I'm a subscriber to the VOACAP mailing list, and here's a recent (just a
few weeks ago) comment from George Lane, one of the key original members
of the IONCAP development team.
"Beware of using CCIR Data Base D or D-1, etc. When I was on the
Working Party 6 of the CCIR, I discovered that the Data Base D had been
‘normalized’ to remove the antenna gain data based on takeoff and
arrival angles dependent totally on path distance! This totally
corrupted the data base. This is one reason I totally suspect REC.
533. Further when I ran REC 533 back in 1996 when I still worked at VOA
using Greg Hand’s version, I found that signal power could increase as
one went from 1 hop to 2 hop and 3 hop distances. For some reason I
just don’t believe the Ionosphere works as an amplifier until you get
near the antipodal location. Perhaps, that has been fixed, I hope."
For what it may be worth ...
73,
Dave AB7E
On 7/22/2013 7:01 AM, VE5ZX wrote:
One could also check Zoneprop ( http://www.radiosport.ca/zoneprop/ ).
ZoneProp uses a widely accepted propagation engine to determine the
band on which a contestant in one CQ DX zone is likely to be able to
contact a contestant in another CQ DX zone taking into account the
current geomagnetic activity.
ZoneProp produces a 40 zone by 40 zone matrix that is updated hourly
at approximately 20 minutes past the hour. The intersection between a
row and column gives the band on which a contestant in the zone
represented by the row is mostly likely able to contact an contestant
in the zone represented by the column. The zone numbers in the left
hand column are clickable. Once clicked the information for that zone
is displayed in isolation above a map of CQ DX zones. The pages are
refreshed every 10 minutes in order to capture hourly updates of the
matrix
Technical details
At the heart of the ZoneProp program is REC533, an NTIA/ITS rendering
of the ITU-R P.533 package. It was chosen following many years of
NCDXF Beacon Chain monitoring results from various sources, and
comparisons with actual ionosonde data. As with any propagation
predictions program the input parameters require careful consideration
and calibration. The results from the above mentioned studies
contributed to the monthly publication of various predictions tables,
in the RSGB’s - RadCom and the Italian - Radio Rivista magazines to
name but two. This continuing experience has been applied to the
production of ZoneProp.
The web output of the model first queries the WWW for the relevant SSN
and an up-to-date K-index figure. These are used to build an input
file that is then passed to the prediction program for the required
results, FOT (Frequence Optimum de Travail), or Optimum Working
Frequency. Unlike the vast majority of predictions programs the
K-index is utilized to adjust the FOT as it rises and falls. The
International Reference Ionosphere (IRI) and actual ionosonde outputs
were used to determine the variations in FOT.
The other input variances are the co-ordinates for the zones, which
are the CQ-WW zones. The zone co-ordinates were chosen to be either in
the center of the zone or at the highest population density that is
nearest to the center. The correct method of reading the matrix is to
use the left hand list of zones as the starting point and then to take
the destination zone from along the top. This will show the correct
FOT for the time of day, propagation is not always reciprocal. An
example of this is on an East/West path when one end of the path is in
darkness and the other in daylight. During the morning between W1 and
W6, is a good example.
Syl -VE5ZX
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