R&S SMIQ as a replacement for a general signal generator? - Page 1
Forum section: electronics / testgear

author: davorin
author_rank: Unknown
timestamp: October 21, 2015, 06:31:52 am
content: As I'm thinking of getting a vector signal generator I saw in the SMIQ specs that it can also do general AM/FM modulation which I sometimes also need for testing AM/FM radios (mostly those old vacuum tube ones ;o)Is a SMIQ03 basically just a SMT03 with additional QAM option (besides higher frequency start).Or are there better alternatives in this price range the SMIQs pop up on Ebay?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 21, 2015, 11:57:44 am
content: Quote from: davorin on October 21, 2015, 06:31:52 amThe R&S SMIQ is based on the SME (the SMT is a SME intended for VOR/ILS testing) and is a true vector signal generator which can create a range of complex modulation signals. It's essentially R&S counterpart of the Agilent ESG-D Series (the SME is the equivalent to the Agilent ESG-A), although the SMIQ supports more modulation variants than the ESG-D.Both ESG-D and SMIQ can be equipped with a built-in AWG to generate I/Q signals, but the one for the SMIQ only offers 512k (1M for the ESG-D). However, the SMIQ offers some slightly better specs than the ESG-D, and the SMIQ's display is much better than the poor LCD in the ESG Series.In terms of software, Keysight offers some old version of IntuiLink for download which allows you to transfer waveforms into the AWG option of an ESG-D, but it's really old and very simple (it works directly from MS Office, although not with newer versions). R&S offers some better tools (i.e. WinIQSim) for the SMIQ, and while older, they work fine even on Windows 8.1 x64.QuoteThe Keysight ESG-D could be an alternative, but prices of SMIQ and ESG-D are pretty similar. The ESG Series has a common fault in the output stage (shows UNLVL on the display even when AGC is enabled) which isn't too difficult to repair. The SMIQ (like the SME) is pretty robust and doesn't show any similar common faults, however the metallic coating of the display glass tends to deteriorate over time which looks a bit like someone has put some glue on borderline of the glass. It's purely optical but replacement glass isn't cheap.You should be able to get either one for a good price if you're patient. If I had to choose however I'd take an SMIQ over an ESG-D any day, mostly because of the better display and (with the exception of the AWG memory) slightly better specs.

author: davorin
author_rank: Unknown
timestamp: October 21, 2015, 12:39:40 pm
content: Well...I would prefer the R&S SMIQ over the Agilent model....quick look on ebay shows me that the Agilent E4432B is over US$ 2k while the SME03 is under 1k...some of them even lower but faulty with error numbers 172 and the like..not sure if fixing would be easy then...Doesn't look though that the SMIQ would accept analog AC input for AM/FM modulation directly...only 0 - 1V....

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 21, 2015, 12:50:06 pm
content: Quote from: davorin on October 21, 2015, 12:39:40 pmThe SME is not vector signal generator, so it's clear that prices are lower.QuoteOften its just a dead battery, but before buying I'd ask in the R&S Yahoo forum for opinions as there should be a few people who have experience fixing them.QuoteNot sure what you mean. You can input an external AM/FM modulation signal but as you said the voltage should be 1Vpk (the limit is+15V).It's the same with the Keysight ESG-D.

author: davorin
author_rank: Unknown
timestamp: October 21, 2015, 01:20:40 pm
content: Did I write SME03? No should be SMIQ03 of course..my fault (o;Yes I definitively need to get more information on those errors and how it could be fixed...yahoo was always a good source for that kind of information...Is there an equivalent NNTP group?Hmm...not many youtube videos of the SMIQ in use besides booting it up (o;

author: KJDS
author_rank: Super Contributor
timestamp: October 21, 2015, 01:27:25 pm
content: Anritsu have an assortment of similar sig-gens that are worth considering.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 21, 2015, 01:32:46 pm
content: Quote from: KJDS on October 21, 2015, 01:27:25 pmTrue, but getting service/calibration manuals and (when required) spare parts for Anritsu kit can be challenging. It's often a lot easier for the western brands.

