[OZAPRS] HF APRS

[Ray Wells]

Rob,

Do you think that both ZLs and VKs might be a bit parochial, perfering 
to hit Igates in their own country, or don't they care? I have no 
opinion either way, just letting my mind do some wandering and wondering.

For point-to-point (and small area) plots I find the IPS Grafex charts 
useful as well. (You need java, and pops enabled for the site to see the 
chart). Grafex shows a range of frequencies for various times of the day 
- optimum working, maximum useable, etc, and propagation modes.
http://www.ips.gov.au/HF_Systems/7/1/4

Having used (0k3) HF for packet since 1997 or 1998 when I started with a 
30m bbs port, and then added both 20m and 40m ports, my observations 
about phase distortion don't align with Rob's. We found that it was a 
curse on 20m on an 1100km path from here to a vk5. It can also be a 
curse on 40m. Strangely, it seldom affected 30m, and I don't know why. 
I'm not saying it didn't happen, but if present it had little over all 
impact on forwarding. Of course, with bbs forwarding, one isn't 
constantly monitoring the frequency and as long as the mail moves one 
can conclude that things are ok, even if at times they are not.

The reality of the situation with HF is that it suffers from the mood 
swings of Mother Nature and any band can be affected from time to time, 
and we need to be as flexible as we can to cater for those times. That 
may even mean adopting Rob's idea and becoming familiar with propagation 
charts, in advance of a trip, to optimise the possibility of being heard.

Regardless, the largest network possible, utilising the maximum number 
of bands will provide the best outcome, in my opinion.

Ray vk2tv


Rob wrote:
> Hi All been looking at the IPS web site
> http://www.ips.gov.au/HF_Systems/1/1/2  for a ZL VK HF system I think we
> would be better on 14 MHz if you look at what band gives the most
> propagation and assuming most mobile stations are on the move during day
> light hours. This band also is better for HF data reception introducing less
> phase distortion to the received signal.
>
> What we need is a VK6 station a VK4/3 and a ZL one 3 gateways would give us
> good coverage and if we have 3 more in the same area on 7MHz then we will
> have close to 90% coverage. You need to remember this is not a static
> situation and as the Sun spot numbers increase we need to move the
> frequencies up
>
>  
>
> Regards Rob ZL3RX
>
>
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>   

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