What is the referenced bandwidth for the noise? 3 KHz? And what if I
narrow the filter bandwith to just the occupied bandwidth of each signal?
With fldigi when I have filter narrowed the measured snr goes to 30 dB.
So the snr algorithm is very sensitive to filter width. Have not looked
in the code to try to figure out if the snr measurements are comparing
the signal to adjacent empty FFT buckets.
73, tom w7sua
On 7/20/2018 10:49 AM, Allan Zadiraka wrote:
I don't recall where this table of Relative Sensitivity of Communication
Modes came from but for what's it worth::
Mode
Signal to Noise Ratio Threshold
WSPR
-27 dB
JT65
-24 dB
FT8
-20 dB
Olivia
-17 dB
PSK31
-7 dB
CW
-1 dB
RTTY
+5 dB
SSB
+10 dB
*Allan Zadiraka*
*AB8OU*
4110 State Rd Akron, OH 44319 Work: 234-738-4578 Cell:
330.760.4569 Home: 330.644.1839
On Fri, Jul 20, 2018 at 1:03 PM George Pasek <[email protected]> wrote:
I have used WSPR through the past years and have always been amazed at how
far one can go on so little power. I have always wondered how does it’s
Signal to Noise Ratio figures I’m getting from the reporting stations mean
in relation to being heard using CW. In other words, how close to a SNR of
0 do I have to be to say that if I were on CW they would hear me and not
need a computer? I take it that anything on the + side of zero would make
it, but when watching the waterfall and listening to my receive audio (KX3)
I can hear stations that I am reporting a SNR of –10 for example. I’m
running 500mw into a 40m EFHW inverted sloper and have received a few SNR 0
and +1. I have attempted to look up this information but got bogged down
in the math and formulas, most of which I don’t understand.
So would a reported SNR of –10 represent a reasonable number at which the
reporting station would hear me if I simply switched from WSPR to CW, all
other things remain the same, or is 0 the break point?
tnx
de George
WD0AKZ
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