Which Spectrum analyzer would you get? - Page 1
Forum section: electronics / testgear

author: luckyflyer
author_rank: Contributor
timestamp: July 20, 2016, 09:57:58 pm
content: Trying to decide which spectrum analyzer to get.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 20, 2016, 10:25:10 pm
content: Why didn't you put the Rigol DSA815-TG in the list?BTW: I noticed that Rigol launched an Economy version of the DSA832, called the DSA832E.Does anybody know here on the forum what the difference is between the E version and the normal version? I could not find the difference based on the specifications

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 20, 2016, 10:33:36 pm
content: DSA832E combines the dirt-slow update rate of the DSA815 with the sky-high price of the DSA832.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 20, 2016, 10:46:08 pm
content: I understand that the Siglent wins miles from the Rigol if the low-end model can be "upgraded" to the high-end model

author: razberik
author_rank: Frequent Contributor
timestamp: July 20, 2016, 10:49:13 pm
content: I am in favor of old 8560E, because I simply love ancient instruments built like tank.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 21, 2016, 01:49:15 am
content: I keep looking at the Signal Hound to replace one of my old relics. Looks like they offer a tracking generator.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 21, 2016, 05:11:28 am
content: Quote from: luckyflyer on July 20, 2016, 09:57:58 pmAny reason why your choice is between an old HP antique and a Chinese B-brand? I mean, not that the HP is a bad instrument, but there are various other alternatives on the market.You also didn't say what you want to do with it, what RF performance or features you want, or what bandwidth you require. Or what your budget is.If I had to choose between these two then I'd go for the HP if it's in good condition (but I'd never pay anywhere near $1900 for it), simply because it's superior RF performance and because I don't trust Siglent with firmware. If not then I'd take neither of them as not too long ago I paid less than $1k for a 13.2GHz Anritsu SA manufactured in 2012.

author: rf-loop
author_rank: Super Contributor
timestamp: July 21, 2016, 05:15:39 am
content: Quote from: pascal_sweden on July 20, 2016, 10:46:08 pmAnd if it stay 2.1GHz (SSA3021X) it still outperform Rigol clearly if we compare DSA815. SSA3021X and SSA3032X are just same in all things exept frequency.In all other things they are same, not like low-end and high-end if think how we normally classify things to "low-end", "high-end" and "state of art" categories. All these spectrums, whole DSA800 serie and SSA3000X series are in "low-end" category if we talk stand alone table top spectrum analyzers. Bit, there is "low-end" category SSA3000X is in top corner, far over DSA815.Just only one example:Due to low near carrier phase noise down to < -90dBc/Hz @100Hz distance from carrier (-91dBc/Hz in this image including RBW normalization to 1Hz and then +2.5dB correction for 1Hz noise BW) you really can use RBW10HzYou can not do there just anything with DSA815. Same if you try put cow to fly.This is standard SSA3021X out from factory box. Trace A, signal from HP8644B free running with its own internal reference and SSA free running with its own reference. Trace B signal from SSA own 10MHz reference out. (this is from very different work but it can use also here as example.)In this image trace C is also on but not visible but it is there if move screen to more down, C is there for detect displayed average base noise level (in this case -127dBm/Hz)

author: nctnico
author_rank: Super Contributor
timestamp: July 21, 2016, 07:18:07 am
content: Quote from: Wuerstchenhund on July 21, 2016, 05:11:28 amSame here. I had a similar choice recently and I went for proven technology. Good deals on spectrum analysers from Anritsu and Advantest (both Japanese) can be found on Ebay so no need to put up with incomplete firmware.

author: JPortici
author_rank: Super Contributor
timestamp: July 21, 2016, 09:18:11 am
content: I think I would go with older hardware, provided it's calibrated and tested, because it would be easier to service...Even though the new siglent looks very promising both in the teardown (set of separated boards so in case of servicing worst case scenario you replace the input board/the acquisition board/the TG board/ power supply, ...) and in the software updates that are happening very fast and all the software featuresIf it's an old uncalibrated spectrum analyzer... no i will go for the siglent.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 21, 2016, 09:37:59 am
content: Quote from: JPortici on July 21, 2016, 09:18:11 amTested, sure, but I don't care if it comes with a calibration certificate or not.QuoteI wouldn't. Not every older SA requires constant re-adjustment to maintain its specs. Especially instruments made in 2000 and later usually exhibit excellent long-term spec adherence, and many come with self-calibration functionality that compensates for any parameter shifts due to ageing. There also isn't a lot to adjust in a newer SAs anyways.And as calibration is concerned, good luck trying to get a Rigol or Siglent SA calibrated by anyone else than the manufacturer. Most bigger calibration facilities won't touch them if you require traceable calibration.

author: dxl
author_rank: Regular Contributor
timestamp: July 21, 2016, 09:50:12 am
content: Over the last year i bought a HP 71910A Wideband Receiver (which basically is a 26.5GHz Spectrum Analyzer with up to 100MHz Bandwidth) for about ~2K. While this device is about 30 years old and probably wasn't calibrated during the last years, it still matches the Keysight MXA i have at work which is calibrated periodically. So i would also go with an older SA except if size and weight is important. The old HP SAs are build like a tank, but also much heavier than any Siglent/Rigol.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 21, 2016, 10:16:12 am
content: The user interface on these old devices, doesn't look bad at all. On the contrary, it looks beautiful!

author: tautech
author_rank: Super Contributor
timestamp: July 21, 2016, 10:30:45 am
content: Quote from: pascal_sweden on July 21, 2016, 10:16:12 amThat image only shows the GUI, not the UI.

author: Unknown
author_rank: Unknown
timestamp: July 21, 2016, 12:45:28 pm
content: "And as calibration is concerned, good luck trying to get a Rigol or Siglent SA calibrated by anyone else than the manufacturer. Most bigger calibration facilities won't touch them if you require traceable calibration."In North America, Transcat is a calibration partner with Siglent. They have 23 calibration labs in the USA, Canada, and the Caribbean. They do offer traceable certified calibration.

author: 1design
author_rank: Regular Contributor
timestamp: July 21, 2016, 02:18:59 pm
content: Maybe I am the only one that thinks boat anchors are mostly for anchoring boats. Most of them have unobatnium front ends, custom bonded mixers/attenuators and other components. Many have dried capacitors all over them etc. I think they are a wonderful way of spending time working on them if that is the goal. A nice repair and the feeling of satisfaction that comes with it is something I can understand and have experienced before.If I look from a user perspective, I would never buy something I am dubious about its reliability due to normal aging. Especially when I need to do other projects with it and don't want to spend additional time on something I already spent a lot of money on. Maybe it is just me, since I see instruments as tools, I guess if you are a carpenter you don't want to spend 20-30% of your time fixing your saw or being afraid it might brake soon.It is like buying an old car for the sake of fixing it, then it is a project not a usable every day car that you use to drive to work and run errands.BR

author: luckyflyer
author_rank: Contributor
timestamp: July 21, 2016, 02:35:48 pm
content: Point taken, the reason I listed these 2 in the poll is because they are the 2 that I've done my research on. These two represent in some ways the two ends of the spectrum if you will (pun intended). Meaning on the one hand we have an over built American unit with great performance and reliability, a proven track record whose main draw back is its age. On the other hand a lightly built and likely a well engineered Chinese unit with not nearly the history of the Hp units and questions of support by some regarding firmware etc. I acknowledge that there are many good choices out there but constraints on my time have limited me to these two. I'm not in a big hurry so as time permits I will start investigating some of the other brands.Regarding the Anritsu my question would be do they have the numbers of in service units that Hp/Agilent/Keysight has. Is there the base of knowledge and spare parts available for the Anritsu that there is for the old Hp's? And finally do they hold their value. These factor weigh heavily with me and are questions that will be ask of any brand I consider.Regarding the what are you going to do with it question. Initially it will be used for HF work checking filters and band pass shapes, looking for spurs etc. Mundane stuff really, but it would be nice to have an analyzer that has the ability grow as my needs expand. That is where the Siglent has an advantage imop, pay for it enter a code and bam the feature is there. $2k is my ceiling for price for now but that changes from month to month. Aah so many choices, so little time.Quote from: Wuerstchenhund on July 21, 2016, 05:11:28 am

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 21, 2016, 03:18:44 pm
content: Quote from: luckyflyer on July 21, 2016, 02:35:48 pmAnritsu is, among Rohde & Schwarz and Keysight, one of the key supplier of the mobile phone industry for RF test kit. They have support centers all across the globe, and offer support and spares for their gear.As to "holding their value", I don't know what you expect when the purchase price is already a lot lower than what you pay for a much older device from a company with a more widely known name (for fun, check out how much you'd pay for a Keysight 13Ghz SA from 2012, I'd bet it's a lot more than just $1k or even $2k). Resale value shouldn't matter much when you buy used gear which you plan to keep for a considerable amount of time, especially not when you consider going for an 20+yr old boat anchor.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 21, 2016, 03:29:43 pm
content: As with all HP test gear, there is a self-test in the device, that produces a specific error code when there is an issue with the device. These error codes can vary a lot, and the total list of error codes is very big.Here is an overview of the error code list for the HP 8560E in particular:https://www.custom-cal.com/Spec_8560E_1E_2E.aspxWhen I saw that list, I was wondering if there is a similar list of error codes in Rigol and Siglent test gear?I mean, suppose you buy a second hand Rigol spectrum analyzer, or a Siglent spectrum analyzer, is there any way to run a self-test to build up some basic confidence?Or even as a first owner, is there such a self-test which you can run once in a while, to double check if your spectrum analyzer is still reliable?

author: luckyflyer
author_rank: Contributor
timestamp: July 21, 2016, 04:27:04 pm
content: As to "holding their value",Certainly resale value should be a minor consideration (and is with me) when purchasing used equipment however the high prices of old Hp equipment is a strong testament to their popularity and underscores their longevity in the marketplace.

