[Elecraft] P3 SVGA - measuring occupied bandwidth

[Joe Subich, W4TV]

On 2018-05-23 3:54 AM, Richard Lamont wrote:
 >
> Jim - in this context, are you using the definition of "occupied 
> bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you
> do that with the P3 SVGA?

Whilst it's not completely accurate, it is very easy to approximate
the "occupied bandwidth" of reasonably strong signals using the P3.
Set average to maximum and look at the points 20 dB down on either
side.  This will over estimate the bandwidth of a signal depending
on the peak to average ratio of the given modulation (e.g., level of
clipping of an SSB signal) but still provides a useful first order
approximation.

The greater difficulty is in measuring the occupied bandwidth of very
narrow modes (e.g. JT65, JT9, FT8, RTTY or even CW) due to the 2 KHz
minimum span of the P3 ... a 500 Hz span would be better for measuring
narrow modes.

73,

    ... Joe, W4TV


On 2018-05-23 3:54 AM, Richard Lamont wrote:
> On 22/05/18 19:57, Jim Brown wrote:
> 
>> Yes. AND in the hands of a knowledgeable engineer/technician, a near
>> lab-quality test instrument, with a display that can easily be
>> calibrated to the signal level at the antenna input. I've used it to
>> measure occupied bandwidth of transmitted signals to precision of a few
>> Hz, and the SVGA board, with it's separate, higher res FFT, improves
>> that to one Hz.
> 
> Jim - in this context, are you using the definition of "occupied
> bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you do
> that with the P3 SVGA?
> 
> 73,
> 
> Richard G4DYA
> 
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