Hello Dick and all,
Thanks very much for your figures. I am not srprised at program predicting
accuracy because attenuation is not very much different from 6dB for every
doubling of distance and not much affected by type of ground. I consider
+/- 3dB to be not very much where 300 km radio propagation is concerned.
;o)
I have just checked the source code in program GrndWav3. It does make use
of CCIR curves and data for refraction over the horizon although I have had
to use some intelligent guesswork to extend to 30 MHz. It's good to be
reassured I havn't introduced any bugs.
What DOES surprise me is the accuracy of the group's measurements. There
should be prizes given for such careful meticulous work !
When available I would be pleased to have some figures of 500 to 2000 km
propagation.
========================
Regards from Reg G4FGQ
Free Radio Design Software
Go to http://www.g4fgq.com
========================
----------------------------------------------------------------------------
-------
Reg Edwards, G4FGQ, has a free program called "Grndwav3" on his web site:
www.btinternet.com/~g4fgq.regp/page3.html#S301.
Entering Jim's EMRP=218mW and distance 329km the program predicts for the
field strength at PA0SE the following:
Sea water: 10.35 microvolt/m
average: 8.18 microvolt/m
pastoral: 9.50 microvolt/m.
I measured 11 microvolt/m so Reg's program can also be used when the CCIR
curves are not available.
73, Dick, PA0SE
| 