author: G0HZU
author_rank: Super Contributor
timestamp: July 21, 2016, 04:31:39 pm
content: FWIW, of all the analysers mentioned so far, only the HP8560E would make it into our design labs at work. We still have several HP8560E and 8563E analysers and they still get used. However, the PSA and PXA are the top choice. But we have kept the HP8560E analysers and the RF performance is good enough to do some serious RF design work. For many years the HP8560E was my favourite analyser to work with. I think that all of our HP856x analysers were bought new and some are quite old now and have seen a LOT of use over the years.But that doesn't make it the automatic winner for this poll. I think most hobbyists and small companies would be better off with something like the Siglent because it offers a warranty, and there will be a growing community of users on here to give advice etc. Also it has a modern display and modern connectivity. The HP8560E is going to look very dated when sat alongside the Siglent and the extra performance of the HP8560E probably won't be needed or appreciated by many. By contrast, I would take the HP8560E in a heartbeat but I'm a fairly serious user of a spectrum analyser and I'm used to using the high end stuff and I often need all the performance they offer.There are a few niggly issues with the HP8560E as well. The first ones we bought all had CRT displays and the displays are looking quite dull and tired now. It could just be that the front glass needs removing and cleaning as this can often make a big difference.Also, the front panel membrane for all the push buttons isn't very durable and I think that all of our older HP8560E and 8563E analysers suffer with a few deaf/intermittent buttons. Usually it's the up/down buttons and the 1 and zero buttons that fail first. Once it gets like this the analyser becomes more and more frustrating to use. These analysers were in constant demand/use at work and the front panel membrane only lasted a few years before the problems started to appear. It's unlikely that the average user would use these analysers this intensively but the button membrane is a weak point to look out for. Do all the buttons work OK on the one you want to buy?I've heard rumours that the YIGs can fail in these analysers but I think all of ours have been OK in this respect. I'm guessing that we have about a dozen or so of these HP856x analysers in the various labs and production/support areas.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 21, 2016, 06:06:07 pm
content: Quote from: luckyflyer on July 21, 2016, 04:27:04 pmMaybe, but more than anything it's also testament to the fact that the only brand names many hobbyists know or think of are HP and Tektronix (just look at how much even a lowly ESA analyzer goes for, or old Tek gear). HP has without doubt built some great SAs (Tek not so much) but they weren't the only ones. R&S' SAs are pretty much in the same performance class as HP/Agilent/Keysight, slightly better in some areas, slightly worse in others (and some of their SAs come with some pretty unique features). Below the high-end segment there's also Advantest and Anritsu, two Japanese manufacturers who also offer some great analyzers. And pretty much all these manufacturers build their kit like tanks.The point I'm trying to make is that HP isn't the only one who offers top-notch RF performance, and that considering a manufacturer that is less mainstream (amongst hobbyists) might get you a better deal. It's rare to find them amongst the stuff everyone rushes for, though.

author: luckyflyer
author_rank: Contributor
timestamp: July 21, 2016, 08:15:45 pm
content: Good points Wuerstchenhund, I had a little time and checked into the Anritsu-MS2670A. It's a 1990's era military version of one of their other sa's. It has a tg and goes for relativity cheap. One user reported that it was almost impossible to get the service manual for it but said that was a good for what he needed an sa for. So defiantly more than just a few choices out there.

author: luckyflyer
author_rank: Contributor
timestamp: July 21, 2016, 08:24:08 pm
content: Quote from: G0HZU on July 21, 2016, 04:31:39 pmThis address's my reasoning for considering the 8560E. Although I don't need all of the performance the 8560E offers now I may in the future and by going with the higher performance unit to start with it may save me from buying twice.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 21, 2016, 08:49:41 pm
content: Quote from: luckyflyer on July 21, 2016, 08:15:45 pmYes, but really, with a $2k budget, don't just look at 20+ year old kit, with a bit of patience you can find a lot younger instruments in that range.Quote from: luckyflyer on July 21, 2016, 08:24:08 pmMaybe, or it might just fail when you need it. The older an instrument is the more likely it is to fail.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 21, 2016, 09:16:43 pm
content: What about the spurious response (both internal spurs without signals connected, or spurs as a result of the interaction with a connected signal) in the analog spectrum analyzer HP 8560E?Are analog spectrum analyzers better than digital spectrum analyzers in this field? Or are they worse?Are there different variations possible in the build up of the various stages in the spectrum analyzer,and are some variations less subject to spurious response compared to others?Is the build up of the stages in most spectrum analyzers the same or very similar, or are there 2 or more fundamental variations and approaches that are completely different from each other, and that have a completely different internal spurious response by design?

author: tautech
author_rank: Super Contributor
timestamp: July 21, 2016, 09:36:37 pm
content: Quote from: pascal_sweden on July 21, 2016, 09:16:43 pmThe best explanation of this on the forum is here:https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg981095/#msg981095

author: G0HZU
author_rank: Super Contributor
timestamp: July 21, 2016, 09:54:23 pm
content: QuoteThe level of internal spurious terms will be a function of the frequency plan of the analyser, also the bandwidth of the various IF filters, also the conducted and radiated isolation between mixer (and LO) stages and also the gain plan of the analyser.There are lots of tricks you can do to minimise or hide spurious terms. Back in the 1990s my day job was designing high performance RF converters (with several GHz tuning range) that fed into a digital IF. One of the key design parameters was to achieve low internal spurious performance so I had to design the frequency plan very carefully and also make sure there were no leakage paths between the mixers or synthesisers up at many GHz. If you get this wrong, the level of spurious terms will be terrible. If you have a decent attempt at the frequency plan and adopt various filtering/screening/isolating techniques you can get the spurious quite low. But to get them really low requires various sneaky tricks in firmware and hardware.It gets much harder if the converter has a wide IF bandwidth, eg a ballpark 20MHz IF BW because there is a much bigger target area for the spurious terms to fall into.if you look at the PCB layout for the Siglent analyser in Dave's teardown you will see there are three obvious filters in the first IF path beween the two RF mixers. There is the main printed IF1 BPF and there is also a bowtie LPF and also a little white Minicircuits roofing LPF. Together, these are designed to give a reliable stopband performance between these two mixers and this helps reduce internal spurious generation by increasing the (conducted) isolation between the mixers across a wide bandwidth that includes the harmonic frequencies of the first and second LOs. However, I think there are more tricks that could be done than thisMy spec for internal spurious was -120dBm and this was verified in production test on every unit shipped (took several days to do this test on each unit!) and the customer repeated this test on delivery. So I had to meet this spec

author: G0HZU
author_rank: Super Contributor
timestamp: July 21, 2016, 10:14:12 pm
content: In this old EEVlog thread you can see me help diagnose internal spurious problems with the HP8562B analyser Shahriar was repairing.https://www.eevblog.com/forum/testgear/video-teardown-repair-and-analysis-of-an-hp-8562b-22ghz-spectrum-analyzer/You can see the importance of the coaxial roofing filter that sits between the two mixers and how bad the spurious performance was when Shahriar had omitted it. This filter looks like a bit of stiff/rigid coax cable but it is really a high performance LPF with very good stopband performance out to many GHz.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 21, 2016, 10:18:17 pm
content: With the knowledge you have, you can provide consultancy to Siglent and Rigol to further improve their spectrum analyzer line

author: KE5FX
author_rank: Super Contributor
timestamp: July 21, 2016, 11:25:38 pm
content: Quote from: 1design on July 21, 2016, 02:18:59 pmIn this case, it's more like a comparison between the Snap-On tools that have been in your dad's toolbox for 30 years and whatever they're peddling down at Harbor Freight this week.Sometimes the Harbor Freight special is just the ticket. And sometimes, you need a more elegant weapon from a more civilized age.

author: cncjerry
author_rank: Unknown
timestamp: July 22, 2016, 01:36:10 am
content: Maybe I'm just getting old but I believe in the old stuff, said it a bunch of times. For instance, my upgraded TDS784 is just such a pleasure to use over my Owon SDS7102V. The CRT is crystal clear and the colors are almost hypnotic. Yes, the Owon is about the size of a few paperbacks and TDS744 is the size of the library but when I want precision, I go to the Tek.I have an 8568b with TG and preselector/preamp and a recently acquired 8566b. The 8568b setup easily comes in over 150lbs. Compared to my advantest the HP analyzers are much easier to use and clearly have better 'resolution' if that's the appropriate word. I was playing with the three of them today measuring a 1G signal. Both HP analyzers were right on the money for frequency and amplitude and the advantest was 2db in amplitude off. Go figure, maybe there is something wrong with it but the last I looked, I couldn't even get it apart. I also know I can fix the HP boxes if they break.What we need is a thread with a common, easy to reproduce signal, say 1G modulated with 1K or something more difficult, where everyone posts their analyzers best trace. I think it would be interesting to see the trace comparisons in one place.So I voted for the 8560E. I saw some really nasty reviews of the Sig analyzers with TGs. I can't remember if the TG was the problem or what. also, that 10Mhz glitch in the Rigol SA with TG would drive me crazy.

author: tautech
author_rank: Super Contributor
timestamp: July 22, 2016, 02:25:06 am
content: Quote from: cncjerry on July 22, 2016, 01:36:10 amIt was, now fixed.Openly discussed here:https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg895153/#msg895153https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg907575/#msg907575

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 22, 2016, 05:11:59 am
content: Quote from: cncjerry on July 22, 2016, 01:36:10 am+1A set of some simple standardized tests which aren't overly complex to setup (i.e. which can be done with a RF gen, or with a 10MHz signal from a frequency reference source) would be good to give a general idea of how a SA performs, which would certainly help people like the OP to find a suitable instrument. And it would show how the devices from the brands that are less widely known amongst hobbyists perform in comparison with the mainstream brands.

