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VE2HAR > MT63 10.03.05 19:36l 253 Lines 6757 Bytes #-7496 (0) @ WW
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Subj: Re: [MT63] 20 kHz wide Digital Proposal (Was: ARRL MUST GET
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Quoting karl larsen <k5di@zianet.com>:
>
> Hi Walt, what your suggesting really is that 56baud telephone modem
> technology can be adapted to HF data transmission. This works fine on a
> VHF/UHF channel with little or no noise. Now HF is a different animal.
> The work in MT63 and Olivia has been put into getting the data through
> the HF noise and fades.
NO...not anything like the old 56KBaud telephone modem. This would be an OFDM
type modulation, quite similar to IEEE 802.11g type modulation but with
different tones, tone (carrier) spacings and modulation on the tones as well
as different detection methods and heavy FEC on each carrier channel.
MT63 and Olivia are simple or basic OFDM type signals...we are expanding on
this. While 56 KBPS is a goal for HF, that may not be possible; but, its
still a goal. Perhaps we will only reach 24 KBPS but still that's a remarkable
improvement over MT63 or Olivia and we're talking about robustness at the same
level that MT63 and Olivia give you.
>
> There is nothing wrong with adapting the MT63 approach to a 20 KHz
> bandwidth, but it is not clear to me what it will do. At least it would
> be a Forward Error Correction device and not a Pactor Handshake cludge.
The idea is to be able to send more data faster and to get on-the-air and
off-the-air and multiplex/share the channel...or if a huge file needs to be
send, it can be and not take a long time to transmit the file.
>
> The experiment has merit and it should go on. I suggest 20 meters.
Well right now the proposal is to experiment on 10 or 6 Meters and then bring
it down to the other HF bands.
The next QEX magazine will have an article on the HSMM project.
Walt/K5YFW.
>
> karl
>
>
> dubose@texas.net wrote:
>
> >Brian,
> >
> >Well yes and no. What the HSMM is suggesting is that you allow up to 20
> KHz
> >signals. But we're taking about 56KBPs throughput that would allow one
> or
> >more voice channels actually multi-mode all on one signal.
> >
> >You might see 56KBPs data but it would only be on-the-air for a short
> time.
> >The "channel" would be shared.
> >
> >Right now we have MT63 at 200 WPM thoughput on a 2 KHz wide bandpass at a
> -5
> >dB SNR on a poor CCIR channel. But we really need to push 800-1200 WPM at
> the
> >same signal level. I don't see doing that with less than a 6 KHz channel
> even
> >exploiting some of the new OFDM type modulation protocols being developed.
>
> >
> >How many CW QSOs running at 20 WPM will it take to produce 1200 WPM error
> free
> >copy at a signal level that MT63 can copy? These are signal levels that
> even
> >the best CW operator can't copy a signal at. So the answer is that NO
> number
> >of CW QSOs can produce the throughput of 1200 BPS, near error free, at a
> -5 dB
> >SNR on a poor CCIR channel.
> >
> >All this IS possible if we are willing to step out of the box.
> >
> >AND the new modes that will develop will be FAR SUPERIOR to Pactor III or
> >anything being done today on HF.
> >
> >We're also looking at doing much of this work using a computer sound card
> so
> >separate controller hardware is not needed.
> >
> >73,
> >
> >Walt DuBose/K5YFW
> >Asst Chairman
> >ARRL HSMM WG
> >
> >
> >Quoting Brian Carling <bcarling@cfl.rr.com>:
> >
> >
> >>On 8 Mar 2005 at 19:11, David J. Ring, Jr. wrote:
> >>
> >>
> >>
> >>>I don't think the digital signals they want are 20 kHz wide!
> >>>
> >>>
> >>Want to bet on that?
> >>
> >>There IS in fact a proposal out now for a digiotal mode that IS 20
> >>kHz wide for high speed data transefer on HF ham bands.
> >>(as if Cra... er, I mean Pactor is not jamming the HF bands enough
> >>already!)
> >>
> >>Here it is:
> >>
> >>On Janauary 19, 2005, John Champa, K8OCL,ARRL Chairman, High Speed
> >>Multimedia Networks Working Group, issued the Technology Task
> >>Force report to the ARRL Board of Directors, which includes the
> >>following:
> >>
> >>"At a minimum, 20 kHz wide emissions should be allowed in the
> >>following segments:
> >>
> >> 3.58 - 3.725 MHz
> >> 7.035 - 7.125 MHz
> >> 14.065 - 14.15 MHz
> >> 21.08 - 21.2 MHz
> >> 29 - 29.7 MHz"
> >>
> >>Obviously, a *single* HSMM transmission, 20 KHz wide, could
> >>totally wipe out all PSK31, MFSK16, RTTY, and many CW and DX
> >>operations on 80m, 40m, and 20m, where they are now used
> >>worldwide. Dozens of CW QSOS could be obliterated within
> >>one 20 kHz swath. NOT a good idea at all!
> >>
> >>We have never seen such a lack of concern and compassion for the
> >>majority of radio amateur activities as evidenced by the ARRL
> >>Committee on HSMM and ARRL support for Winlink's attempted
> >>domination of the HF frequencies, in both cases, to sacrifice the
> >>hobby on HF for everyone else in order to favor a
> >>very small special interest group.
> >>
> >>I can only hope that they really are coming to their senses at the
> >>top level of leadership, but this is cause for alarm.
> >>JIm Haynie says that they are going to have a new band plan by
> >>July.
> >>I hope it is a workable one that averyone can live with.
> >>The Winlink/Pactor mess will hopefully get reined in by this.
> >>
> >>OK back to some fun CW contacts now, and a little less grumbling!
> >>
> >>73 de AF4K
> >>
> >>
> >>
> >>
> >><< Try MT63 on 80m - great fun!>>
> >>
> >>- The MT63 Reflector -
> >> MT63@egroups.com
> >>
> >>(To unsubscribe. send email to
> >>MT63-unsubscribe@onelist.com)
> >>
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> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
> ><< Try MT63 on 80m - great fun!>>
> >
> >- The MT63 Reflector -
> > MT63@egroups.com
> >
> >(To unsubscribe. send email to
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> >
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> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
> << Try MT63 on 80m - great fun!>>
>
> - The MT63 Reflector -
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>
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