any signal in the Amateur HF bands, given the finite spectrum and
many interests?
There's the billion [insert local currency here] question. Or
actually two questions: what's the
The maximum accepted bandwidth for most modes is the width of an SSB
transmitter since you can not go wider than that and communicate with
the typical rigs of the day.
We already have the basic modes to work high speeds with good conditions
and slower speeds under difficult conditions. What we
If radiated power is not limited, data rate is directly proportional to
bandwidth, but the maximum data rate per kHz depends on the amount of time
(multipath) spreading and amount of frequency (Doppler) spreading. NVIS has
a multipath spread of 6-12 ms and there needs to be a gap between symbols
: [digitalradio] USA: No Advanced Digital HF Data Comms for
HamsRe: RFSM2400
Rick,
To me it all depends on the channel behavior. On HF, with multipath,
the parallel modem wins because the symbols can be made longer than
the delay spread.
Just observing the succesful implementations may lead anyone
DuBose Walt Civ AETC CONS/LGCA wrote:
Jose,
This is what I have been saying for a couple of years now.
Se we are not alone.
Research done by independent research laboratories and universities
confirm that the best bet to increase throughput and robustness on HF
channel modems is to
Rick,
To me it all depends on the channel behavior. On HF, with multipath,
the parallel modem wins because the simbols can be made longer than
the delay spread.
Just observing the succesful implementations may lead anyone to see that
in an ionospheric channel, generally, parallel tone modems
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