author: rf-loop
author_rank: Super Contributor
timestamp: July 22, 2016, 06:31:40 am
content: Quote from: Wuerstchenhund on July 22, 2016, 05:11:59 amIdea is good. Problem is that peoples have so different skills and knowledge about things and very importantly, very different quality sources for test signals. i.e. which one is DUT, SA or signal source. With good SA but crap source you get image about this signal source quality and nothing about SA quality. Test signal source need be over SA quality, and better with high marginal.If I take HP8642B what is overall still "good" RF generator and if I go very close carrier, which one uou see, Siglent SSA quality or HP RF gen quality. This I ask with reasons.Also 1kHz AM with 90% mod is easy for what ever modern SA. But with 10% or 1% mod depth there may see some differencies.If I and hundred others all with different knowledge, skills and equopments do these kind of tests and then send image here, what we know after then. I can see here peoples who can not even tell what they have measured and how. But then here is also professionals and higher end hobbyists with lot of wide range knowledge and huge long time experience enen up to state of art class.How we can avoid errors.One may use some super crap FEI Rb for example as 10MHz source what look with SA or even more bad he can connect this crap for SA refeerence or even something more crap and then wonder why good SA show this and that.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 22, 2016, 08:23:09 am
content: Quote from: rf-loop on July 22, 2016, 06:31:40 amThat is correct, but I'd say this can mostly be compensated by simply a throrough description of the test setup.As I understand it the idea is to see how a certain SA behaves in a specific situation, not to confirm a SA's specifications or to find the 'Best SA Ever'. And even if the signal source is slightly worse than the SA, as long as it's performance is known then you can still get some impression about aspects of SA performance (e.g. phase noise, which is additive). Of course there's not much point in posting screenshots of a $150 china AWG.But at least when the test parameters and devices are specified you can decide how much value you put to the screenshot.

author: rf-loop
author_rank: Super Contributor
timestamp: July 22, 2016, 03:40:18 pm
content: Quote from: Wuerstchenhund on July 22, 2016, 05:11:59 amHere is some trivial basic examples. I select 10MHz for test signal because many peoples have maany kind of signal generators and perhaps least acceptable quality 10MHz is more easy to find(?) Also cheap 10MHz OCXO can use for example get some imagine about SA base noise roughly.Signal from Agilent/HP 8644B. Cable 3m Huber+Suhner Sucoflex 104PE(A) (10mm)Generator free run with its internal High stab ref.SSA3021X free run with its normal internal ref.-70dBm 10MHz signal with 20% 1kHz AM modulation.This can also show something about base noise level. (here PreAmp on and detector PosPeak)10MHz 0dBm, 400Hz,1%AM MaxHold, PPK-Ave, MinHoldNote: 0dBm signal is fully ok there over display top. Also cursor measure it 0dBm.10MHz 0dBm, 400Hz,0.1%AM MaxHold, PPK-Ave, MinHoldNote: 0dBm signal is fully ok there over display top. Also cursor measure it 0dBm.10MHz 0dBm, 400Hz,2%AM, RBW 300Hz, 100Hz, 30Hz, 10Hzall traces RBW:VBW = 10:1(note: RBW 10Hz can use only Sweep mode: FFT. Others done using Sweep mode: Sweep)ETA: Added missed image -70dBm-AM-50Hz-0.1%(but this start also show limits, without averaging these 0.1% modulation 50Hz sidebands are nearly impossible to detect without averaging, even 2-3 trace average is anough but more measurement accuracy with more averaging. (too near carrier and too near total noise)

author: Dwaine
author_rank: Frequent Contributor
timestamp: July 22, 2016, 04:32:43 pm
content: Quote from: G0HZU on July 21, 2016, 09:54:23 pmWow.... Maybe Siglent and or Rigol could hire you. I get the feeling they don't take their design to the same level. Certainly not test every unit that leave the production line.It would be nice to see just how much effort Rigol and siglent put in their product designs.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 22, 2016, 06:16:51 pm
content: Quote from: Dwaine on July 22, 2016, 04:32:43 pmDesigning high end RF gear doesn't come easy or cheap, which is one reason why Keysight & Co can charge large amounts of money for their top-notch high-end SAs.Siglent and Rigol pretty much put enough effort in their design to allow them offering bottom-of-the-barrel instruments at bargain prices.The old sayin' that you get what you pay for holds still true.

author: tautech
author_rank: Super Contributor
timestamp: July 22, 2016, 08:34:19 pm
content: Quote from: Dwaine on July 22, 2016, 04:32:43 pmWhat evidence do you have to make such a BS statement.Every Siglent instrument must meet advertised spec. Period.Every Siglent instrument is shipped with a Cal cert.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 22, 2016, 08:44:00 pm
content: Maybe Siglent and Rigol should ship some test units to Wuerstchenhund, and ask him to use the equipment for a full week. After we might get some respect for Siglent and Rigol gear from the non-believersThe screenshots from the Siglent spectrum analyzer clearly show that the device is very capable!But I have the impression that some people here just refuse to look at the screenshots.

author: nctnico
author_rank: Super Contributor
timestamp: July 22, 2016, 08:59:38 pm
content: Quote from: pascal_sweden on July 22, 2016, 08:44:00 pmSome people (me including) do have hands on experience with Siglent equipment and the trouble starts when you want to use the advanced features and/or start putting things under a magnifier glass. I admit the SSA3000 series spectrum analysers look mighty interesting but since I'm not an expert on spectrum analysers and I may not have the equipment to verify them fully so I have to trust the numbers they produce. And this touches on Dwaine's posting: Ofcourse Rigol & Siglent test the hardware before it leaves the factory. However they don't test / quality control the software at all. So how do I know things like averaging, power, quasi peak (part of EMC testing), etc, etc are implemented correctly? What if a spectrum analyser gives me the wrong number and I waste a couple k euro due to that?

author: KJDS
author_rank: Super Contributor
timestamp: July 22, 2016, 10:04:43 pm
content: No company ever tests every test equipment to every parameter on the production line. It's just a subset that should be sufficient to ensure that the unit meets spec, determined by some extra qualification testing which won't cover every parameter completely.Don't believe me? I'll put a lot of money that the effect of mains frequency variation of the supply isn't checked over temperature. I doubt that spurious response is checked over mains voltage variation. IP3 won't be checked at every possible frequency and amplitude even at room temperature, let alone over temperature, or during vibration, and yes, there will be an operational vibration spec.Get the subset of tests for qualification and production testing correct, and ensure that a sensible sample, usually a few percent of production undergoes extra testing, over temperature, over mains voltage etc and things can be kept under control, however it's very easy to save a few pounds by omitting some more complex tests, and some of the extra testing and then quality can easily drift even if the design started out good.The only time the testing is anywhere near complete is if a product is going into a satellite, and even then there are still holes in the regime.

author: G0HZU
author_rank: Super Contributor
timestamp: July 22, 2016, 10:41:21 pm
content: I didn't intend to kick off a debate about production testing but in the case of the stuff I was designing the customer (and there was only one customer) insisted that every RF converter unit was tested across the full tuning range (several GHz in small steps) and every spurious signal above the MDS of the back end DSP was logged across the IF bandwidth of quite a few MHz. Back in those days this took several days per unit because each one had to be tested across more than one pass because certain modes had to be checked as well. We had to get this right because the customer did exactly the same tests on delivery. These weren't cheap converters BTW, the filter(s) used in the first IF each cost about half the cost of the entire Siglent analyser. Each filter was a custom design produced in the USA.I don't know how Siglent and Rigol manage to produce their analysers at such low cost. For this reason it's hard for me to criticise these analysers in terms of the RF performance they offer. Overall I think it's amazing value for money for a new instrument. What will they be producing/offering in 5 years' time I wonder?The only criticism I can offer is that nobody ever reviews or tests the Rigol or Siglent analysers thoroughly. So I'm still left wondering how good/bad the performance really is.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 23, 2016, 12:34:16 am
content: Having spectrum analyzer that does not cover 2.5 GHz range kind of suck for obvious reasons. Even 3 GHz is not that good because you cannot look at second harmonic at that frequency.Perhaps best option is to buy Both - old Agilent/HP and Siglent, compare noise floor, selectivity ... and then keep the best and sell another one back on Ebay. I don't see why Siglent, unless it is defective, would not match main performance characteristics of HP/Agilent or Anritsu on such limited, low frequency range of 0.01 - 2.1 GHz.This doc tells how to do comparison:http://literature.agilent.com/litweb/pdf/5965-7920E.pdf

author: Dwaine
author_rank: Frequent Contributor
timestamp: July 23, 2016, 02:17:17 am
content: Quote from: tautech on July 22, 2016, 08:34:19 pmpll problem with their scopesThe DMM meter that was completely a mess inside.Scratched LCD Screens on their scopesFirmware with spelling mistakes and RMS measurement problems.I have both Rigol and Siglent equipment. But I do understand that they don't have the same level of quality as the bigger companies. I think most things these days don't have any passion around it. It seemed better back in the older days.I do enjoy my Rigol and Siglent equipment.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 23, 2016, 02:22:21 am
content: I don't need much for my home use. Really like the look of the Siglent. One day .... My newest SA is a 3589A. Shown with an even older 8640B with 20Hz AM modulation on 10M carrier.Second set showing 33120A sitting about 20Hz away from the 8640B. Last picture, turned up both the 33120A and 8640B. You can just see the -100dB from the 8640 down in the muck. No way I could see anything this close with my old Tek or other HP.

author: Dwaine
author_rank: Frequent Contributor
timestamp: July 23, 2016, 04:33:38 am
content: Quote from: joeqsmith on July 23, 2016, 02:22:21 amI wish they could use the same build quality and just put a colour LCD display in the older units.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 23, 2016, 08:52:17 am
content: Quote from: pascal_sweden on July 22, 2016, 08:44:00 pm'Non-believers',? You seriously think buying test gear is some for of religion?As to sending me some Siglent gear: no need to, I already had my fill of Siglent 'goodness', like the SDG1020, and later Siglent's crème de la crème of scopes, the SDS2204. The SDG1020 was released with buggy firmware and a hardware design flaw that lead to excessive jitter, but considering it was really dirt cheap it wasn't a bad purchase, and apparently most (not all) of the bugs have finally been fixed (I can't say for sure, I no longer have this device). The SDS2204 wasn't a cheap scope, and while I got mine for a low price it turned out to be pretty much useless due to it's bug-ridden firmware even two years after release. I got rid of it but I recently had a look at the V2 firmware thread and it seems that there are still silly bugs in the firmware.Having said that, I do have a lot of respect for Siglent because, unlike Rigol, they have shown the capability to produce really good hardware at reasonable prices. If buying test gear was solely down to hardware quality, I wouldn't hesitate to buy their kit. But fact is that they have proven to be utter incompetent as to developing proper firmware for their gear. Pretty much every Siglent device came to market with ridiculous bugs which tells you that the affected function clearly has never been tested by Siglent, and the SSA3000X was no exception (like the screen shot bug where the fle name dialog was in the screenshot). The only instrument made by Siglent that came to market in a mature state was the SDS3000 scope, and that is only because the firmware is developed by someone else away from Siglent, which resulted in an excellent product. But it also shows how much better Siglent stuff in general could be if it didn't came with crap firmware.I know Siglent has pushed firmware updates for the SSA3000X, and it could well be that the SSA3000X is now in a mature state where it can be considered reliable, but at the end of the day we don't know because there isn't much experience/thorough reviews out there (especially not by people not affiliated with Siglent). Until that is the case, and considering Siglent's track record, I'd be very careful before investing two grand into their new, unproven product.QuoteThe screenshots look good for an low-end SA in that price class. But screenshots tell you little about the overall maturity of an instrument (there are some nice SDS2000 screenshots in some of the related older threads, it doesn't change the fact that the scope was a buggy mess).But even when leaving the question of Siglent's firmware quality aside, there's always the 2nd hand market. While the performance of the SSA3000X seems to be perfectly fine for a low-end SA, there's still the option of buying a 2nd hand big brand SA for the same or even less money, with a larger bandwidth and much better RF performance. And it would be silly to not at least consider that option.