author: G0HZU
author_rank: Super Contributor
timestamp: October 21, 2015, 02:18:58 pm
content: I would definitely recommend the ESGD if it has the highly desirable dual arb option fitted. I have an E4433B with this option and it's a very powerful sig gen.However, neither the SMIQ or the ESGD are going to deliver anything like lab grade performance in terms of phase noise or spurious. These are very much economy grade generators in terms of their basic frequency synthesis but they offer lots and lots of features including a vector modulation capability.They look pretty impressive on the outside but don't expect old school lab grade performance in terms of phase noise or spectral purity from these basic old workhorses. For this reason it's best to go for one with the best options fitted because that's where their true value comes from IMO.I recently bought an ESGD E4433B for £1k with the dual arb option and several other options. This is probably half the normal used price but the price of these should start to drop soon because they offer limited capability in terms of dual AWG performance/bandwidth and also the Agilent support tools are pretty lame (obsolete). So many companies will be moving over to the later MXG type generators.AFAIK the SMIQ is inferior to the early ESGD models in terms of AWG performance so I would avoid it unless very cheap. If you want the ARB capability I would consider it a no brainer to go for the Agilent unless there is some other unique feature that you need from the SMIQ.If funds permit then consider the E4438C. This looks the same as the E4433B but it does have better performance in several key areas including its (now 16 bit) AWG and it is supported by the 89600 SW.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 21, 2015, 03:37:16 pm
content: Quote from: G0HZU on October 21, 2015, 02:18:58 pmI disagree with the notion that ESG and SMIQ are not "lab grade" (which is a silly term anyways), unless you think "lab grade" means "best specs ever in all areas" (which it doesn't).SMIQ and ESG-D are most certainly "lab-grade" equipment ('lab-grade' does *not* mean offering the best specs possible in all areas), and at new prices in excess of $30k I'd say calling it "economy grade" (a term usually reserved for entry level kit like the stuff from Hameg) is quite a stretch.But that doesn't change that both SMIQ and ESG-D are pretty much "lab-grade" instruments, and the fact alone that they found use in a huge number of labs around the globe puts the notion that their performance isn't up to scratch for professional use clearly into the sphere of nonsense.QuoteThat cycle has passed many years ago already, at least for the first generation ESG-D (B models). At the moment its the later ESG-D (E4438C) that are being replaced.The same is true for the SMIQ, which has been replaced with the successor (SMU) a long time ago, and similarly this successor is now slowly being replaced with the current modell (SMW).Most of the ESG-D B models and SMIQs on the market are probably coming from second or third hand users.QuoteCan you elaborate? The only difference between the AWG in the early ESG-D models and the SMIQ is the sample memory (512k/ch on the SMIQ vs 1M/ch on the ESG-D), and both values are pretty tiny by today's standards anyways.The second generation ESG-D (which is more comparable to the R&S SMU200A) offers a much better AWG performance, but that clearly comes at a cost.

author: G0HZU
author_rank: Super Contributor
timestamp: October 21, 2015, 04:08:41 pm
content: QuoteIf you read what I said again I said they are not lab grade in terms of phase noise or spurious.I know the ESGD pretty well and in terms of close in phase noise in the LF/HF/VHF bands the phase noise performance is very, very poor because the generator uses a very simplistic mixer based frequency plan to generate signals down here.In terms of close in phase noise down in these bands the ESGD is a total dog compared to a high end sig gen. Easily 35-40dB worse than something decent. Even a novice could build a simple homebrew oscillator with phase noise that would be 30-40dB better than the ESGD down in these bands.QuoteI've not used the SMIQ AWG but I think the SMIQ is only a 12 bit AWG and the E4433B ESGD is 14 bit? I've produced my own AWG analysis/support tools for my ESGD and it asks for 14bit data for the AWG in the manual.

author: G0HZU
author_rank: Super Contributor
timestamp: October 21, 2015, 07:03:25 pm
content: QuoteBack in the 1990s Hewlett Packard classed/marketed the first ESG signal generators as "Economy Signal Generators" and the A and D variants use the same basic frequency plan. So the close in phase noise performance for sig gen frequencies from LF through to lowish VHF frequencies is dire on both A and D versions because of the shared frequency plan.

