Keysight MXA Signal Analyzer / Spectrum Analyzer Review, Analysis & Experiments - Page 1
Forum section: electronics / testgear

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 06, 2017, 02:01:57 am
content: In this episode Shahriar reviews the long awaited Keysight MXA Signal Analyzer (N9020B). The new X-Series Spectrum Analyzers from Keysight offer an entirely re-designed GUI interface which supports multiple tabs as well as multi-touch interaction. The review is organized as follows:1:07 – Model comparison and overview of x-series spectrum analyzers.7:08 – Instrument physical overview.11:49 – New GUI overview and demonstrations.22:44 – Instrument block diagrams and analysis.28:46 – Brief look inside the MXA spectrum analyzer.32:53 – Back-scattering communication experiment block diagram and description.37:16 – Phase noise characterization of doubler and amplifier.51:54 – Complete back-scattering experiment measurements and analysis.1:04:45 – Analysis of broadband modulated signals by using the S-Series scope and MXA Signal analyzer at the same time.1:13:56 – Concluding remarks.You can watch the video here: [1 Hour & 15 Minutes]youtu.be/RIIv1KyoXssThe Signal Pathwww.TheSignalPath.comwww.YouTube.com/TheSignalPathwww.Patreon.com/TheSignalPath

author: videobruce
author_rank: Frequent Contributor
timestamp: March 06, 2017, 02:02:43 pm
content: From what I could read on that chart, the cheapest one was $13 large.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 06, 2017, 04:40:05 pm
content: Quote from: videobruce on March 06, 2017, 02:02:43 pmYes, these are pro units for sure. The MXA that I tested with all the options is $150k at the minimum.

author: BFX
author_rank: Frequent Contributor
timestamp: March 06, 2017, 10:30:58 pm
content: Yes I think I have to buy one to every my room

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: March 07, 2017, 05:54:40 am
content: Thank you for the well made video, it was most informative. We *may* (keeping fingers crossed) have enough money in our budget this year for a new instrument, maybe our existing MXA (2008 model) has enough trade-in value to get us a new MXA. I'll be sure to let the Keysight rep know about your video if we do!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 07, 2017, 03:37:07 pm
content: Quote from: radar_macgyver on March 07, 2017, 05:54:40 amThat would be great! Thank you.

author: rachaelp
author_rank: Unknown
timestamp: March 07, 2017, 07:14:14 pm
content: Awesome video as usual Shahriar. I'm looking to buy a spectrum analyzer this year but unfortunately my budget won't stretch to an MXA.... I can always dream I guess...

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 08, 2017, 07:07:35 pm
content: Quote from: rachaelp on March 07, 2017, 07:14:14 pmIt all depends on what range of functions you need at the end. Either way, all X-series ones are pricey.

author: technogeeky
author_rank: Frequent Contributor
timestamp: March 08, 2017, 07:25:43 pm
content: Quote from: Hugoneus on March 08, 2017, 07:07:35 pmComing from the software world, I really do not like how the price of software options causes the price of these devices to rise exponentially. At the very least, I would prefer that you at least had the option to build and develop the software on your own and take advantage of the hardware. I do understand that they have to use a pricing model that allows them to recoup the tremendous cost of R&D on the custom hardware they put into these devices. I also understand that most of their customers are corporations and laboratories that can (and do) afford the cost of these devices. If the labneedsit, they will pay for it. But it seems like the hobbyists and prosumers get left out of this at the end of the day, which is disappointing.Butmanis that thing fast. The speed at which that device makes measurements and changes from one measurement to another is really astonishing.

