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[Q] vector signal analyzer, dynamic signal analyzer, carrier noise test set

I'd like to ask a few questions.

First of all, I am an optics person rather than electronics.

I am interested in the phase noise of carrier frequency.

I've heard that equipments such a vector signal analyzer, a dynamic signal analyzer and a carrier noise test set can measure the phase noise of carrier. [Q1] Is that correct?

If yes, [Q2] would you tell me a difference?

In electronic applications, [Q3] would you tell me the main purpose of these equipments ?

Reply to
Q-man
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The gear you'd need to measure phase noise depends entirely on the amount of phase noise you're talking about. :) What sort of "carrier" is being tested?

UHF/microwave sources of low to medium quality can be measured directly on a spectrum analyzer... at which point you need to decide if you can ignore AM noise, which will appear alongside the PM/FM noise on the analyzer unless you use a saturating mixer or limiter between the source and analyzer.

Higher-quality sources can be measured with the help of a frequency multiplier. A multiplication factor of N amplifies the frequency-domain noise by 20*log(N) dB, making it possible to 'see' noise levels on a spectrum analyzer that would otherwise be obscured by the analyzer's own LO.

Extremely-high quality sources (crystal oscillators and such) are typically downconverted to DC by mixing with a known-clean source. The noise profile beginning at 0 Hz is then observed on an LF spectrum analyzer. This type of arrangement often requires phase-locking between the reference source and source being measured.

Mini-Circuits has a decent app note at

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if you haven't seen it already.

I have no experience with dynamic signal analyzers or specialized carrier test sets, but I've recently put together a pretty nice Windows application for spectrum analyzer-based noise measurement (

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). It was inspired by the HP 85671A software that runs on their higher-end analyzers. It won't be necessary or useful if you are working with dedicated noise-measurement equipment, though.

-- jm

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Reply to
John Miles

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