author: rf-loop
author_rank: Super Contributor
timestamp: July 23, 2016, 09:04:13 am
content: Quote from: joeqsmith on July 23, 2016, 02:22:21 amHere is test with "unknown" SA. (it may only tell that equipment may have more resources what is configured for use in models what are available, example Siglent SSA3000X)Quote from: joeqsmithAnswer to first and second image is quite easy (somehow combined in this first image).But then, last image.Quote from: joeqsmithThis old gear beats this unknown modern SA clearly. Why. Answer is very simple and straight. Phase noise. (Btw, this phase noise level can not reduce using better External Reference- major part of pn do not come from reference )If do MinHold and TraceAverage long time it can show -90dBm in this same setup but this is so borderline that I do not want even show. Even this -80dBm here need bit averaging for better and more accurate result.So, here is one "game over" point but this was also expected. Why there in my image is attenuator set for 10dB. Max mixL is -20dBm, not so much other reasons.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 23, 2016, 10:44:37 am
content: Quote from: Wuerstchenhund on July 23, 2016, 08:52:17 amYou have a point! I will definitely consider looking at used HP gear or R&S gear.Considering used HP spectrum analyzers. There seems to be such a wide variety of different models.Some examples: HP 8559A, HP 8560E, HP 8590A, etc.Any guidelines on what their respective age is, where to start, and which one to pick?

author: KJDS
author_rank: Super Contributor
timestamp: July 23, 2016, 10:59:51 am
content: The 856X series has better phase noise and better (narrower) resolution bandwidth than the 859X series. That's usually reflected in the price. I suspect that it would usually end up cheaper buying an E4406A if you wanted to look close in at modulation and an 859X for broadband sweeps. It's rare for either the 6x or 9X to come with the tracking generator. If a business is buying something to measure insertion loss then it usually also wants to measure return loss and it's far more effective buying a Network Analyzer so that there's reasonable accuracy in the measurement.Generally Anritsu and R&S kit will be cheaper than the equivalent HP, however support is often more difficult to come by.If you need a tracking gen, then either a noise source can be used to give an indication, or else if there is a 1st LO output then this can be mixed with a fixed signal to give a tracking gen.

author: rf-loop
author_rank: Super Contributor
timestamp: July 23, 2016, 11:21:41 am
content: Quote from: pascal_sweden on July 23, 2016, 10:44:37 am8590A throw away, do not even think8559A throw away this boat anchor exept if you want collect for museum (also need be careful with its mechanics because it is very fragile after it come old)8560E it have still value in use (depending also options)Do not buy if seller can not do tests and do these tests what you ask and you need know what to ask. Exept if you know these equipments so that the thumb is not in the mouth if need repair, adjust etc, and you can smell out what is more like ok and what is in "awoid" class. These are best to buy locally and if there is possible to do own tests.Btw, R&S do really nice SA's.(HP) Look serial number prefix and add 60 (im not sure if this works with all models and years)

author: VK5RC
author_rank: Unknown
timestamp: July 23, 2016, 11:40:13 am
content: The sheer number of 856x SAs out there (quite a bit of website fixit if needed) and not too many unobtanium parts and HP-AG-KS tendency to keep manuals on their website has me voting with my feet to an older HP SA.The Siglent and Rigol gear do represent amazing value.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 23, 2016, 12:48:25 pm
content: OP seems to want to do some sort of network analysis with the TG option. The 3589 has a built-in generator and some limited measurements. Really, I need to write some software for it but never had the need. Has software for SOT.Plots showing a short and 50 ohm terminator.Oops. Showed the same picture twice due to lack of coffee. So here is the actual cal'ed 50 ohm then a crappy old Ethernet 50 ohm terminator. As you zoom in on a Smith chart, it switches to a polar chart for some reason. Last picture showing a Showa SF0922B 9.0MHz crystal filter.For me, the down side to this old beast is that it is limited to 150MHz.

author: Performa01
author_rank: Super Contributor
timestamp: July 23, 2016, 08:22:40 pm
content: Quote from: rf-loop on July 23, 2016, 09:04:13 amWell, it’s about time that I pull out some real high end SA thenAlso an “unknown” instrument, no extra resources, no life, no nothing. Just high end.Despite having such a fantastic instrument, I lack the pair of high end RF-synthesizers required to take on the challenge of placing a tiny signal in the middle of a modulation spectrum. So I had to make do with just one signal, but with a little more complex modulation signal (XXX_-11dBm_10MHz_AM_15_20_50Hz_max)This screenshot shows a -10.7dBm 10MHz signal (marker 1) that is amplitude modulated with three signals at the same time:1. 20Hz pulse, 10% duty cycle (marker 2) in an attempt to resemble what joeqsmith has shown us.2. 15Hz sine (marker 3) just for the “little extra”.3. 50Hz mains hum (marker 4) which cannot be missing in any high end test setup!Max. detection and no video averaging.Please note the vertical scaling which is 12dB/div. so you can see the extra 20dB down to -130dBm. Otherwise you might have missed the mains hum…

author: tautech
author_rank: Super Contributor
timestamp: July 23, 2016, 11:06:46 pm
content: Quote from: joeqsmith on July 23, 2016, 10:54:31 pmYep.There's no mention of it in the datasheet however the manual describes it:3. Earphone JackThe analyzer provides AM and FM demodulation. Insert the earphone to the jack to acquire the audio output of the demodulated signal. You can turn on or off the earphone output and adjust the volume via Demod ->Volume.The audio jack is on the lower front panel alongside the USB socket, easily visible in the website pics.http://www.siglentamerica.com/pdxx.aspx?id=1546&T=2&tid=227

author: joeqsmith
author_rank: Super Contributor
timestamp: July 23, 2016, 11:29:10 pm
content: Quote from: tautech on July 23, 2016, 11:06:46 pmDang, I bet it even sounds better than the 496!I am looking on ebay and drooling... Lot of cheap SAs out there, so much better than I have. Still I would get a digital one. I wonder if any of them can decode digital TV. Maybe I could get it past the wife then.

author: tautech
author_rank: Super Contributor
timestamp: July 23, 2016, 11:31:50 pm
content: Quote from: joeqsmith on July 23, 2016, 11:29:10 pmNot if she can't see the pictures.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 23, 2016, 11:36:04 pm
content: In that case you would need to get an MPEG analyzer from Tektronix or the likehttp://www.tek.com/mpeg-test-video/mpeg-analyzerNote that this only works on unencrypted video streams.Most video streams of your cable provider will be encrypted.The headers of the MPEG-2 streams are in the clear, but the video payload is encrypted.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 24, 2016, 12:51:27 am
content: Quote from: tautech on July 23, 2016, 11:06:46 pmI remember seeing a "Demod Time" setting in a screenshot of the SSA3000x somewhere. If it works like "Demod Time" in the DSA815, then it can't demod while performing a sweep, so it will play radio for the demod time, interrupt radio to perform the sweep, and repeat.

author: tautech
author_rank: Super Contributor
timestamp: July 24, 2016, 07:51:52 am
content: Quote from: jjoonathan on July 24, 2016, 12:51:27 amExactly ^^^Here's a shot using the human body as an antenna for the most powerful Auckland AM station that's ~15 km away.Audio was crystal clear on #1 volume setting for the bits heard at the end of each sweep.Subject station:http://www.newstalkzb.co.nz/news/

author: rf-loop
author_rank: Super Contributor
timestamp: July 24, 2016, 07:57:00 am
content: Quote from: jjoonathan on July 24, 2016, 12:51:27 amYes. And, of course.For listening AM or FM then need stop sweeping. This is single pathway machine, not radio with rf band panorama display.Tune center freq to station and press zero span. Depending station AM or FM on.note, RBW filter setting! This is just as radio IF filter width. If someone do not know how to do, just start point for AM use 10kHz RBW and for (wide)FM example 100kHz or EMI filter 120kHz.One day I did many things in lab without needing SA at all, mostly paper work. IJust for fun I use SA as radio and listening some SW commercial stations and some FM.Sure it can not do what my Racals etc can do, or not even what cheap Tecsun can do.There is no SSB, there is not beat osc for CW and so on.And then very important thing is that there is not any kind of automatic RF and Audio level control. (if go more deep there is some but not what radio need). With fading signal there need continuously adjust attenuator, PA and Audio level.Note: With antenna do not destroy SA input circuits. Use some protection. Without protection it is gambling.Also it is good to realize that input is always widely open for full frequency band. If you listen 12MHz weak AM station and there is high signal in GHz range it also come directly to mixer.Maximum: RF power 33 dBm, 3 minutes,input attenuation >20 dB !