author: rachaelp
author_rank: Unknown
timestamp: March 08, 2017, 10:46:35 pm
content: Quote from: Hugoneus on March 08, 2017, 07:07:35 pmI think the problem is finding the right balance between what I need for my work and what I want for experimentation/learning and just having fun with cool stuff. I'm a test equipment junkie and the really high end equipment like the MXA fascinates me but it's all out of my current budget. You certainly have access to a lot of really great kit, I have serious lab envy when I watch your channel!Best Regards,Rachael

author: G0HZU
author_rank: Super Contributor
timestamp: March 08, 2017, 10:52:43 pm
content: Nice intro and overview as always.... however the doubler test setup for the phase noise test was a bit bizarre.It looked to me like the amplifier after the doubler has a lot of gain (45dB?) and the doubler was being under driven to compensate for this. All very strange.Would it not have been better to drive the doubler properly and dispense with the Avantek amplifier? The phase noise test would have had a bit more credibility. Also I suspect that the phase noise of the analyser itself would be playing a part in your tests. Especially at offsets very close to carrier.Finally, I can't understand why you think your backscatter test was 'really testing' the dynamic range of this analyser. It didn't look to be a tough test at all. There are various ways to really test the dynamic range of this analyser but I don't think that was one of them.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 08, 2017, 11:53:53 pm
content: Quote from: G0HZU on March 08, 2017, 10:52:43 pmThe amplifier has about ~25dB of gain at 8GHz. The doubler would have been sufficient without the amplifier.QuoteThe purpose of the amplifier was to show the rise of the noise floor and its impact on the phase noise measurement. The whole point was to show how three regions of the phase noise measurements are impacted by various effects:1) Close in phase-noise is dominated by the instrument's own internal phase noise and thus the two measured curves line up. I offered this as a puzzle to the viewers.2) Mid-range phase noise is scaled mathematically based on the consequence of the doubler.3) Far out phase noise is increased beyond the expected 6dB due to the excessive noise from the amplifier.This is a valuable test to teach people what to watch out for. Other than that I know how to optimize phase noise if it was the only goal.QuoteThe backscatter experiment does not really test the dynamic range of the instrument during regular measurement but it shows the limit during real-time measurement and that was the point. I chose the TX/RX power to be close to the limit of the real-time digitization dynamic range. Also, I need to make a fun experiment not just "verify" the spec, anyone can just look that up from the datasheet.

author: G0HZU
author_rank: Super Contributor
timestamp: March 09, 2017, 01:02:32 am
content: QuoteAre you sure about that? That amplifier should have a low noise figure, maybe 4 or 5dB so it would need to have about 45dB of gain to produce the high noise level on the analyser via the resistive splitter and the coax that feeds to the analyser. How else do you explain the -35dBm of noise power (in a 6GHz BW) that you measured on the analyser?Your tests suggest to me that the amplifier probably has a gain of about 45dB if we assume a sensible/realistic noise figure of (approx) 5dB for such a wideband amplifier.This would produce the 6GHz wide noise pedestal you saw on the analyser if you take into account the loss in the splitter and coax after the amplifier.

author: technogeeky
author_rank: Frequent Contributor
timestamp: March 09, 2017, 11:58:12 am
content: Quote from: G0HZU on March 09, 2017, 01:02:32 amThedatasheet for the amplifieris available. It's the AGT-8235 part. We never actually saw the exact setup in the video (due to Shahriar's usual meticulous attention to detail I assume this is an oversight). But we can assume that the gain is somewhere between 45dB and 25dB. The voltage control of the gain is inverted and cutoff; so at 0V gain control the gain is 45; any increase in voltage decreases the gain until you get down to 25dB. It appears the noise goes up when you do this (from 5.5dB to 7dB).So I guess the phase noise shown must come from a combination of phase noise from the doubler and the amplifier together? Or the amplifier is not functioning perfectly?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 09, 2017, 05:52:13 pm
content: Thanks for the details. I was quoting the gain from memory and I could be off. But I will measure it tonight.