author: davorin
author_rank: Unknown
timestamp: October 21, 2015, 08:41:43 pm
content: Nice discussion I have started (o;Well for sure I know it's not gonna be the Signalhound VSG25A....Speaking of the Agilent model...can the VSA software control the E4406A and the E4433B at the same time?

author: G0HZU
author_rank: Super Contributor
timestamp: October 21, 2015, 09:11:04 pm
content: Sadly no...The E4433B isn't directly supported and it also uses a different scheme to download IQ data to it via GPIB. So it's a double no in this respect unless someone knows otherwise? Maybe an older version supports it?I'm using the E4406A and the E4433B together as part of a research project so I've created some reasonably powerful Windows based tools to allow me to view/edit/process captured IQ data from the E4406A and it converts the format and sends it to the E4433B for playback. These tools do some specific things unique to my requirements and I'm afraid that I can't give away my software tools for various reasons.Note that I'm not a SW engineer and it really isn't difficult to create apps like this using something like VB anyway

author: davorin
author_rank: Unknown
timestamp: October 21, 2015, 09:23:27 pm
content: Well I just started recently with C#...and was impressed how easy it is to develop a websocket communication app for Windows phone talking to a Raspberry Pi via Amazon server (o;I'm still not sure which model I should choose...Agilent or R&S....I like both brands....I'm very happy with me new E4406A...but also like R&S...otherwise I wouldn't have two CRTU-RUs and a SMT03 now...kinda weird hobby collecting old equipment for studying and learning RF technology....And since it's a private hobby I tend more to go for a device with lower price.....but currently most SMIQs on Ebay are listed as "for parts only" with a low price...or Agilent models starting at US$ 2500....Hmm..speaking of self written software....is there a software API how to directly dump I/Q from a E4406A via socket communication?

author: ivaylo
author_rank: Frequent Contributor
timestamp: October 22, 2015, 05:45:45 am
content: I replied to your other thread. E4433 with UND can be found cheaper in the states and many sellers ship internationally.Why are those E4406 so cheap (well, so to speak)? Limited spec or what?

author: KJDS
author_rank: Super Contributor
timestamp: October 22, 2015, 06:46:13 am
content: Quote from: ivaylo on October 22, 2015, 05:45:45 amE4406A are cheap because they're no longer wanted my modern businesses and Nokia put about a thousand onto the second user market a few years ago. I've never seen more than ten signal generators for sale at the same time.

author: trukresom
author_rank: Contributor
timestamp: October 22, 2015, 08:51:11 am
content: Since the OP mentions the possible use of an SMIQ with AM and FM I would like to underlinethat the basic SMIQ is not equipped to do FM. For FM and PM the SMIQ has to be fittedwith the Option B5.A characteristic of the SMIQ which I find is very pleasant is the fact that when making smallchanges in frequency with the knob, the output amplitude remains constant. This is not thecase for example with my HP8644B; even the smallest frequency change (0.01 Hz) causesa drop of the output amplitude of almost 100% for a few milliseconds.

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 11:58:35 am
content: QuoteLooking at your wanted ad in the Buy/Sell section are you sure you really need to purchase a generator like this?If you just want to learn stuff about vector modulation I'd recommend either making your own basic vector modulator or maybe just buy a basic vector modulator chip (or eval PCB) from one of the major chip manufacturers. eg Hittite or RFMD etc etc.Build it and play with it and maybe use your C# skills to use a PC soundcard to drive it?I really do think you will learn a lot more and learn it faster if you do it this way?But if you really do want to buy a vector sig gen then either the Agilent or SMIQ will be fine for general research or learning.However, you are going to end up with your head in their manuals a lot of the time doing stuff their way in terms of programming etc.I would still repeat the warning about LF >> VHF phase noise performance though. Especially for the ESGD series from Agilent. If you expect this generator to 'replace' a decent shortwave band RF generator in terms of noise performance then you could hit problems if you wanted to do any critical receiver testing of something like a decent HF ham radio. The same applies if you wanted to use it as a temporary LO in a shortwave converter. The relatively high phase noise will markedly limit the performance of the converter in terms of reciprocal mixing compared to even a simple homebrew oscillator.