author: G0HZU
author_rank: Super Contributor
timestamp: July 24, 2016, 05:55:44 pm
content: QuoteI guess it depends on how hard you look and where you look for the limits of the performance of any analyser.If I had the Siglent analyser here I think I could find several aspects of its performance that are going to be much worse than a classic HP/Agilent analyser from >=15 years ago. But some things would hopefully be better with the Siglent because the Siglent analyser has a modern digital IF.One aspect of the Siglent analyser that worries me a bit is that they have used a frequency doubler in the first LO. This would make it harder to maintain a low internal spurious qty/level.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 24, 2016, 05:58:00 pm
content: Please define "several aspects". If there are several aspects, you can at least name some specific aspects, to have the figures on the table. Even better, get both units, and make the measurements to confirm it with a test report.

author: G0HZU
author_rank: Super Contributor
timestamp: July 24, 2016, 06:13:27 pm
content: Mismatch uncertainty, far out phase noise, attenuator performance, dynamic range at low frequencies, internal spurious levels and qty, external spurious responses.

author: nctnico
author_rank: Super Contributor
timestamp: July 24, 2016, 06:22:44 pm
content: Quote from: G0HZU on July 24, 2016, 06:13:27 pmWould it be possible to determine (or at least make an educated guess about) things like these based on the datasheet of a typical spectrum analyser or do you really need to measure this yourself?

author: KJDS
author_rank: Super Contributor
timestamp: July 24, 2016, 06:24:37 pm
content: Quote from: pascal_sweden on July 24, 2016, 05:58:00 pmOne crucial thing with a spec ana is the spurious free dynamic range.No matter what signals you add in the front end, then so long as they are not above the top of the screen then there should never be a spurious signal visible. There usually is, somewhere, however it will often take some searching for. Also, signals outside the specified frequency range shouldn't ever cause a signal to appear on screen.Let's take a look at a classic scheme for a 1GHz analyzer. The input will come into a mixer via some switched attenuators to be mixed with the first LO. The first LO will typically run from 1.4 to 2.4GHz to give a 1.4GHz 1st IF. Put in a signal at 1.4GHz and it will leak through the mixer into the 1st IF, so it needs a lot of filtering, probably at least 70 to 80dB of filtering. Similarly, frequencies out at 3GHz could also be mixed down to 1.4GHz when the 1st LO is at 1.6GHz, so the front end filter needs to stretch a long way up with a lot of rejection.Additionally, there will be a point where the third harmonic of the input will mix with the second harmonic of the LO to land at 1.4GHz. The mixer therefore needs to be sufficiently high performance in order to ensure that the spurious it generates are of a very low level. High performance mixers aren't cheap, and need driving with a high level LO signal so the amp to drive it becomes more expensive and the shielding requirements to stop the higher level signal going places it shouldn't become more demanding. If you know the architecture, you can calculate where the 3-2 harmonic will fall, put in a signal of the appropriate level and go hunting for the spurious. On a cheaper instrument it's much easier to find.The other issue is phase noise and frequency stability. This is far less of an issue on modern instruments than it was in earlier times. Fractional N PLLs made things much easier, then with a digital IF it becomes simpler still, just step the LO every few MHz and let the digits sort out the IF filtering.There's lots of other issues too, a few of which have been highlighted in the previous post, but if you want to make a measurement of a filter insertion loss and the filter only has a 12dB return loss and the analyzer only has a 20dB match then you're left with some horrible uncertainty of 1dB, which is hopeless if your filter only has 1dB insertion loss.

author: G0HZU
author_rank: Super Contributor
timestamp: July 24, 2016, 06:31:04 pm
content: Quote from: nctnico on July 24, 2016, 06:22:44 pmThe datasheet can be a good guide but there will often be some weasel wording to hide the areas where the analyser will be weak. For example, the dynamic range is often quoted within certain frequency bands and is left undefined in other places. Also, some datasheets quote guaranteed specs and others quote typical specs (or both) and some show nominal figures.Note that the weasel wording tactics are used by all manufacturers including the big names so I don't mean to imply that this is only carried out by Siglent or Rigol or anybody else

author: rf-loop
author_rank: Super Contributor
timestamp: July 25, 2016, 04:11:08 pm
content: There is so many near carrier tests so here is bit more far from carrier. 0-5MHzTrace AIn attached image there is 989MHz 0dBm carrier (checked that SA measure peak and result is 0dBm. This measured using P-Pk detector using 20dB attenuator setting (also checked with HP Power meter so that least not significant error)Ref level changed to -80dBm.Then measured sideband noise figure using Video Average detector (also Noise marker function need it)Because signal is 0dBm Marker levels can read also as dBc/Hz (in this function Siglent use also correction to 1Hz noise bandwidth using 2.5dB correction what is because RBW gaussian style shape and detector etc things need normalize for (rayleigh distribution) noise . More deep explanation can find example from HP/Agilent app notes)RBW and VBW 10Hz.SA with its internal standard reference.Signal source HP8644B with its internal Optional High Stability OCXO.Cable between G and SA was bit better shielded Sucoflex for keep possible environment noise away.Trace C:All same as trace A but SA input terminated (Narda 50ohm N.)Both traces also averaged using trace average.Not very bad but if they some day launch version where also 1Hz RBW is activated lets hope they can also reduce phase noise.

author: Jester
author_rank: Frequent Contributor
timestamp: July 25, 2016, 07:15:10 pm
content: I can get a HP 8566 locally (supposedly) in working order for $400.Is this a good unit?Anything to look for?I want to use this for pre-compliance EMI testing

author: G0HZU
author_rank: Super Contributor
timestamp: July 25, 2016, 07:27:16 pm
content: Probably best to start a separate thread about the HP8566B... But FWIW I have one here and you could use this analyser for EMC/EMI testing but it doesn't have an internal quasi peak detector. You have to buy an external box for this.The HP8566B is a fabulous old analyser from HP in terms of RF performance but it is also very big and extremely heavy at about 50kg. It also makes an awful lot of fan noise and consumes a lot of power. You don't want to use this analyser in a small room unless you can live with the fan noise and the heat it gives off.It's also going to need fairly regular maintenance in terms of swapping out old failed parts (usually wet tantalum caps) and the CRT is a weak point in that the CRT can lose brightness and focus over time.I've had mine for about 5 years and it is still running fine although it's been apart for minor repairs/tweaks several times. None of the repairs were costly in terms of parts.My advice would be to look elsewhere if you just want to do EMC/EMI testing but $400 is a very low price for a working HP8566B. I'd expect it to be tired/faulty/damaged for that price?

author: G0HZU
author_rank: Super Contributor
timestamp: July 25, 2016, 09:51:36 pm
content: QuoteIf you look at rf-loop's phase noise plot for the Siglent analyser at 1GHz then the phase noise at 100kHz offset is -98dBc/Hz.On my old 1800MHz Advantest analyser here, the (measured) phase noise for a 1GHz test signal at 100kHz offset is -128dBc/Hz . So that is 30dB better than the Siglent. This analyser was first produced in 1981. It's a massive (and ugly) thing, even bigger and heavier than the classic HP8568B and it cost a lot more money when new than the HP8568B. It uses a big and expensive YIG oscillator for the LO and this is why it has very low phase noise at 100kHz offset.Obviously, it's a bit unfair to expect the Siglent to match the Advantest's YIG oscillator but there is a 30dB margin in noise performance here...

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 25, 2016, 10:00:08 pm
content: What is the difference between HP8568B and HP8566B?Is there an easy number and letter scheme to recognize the differences between all these model numbers? Some end with A, others with B or E. Some start with 856x, 859x, 892x, etc.

author: G0HZU
author_rank: Super Contributor
timestamp: July 25, 2016, 10:12:08 pm
content: Probably best to read the official HP literature about the HP8568 and HP8566 but the HP8566 was HP's ultimate 'doomsday' analyser designed for use up past 20GHz where performance was more important than the huge dev costs or the massive purchase price. It's dev work traces back to the late 1960s and dev work on the HP8568 began later, some time in the early 1970s. The HP8568 was a 1500MHz version of the 22GHz HP8566.http://hpmemoryproject.org/technics/bench/8568/bench_8568_home.htmThese HP8566A and HP8568A analysers were released on sale in the late 1970s and caused an absolute sensation. They were miles ahead of anything else at the time. The B version of each was released a few years later and it has a Motorola 68000 based processor card and this runs the GUI and display a bit slicker than the A version that used HP's own processor.They look very similar on the outside and the top display section is supposed to be the same. But there are lots of differences in the RF section and not much in common in the signal path. But both analysers were regarded as the industry standard (for their respective frequency ranges) for about two decades.The HP8560 is a portable (but still very heavy) analyser and this covers up to 2.9GHz.http://equipland.com/objects/catalog/product/extras/6497_8565E.pdfThe HP8561 is similar to the 8560 but it covers up to 6.5GHz.The HP8562 is similar to the 8560 but it covers up to about 13GHz.The HP8563 is similar to the 8560 but it covers up to about 22GHz.The A versions have 'all analogue' RBW filtering but the E versions are newer and ise digital RBW filters for the narrowest RBW filters and this means they are a bit more accurate and sweep faster when these filters are selected.Note: You need to be wary of the B versions of these little portable analysers here because I think they omit the front end image/preselector filtering on the upper frequency ranges on the B versions. I've never seen/used a B version but I'd avoid the B version if I were you

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 25, 2016, 10:31:43 pm
content: Now here comes the big question: does that extra 30dB justifies the difference in weight of a ton and the extra bench space of half a meter?Is it really that critical to have that low phase noise for most applications at those frequencies?Quote from: G0HZU on July 25, 2016, 09:51:36 pm

author: G0HZU
author_rank: Super Contributor
timestamp: July 25, 2016, 10:47:17 pm
content: QuoteIt depends on what you are designing, I guess. Back in the early 1990s at my place of work I was designing a lot of high performance RF downconverters and I was originally supplied with an HP8568B analyser (supplied free by the customer) to help the design proving. So synthesiser phase noise and downconverter spurious testing demanded a very high performance analyser.The HP8568B didn't have the same phase noise performance at 100kHz offset as the TR4172 Advantest analyser and also the HP8568B didn't have the same IP3 performance or 2HI performance as the Advantest analyser. So the customer supplied me with a free £££ TR4172 analyser to replace the HP8568B because I needed the phase noise performance and also the SFDR of the TR4172 when operating down at the IF output frequency of my downconverters.That doesn't mean the TR4172 is a better analyser than the HP8568B, but it did outclass it in certain areas. Basically, I needed every last drop of performance these analysers could deliver and neither of them were good enough for some tests. Often one was better than the other for certain tests. But they were still very special pieces of equipment and nothing else could compete with them apart from the 400MHz Marconi 2382 analyser. That had very good performance too.Here at home I've still got the very same TR4172 analyser and the very same HP8568B that the customer donated 25 years ago. They were declared obsolete at work many years ago and I now own them

