[aprssig] HAAT Approximation in PHG (was: Entering PHG into UIview)

[Robert Bruninga]

>>> greg at clubnet.net 1/19/05 9:30:17 PM >>>
>Is there a preferred way of rounding the HAAT value into 
>the discrete steps of PHG statement? 

No.  Although HAAT can be "precisely" calculated, the 
value is practically of little value other than a general feel
for height.  And since then it varries greatly depending
on the particular direction, then it is even less precise.

So I would round up if the predominant users are in the
area of better coverage and round down if the better
direction from a digi is not towards the majority of users...

> I am particularly  interested in the high level digi 
> of say 2000 feet...

For Mountaintop digis where almost always the actual 
direction of the users is in the direction of the greater 
height difference, I would round up.  *BUT* then recognizing 
the QRM, that such a high-site will hear, and the fact that 
it will rarely if ever hear out to its full RF range due to other 
constant signals on the air, then I would round down....

In general, I would round down to be conservatrive.

> Of late, I have tended to favor the lower step 

I agree with you completely...

At first glance the steps seem very large indeed, but then the
rule of thumb is that it takes a doubling of height to gain
only 6 dB.  So the difference between 1500' and 3000' is
only 6 dB.  The edge of the earth comes up very rapidly
at those ranges...

So I agree, round down....
BOb
WB4APR