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 01:03:22 pm
content: QuoteGenerally speaking, a decent lab sig gen should produce phase noise performance in the same ballpark (or better) as a fairly basic oscillator designed for that frequency.HP set the bar for this way back in the early 1970s with the HP8640. AFAIK HP designed this solid state generator to try to emulate the excellent phase noise performance of the vacuum tube based sig gens of the 1960s. They did it using a mechanically tuned octave bandwidth cavity oscillator (256-512MHz?) followed by a chain of dividers and roofing filters and a classic ALC levelling circuit.In doing so they created the industry benchmark for phase noise (and spurious) performance for many years.This old generator will produce very low close in phase noise when used in the MW and SW bands. The problem is that this type of generator is expensive and it also needs lots of switched LPFs to cover all the divider ranges. Also, using division means that accurate calibration of FM deviation has to be achieved at the cavity oscillator for every divider range.Lots of other makes of sig gen have since adopted a similar oscillator + divider approach and a decent lab generator should at least try and get close to the phase noise performance of the old HP8640 across 'most' of its range.(Modern generators often use several VCOs to replace the big old cavity oscillator in the HP8640 and this usually compromises performance. However modern generators can use modern synthesis techniques to clean up very close in phase noise so they can outperform the HP8640 in some areas)Because it uses a cheap mixer based frequency plan to generate low frequencies (rather than using dividers and filters) the ESGD (AKAEconomySignalGeneratorDigital) generator fails this benchmark by about 40dB down in the lower parts of the SW band. eg for phase noise offsets of a few kHz at a CF around 10MHz or so. That's a pretty significant fail in terms of phase noise

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 02:41:02 pm
content: In terms of vector modulator performance I can comment on the E4433 ESGD as I have a couple of them here. Both give very similar modulator performance but there are a few niggles...The basic calibration of the IQ modulator is fairly good. I can run a full modulator calibration across the full range of the generator (takes a while to do this) and then not bother to recalibrate it for quite a while and still get pretty decent carrier and image rejection on something like a multi carrier SSB plot. I generally don't bother to calibrate it for most tasks so it can go for weeks without a calibration.However, for critical applications it does allow a User Cal that lets you calibrate the modulator across a narrow band of interest and this takes a few seconds. The performance of the IQ internal cal is quite good in terms of image rejection but if I had to fault it, the resolution of the manual trim is too coarse.With a raw auto calibration it can deliver about 50dB carrier suppression and over 60dB image suppression for simple narrowband waveforms but the manual trim step size is too coarse to let you 'improve' the carrier null much beyond the auto calibration. The image suppression obviously degrades a bit for wider bandwidth signals that get close to the full modulation bandwidth of the modulator.Overall, it's pretty good but I think it could be better.Note: One of my E4433 generators is an older A model and it has a scary bug/feature during IQ calibraion in that it does the calibration with the generator set at full level with the output enabled!This is not good if you have a circuit connected that could be damaged by a +20dBm signal!The B version (sensibly) sets the attenuators to max during IQ modulator calibration so no signal leaks from the generator during IQ calibration.It could be that my generator is faulty in this respect but I suspect that this is a firmware bug in this early model.

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 03:21:00 pm
content: One (optional?) feature of the E4433 is that you get raw baseband IQ outputs at the rear of the instrument.So if I set one (the E4433B) to give out a 4 tone SSBSC signal using the AWG and then feed the IQ out into the analogue IQ inputs of the E4433A I can look at how well the two perform when daisychained like this.In the plot below you can see that the 4 image terms are now visible on the left side of the suppressed carrier. The suppressed carrier is the tone at the centre of the display. On the E4433B the image terms are much lower and the carrier is at about -50dBc rather than -45dBc in the image of the E4433A below.But it's still pretty good if you consider that this is being driven from the baseband generator from one generator and fed into the IQ inputs of another. I did a User Cal on the E4433A IQ modulator prior to feeding in this signal and also the ALC is turned off as the ALC action degrades the performance slightly.

