[time-nuts] Spectrum Analyzer Specifications

Bob Camp kb8tq at n1k.org
Wed Mar 23 07:11:22 EDT 2016


Hi

If you can see harmonics down to -60 dbc, that is about the most a normal spectrum
analyzer will do for you on a frequency standard. This *assumes* the part has a sine
wave output. Most standards are in the 10 MHz range, so an analyzer that will work to
>= 40 MHz is probably a good idea. 

Can you do this with a USB gizmo? Sure you can. Can you trust the results? That will 
depend on the exact unit you get and your ability to calibrate it. Might it “only” be useful
to -50 dbc? Might it work to -100 dbc? That is part of the “did you pay $X or 10 times 
that much question. 

Bob



> On Mar 23, 2016, at 1:23 AM, timenut at metachaos.net wrote:
> 
> Hi,
> 
> I have another question about test equipment. When using a spectrum analyzer
> to examine the output of a frequency standard, what are the minimum
> specification needed? Bandwidth, resolution, sensitivity, etc?
> 
> Looking at spectrum analyzers on eBay, I see quite a bit of difference between
> various models. Some have a resolution of 10Hz but others are 30Hz or even
> 100Hz. Some have a minimum frequency of 0.01Hz, 100Hz or even in the kHz
> range. Some are only sensitive to 60dBm, but others over 100dBm.
> 
> Are any of the cheaper USB spectrum analyzers worth getting?
> 
> Most of these are appallingly expensive, so knowing what is needed can
> certainly help guide a purchase or to minimize cost. And if a "deal" is found,
> knowing that it is or is not adequate can help.
> 
> Clearly, better specifications are preferable, but I'm also sure that the
> intended application makes a large difference. What is needed for examining a
> 10Mhz frequency standard might be remarkably different from what is needed for
> high-frequency RF work.
> 
> 
> Mike
> 
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