Electronics > Beginners
Which Spectrum Analyzer Measures Very Low Frequencies?
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innkeeper:
the first thing I noticed in my hp dsa schematic is the whole front end up to the DAC is DC coupled.
there is a lot of balanced circuitry in there, and although there are a lot of opamps there are some dual fets that are internally matched and will track from a temperature standpoint.
a lot of care is taken for LF noise entering the system.
its a purpose-built system for dc-100khz

grab a schematic for a hp3562 or a 3561 and look at the front end... its interesting.


Gerhard_dk4xp:
The applicable EMC standards require 9 KHz as a lower measurement limit.

regards, Gerhard
coppice:

--- Quote from: Gerhard_dk4xp on July 05, 2018, 01:26:11 am ---The applicable EMC standards require 9 KHz as a lower measurement limit.

regards, Gerhard

--- End quote ---
Spectrum analyzers were starting at 9kHz before things like ITU K.76 and CISPR 16 were around.
JS:
The scope option isn't the best but you probably need an scope or already have one and might cut it for your requirements. Analyzing data in the PC is a great tool. Big memory depth would be your biggest friend for fft to be usable. Capturing a sample from the scope to the PC and running a script is quite easy and doable, I use my Rigol ds1054z and capture directly from matlab or octave via usb or network. I wouldn't even think using a pen drive, I did that in the university where I needed to take the samples hone to play around but doesn't make sense at home.

Now you are just limited by your programming skills (and the 8 bits, but that's quite a lot with 24M of memory, as long fft gets things well under 1LSB)

I think capturing data directly from the computer with an scope is a very very very useful tool for data analysis, the scope is a great tool for a lot of things as stand-alone, but post processing opens a whole different universe, given math functions of the scope are mostly toys. I think THE thing missing from scopes is the lack of user script addons as math functions! Maybe some have but I haven't came across them and I even less know the features and limitations they would have.

JS

joeqsmith:
My old HP3589A is spec'ed down to 10Hz.   Shown with a 0.5Hz signal using the high resolution narrow band.  It is VERY slow.   Many years ago, I was using an old HP3582 that was designed for this kind of work.  It had two channels and I think it even had GPIB. 

Personally, for the 0.1 to 4KHz you are asking about, I would buy a data acquisition board and use the student version of Labview on a PC.  Then you could do what ever you want.
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