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 22, 2015, 03:40:11 pm
content: .... the 4 image terms are now visible on theleftright side of the suppressed carrier.you had me staring at the image there for a while

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 04:23:22 pm
content: Sorry for any confusion... by image terms I mean the 'unwanted' image terms on the left of the carrier as arrowed in blue below. If there was only 30dB image rejection there would be a set of 4 (unwanted) image tones on the left of the carrier that sit 30dB lower than the (wanted) terms on the right of the carrier. These would appear as per the dotted yellow lines below.I only have to manually trim the IQ calibration slightly away from the auto cal settings to upset the modulator and make these unwanted terms begin to appear as per the yellow lines

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 22, 2015, 05:20:00 pm
content: Ah, I see, thanks for clarifying that, it's the unwanted sideband you are talking about.

author: G0HZU
author_rank: Super Contributor
timestamp: October 22, 2015, 05:32:39 pm
content: For a bit of fun I tried capturing a similar 4 tone SSBSC signal with the E4406A and the VSA SW and I then sent the captured IQ data back to the E4433B as an ARB file for playback. So in an ideal world the signal should look the same as the raw signal from the E4433B.However, to prevent glitches on an analyser that would appear at the loopback (start/stop) point of the captured segment my software can crop the data to make sure there is a fairly seamless crossover at this point. This removes a huge discontinuity at the loopback point and improves the playback.Without this, the analyser would show jumpy glitches and something like an old school swept analyser would show a huge fan of spiky clicks across the spectrum.This plot below is my second attempt BTW. The first one had lots more distortion terms. I managed to improve this by setting up the VSA interface in a better way on this second attempt.The result is pretty good although I think it can be better with a bit more experience on my part. I'd imagine something like the SMIQ (or a decent Anritsu vector sig gen) would give similar performance if I used it instead of the E4433B.But I guess the system performance here is set by the E4433B and also the combination of the linearity of the RF converter in the E4406A and the performance of its 14 bit ADC/digital IF and also the VSA SW and also the way I process the captured VSA data to make it compatible with the E4433B before sending it to the E4433B for playback via its 14 bit AWG.

author: G0HZU
author_rank: Super Contributor
timestamp: October 24, 2015, 01:20:58 pm
content: Just to show Davorin how poor the ESGD is when it comes to its phase noise performance in the shortwave bands I set up a very simple experiment/comparison.I compared my E4433B against an old Marconi 2019 that dates back maybe 35 years. The Marconi 2019 was a regular sight in test and service departments throughout the 1980s and 1990s. We even had a couple of them in our design labs in the 1990s as the phase noise performance was pretty good across 2MHz-30MHz.The performance of the 2019 isn't so impressive once you get up into the VHF/UHF ranges and they aren't very reliable either but even this old generator can be seen to totally outclass the ESGD for close in phase noise on the SW bands.The 2019 uses dividers to synthesise outputs down to about 2MHz so it achieves good (but not spectacular) noise performance in the SW bands.I set each generator to a few kHz outside the passband of a 10.7MHz crystal filter and set the level to +4dBm to account for filter and cable loss. So the sideband phase noise that leaks through the filter in its passband can be read as -dBc/Hz. The leaked carrier can be seen on the right of the analyser plot and it's level is about 60dB lower than normal because it is being attenuated by the filter stopband.If you look at the plot below there are two traces stored on this old HP8568B analyser. Can you guess which is which? Yes, the one that is over 30dB higher in noise level is the ESGD. When measured on a signal source analyser they typically produce about -100dBc/Hz at a few kHz offset down on the SW bands and maybe -108dBc/Hz at 10kHz.The creaky old 2019 that I've owned for about 20 years manages about -133dBc/Hz at about 5kHz offset at 10MHz CF. The ESGD shows about -101dBc/Hz at the same offset in the plot below.A Marconi 2024 should manage about -138dBc/Hz here and I'd expect the HP8640 to better this by several dB. I'm guessing maybe -145dBc/Hz but I've not had my hands on an 8640 for many years. But a decent 8640 should deliver about -115dBc/Hz at 5kHz offset up at its cavity oscillator at 320MHz and the dividers should clean this up by 30dB when dividing by 32 to get 10MHz. So it could (reasonably) be expected to achieve -145dBc/Hz at 5kHz ofset at 10MHz CF. Thats over 40dB better than the ESGD.So anyone choosing to replace a regular sig gen for use on shortwave (AM bands) should be aware how poor the ESGD is for phase noise down here. Because it is at least 30dB off the pace here it can't be taken seriously as a lab sig gen for typical performance checks of a decent SW receiver for example. Even the 2019 will struggle here when testing a decent Ham radio for blocking or adjacent channel performance despite being >30dB betterthan the ESGD.

