Hello Mike and all others interested in their performance (signal-wise),
thank you for your comments. I knew this 1 W ERP line and the measurements
would create some discussions ;-)
Mike, G3XDV wrote:
So, is there something wrong with the 1W ERP line or with our ERP
calculations, or with the signal measurements? My money is on the
1W line being too high, but perhaps Geri and others with bigger
brains than me can come up with the answer.<
well, as far as I recall, I developed the estimated 1 W ERP line from some
assumptions:
1. I assumed that everybody sticks to the law and the highest signal
levels would roughly be in the 1 Watt ERP range
2. I used the CCIR curves for signal strength vs. distance to estimate how
a 1 Watt ERP signal would develop vs. distance
3. I tried to find a "best fit" so that I have an envelope curve fitting to
the strongest signals in the U.K. and OH assuming those would be coming
close to 1 Watt ERP.
4. The difference between the 1 W ERP line and the commercials is
approximately 40 to 45 dB, this would come close to the 25 to 100 kW ERP
(?) those stations might have.
Alan, G3NYK has asked me to supply a graph with a logarithmic distance
scale, which I will put on that page (http://www.qru.de/signals.html) later
today. Alan mentioned that my 1W ERP line drops at 30dB per decade while
20 dB per decade would fit better for most of the signals, so that this
might give another picture (I will play around with these figures a little
bit tonight).
On the other hand, there is Vaino's (OH2LX) comment, that according to his
long-lasting experience it is not possible to estimate a station's ERP from
the field strength at a far distance ...
Anyhow, what you can do ois to compare you own signal to the signal of a
neighbor station, especially, if the measurments were taken in the same
instance (as Dick did it). My measurments might be a little bit misleading
in this respect, because they were taken over a long period of time.
However, the results did fit very nicely ... and shows the poor German's
QRP situation, too (provided we all stick to the law ... ;-).
Best 73
Geri, DK8KW (W1KW)
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