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 25, 2016, 10:50:01 pm
content: Do some of these HP8566B or HP8568B come with a built-in Tracking Generator option, or does this always have to be purchased separately as a rack option to be put on top of the display?What is the model number of the Tracking Generator that fits best for the HP8566B and HP8568B respectively?

author: G0HZU
author_rank: Super Contributor
timestamp: July 25, 2016, 11:03:25 pm
content: Quote from: pascal_sweden on July 25, 2016, 10:50:01 pmHP produced a (big external) generic Tracking Gen module for all of the HP856x range (except the HP8568) in the form of the HP85644A and HP85645A .There is an older external T gen module that supports the HP8568B but I've forgotten the number.But the HP 85644A and HP85645A are VERY expensive items. They were well over $20k USD when new 20-25 years ago and they still fetch big money today. I've got one here but I rarely use it in T Gen mode with my HP8566B. You connect it up via several BNC coax cables and then enter the analyser model number in the front UI by scrolling through all the analysers that are displayed/supported.http://cp.literature.agilent.com/litweb/pdf/85645-90020.pdfYou can also use it as a crude signal generator as you can see below with my old HP8566B. It's almost as big and heavy as a HP8560 portable analyser!I think it also supports some of the HP859x range of portable analysers.

author: cncjerry
author_rank: Unknown
timestamp: July 26, 2016, 03:10:30 am
content: Ditto, I have them both as well, 8568b and 8566b.Big, noisy, hot, etc, but they still have great performance and the best bang for the buck compared to new if you find one that has been well maintained. $400 is too little for an 8566b. If it looks complete I would snatch it up in a heartbeat. It's worth more than that as a parts unit.If I have the signal generation capabilities, I will setup the signals that I see in threads like these to see how the old HP analyzers compare. Rarely does anything give better performance. These new Siglents have some interesting capabilities for the money.

author: KE5FX
author_rank: Super Contributor
timestamp: July 26, 2016, 03:19:44 am
content: Quote from: pascal_sweden on July 25, 2016, 10:50:01 pmI built a nice one for my 8566 (described here), and you can also use one ofDKD's modulesto make the construction process easier. But like G0HZU says, the "official" ones are still very pricy, especially the 85645A.QuoteSet your TIME/DIV switch to 'Auto.'

author: KE5FX
author_rank: Super Contributor
timestamp: July 26, 2016, 03:36:55 am
content: Quote from: G0HZU on July 25, 2016, 10:12:08 pmInteresting choice of adjectives -- that was its in-house code name.

author: cncjerry
author_rank: Unknown
timestamp: July 26, 2016, 05:36:37 am
content: Quote from: KE5FX on July 26, 2016, 03:36:55 amSomehow that codename is so appropriate.The TG for the 8568 was an 8444a with option 059 which added a 500Mhz internal oscillator. I have one and it works well. Also note that some of the later 8568B models went to 1.8G.

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 26, 2016, 07:08:51 am
content: Taking into account the price tag of a working HP8566B spectrum analyzer in good condition, together with a working HP85645A tracking generator in good condition, the Siglent SSA3021X with built-in tracking generator, seems the most viable option, for hobby spectrum analyzer use

author: dxl
author_rank: Regular Contributor
timestamp: July 26, 2016, 08:12:47 am
content: Quote from: pascal_sweden on July 26, 2016, 07:08:51 amYou can't compare that - the HP8566B and HP 85645A is a combination up to 22GHz (the TG up to 26.5GHz). I guess the Siglent doesn't do 22Ghz.

author: G0HZU
author_rank: Super Contributor
timestamp: July 26, 2016, 08:19:40 pm
content: Quote from: KE5FX on July 26, 2016, 03:36:55 amI must confess that it wasn't my choice of adjectives. So no coincidence hereI've seen the 8566 referred to as the 'doomsday machine' and the 'Ultimate Spectrum Analyser' in several docs from HP over the years. I assume they used these terms because it probably cost a lot of time/money to develop whilst the engineers were let off the leash to make the 'ultimate spectrum analyser'. I wonder if the various (non engineering) depts at HP affectionately coined it 'doomsday machine' because the project took a long time and consumed a lot of NRE costs. Maybe they had a few Sci Fi or Star Trek fans amongst the staff?

author: G0HZU
author_rank: Super Contributor
timestamp: July 26, 2016, 08:42:06 pm
content: Here's a couple of images of my old TR4172 at 1GHz with a test tone to show the phase noise at 100kHz offset. The first plot shows the phase noise at -124dBc/Hz but the noise level is limited by the 95dB log range of this old analyser.So to measure the noise more accurately I've turned down the ref level 15dB in the second plot. This brings the noise well inside the accurate range of the logamp. Noise is best measured at least 15dB inside the effective range of a logamp. So this is why I've done this. It looks a bit scary but this is a known/valid/accepted method on this type of swept analogue analyser and you can see the phase noise is -128dBc/Hz at 100kHz at 1GHz test frequency.Sadly, my camera does not take images of CRT screens very well so the images look a bit tired and gloomy. The display does look much nicer than this in reality when set to normal brightness. If I turn up the brightness the camera just blooms and the camera makes the trace quality look bad.You might wonder what use this level of performance is if you have to resort to the ref level trick to overcome the limitation of the 95dB log amp range.. But when used like this the analyser was very useful when testing various VHF and UHF synthesiser designs for phase noise at 100kHz offset.

author: KE5FX
author_rank: Super Contributor
timestamp: July 27, 2016, 03:11:07 am
content: Quote from: G0HZU on July 26, 2016, 08:42:06 pmPretty common to deliberately overdrive the analyzer a bit when measuring noise. I've never used a TR4172 myself, but a user of my PN app sent me a patch for it a few years ago, along with a baseline plot:Unfortunately he used a relatively weak test signal (-20 dBm) and 10 dB of RF attenuation. So even though he overdrove the reference level by 10 dB, he got worse results than he should have beyond 30 kHz.

author: cncjerry
author_rank: Unknown
timestamp: July 27, 2016, 04:47:48 am
content: Maybe they should have called the 8568 the doomsday analyzer...

author: pascal_sweden
author_rank: Super Contributor
timestamp: July 27, 2016, 06:40:59 am
content: Shouldn't every spectrum analyzer come with a Tracking Generator by default, if you need to buy it anyhow separately later on?Can you SA experts list a short overview of:1) Tests that can be perfectly done without any TG at all, and neither any workaround to simulate TG;2) Tests for which you strictly speaking need a TG, but where you can use a (cheaper) workaround approach such as an external device to take the role of TG;3) Tests that can't be done at all without TG, and where a workaround is not feasible or recommended with regards to expected test results and accuracy;

author: KE5FX
author_rank: Super Contributor
timestamp: July 27, 2016, 07:51:47 am
content: Quote from: pascal_sweden on July 27, 2016, 06:40:59 amShort answer: if you need a tracking generator, you probablyreallywant a network analyzer.Tracking generators are mainly good for aligning filters and making basic scalar measurements (magnitude only, no phase) on antennas.If you have a sweep generator, you can run essentially any test you could run with a tracking generator, but it will take (perhaps literally) forever.TL;DR: if your budget is limited, consider a sweep generator, and if it's less limited, consider a VNA.

author: cncjerry
author_rank: Unknown
timestamp: July 27, 2016, 03:33:45 pm
content: You can also use the Peak Hold or Max Hold function with a noise source to get a view of a filter on an SA. Never used a noise source with a reflection bridge on an antenna but it might work as well.

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 27, 2016, 04:58:38 pm
content: Id definitively buy a siglent because its hackable, will have a large user base of SDR/ham radio user enthusiasts, digital technology, its fast, nice screen, multiple cursors or USB support. So that its phase noise is worsethan some models from the 80s..., well I'm not building a satellite transceiver anyway... in short the siglent would meet my needs.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 27, 2016, 05:31:20 pm
content: If you care about colors and USB rather than Noise Figure it makes me wonder what do you use Spectrum Analyzer for? My spectrum analyzer has LCD display with Windows 98 - I can play Tetris on it. People that need SA for "HAM Radio use", whatever it means, probably want to see that little moon bounce or asteroid bounce signal not being buried in noise.You can take a photo of screen with your camera and color it up in Photoshop - can you bring the Noise Figure down?

author: nctnico
author_rank: Super Contributor
timestamp: July 27, 2016, 05:40:13 pm
content: You can always hack a color TFT display into test equipment with a monochrome screen:

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 27, 2016, 05:50:54 pm
content: Quote from: Alexei.Polkhanov on July 27, 2016, 05:31:20 pmI'll bite. I do care about phase noise, as I said the specs of the siglent are good enough for me, hell its *way* better than the Rigol 832 that lots of hobbyist use and no one seems to complaint about. I'm not trying to optimize one particular figure in the equipment, but get an overall "pass" or "very good" in each feature.

