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23-Jul-2010, 2:52 AM   #3
tripelo
Senior Member

Join Date: Jan 2010
Location: Dallas, TX
Posts: 127
Thanks Andy, for your information and explanation.

Quote:
 ...Can you give me a coordinate to try?...
In a fairly smooth but hilly terrain, these are a couple of coordinates along with example heights for a 2Edge to 1Edge transition for station WCTE-DT.
37.068331, -84.967819
In: 'Online TV Maps'
Antenna height = 46 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -7.5

Antenna height = 47 feet
Callsign = WCTE-DT
Path = 1Edge
NM (dB)= -1.7
Note: The 2Edge to 1Edge transition occurred between 46 and 47 feet AGL.
** Note the differences (below) from the above result.**
Antenna height = 47 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -10.6

Continuing in 'Online TV Maps'

Increasing Antenna Heights (one foot at a time) & Press 'Make Radar Plot'
Antenna height = 48 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -9.8

Antenna height = 49 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -8.9

Antenna height = 50 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -8.0

Antenna height = 51 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -7.0

Antenna height = 52 feet
Callsign = WCTE-DT
Path = 1Edge
NM (dB)= -2.0
Note: The 2Edge to 1Edge transition occurred between 51 and 52 feet AGL.

The following results starting with 'Signal Analysis' is in agreement with the second group of numbers listed above.
Antenna height = 51 feet
Callsign = WCTE-DT
Path = 2Edge
NM (dB)= -7.0

Antenna height = 52 feet
Callsign = WCTE-DT
Path = 1Edge
NM (dB)= -2.0
Earlier, I thought I saw other differences when starting in 'Signal Analysis', but now it is in agreement with starting in 'Online TV Maps' & Press 'Make Radar Plot'. At that time, a five decimal place number was used for latitude.

Quote:
 ... There is supposed to be a "soft" transition between 1Edge and 2Edge, ..
In the first case above, the 1Edge to 2Edge transition signal level change is 5.8 dB (for one foot change).

In the second case (transition), it is about 5.0 dB.

The differing displayed values between 'Online TV Maps' and 'Make Radar Plot' or 'Signal Analysis' has been noticed at another location, namely Garland TX (northern suburb of Dallas) looking further north to station KXII-DT.