author: G0HZU
author_rank: Super Contributor
timestamp: October 24, 2015, 02:20:38 pm
content: I dug out an old E5052A library plot of a 2024 set to 10MHz and +13dBm.This is one of the 2024 generators at work and it showed a curious blip in the phase noise at about 1.5kHz offset (green arrow)But you can see that this generator manages about -140dBc/Hz at 5kHz offset at 10MHz. Apart from the blip, this generator was slightly better than a few other 2023 and 2024 generators I measured in comparison.The red trace is hand drawn by me and represents the typical phase noise of an ESG4433 at 10MHz. It is much, much worse as you can see.The blue trace is also hand drawn and it represents the typical phase noise of a simple homebrew LC oscillator at 10MHz. i.e. something you could make with a transistor, and a few resistors, caps and an inductor.

author: analogNewbie
author_rank: Regular Contributor
timestamp: October 24, 2015, 02:54:05 pm
content: I'm also looking for a signal generator these days.Anyone has the experience with Agilent 8665A? This heavy guy takes about 6 minutes or more to do the cool boot calibration. Does anyone know what is this guy calibrating? I think the phase noise performance of 8665A is not bad, any comments on this unit?Thanks

author: G0HZU
author_rank: Super Contributor
timestamp: October 24, 2015, 04:34:29 pm
content: The 8665A is an early PSG model. I've never used one because when these were being sold 20-25 years ago the company couldn't afford the PSG range. By the time the company grew enough to buy a £££ sig gen we bought the later PSG models. So I have zero experience of them.However, I think that the early range of PSG models use a precision delay line based discriminator as part of a PLL+FLL. This allowed a useful reduction in phase noise compared to a basic single loop PLL if the user selected this FLL mode. However, this complex/expensive FLL mode may be a factory option. I'm not sure.This mode will be slower to tune and lock but gives better phase noise.But (I think) the delay line in the FLL and the VCO tuning has to be calibrated and in some PSG models these delay lines are even heated by an oven to make them more stable so 'maybe' this is what takes all the time to stabilise after a cold boot.But all of this is just a guess. Maybe someone on here has one and has serviced it etc.In terms of phase noise, I think this model still resorts to using a mixer to get its lowest frequencies (eg LF through to VHF) so I would guess that its phase noise could be as bad as the ESGD down here unless its FLL 'noise cleanup' mode is enabled. In this mode it will be much better than the ESGD but I doubt it will be as good as something like a basic Marconi 2024 down in the SW bands. Note: the Marconi 2024 also uses a mixer to get its very lowest frequencies but this applies below about 10MHz and the phase noise is still much better than the ESGD below 10MHz despite this.Up at UHF>>xGHz the 8665A phase noise performance will be extremely good. Much better than a 2024 because it has the FLL mode to exploit in order to achieve low phase noise across maybe 2kHz to 100kHz offsets and it uses a YIG oscillator.Basically, the 8665A isn't a generator that would be on my wish list unless I really 'needed' its low phase noise up at UHF. It's very big, very heavy and offers limited modulation capability.Maybe someone on here has one and can comment?

author: analogNewbie
author_rank: Regular Contributor
timestamp: October 25, 2015, 09:41:22 am
content: Thanks for the detailed info about 8665A. The close in phase noise is not as good as 8662/8663A, but the 1k+ phase noise is pretty good.I want to ge one with 4GHz capability and phase noise shoud be good. Now I found one 8665a and one R&S SMHU. The second hand ESG series are all over the place and the prices are much higher than these old heavy tanks.Since I want to do some experiment to homebrew GHz spectrum analyzer and GPS recievers, which model do you suggest? I can live with poor phase noise performace under 10MHz range .