author: PartialDischarge
author_rank: Super Contributor
timestamp: July 27, 2016, 06:00:37 pm
content: By the way, just to demonstrate that im not biased towards color screens or even against HP look at what I just bought, an audio spectrum analyzer from the 80s, an HP 3580aAn awesome piece of technology with digital storage,tracking generator, frequency log scale, 1dB/10dB/div or linear vertical scale, and battery power option

author: G0HZU
author_rank: Super Contributor
timestamp: July 27, 2016, 06:04:36 pm
content: QuoteYes, the DANL for the TR4172 is typically -146dBm/Hz and up at 1GHz it's more like -145dBm/Hz.With the 10dB attenuator selected this will degrade to -135dBm/Hz. So for a -20dBm test tone this becomes -115dBc/Hz so it's no surprise to see the noise plateau at this level in that plot.However, that analyser looks to be a couple of dB worse than this and I wonder if it has a problem? A while back my TR4172 developed an age related fault in the IF1 section where the adhesive they used for some RF absorber had gradually eaten away at a printed resistor trace (used as the bias resistor for the IF1 amplifier) and this made my analyser slowly go deaf and it also lost a lot of SFDR.I removed the adhesive and used RTV instead and I fixed the part of the PCB with the damaged resistor. The noise floor improved back to where is normally was and the system IP3 went back up to normal. I think the production people at Advantest glued the absorber in place and immediately assembled and sealed the IF1 module and the adhesive then caused corrosion as it cured and the chemicals stayed entombed inside the module. It also rotted the nearby PCB traces making them go soft like rotten paint and it also caused all the plated screws to corrode. The sections without the adhesive still looked shiny and new inside.The same thing happened inside the attenuator module. The adhesive was used on some RF absorber ant it rotted through an adjacent PCB trace and the analyser then lost an attenuator setting (now repaired). So I suspect that every TR4172 will have this issue at some point. I have a spare TR4172 here and the same thing was happening in both modules in that one too (but not as bad, as the PCB traces were soft but still intact)

author: KE5FX
author_rank: Super Contributor
timestamp: July 27, 2016, 10:21:19 pm
content: Quote from: G0HZU on July 27, 2016, 06:04:36 pmInteresting, that does seem plausible. Sounds like acetic acid in action...

author: cncjerry
author_rank: Unknown
timestamp: July 28, 2016, 01:05:22 am
content: Quote from: nctnico on July 27, 2016, 05:40:13 pmHey nicotine, how did you do that?

author: rf-loop
author_rank: Super Contributor
timestamp: July 28, 2016, 06:09:24 am
content: Quote from: nctnico on July 27, 2016, 05:40:13 pmAmusements.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 30, 2016, 01:08:18 am
content: hp 8566B lives next to the Tek 7104. Both gets used a LOT.. Both have been quite reliable, problem free for years. It is possible the later production 8566Bs had most of their problem resolved as this 8566B has a production date in the mid-1990's. Not often discussed or considered is the user interface on the 8566B is good and it has a complete service manual that allows fixing (built to be repaired as required as well as being around for a while) and much learning of how it works by studying the hp 8566B service manual.Speaking of "Doomsday" hp efforts another notable is the 8662A and later 8663A.BerniceQuote from: cncjerry on July 26, 2016, 03:10:30 am

author: Muxr
author_rank: Super Contributor
timestamp: August 06, 2016, 09:19:57 pm
content: Been on a lookout for a SA for a long time now.. on and off for a year or so.. and finally pulled a trigger on a Rohde & Schwarz FSEA-30I've considered the new Siglent as well as the Signal Hound, but in the end the RS won.

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 06, 2016, 09:25:14 pm
content: That HP8566B and Tektronix 7104 look very nice!

author: luckyflyer
author_rank: Contributor
timestamp: August 07, 2016, 03:45:38 am
content: They appear to be great machines. Was there a feature or a technical reason that made you go for the R&S? I'm still in the research mode but will make my move someday as you did.Quote from: Muxr on August 06, 2016, 09:19:57 pm

author: Muxr
author_rank: Super Contributor
timestamp: August 07, 2016, 04:32:32 am
content: Quote from: luckyflyer on August 07, 2016, 03:45:38 amA few reasons really, played the role. The fact that it goes from 20hz all the way to 3.5Ghz was a big factor. I like the fact that it covers those audio frequencies and I am also doing some stuff with IR in that low Khz range as well. I also wanted to have the ability to measure in the 2.4Ghz band as well.Was going to go with the Signal Hound for a long time.. but I don't use Windows so that was kind of a deal breaker. In the end I saw an FSEA-30 for a reasonable price and decided to go for it.I also have an RTM 1054 and I enjoy RS UIs so hopefully that will translate to the FSEA-30 as well.Haven't received it yet (I should get it next week), so hopefully I made the right choice.

author: Performa01
author_rank: Super Contributor
timestamp: August 07, 2016, 10:21:31 am
content: Quote from: Muxr on August 07, 2016, 04:32:32 amCongratulations!From your answer it appears you may have missed the main reason why someone would want to get a R&S FSEA30:It appears to be one of the (perhaps eventhe) most cpable semi-modern SA in terms of dynamic range, resolution bandwidth, intermodulation and phase noise performance, that amateur money can buy.Where else would you get 20Hz ~ 3.5GHz, 1Hz RBW, -123dBc/Hz phase noise @ 20kHz and 110dB intermodulation-free dynamic range?Congrats again and I'm positive you'll be very happy with your new high-end toy!

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2016, 02:21:13 pm
content: Quote from: Performa01 on August 07, 2016, 10:21:31 amAlmost. There's still the FSIQQuoteIf I remember right the FSIQ (a Signal Analyzer which is pretty much an FSEx on steroids) offers even slightly better specs in some areas. Plus it comes with the various signal analysis functions.But yes, back then these were pretty much the best SA's on the market - and that includes HP's/Agilent's counterparts.

author: Muxr
author_rank: Super Contributor
timestamp: August 07, 2016, 02:39:32 pm
content: I sort of knew it was highly regarded by folks in the industry, but this is my first SA so I don't know yet how much of a difference those capabilities will make in my day to day use of it, I had very basic requirements. Happy to hear it's a great performer.Once I get it, will probably do a few mods to it.. like backup the disk image and perhaps do an SSD conversion.. maybe even floppy USB emulator, also check for batteries that might need replacing.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 07, 2016, 02:51:14 pm
content: Quote from: Muxr on August 06, 2016, 09:19:57 pmSCORE! What options does it have?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2016, 02:57:10 pm
content: Quote from: Muxr on August 07, 2016, 02:39:32 pmIt is. The UI is a bit cumbersome in some areas but not overly so, and the good thing is that if you can drive the FSEA then you can also operate most of R&S' later models as the UI is the same.QuoteThe SSD conversion is a good idea (just leave some space unused so the SSD's GC can do its thing). I'd also replace the coin cell on the FMR (the "PC" controller).I'd not bother with the floppy emulators, unless you really need USB storage. You can retrofit an Ethernet adapter if your doesn't already come with it. The FSxx Series is based on x86 PCs with ISA bus. There's an old SMC network card that would work (can't remember the model, though, but it was a fairly common card back then). If you have one of the later FSEAs which run Windows NT then you should be able to use pretty much any ISA network card that comes with WindowsNT drivers.Also, if you have NT, I'd install the last Service Pack (6a) and upgrade the scope software to the last version.

author: Muxr
author_rank: Super Contributor
timestamp: August 07, 2016, 03:11:34 pm
content: Quote from: joeqsmith on August 07, 2016, 02:51:14 pmBased on the seller's description it's pretty vanilla.. no TG or Vector Analysis.. just B15 Computer Function and B16 Ethernet (which is nice).I've picked up a cheap wide band noise generator though, for now.Quote from: Wuerstchenhund on August 07, 2016, 02:57:10 pmThanks for the info.. yup will look to do all those things. One of the reasons I wanted to do the floppy USB conversion, other than just the convenience of having a thumb drive for data was that the floppy drive has yellowed over the years, silly I know

author: luckyflyer
author_rank: Contributor
timestamp: August 07, 2016, 03:24:20 pm
content: HP/Agilent/KS has a very active users group herehttps://groups.yahoo.com/neo/groups/hp_agilent_equipment/infoDoes RS have a similar group somewhere? I did a search and came up empty.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2016, 06:59:39 pm
content: Quote from: Muxr on August 07, 2016, 03:11:34 pmI can't remember if it was available for the FSEx but many R&S SA's have an option called 'external generator control' which allows to use a standalone RF generator as TG. The best thing is that it doesn't just support R&S generators (i.e. SMIQ) but als some HP/Agilent ones as well.QuoteNot at all. It's one of the things that annoys the hell out of me as well. I usually replace such drives, i.e. find a better looking white/grey/black one, a blank, or (if it's useful, i.e. it can be functional with the specific instrument) some usb module or media card reader.For an FSEx I'd probably look at some IDE to PCMCIA or IDE to CF adapter in floppy format. Not hot-pluggable but gives you lots of removable storage for screenshots and data.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2016, 07:01:38 pm
content: Quote from: luckyflyer on August 07, 2016, 03:24:20 pmhttps://groups.yahoo.com/neo/groups/Rohde_Schwarz/infonot sufficient?

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 07, 2016, 07:33:43 pm
content: schalke04.rs-fanclub.wuerstchenhund.sa

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 07, 2016, 08:08:23 pm
content: Quote from: pascal_sweden on August 07, 2016, 07:33:43 pm

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 07, 2016, 08:15:25 pm
content: Sorry, I could not let that one go

author: luckyflyer
author_rank: Contributor
timestamp: August 07, 2016, 09:39:30 pm
content: Hmm, I think I did a Rhodes & Schwarz instead of Rhode. Picky search engines they do what you tell them, not what you want. ............ThanksQuote from: Wuerstchenhund on August 07, 2016, 07:01:38 pm

author: Muxr
author_rank: Super Contributor
timestamp: August 16, 2016, 02:03:11 am
content: R&S FSEA30 arrived today.. self. cal passes and it looks good so far.Going on a trip soon but once I get back will have to do the SSD conversion etc..

