Measuring Phase Noise
- Thread starter VK3YNV
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VK2RK
Active member
I don't have a spec analyser that provides 10 Hz RBW best I can do is 300 Hz on my IFR
Then phase noise when its greater than 80 dBc down is of no consequence and more a function of Allan noise variances and the type of crystal in the oscillator.
As the video shows he is at the limits of his instruments and the exercise is pointless and validation of the specifications requires very very expensive instrumentation.
Allan Variance
en.wikipedia.org
Image shows best I can do with my $5000.00 second hand Spectrum analyser measuring the GPS locked reference, what it shows is the increase in band noise due to the filter action converting the oscillator square wave to a sine wave, this can be further reduced with better filter design as some of the phase noise is also contributed by the filter. I think 68 dBc is good enough.
We can get all get caught up with the ultimate unachievable specification that we cant validate, been down that road several times.
This measurement is done by IFR auto measuring function and shows channel power
Then phase noise when its greater than 80 dBc down is of no consequence and more a function of Allan noise variances and the type of crystal in the oscillator.
As the video shows he is at the limits of his instruments and the exercise is pointless and validation of the specifications requires very very expensive instrumentation.
Allan Variance
Allan variance - Wikipedia
en.wikipedia.org
Image shows best I can do with my $5000.00 second hand Spectrum analyser measuring the GPS locked reference, what it shows is the increase in band noise due to the filter action converting the oscillator square wave to a sine wave, this can be further reduced with better filter design as some of the phase noise is also contributed by the filter. I think 68 dBc is good enough.
We can get all get caught up with the ultimate unachievable specification that we cant validate, been down that road several times.
This measurement is done by IFR auto measuring function and shows channel power
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The Siglent VNA will go down to 1Hz RBW, 1Hz VBW but doesn't help get a meaningfull measurement. Even with lots of averaging.
But there is a mode CNR which I'm going to have a play with. It looks like it measures noise power in a chunk of spectrum that can be offset from the carrier by a variable amount.
But there is a mode CNR which I'm going to have a play with. It looks like it measures noise power in a chunk of spectrum that can be offset from the carrier by a variable amount.