Author Topic: A brief spectrum analyzer comparison guide for beginners  (Read 602 times)

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Offline nexus

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A brief spectrum analyzer comparison guide for beginners
« on: January 02, 2020, 07:49:19 pm »
Hi all,

As a non-RF engineer, I found myself a bit lost when trying to make a purchase decision for a spectrum analyzer. I wanted to get something with enough capability for my foreseeable needs (mostly 2.4 GHz ISM band radio and near-field EMI probing), while not totally draining my bank account or buying a boat anchor full of leaky capacitors.

Anyway, after a few months of careful research and bringing myself up-to-speed with the fundamentals, I wanted to put together something understandable that would've made my life easier had I stumbled across it from the start.

I hope someone out there finds this useful: https://neonkev.com/2020/01/02/buying-spectrum-analyzers-a-brief-guide-for-non-rf-engineers/
 

Online tautech

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Re: A brief spectrum analyzer comparison guide for beginners
« Reply #1 on: January 02, 2020, 07:52:26 pm »
You should also look at this range for something better priced and suitable capable for your needs:
https://siglentna.com/spectrum-analyzers/ssa3000x-plus/
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Offline DaJMasta

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Re: A brief spectrum analyzer comparison guide for beginners
« Reply #2 on: January 02, 2020, 09:58:04 pm »
The "total" dynamic range is sort of a meaningless factor - you're never going to see close to that dynamic range in a sweep, so it's not really a useful metric.  If your preamp is on, all of your attenuation is switched out and your maximum input signal without overloading is probably like -40dBm or something, at best.  Also worth mentioning spurious free dynamic range - which is probably the Tek RSA's biggest flaw - it may be able to display a good bit of dynamic range, but if you happen to need something in the band that its internal harmonics is in, you effectively get much less usable dynamic range unless you factor in the mixing issues caused by the internally generated tones that show in the spectrum.

An important feature for a lot of people looking for SAs is a tracking generator, so looking for the option and what range it covers (often not the full range if the bandwidth is above 3GHz) - could be a useful discussion in such an intro.  If you're looking for a used SA, consider the minimum RBW - a lot of older instruments will stop at 100Hz or 1kHz and just can't zoom all the way in on a signal and get the low noise that comes with it (though maybe that's outside the scope of this one).

A big factor in usability is also sweep speed, this is highly variable even on the same instrument and it's not expressed that consistently in datasheets.  Some will advertise a number of sweeps per second at a specific setting, or a time per acquisition in a sweep... but a lot don't advertise and there are certain architectures that slow down a LOT when in fine RBW settings whereas other slower sweeping architectures end up being faster in the very narrow span measurements.  Someone with hands-on experience with the unit (or just seeing it on a video) can give you a much better picture of how fast it sweeps than just the datasheet numbers.

There's a lot of variety and options when it comes to SAs, so I'd say don't be afraid to dig into things you don't really know about to try and figure out if one option or feature actually means anything to you.  It's tough to put an introduction to them together just because you have to have some understanding in a lot of supporting places to even get in the proverbial front door.
 
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Offline nexus

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Re: A brief spectrum analyzer comparison guide for beginners
« Reply #3 on: January 03, 2020, 12:06:29 am »
I agree that there are a lot of points of discussion on the topic of Spectrum Analyzers. I wanted to do some comparisons of other specs like spurious free dynamic range and sweep time, but like you pointed out these specifications are often defined with specific instrument settings that may or may not apply to other modes of general use. For example, looking at the datasheets side by side for the 4 units I compared, SFDR was defined in totally different terms for each one. Unless I could get my hands on each of these and do apples-to-apples comparisons, I'll try to correlate only the parameters that are commonly defined. I did try to include some relevant reading on my website to further elucidate important measurement concepts, https://neonkev.files.wordpress.com/2020/01/reading4.pdf

For 3 out of the 4 instruments, the signal path has done teardowns and experiments with each one. I haven't rewatched all of these to see if the same experiment is performed twice, but these videos do showcase each instrument pretty well with respect to both general and unique features:

R&S FPC1500:
Tek RSA306:
SH BB60c:

I'll be sure to back-link this topic to the site so that readers can view and weigh this discussion for their own understanding.
 

Online tautech

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Re: A brief spectrum analyzer comparison guide for beginners
« Reply #4 on: January 03, 2020, 12:52:24 am »
For 3 out of the 4 instruments, the signal path has done teardowns and experiments with each one.
Also Shariar has done reviews on Siglent's SSA3000X and SVA models. SSA was done a good while back and these have much improved firmware now but they don't have all the fruits of the later SVA and SSA3000X Plus models.

Hunt them out or come back asking and I'll dig out the links to these.
« Last Edit: January 03, 2020, 01:02:07 am by tautech »
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