Re: [TowerTalk] HFTA Angles Data

[David Gilbert <xdavid@cis-broadband.com>]

I agree with all of that.  I'm just not sure that the TANGLE calculation 
from VOACAP accurately captures all of that, and that's what the 
Figure-of-Merit calculations in HFTA were based upon.  I recently 
upgraded my computer and don't currently have VOACAP installed, but if I 
get a chance I'll try to load it up and check the effects of different SSNs.
73,
Dave   AB7E



On 8/1/2013 1:42 PM, K8RI wrote:
> On 8/1/2013 12:33 PM, David Gilbert wrote:
> > If I remember correctly, Dean Straw said that the ARRL crunched the
> > numbers back in the mid-90's using a computer that took a few days,
> > but I'm not sure it really matters.  We're talking optimum
> > takeoff/arrival angles here, and I'm not sure that angle is a strong
> > function of F-layer densities.  It would be pretty easy to check ...
> > just run a few paths in VOACAP for the same hour of the day using two
> > different SSNs and compare the TANGLE results for various
> > frequencies.
> Although layer height varies, these layers are relatively thick. The
> effective height of a layer at a given height varies with density which
> is why we talk about refraction instead of reflections.
>
> So antenna optimum antenna height does change withe the effective height
> of the layer(s)
>
> 73
>
> Roger (K8RI)
>
> > 73, Dave   AB7E
> >
> >
> >
> > On 7/31/2013 8:42 PM, Roger wrote:
> > > But is average really average.  The sunspot cycles highs and lows
> > > we have recently experienced are quite different than previous
> > > cycles and so far this is reportedly, the lowest in a hundred
> > > years. From what cycle are the averages taken, or is the
> > > information updated to reflect current cycles?
> > >
> > > I don't remember 40 ever being consistently as good for DX
> > > throughout the nights as it was for 4 or 5 recent years.
> > >
> > > 73
> > >
> > > Roger (K8RI)
> > >
> > > _______________________________________________
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