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2016, 03:15:32 am
content: Wow, that looks real nice! Have fun on your trip. Looking forward to see this thing in operation.

author: rf-loop
author_rank: Super Contributor
timestamp: August 16, 2016, 06:37:55 am
content: Quote from: Muxr on August 16, 2016, 02:03:11 amWhat is signal in this image?Can you show exactly same also without signal. (this noise level is bit high but it can be also this signal what is now totally undefined)

author: Muxr
author_rank: Super Contributor
timestamp: August 16, 2016, 09:35:12 am
content: Quote from: rf-loop on August 16, 2016, 06:37:55 amSignal is coming from a cheap Chinese DSS my other Sig Gen is too far on the other side of the office. (I've put the this SA on my free bench space since I want to do a teardown and some preventative maintenance.. like SSD conversion and battery change).I suspect the high noise floor comes down to the attenuation / ref. level I am set on.This is what it looks like with just a 50 ohm termination:If I change the ref. level so that the attenuation goes down to 10dB (from 20dB):If I really narrow the span and use the highest resolution available (1Hz):

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2016, 11:53:23 am
content: We need a sticky SA spreadsheet next.I wonder how the systems are designed. My old analyzers were swept with analog filters. The 3589A is swept but sampled with digital filters. The Signal Hound is a whole different animal with it's 27MHz bandwidth (which I have yet to try, come on new PC). I attempted to repeat your setup with the BB60C. Sweeps times are as slow as it goes. Gain was set to 3 for all tests.

author: Performa01
author_rank: Super Contributor
timestamp: August 16, 2016, 11:55:37 am
content: The specs say: <-145dBm, typ. -150dBm for >10MHz center frequency, 10Hz RBW, 1Hz VBW and 0dB attenuation.You still have 10dB attenuation, so without that the displayed noise floor would be somewhere near -150dBm. Since you’re using 1Hz RBW, we’d expect <-155dBm - maybe there’s still some other setting left to optimize.The 1st order dynamic range is specified as 165dB for 1Hz RBW and the 1dB compression point is +10dBm (which is 10~15dB higher than the usual candidates and this is what makes the FSE analyzers so great), which confirms that the noise floor should indeed not be higher than -155dBm in this scenario.But even if your particular unit doesn’t quite meet its specs and the noise floor is some 5dB higher than expected and the 1st order dynamic range is “only” 160dB – don’t worry. There are still not many other analyzers that could compete.The usual Chinese budget SA have some -5dB CP – and consequently would have to display a noise floor of -165dBm/Hz (or -170dBm/Hz to meet the R&S specs for the 1st order dynamic range) withpreamp off.Not to mention the FSEA30 phenomenal 115dB 3rd order dynamic range (above 50MHz), which is the one that really counts. And this doesn’t require the lowest possible noise floor, but exceptional linearity in the entire signal path up to the point, where the narrow band filtering occurs, which for narrow RBWs is the digital processing after the ADC in the final IF…

author: rf-loop
author_rank: Super Contributor
timestamp: August 16, 2016, 11:58:33 am
content: Quote from: joeqsmith on August 16, 2016, 11:53:23 amWhy? With R&S there is no preamplifier. You need use gain 0 for same.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2016, 12:07:55 pm
content: The HP3589a in narrow band mode.

author: rf-loop
author_rank: Super Contributor
timestamp: August 16, 2016, 12:09:35 pm
content: Quote from: Performa01 on August 16, 2016, 11:55:37 amOne problem with atten settings is that different SA have different design. (example real mixer level)If really want compare there need be some comparable settings. If change atten of course noise floor level drops but what is noise floor distange from useable maximum signal level without clipping or compression.Example If in Siglent drop attenuator to 0 there can not at all measure 0dBm "high level" signal. There is not rules exatly for this and every manufacturer can do what they want.Overall FSEA30 is very good quality SA and belongs to high class. Also its new price tell something..

author: Muxr
author_rank: Super Contributor
timestamp: August 16, 2016, 01:08:01 pm
content: Quote from: Performa01 on August 16, 2016, 11:55:37 amThanks for the explanation. Learning my way around it still. I did notice the mixer level has something to do with the noise floor as well. For instance if I use the low noise preset it sets it to -20 dBm. Also things are a bit better at higher frequencies.

author: Performa01
author_rank: Super Contributor
timestamp: August 16, 2016, 02:13:28 pm
content: We need to distinguish between sensitivity, signal handling capability and dynamic range. The corresponding specs for an SA are DANL (Displayed Average Noise Level), 1dB CP (1dB Compression Point - the input level where the gain decreases by 1dB due to signal limiting/clipping) and 1st order dynamic range, which is usually defined as the difference between CP and DANL. But one can easily make mistakes there…Quite obviously, we can increase the CP as much as we like by adding internal and/or external attenuation. With 20dB attenuation, the CP will increase by 20dB as well. Of course, there is only so much power a certain attenuator can handle and the internal ones will usually only tolerate up to +30dBm at best, but it depends whether these attenuators are mechanically or electronically switched (be careful, without studying the specs, +20dBm would be a reasonably safe value). With the appropriate external attenuators, we can indeed go up as high as +50dBm and even more. But the attenuator will raise the noise floor by the amount of its attenuation.We also can increase the sensitivity close to the limits of thermal noise by means of a preamplifier, once again either internal or external. With a low noise, high gain external preamp (NF <3dB), we can theoretically make any SA perform a DANL of <-160dBm/Hz. But the preamp will lower the CP by its gain at least – some preamps might even have a lower output CP than the input CP of the SA, thus further reducing the total system CP.So even though we can have a very low noise floor as well as a very high CP, we cannot have them both at the same time. Consequently the 1st order dynamic range is the difference between CP and DANL within one setup. The whole point of a dynamic range definition is the ability to analyze weak signals in presence of strong ones. For example, if you want to verify the harmonics of your newly designed HF-PA to be <120dBc, you either need an SA that has a dynamic range in excess of 120dB or you have to use some tricks, like using a notch filter to suppress the carrier.To cut a long story short, it doesn’t mean a thing if someone shows the maximum sensitivity of their gear – simply because it still tells absolutely nothing about the dynamic range.Here’s an example with the SA44.With 0.8Hz RBW, preamp off and 10dB attenuation, the noise floor is about -133dBm, which appears at least 6dB higher than the R&S FSEA30 in the similar situation shown by Muxr in Reply #128 (SA44_Noisefloor_REF-80dBm_ATT10dB)Still not too bad, but what is the dynamic range? What is the maximum signal it can handle, i.e. measure with reasonable accuracy? Since the reference level is set to -80dBm, we are limited to some 53dB anyway, since we don’t want to count on measurements outside the display range.All in all, this measurement is almost meaningless for judging the capabilities of the instrument. In a situation like the one above, we would certainly use the preamplifier and the noise floor would drop by more than 20dB – and that would make perfect sense, since the preamp easily copes with signals in the range of -80dBm and lower, of course.So we now set the reference level to +10dBm (SA44_Noisefloor_REF+10dBm_ATT10dB)Oops – the noise floor has increased by some 12dB to -121dBm, but now at least we can hope to measure signals up to +10dBm. Let’s try -10dBm first (SA44_-10dBm_REF+10dBm_ATT10dB)This works – I’ve just switched the vertical scale back to 10dB/div, because the noise floor isn’t visible anymore anyway, due to the strong phase noise of the analog synthesizer signal. Anyway, reference level and attenuation remain unchanged and we get an accurate measurement, so this already covers a dynamic range of -10 - -121 = 111dB.Now let’s try +10dBm (SA44_+10dBm_REF+10dBm_ATT10dB)This still works, although we can see a slight hint on gain compression, as the marker reading is already 0.1dB low. This is in accordance with my previous experiences, that this analyzer has a 1dB compression point (at the mixer input) somewhere at +1.5dBm. With 10dB attenuation, it would be about +11.5dBm of course.This gives a total first order dynamic range of +11.5 - -121 = 132.5dB.Not too bad, but still nowhere near the R&S FSEA30.

author: Muxr
author_rank: Super Contributor
timestamp: August 16, 2016, 02:36:23 pm
content: That makes perfect sense, thanks Performa01!

author: rf-loop
author_rank: Super Contributor
timestamp: August 16, 2016, 02:56:19 pm
content: Quote from: Muxr on August 16, 2016, 09:35:12 amThis is how it looks with around same settings using Siglent SSA3021X. (exept that start is 0Hz and stop 20MHz (20MHz Span)ATT 10dB, RBW=VBW=3kHz. R&S RBW is 2kHz. This difference is around 1.8dB in noise level (R&S looks this amount better due to RBW) so in this case around nonsense because if we go more deep in various tests of course R&S is very different class SA.

author: Muxr
author_rank: Super Contributor
timestamp: August 16, 2016, 04:15:27 pm
content: Just wanted to add one more thing. The reason why my measurements above were taken at -10 dB attenuation is because that's the lowest attenuation I could set with the dial. It tells me the limit was reached when I try to get lower. However I am able to punch in the 0 dB attenuation with the keypad. Just realized that (duh). I am guessing it's a safety measure. The noise floor drops further with attenuation off as expected.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 16, 2016, 05:11:22 pm
content: Quote from: Muxr on August 16, 2016, 04:15:27 pmIt is, pretty much all R&S SA's do that.

author: rf-loop
author_rank: Super Contributor
timestamp: August 16, 2016, 05:43:30 pm
content: Quote from: Muxr on August 16, 2016, 04:15:27 pmI remeber this was same with my previous R&S also. 0dB Atten only using keyboard. And this is not alone R&S special. This is also least in some HP/Agilent models. For safety!But then, noise level drops but also max signal what can measure drops.Example with Siglent SSA3000X Atten 10dB and maximum signal is around 0dBm. (or bit over)Signal level is exactly 0dBm. (Far over screen top. Yes it is theere still in good condition. It can look adjusting Ref level. SSA3k max display window vertical range is 100dB) Peak measured, -0.27dBm. With 10dB atten, level accuracy bit better.RBW11kHz. Span 20MHz. Signal near 11MHz. If I drop Atten to 8dB it start warning ADC overload and level result is bad and noise level rise lot of etc..If I set atten to 20dB max good signal level is +10dBm. With Atten 10dB it can say max signal is 0dBm.Noise level follow "exactly" Atten level, naturally.Of course If now drop RBW also noise floor drop. If drop from 1kHz to 100Hz naturally noise floor drops 10dB but still maximum signal peak is same. And with 10Hz RBW agen 10dB more low noise level.In image can see average noise floor around -115dBm and max signal level what can measure is 0dBm. (RBW 1kHz)If now drop RBW to 10Hz then average noise floor is around -135dBm and max signal peak is still 0dBm. But if there is signal level same as average noise level it can not measure so it can not claim at all that it can measure 135dB difference at once. But 110-120dB difference, yes.(of course IF there is SSA3021X+ where can use 1Hz RBW it give bit more. But then ther come other limiting factor. Phase noise. With narrow spans phase noise floor is far higher than base noise floor. So, limit here, limit there and so on...