[Elecraft] Monitor output...

[Jim Brown]

On 5/16/2011 12:50 AM, Ian White GM3SEK wrote:
> However, the increase in vertical (time) resolution should be even more
> dramatic.

Thanks to Heisenberg's uncertainty principle, the product of the 
frequency resolution and the time resolution of ANY measurement is 
unity. The frequency resolution in Hz Fr is 1/Tr, the time resolution in 
seconds. Tr = 1/Fr.  Fr and Tr are established by the FFT parameters, 
and further modified by the filter parameters.  The display cannot 
improve on what the FFT has produced. Another way of saying it is that 
we cannot know infinitely about frequency AND time in any given 
measurement.  If we want high precision of frequency (and bandwidth of a 
signal) we must sacrifice accuracy of WHEN the signal was on that 
frequency.

In the world where I have worked professionally for 40 years, we bumped 
up against this around 1980 when we began using Time Delay Spectrometry 
(a measurement system that uses a swept oscillator and a swept detector 
and an FFT to display the result),  to measure audio systems, equipment, 
transducers, and room acoustics.  The uncertainty principle applies no 
matter HOW the measurement was made -- swept or FFT or some guy staring 
at a meter. In the case of swept measurements, resolution is determined 
by the sweep rate and the bandwidth of the detector.

73,  Jim Brown K9YC