[hpsdr] Janus Lives!!

[Robert McGwier]

That is incorrect.

The S meter,  which integrates the power inside the 500 Hz filter,  
reads -159 dBm.  I wrote the code.

Bob



Alberto I2PHD wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Robert McGwier wrote:
>   
>> If this were calibrated and we saw -159 dBm in 500 Hz ( the meter is the 
>> integrated noise power in the 500 Hz bandwidth in PowerSDR),   then at 1 
>> Hz,   if we could do such a filter,  we would get approximately 26.9 dB 
>> less power in the 1 Hz bandwidth  (  10* log_10(1/500)).   This is below 
>> the theoretical noise floor since 1 Hz cannot be less than that for room 
>> temperature since this is not in a system, it is the naked A/D.  It 
>> cannot be calibrated.  Gerald is right.
>>
>>     
> Bob,
>     yes, you would be right if we were seeing -159 dBm in 500 Hz, which is not....
> we are seeing -159 dBm in the bin size of the FFT, which Gerald in his second message said to be about 11.7 Hz
> The -159 dBm are not what is reported by the meter, but what is visible on the spectrum display.
>
> 73  Alberto  I2PHD
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>   


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