[hpsdr] IP3 >+50 dBm ?

[Robert McGwier]

Ron:

It is really simple.  IP3 is not dynamic range.  There is a formula for 
computing IP3 from imputed dynamic range when you mix two tones and get 
a third order product and measure its amplitude.

But if the noise floor is raised,  you have lowered the SNR and 
therefore, CANNOT have the dynamic range implied by this computation.

IP3 != Dynamic Range.

Bob


Ron Skelton wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> 
> 
> ------------------------------------------------------------------------
> 
> I don't comprehend the argument that such a high dynamic range is not 
> meaningful in view of the phase noise of oscillators and would 
> appreciate someone lightening my darkness.
> 
> My understanding is that dynamic range is defined and bounded by noise 
> entering or created at the front end and the signal level where any 
> portion of the chain becomes saturated (for want of a better term). This 
> being so we can increase dynamic range by lowering the noise floor or by 
> increasing the point of saturation or both. The achievable noise floor 
> at HF and below  is determined by incoming not internal noise.  In any 
> event it seems to me the highest possible point of saturation is 
> required assuming the usual case of exposure to high levels of unwanted 
> signals.
> 
>  
> 


-- 
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"If you're going to be crazy, you have to get paid for it or
else you're going to be locked up." Hunter S. Thompson

 1188167809.0