Jarin OH6BG uusin päivitys:
VOACAP POINT-TO-POINT GRAYLINE ANALYSIS
URL: http://voacap.blogspot.fi/2017
* Predicting probable grayline propagation enhancements *
Not going to any deeper theoretical discussions here, there are basically three periods of time when distinct propagation enhancements have been reported on low bands.
These are as follows:
1. Both the Transmitter (TX) and Receiver (RX) are situated in the terminator zone. In my calculations, the terminator zone has been defined as the zone limited by DAWN and POST (post-sunrise) in the morning as well as PRE (pre-sunset) and DUSK in the evening. If there is an overlap between the Transmitter's and Receiver's morning/evening terminator zones, the times will be colored as follows:
a) TX DAWN-POST and RX DAWN-POST zones overlapping:
TX DAWN-RISE-POST: red
RX DAWN-RISE-POST: red
b) TX DAWN-POST and RX PRE-DUSK zones overlapping:
TX DAWN-RISE-POST: red
RX PRE-SET-DUSK: blue
c) TX PRE-DUSK and RX DAWN-POST zones overlapping:
TX PRE-SET-DUSK: blue
RX DAWN-RISE-POST: red
d) TX PRE-DUSK and RX PRE-DUSK zones overlapping:
TX PRE-SET-DUSK: blue
RX PRE-SET-DUSK: blue
2. The Transmitter (or Receiver) is on the terminator zone and the Receiver (or Transmitter) is in darkness. Whenever this conditions is met, the times in the DAWN-RISE-POST and PRE-SET-DUSK columns will be colored in green. This is one of the most common cases for signal enhancements on the low bands.
3. The Transmitter (or Receiver) is on the terminator zone and the Receiver (or Transmitter) is in darkness AND the midpoint of the path is in the solar midnight. This is a special case of Number 2 in this list but a very important one. Currently, the solar midnight period at the midpoint (labelled as MIDPT MNITE in the tables) is defined as a time period of plus minus 15 minutes from the time calculated and shown in table. The MIDPT MNITE time is the exact calculated solar midnight time but, in my calculations, I consider that the midpoint midnight period is plus minus 15 minutes from that time.
There can be three colors for the time: black (default), red and blue. When the color is black, the midpoint midnight time does not overlap with the DAWN-RISE-POST or PRE-SET-DUSK times of neither the Transmitter not the Reveicer.
The colors of red and blue will be assigned as follows:
a) Midpoint midnight period and TX Terminator zone (morning or evening) overlapping: RED
b) Midpoint midnight period and RX Terminator zone (morning or evening) overlapping: BLUE
As a special mention, if the solar midnight period, a period of +- 15 minutes from the MNITE time at TX/RX, overlaps with the Midpoint Midnight period, the times in the MNITE column will be colored as follows:
a) TX midnight period (MNITE) and Midpoint Midnight period overlapping: RED
b) RX midnight period (MNITE) and Midpoint Midnight period overlapping: BLUE
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