Dear All
I have been inputting some numbers into
the calculator from the link below, clearly some assumptions need to be made as
well as guesstimates but this may be able to give an idea of the range expected
at a given power, and assuming x hops etc.
http://www.aubraux.com/design/rf-link-budget-calculator.php
Putting in Roger’s power of 1mW and
a distance of 990km (his best and reception report of -20dB) then it gives for
a -20dB signal a “gain factor” for WSPR of 65dB.
This seems rather implausibly high so I’m
obviously missing a trick somewhere.
RF Link Budget
Calculator
RF
Link Budget Calculator: To calculate power at the receiver
input, enter values in the empty boxes below.
|
Transmitter Power
|
|
W
|
|
|
Transmitter Center Frequency
|
|
Hz
|
|
|
Transmit Antenna Gain
|
|
dB
|
|
|
|
|
|
|
|
Distance Between
Antennas
|
|
km
|
|
|
|
|
|
|
|
Receive Antenna Gain
|
|
dB
|
|
|
Other Losses
|
|
dB
|
|
|
Results
|
EIRP
|
=
|
-28.20
|
dBW
|
|
Wavelength
|
=
|
596.42
|
m
|
|
Free Space Loss
|
=
|
86.39
|
dB
|
|
|
|
|
|
|
Received Power
|
=
|
-49.59
|
dBW
|
|
|
=
|
1.10E-5
|
W
|
|
|
=
|
-19.59
|
dBm
|
|
|
=
|
1.10E-2
|
mW
|
With best regards
Jim
Dr. James Cowburn
Do we know how many dB
loss (over land and over sea) for a single hop Rik?
73s
Roger G3XBM
2010/1/10 Rik Strobbe <[email protected]>
Jim,
if ionoshperic propagation is involved signal strength (and thus SNR) depends
more of the number of hops involved than the absolute distance.
And each hop "costs" a number of dB's in signal strength.
73, Rik ON7YD - OR7T
Dear LF,
Has anyone any ideas or suggestions on a resource for calculation of a
link budget for WSPR over a set distance?
As it seems I can get up to GM4SLV reasonably consistently on my current
antenna/power setting with a SNR of around -22dB and the limit for WSPR
is around -30dB then is there a means for roughly estimating or indeed
accurately calculating the Expected Max Range (EMR) at that power setting
and antenna configuration?
Clearly, there are differences between separate Rx stations but if one
knows the ratio between two or more Rx stations then it should be
possible to pro-rate or estimate at least the signal strength at a given
Rx based on its performance with other known signals.
If I can do 916km with an SNR of say -22dB then how much further would
the remaining 8dB or so of WSPR detection get me, assuming the
other Rx has the same capability as GM4SLV and if their capability is
different, then is it fine to factor for the dB difference over known
paths/signals?
Thanks in advance for any answers or pointers and best wishes to all for
a great 2010
With best regards
Jim
Dr. James Cowburn G7NKS
E [email protected]<blocked::mailto:[email protected]>
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM GQRP 1678 ISWL G11088