author: G0HZU
author_rank: Super Contributor
timestamp: March 09, 2017, 10:03:17 pm
content: QuoteThanks. I estimated the gain of the amplifier after making a few reasonable assumptions. A broadband $$$ Avantek amplifier like that will have a noise figure of about 4 or 5dB.I assumed that there was about 9dB total passive loss in the splitter/cable after the amplifier.The noise power measured on the analyser in the 6GHz BW was -35dBm and 6GHz BW = 98dB Hz. So the amplifier gain would be approx:Gain = (-35 - 98 - 5 + 9 - (-174)) = 45dBThis seems to agree with the Avantek datasheet if the amp is set to the default gain?Note: looking at the typical gain in the datasheet graphs it is more like 50dB gain for that model at 8GHz. Maybe there is more loss in the splitter/cable part of the test setup that I first thought?It seems a curious choice for a post doubler amplifier because it would mean you would have to really reduce the drive level to the doubler to get 0dBm on the analyser at 8GHz. No wonder the rejection of the 4 GHz fundamental looks poor from the doubler if it isn't being driven into its normal working region?

author: technogeeky
author_rank: Frequent Contributor
timestamp: March 13, 2017, 06:31:58 am
content: Quote from: G0HZU on March 09, 2017, 10:03:17 pmRe-reading this post for clarity, I do think that you have downplayed the fact that he's really trying to show off the capabilities of the instrument, and he's not trying to maximize the capability of the DUT. I don't actually even understand enough yet to have the kind of intuition you two have about the capabilities and noise figures of these instruments, but I do think he did a good job of showing off the instrument with a demonstration of a practical circuit.In any case; Shahriar, did you have time to investigate? What, if anything, did you find?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 28, 2017, 05:38:32 pm
content: Quote from: technogeeky on March 13, 2017, 06:31:58 amThe test was done to show specific performance of the MXA, not optimize the DUT as I mentioned before. The gain of the amplifier has no bearing at all on the test itself, because that is not what is being measured. I still have to measure the gain, but I suspect that it will match the datasheet.

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2017, 06:52:01 pm
content: Yes, but in the video you appeared surprised how noisy the amplifier was and made comments about how poor the doubler performance was. Avantek don't make noisy amplifiers and MiniCircuits make decent doublers. But they only appear decent if they are used sensibly. Your test setup was far from 'sensible'. I've designed plenty of doublers using MiniCircuits parts over the years for many products and so anyone like me is going to spit their drink out when they watch your doubler test and listen to your commentary and see the spectrum on the analyser.

author: diyaudio
author_rank: Frequent Contributor
timestamp: March 28, 2017, 07:27:54 pm
content: Quote from: G0HZU on March 28, 2017, 06:52:01 pmplease make us a video and go into detail about it.. we waiting.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 28, 2017, 07:41:12 pm
content: Quote from: G0HZU on March 28, 2017, 06:52:01 pmYou are still missing the point. The element of "surprise" you refer to is the flair I am adding to make the test exciting and engaging. I know very well that I ampurposelyunder-driving the doubler. I am trying toincorporate specific failingsinto the test so I can both teach something as well as test the instruments.Either way, I think everything should be clear by now.

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2017, 08:15:04 pm
content: QuoteOh wow... yet again on the internet I'm the only slow one. I'm supposed to be able to tell apart 'flair and pretend surprise' from (deliberately) incompetent use of high performance RF modulesQuoteLook, I sometimes comment and contribute to these teardown videos. Sometimes I'm critical and sometimes I'm not. Maybe you should take the time to read my technical contribution to this one below. Maybe I deserve more respect than your 'doubting' popcorn icon.https://www.eevblog.com/forum/testgear/video-teardown-and-repair-of-an-agilent-e4433b-esg-d-synthesized-signal/I don't do presentations, I'm an engineer usually hidden in a lab far away from the general public. My presentations skills are poor and so are my social skills. My video editing and IT skills are even worse. I really don't think you want to see me do a video about doublers.My background is in RF design and what is relevant to threads like this is that I have experience of designing high performance RF converters for use with a digital IF. My experience goes back here to about 1990. So over the years I've designed lots of high performance gear that resembles todays signal/spectrum analysers. So looking inside teardowns of modern RF gear like this is interesting to me. If anyone is going to be critical of anything odd in the presentations then I guess it is often going to be me.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 28, 2017, 08:19:42 pm
content: Nothing wrong with criticism, just commenting on the style of it. Please continue to lend the forum your insight.

