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

[greg at clubnet.net]

Bob,

Is there a preferred way of rounding the HAAT value into 
the discrete steps of PHG statement?  I am particularly 
interested in the high level digi case where you might 
have an actual HAAT of say 2000 feet.  The first 
assumption would be to round up if the value is above the 
midpoint between the two steps and round down if it is 
below.  I'm not so sure this is the best approach for an 
APRS indicator.  Of late, I have tended to favor the lower 
step unless the value is very close to the upper step.  If 
there is a more scientific method, I will be happy to 
change.

73,
Greg
WB6ZSU

On Wed, 19 Jan 2005 13:44:38 -0500
  "Robert Bruninga" <bruninga at usna.edu> wrote:
>>What is the correct format for manually entering the PHG 
>>info into UI-View?  Should this go in the beacon comment 
>>or the status text?
> 
> here is the spec from the original APRS digis.txt file
> 
> PHGphgd goes as the first part of the position comment
> right after the symbol byte.  The "PHG" is just to 
>identify
> the next 4 bytes "phgd" of data.  These bytes are the 
>digits
> 0 through 9 for each of these fields as follows:
> 
>  DIGITS   0  1  2   3   4   5   6    7    8    9  as 
>used in the PHG
> field
> 
> -------------------------------------------------------------------------
>  POWER    0, 1, 4,  9, 16, 25, 36,  49,  64,  81  watts 
> SQR(P)
>  HEIGHT  10,20,40, 80,160,320,640,1280,2560,5120  feet 
>  LOG2(H/10)
>  GAIN     0, 1, 2,  3,  4,  5,  6,   7,   8,   9  dB
>  DIR   OMNI,NE, E, SE,  S, SW,  W,  NW,   N,   .  This 
>offsets the
> range
>                                                   circle 
>in the
> indicated
>                                                   direction
> 
>  THey typical home station might be PHG5230
>  Where 5 = 25 watts
>  Where 2 = 40 feet above average terrain
>  Where 3 = 3 dB typical antenna gain
>  Where 0 = omni directional.
> 
>