[TowerTalk] HFTA Angles Data

[David Gilbert]

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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>>>
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>>
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>>
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> I)
>
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