FW: [psk31] Pactor 3?

[Paul L Rinaldo]

Gang,

FYI

Paul

>An interesting message posted by Peter Martinez this afternoon. Sounds like
>PACTOR III is on the air in Europe, at least experimentally.
>
>
>-----Original Message-----
>From: Peter Martinez [mailto:Peter.Martinez@btinternet.com]
>Sent: Wednesday, February 13, 2002 2:35 PM
>To: PSK31
>Subject: [psk31] Pactor 3?
>
>
>>From Peter G3PLX:
>
>Traditionally, the HF amateur bands have been divided into SSB/voice at
>the top end and CW/digital at the bottom. In the early days this was
>probably done so that operators on the different modes could find each
>other easily. By co-incidence, it's always been the case that SSB is
>about 3 kHz wide and CW/digital modes have always been much narrower.
>The popularity of PSK31, as the narrowest of the digital modes, has
>re-inforced this idea that digital modes are narrow. Nowadays the
>separation between voice and digital modes is not so much about
>concentrating activity where it can easily be found, but serves the
>purpose of minimising the interference which would be inevitable if
>modes of different widths were constrained to share the same part of the
>bands. However, the way things are at the moment, the wording of the
>bandplans is such that the division is between voice and digital, not
>between wide and narrow.
>
>But what would happen if a digital mode became popular which was as wide
>as an SSB signal. The present bandplan rules would insist that such a
>mode operated in the digital sub-bands rather than the voice sub-bands.
>Is this reasonable?  There's a good case for saying that we would want
>to separate two modes, not because one is voice and the other is
>digital, but because one is wide and the other is narrow. Put another
>way, for the purpose of promoting peaceful co-existence between groups
>of people who have to share the spectrum with each other, it makes sense
>to have modes of similar bandwidth sharing. What interference there is
>will be mutual and can therefore be minimised best by co-operation.
>Forcing wide and narrow modes to share the same space would result in
>interference which was NOT mutual and thus cause conflict.
>
>This isn't a new idea. It works very well at the moment for SSTV sharing
>with SSB. What I am going to suggest is that maybe there's a good case
>for a change of emphasis, so that wide-band digital modes ALSO share
>with SSB rather than with existing digital modes.
>
>Yes, all very well I hear you say, but is it likely that wide-band
>digital modes might become popular?  I don't know, but I want to
>stimulate the debate because of signals I have been hearing recently on
>the 80m band here in Europe.  The signals I am hearing (in the digital
>part of the band), are 2.4kHz wide. They consists of up to 18 separate
>100-baud PSK signals spaced 133Hz apart, with the two stations
>transmitting alternate long/wide and short/narrow bursts in an ARQ
>format. The number of tones, and hence the occupied bandwidth, changes
>dynamically, presumably dependent on the band conditions at the time.
>These are amateur signals, not commercial, and I recognise the callsigns
>of the stations doing the experiments. They are associated with a
>well-known manufacturer of digital radio equipment.  It would only take
>a marketting campaign by the company, and a firmware upgrade, and there
>could be hundreds of such signals on the amateur bands. A quick
>calculation shows that they could be transmitting up to about 3000
>bits/sec of data, so it's going to be the message-handling people that
>are likely to to go for this mode for unattended working.
>
>What do we think? Should this kind of SSB-width digital mode share with
>the present narrow-band digital modes? Should it share with SSB? If we
>debate this now and share our views with the rest of the amateur
>community, we can help those who may wish to promote such modes to
>choose the best place for their activity.
>
>73
>Peter G3PLX
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