author: diyaudio
author_rank: Frequent Contributor
timestamp: March 28, 2017, 09:41:58 pm
content: Quote from: G0HZU on March 28, 2017, 08:15:04 pmI don't doubt you, you were a bit harsh your respect was honored a result of your "down to earth come back", not your contribution. just saying.

author: Unknown
author_rank: Unknown
timestamp: March 29, 2017, 02:43:31 pm
content: It's easy to be an armchair critic, but not so easy to step up and produce a quality Youtube channel. I for one appreciate the time and effort put into your videos, thanks and keep up the good work.

author: G0HZU
author_rank: Super Contributor
timestamp: March 30, 2017, 12:53:25 am
content: Quote from: Z80 on March 29, 2017, 02:43:31 pmJeez... have a look at my technical contribution to another signalpath teardown thread here:https://www.eevblog.com/forum/testgear/video-teardown-repair-and-analysis-of-an-hp-8562b-22ghz-spectrum-analyzer/Have another look here at another analyser teardownhttps://www.eevblog.com/forum/testgear/teardown-repair-analysis-of-a-rohde-schwarz-fsh3-3-0ghz-spectrum-analyzer/I waited several days to see if anyone else spotted the errors in the signalpath walkthrough in this last video.. but nobody said anything.If you think it's 'easy' for someone like me to sit in an armchair and contribute the stuff I do then why are you not doing the same? You see from where I sit in my armchair your task seems a lot easier? Maybe I too should just say "Great Video" every time and put down anyone else who is critical and/or pointing out obvious technical errors?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 30, 2017, 12:59:02 am
content: G0HZU, I don't know why this discussion is still going on.But again, the point is not to dismiss the virtue of criticism or your contribution, it has to do with yourstyleof doing it.Your tone (sometimes) can be unnecessarily rude, you make strong assertions where you could simply ask a question or make assumptions which are invalid.By all means continue to provide your valuable insight, no one is suggesting otherwise.

author: Unknown
author_rank: Unknown
timestamp: March 30, 2017, 11:49:55 am
content: QuoteThere you go againdid you read any of my other posts before making that assumption? Look nobody is criticising you for commenting or pointing out possible errors, Dave annotates his videos all the time with corrections it's just the condescending tone you have. Put yourself in the OP's shoes and read your comments as if directed at you and see if you don't think they are a bit harsh. Having gurus like you contributing is a great asset to the forum so take my ramblings as constructive.In respect of the original post can this not turn into a bun fight?

author: G0HZU
author_rank: Super Contributor
timestamp: March 30, 2017, 01:42:15 pm
content: QuoteMaybe you don't realise it but you made a very dismissive statement when you said "it's easy to be an armchair critic". Saying stuff like that can be offensive if a valid point was being made by that criticism. So I tried giving you the same treatment and you seem offended too?It was a 1 hour video and from that I made just two very valid critical points. Looking at the noise pedestal on the analyser I used some basic engineering common sense to predict that the amp probably had about 45dB gain. A bizarre choice. Try and understand my frustration when I asked what the gain was and to be told it was just 25dB. But that doesn't make sense! The amp would have to have to be seriously faulty if this were true. I stood my ground and tried to explain why the gain must (realistically) be about 45dB. Even if the gain of the amp 'was' just 25dB it is still too much gain for a sensible doubler setup that gave 0dBm via the splitter and cable. To me the bizarre nature of that test stood out like bollox on a dog.The dynamic range test didn't seem that harsh and I think this point is valid too. But maybe harsh is open to interpretation I guess.QuoteI'm not great at social skills online but I don't think anyone at work would call me condescending. Maybe you can help me here because in all the links I gave I can't see it. I can see me eventually getting frustrated in some cases. I'm frustrated right now for example...