author: G0HZU
author_rank: Super Contributor
timestamp: October 25, 2015, 12:38:28 pm
content: QuoteThey are both very good signal generators and assuming they are both healthy then I don't think there's a right one or a wrong one. So it may come down to simple human factors as below:I had the pleasure of using the 2GHz R&S SMH throughout the 1990s as a general purpose sig gen. This generator was too expensive for the company to buy but it was donated to us by the customer on a research task. It is a really nice instrument to use, the whirly wheel has a high quality feel as do the buttons and it even sounds nice when the attenuators click etc. The display is pretty basic but it still looks good.It hasn't been totally reliable since then (been back more than once for repairs) but we still have it and I think we first got it way back in the early 90s.The phase noise is pretty good (but not spectacular). I have a library of phase noise plots for lots of our works generators here and here is the SMH at 1500MHz. The noise profile at 1500MHz shows a fairly high pedestal of noise out to 200kHz and you can see this isn't as good as the 8665A.It's quite good down at lower frequencies although I didn't measure it below 10MHz. But there's a plot of it at 10MHz below.Hope this is useful.I would definitely find room for an SMH here, partly through nostalgia and partly because it is such a nice generator to use. However, I didn't ever use any of its modulation modes back then. It was just used as a low phase noise signal source in the tasks I used it for.For me, the human factors of the 8665A make it a non starter. It is huge and it weighs about 35kg and unless I 'needed' the performance of the YIG + FLL mode up at UHF then I can't see why I would want to have this monster taking up space on my workbench. However, it is an amazing piece of technology and I don't want to appear disrespectful to HP with these views.However, I just noticed that the 4GHz SMHU is bigger than I thought. The 2GHz SMH we have at work is only about the same size as a Marconi 2019 but the 4GHz SMHU looks to be very big and is going to be very heavy too.

author: G0HZU
author_rank: Super Contributor
timestamp: October 25, 2015, 12:57:57 pm
content: Here's an old plot of that Marconi 2024 at 1296MHz as a comparison. It still has that odd pip in the noise inside the loop BW and other 2023/4 generators I've tested don't show it.But you can see that the 2024 is only average up here. I'd expect the ESGD to be about the same here (1296MHz) too although I can't find a plot of one.However. if I had to choose between the ESG, the 2024, the SMHu and the 8665 for 'just' doing stuff up at UHF then I'd probably pay the extra for the ESGD or even consider an ESGA version if the price was right.But that would be with a severe warning about its awful phase noise down at LF/HF frequencies

author: G0HZU
author_rank: Super Contributor
timestamp: October 25, 2015, 01:15:02 pm
content: I went through my library of phase noise plots to see which other generators have poor LF/HF/VHF phase noise like the ESGD.Probably the most relevant is the Aeroflex/IFR341x series as this is a vector sig gen. In this case I measured a 3413 model. See below for a plot of the IFR3413 at 10MHz. I think I plotted this on the same day I measured the Marconi 2024 way back in 2012. You can see that down at 10MHz this generator has close in phase noise that is about 40dB worse than the 2024 making it just as bad as the ESGD on the SW bands.This range of generators looks very much like a facelifted Marconi 2024 but in reality this is a different animal inside. These generators support IQ modulation so they have to adopt a different frequency plan to include the IQ modulator.In this case they use a similar scheme as the ESGD with a downmixing plan from UHF to LF to get the low frequency ranges meaning that these generators also have awfully high phase noise down on the SW bands. There is a reason for this and that is that in order to include vector modulation they can't have dividers after the modulator. Also the IQ modulator will probably only work well over a limited range of frequencies and this is usually done up at UHF.So the (cost/size/power/weight) driven solution here is to throw away phase noise performance and just mix down from approx 1GHz to the low frequencies and avoid the use of dividers.So in the case of generators like the ESGD (and the IFR) you get 1GHz related phase noise directly mapped down to (say) 10MHz. If you compute this as a 20*logN ratio you get 40dB. So it's no surprise that these compromised generators are about 40dB noisier than they could be down on the shortwave bands because they will have the same phase noise as the mixer drive signal up at around 1GHz.However, the phase noise performance of the ESGD and the IFR generators will be about the same as the 2024 when used up at high VHF through UHF because the frequency plans will be reasonably equivalent in terms of noise contribution.Compare below the IFR3413 to the Marconi 2024 plot down at 10MHz to see the 40dB difference

