[Elecraft] Noise blanker test.

[Al Lorona]

Hi, Jack,

> The test involves using a function generator that's built into my 
> Agilent DSOX3024.  

Ah, excellent choice. :^)

> The generator is set for pulse mode with a 200mv P-P pulse
> repeating 15.5 every 15ms.  

I don't know what this means.


> I determined that without the DSP or the I.F. noise blanker 
> turned on there are "sweet" spots and "hot" spots.  That is the 
> sweet spots are where the pulse width is adjusted so that the 
> noise is minimum and the hot spots are where the noise is 
> maximum. 

I think what you're probably hearing is the sin(x)/x spectrum of the pulse. 
Every pulse has a spectrum that looks like "sine x over x", or "sinc". Page 9 of 
this document: http://cp.literature.agilent.com/litweb/pdf/5989-4839EN.pdf  
shows the spectrum of a repeating pulse. You'll notice that it has peaks 
and nulls, exactly as you noted. Instead of adjusting the pulse width to observe 
the peaks and nulls sweeping through your receiver, you could have left the 
pulse width alone and tuned the receiver across these peaks and nulls. 

Believe it or not, it's more difficult for the receiver to eliminate pulses when 
you're near a null than when you're at or near a peak. This has to do with the 
noise blanker threshhold.

R,

Al  W6LX