author: Unknown
author_rank: Unknown
timestamp: March 30, 2017, 03:07:16 pm
content: No problem, I wasn't offended, just a little surprised you would think that if you had seen any of my other posts. I apologise if I caused you offense that wasn't the intention, I (and several others) are just trying to point out that it wouldn't hurt to try and be a bit more polite and respect the fact that most Youtubers, like the OP, put a lot of their own free time (and money) into producing content. Social grace isn't in the job description for an engineer and many of us (me included) can get excited / frustrated and say stuff that on reflection may be a bit harsh and unnecessary. The only advice I can give is to do what I do. Pause after writing something, put myself in the shoes of the recipient and think would I be happy reading that from a total stranger?Ok, this is my last word on this here as I don't want to pollute this thread with totally off topic stuff. Happy to chat in another thread or on PM. Keep posting and try not to get too worked up, it's just the internet.

author: G0HZU
author_rank: Super Contributor
timestamp: March 30, 2017, 04:34:16 pm
content: QuoteThat's good advice but I'm always going to struggle here I think. I try and only use nice emoticons yet it seems that my text is laced with hostile harshness (invisible emoticons?). I still struggle to see it.If I look back into the forum in general I see lots of people using the facepalm and the headbanging icon and other mocking icons. If people mimed that stuff for real in meetings where I work I think they would be told off very quickly.Having seen these icons used a lot on this forum I try hard not to use them anymore. Imagine what my posts would be like if I did

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 30, 2017, 04:45:48 pm
content: Quote from: G0HZU on March 30, 2017, 04:34:16 pmMy policy is that I treat my interactions (on this forum) as much as possible like I would when I am writing an email to a colleague whom I will see the next day in person. I am not always successful, but I try.

author: kcbrown
author_rank: Frequent Contributor
timestamp: March 31, 2017, 06:10:59 am
content: Quote from: G0HZU on March 30, 2017, 01:42:15 pmSadly, on forums like this it's very easy to mistake matter-of-factness for shortness/harshness/condescension.As someone who has been in electronic fora of one kind of another ever since Usenet was distributed largely via modem connections (at least for those who wanted their own personal feed), I can say that not ever taking anything personally that is said online is a necessary trait if discussions are to go smoothly. There's just too many ways to misunderstand the underlying intent of others to do anything else. I don't even bother to look for underlying intent in what is said -- I take what people say at face value, and if something looks like an insult, I just ignore that part and limit my attention to the facts.To each his own, of course, but it's not a bad way to do things, IMO...

author: G0HZU
author_rank: Super Contributor
timestamp: March 31, 2017, 11:05:25 am
content: Thanks for that...At work, all engineers have to endure critical design reviews of their designs and documentation etc. In a critical design review (CDR) I could be surrounded by a dozen or more people who have gone through my stuff in detail. They could be from manufacturing, purchasing, test, quality control, security, IT, sales/marketing and a whole load of keen engineers too.http://www.acqnotes.com/acqnote/acquisitions/critical-design-reviewThis can mean me enduring hours of critical analysis surrounded by this lot in a big meeting room. We all have to go through it and it's actually a very healthy environment where we all learn from our mistakes. I've learned to respect all criticism from all departments. Sometimes the sales or manufacturing people say silly things but sometimes they make good suggestions and even the silly stuff sparks debate and stuff gets improved.I'm from an environment where it's normal and actually encouraged to be critical. But on text based internet forums this environment just doesn't (can't) exist and I struggle to fit in. I rarely post early on a thread for this reason and usually let it flow and hope that someone else spots what I'm thinking. Otherwise I become the pantomime villain again? The sad truth is I often regret getting involved in some threads. Especially the ones involving scopes!

