[pskmail] Re: Need PSKMail for Disaster Relief Operations

  • From: karel fassotte <karel.fassotte@xxxxxxxxx>
  • To: pskmail@xxxxxxxxxxxxx
  • Date: Thu, 03 May 2007 08:34:39 -0500

Going on with the theme.
Icom has broader filters to be installed instead of the existing smaller filter. We measured he existing filter to have a bandwidth of 2.9Khz. In out experimental links it showed that other factors like noise and interference were much more likely to slow down the linkspeed, than the actual bandwidth of the filter. By the way not all transceivers have 2.9Khz. bandwidth, most of them only 2.7Khz. Yes I agree, there exists a lot of nonsense about the speed item. Transferring football matches is not really a goal to meet in a thin communication channel. However as you know that a fast mode would permit more traffic been handled in an emergency situation. What did you pursue exactly with the (de)compression? It would be a nice feature if the compression would be handled by the communication software itself. If (de) compression would be accomplished without operator intervention it would speedup file handling of the information stream and enhance effective throughput of the link. Please let us know what did you accomplish with the (de) compression etc.
Very interesting
73 Karel, hc1akp

At 08:00 a.m. 03/05/2007, you wrote:

Yes, the 706 should be able to handle a good signal without modifying
the bandwidth. However, it will degrade the signal and problems will
start to appear with less good signals. A wider rig will not degrade the
signal and it will be able to handle much worse s/n ratios.

Speed is an interesting issue. I was asked to define how much bandwidth
will be needed for satcom on Swedish naval vessels. I started looking at
how many users there are and what systems to feed etc. I quickly
realized that not much is really needed, most of it ended up in the
"nice" column. The "need" column was so small that I couldn't really
mention it without people looking funny at me (hf should actually handle
it nicely). Then again they wanted broadband links to handle streaming
of football matches from the world cup... (so I gave up and gave them
that number ;-)).

But, I agree that more speed provides more possibilities. Rein and I
have been working to enhance compression, at the moment we have had
results that have turned PSK125 into "PSK350" (or PSK250 into "PSK700"
and 2400 bps STANAG4285 into "6720 bps"). The quotes mean relative speed
when compression is applied.

PSK250 is on the horizon and perhaps now even STANAG 4285, things are
looking good.
You mentioned DRM, I think that is interesting as well and I should have
tried that already but...

73 de Per, sm0rwo

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