author: davorin
author_rank: Unknown
timestamp: October 25, 2015, 01:38:36 pm
content: How much equipment do you own? (o;

author: G0HZU
author_rank: Super Contributor
timestamp: October 25, 2015, 01:46:40 pm
content: QuoteI do have quite a few sig gens here, but (sadly) the E5052A signal source analyser used to take the plots isn't mine and none of the generators in the E5052A plots are mine either. I do have a Marconi 2024 amongst my stash of sig gens but it isn't the one used for the plots.The sig gen plots were taken at work using works equipment, usually at lunchtimes on days when I was using the E5052A for design work or verification

author: dkozel
author_rank: Regular Contributor
timestamp: October 28, 2015, 03:54:51 pm
content: Thanks to Dave posting about the NVIDIA auction in the UK, this thread just became of the utmost interest to me.I won the SMIQ 03B with options B1 (OCXO), B11 (Data Generator), B20 (Modulation Coder), and B60 (Arbitrary Waveform Generator). I have to figure out the pickup, but will post my impressions here when I have it on my bench.

author: G0HZU
author_rank: Super Contributor
timestamp: October 28, 2015, 04:27:25 pm
content: Well done on winning the auctionI also tried bidding on a different item in that auction but I think they have discarded my (winning?) bid because there has been no conformation yet. Did they send you a confirmation email that you had won?I think the close in phase noise on the SMIQ will be better than the ESGD when down on the SW bands although the phase noise performance may not be significant to you anyway. But the ESGD is especially poor down here.

author: dkozel
author_rank: Regular Contributor
timestamp: October 28, 2015, 04:51:03 pm
content: No confirmation yet, but I had an email from them that confirmed I was an approved bidder and confirmed my phone number. I won two other items and can send the money today, so hopefully they'll let us know soon.I'm not keenly focused on the phase noise, but we'll see how it goes. I have a nice GPSDO 10MHz/1PPS unit so will have to compare the references.

author: G0HZU
author_rank: Super Contributor
timestamp: October 28, 2015, 05:01:36 pm
content: I tried emailing them wrt the auction and their reply was a bit vague. I guess they are very busy just after an auction..QuoteI'm pretty sure I was the high bidder because the status for that auction ended within my bid range and the status for the item was 'auction ended' with the same price indicated.I guess I'll just have to wait and hope but it seems odd that they will accept large bids based on a simple online registration.I saw the SMIQ 03 in the auction and a few other nice RF items but I only bid once on one big item. One bid one win hopefully

author: Robert763
author_rank: Super Contributor
timestamp: March 19, 2024, 08:13:04 am
content: Really old thread but I've been doing some related work recently.I've been wanting to play with a vector RF generator for a while. It's not a need so was low on the budget list.However I spottted a bit of a "sleeper" generator by R&S. Its a sleeper because its not a signal generator its a "Television Test Transmitter". Model SFQ. While basically a early digital TV test generator, the RF specification isverysimilar to the SMIQ-03. 300kHz to 3.3GHz -13dBm max output etc. More importantly it has an external IQ modulation input as standard. No AWG internally though. So I eventually bought a AMIQ. That was a learning curve. It was listed as working by a ebay business TE seller. On arrival it didn't work so a discount was negotiated. Repairs included replacing all the electrolytic capacitors on the internal PC motherboard. cleaning the floppy drive and replacing the HDD with a SSD (mSATA in PATA adaptor 2.5" enclosure). And the result is a working Vector Signal Generator with AWG. Total outlay under £200There is another sleeper in the R&S TV TE range. The older SFZ. This has less frequency range (70-2025 MHz) and no IQ input BUT it will generate up to three carrriers at once (plus 3 sound subcarriers at fixed spacing if you want). This has interesting possibilities for intermodulation and out of band signal testing.Robert.