[Elecraft] OT: WSPR SNR to CW real world conversion

[Tom Azlin W7SUA]

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 <pasek001 at umn.edu> 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