author: kcbrown
author_rank: Frequent Contributor
timestamp: March 31, 2017, 10:37:25 pm
content: Quote from: G0HZU on March 31, 2017, 11:05:25 amExactly. This is actually a necessary trait for good engineering. You won't (except through luck or sheer brilliance) get a rock-solid bug-free design without critical analysis of the design, and it's best when that comes not just from you but from others as well, since there's always the possibility that you'll miss something simply as a result of perspective. Different viewpoints are useful for the engineering process. Nobody has experienced everything, and experience is a major factor in distinguishing between a solid, workable design and a design that has non-obvious shortcomings.QuoteActually, I disagree, and do so on the basis of experience, as it happens. There's nothing to distinguish a text-based forum from any other gathering of people when it comes to effective critical review. That's on thepeople, not the venue. It has to be understood by all participants that the purpose is objective critical review. That understanding is necessary not only so that the recipient will know not to take anything personally, but also so that those providing critical feedback know that they need to focus solely on that which they're reviewing, and not on who produced that which they're reviewing, as well as to make it clear to reviewers that they don't have to worry about their comments being interpreted as anything personal.The problem arises when not all participants understand that implicit agreement. And that's why I come into any forum with that kind of approach as the default. In particular, I never take anything personally (even if I did, I have a thick enough skin that it wouldn't matter. If someone thinks I'm a moron, that's on them, even if they might well be right! They can provide feedback that would make it possible for me to improve myself, but I simply don't care about anything in that context beyond that).In the software industry, which is where my primary expertise lies, there's a term for doing work in that field which maximizes the potential for improvement through critical review: egoless programming (see, e.g.,https://blog.codinghorror.com/the-ten-commandments-of-egoless-programming/). I think the approach that term applies works just as well for any engineering endeavor.

author: G0HZU
author_rank: Super Contributor
timestamp: April 01, 2017, 12:12:36 am
content: QuoteOk, fair enough if you could control who is present but I was really just referring to public internet forums. You can't easily avoid the bigots or the stubborn types who put their ego ahead of the laws of physics when on a forum. So critical debate often ends up unproductive and inconclusive because stuff doesn't get resolved.This is all way off topic so probably time to stop now...

author: G0HZU
author_rank: Super Contributor
timestamp: April 01, 2017, 12:16:50 am
content: At work we have a couple of the new/black PXA analysers with the new screen. They are both rented and are used in the ATE area so I doubt I will get to use them. But I have seen them running alongside both the classic PSA and the previous gen PXA and the big screen does look good. From what I hear they are much faster at some of the tests so hopefully this will justify the rental costs.

author: kcbrown
author_rank: Frequent Contributor
timestamp: April 01, 2017, 03:11:29 am
content: Quote from: G0HZU on April 01, 2017, 12:12:36 amI admit, it does make it somewhat challenging. But that's where having a thick skin comes in handy!The nice thing is that the people who take their ego out of the discussion can engage each other with aplomb, even in the presence of those who insist on keeping their egos in the mix. Nothing says that you have to engage someone who has a clear ego issue. But there issomevalue in doing so (and actually, there's potentially quite a lot of value, especially if you manage to convince them to engage in an egoless manner). When you don't have ego on the line but they do, it means that you can deal with the factual content of their messages without dealing with the rest. If they get all pissy about what you say, that's their problem. I'd explain to them, once, that what I'm saying is not about them, but about the factual content of their statements, and leave it at that.So the bottom line is this: I encourage you to keep the criticisms coming,most especiallyif you explain the basis for them (that tends to prove most educational, so I greatly encourage it!), no matter what anyone who has some kind of ego on the line happens to think. Those of us who are capable of looking past the style and get to the substance will benefit greatly from it. Those who can't, well ... that's their loss!QuoteHeh. Probably. And normally I'd be inclined to take the conversation elsewhere. But that would break continuity.