Best USB stick/device as Spectrum Analyzer for <= US$ 500 - Page 1
Forum section: electronics / testgear

author: davorin
author_rank: Unknown
timestamp: May 09, 2015, 12:46:16 pm
content: HelloI'm currently using some cheapo RTL DVB-T and a Funcube Dongle Pro as a USB spectrum analyzer and stumbled today upon this device, which can go up to 3.3GHz:http://www.rfinstruments.com/SA0314.htmlHad anyone had some experience with this device, or knows some other USB devices which could cover at least a continous range of 30MHz to 1GHz for EMC measurements?Is there any documentation on how to build an antenna for EMC testing as well?thanks in advancerichard

author: thewyliestcoyote
author_rank: Regular Contributor
timestamp: May 09, 2015, 06:52:51 pm
content: I have not had any experience with that particular device. It seem to be very much like the RTL DVB-T devices in that it is a just a software defined radio. For the price something like the HackRF maybe a better choice as it has 20 MHz of instantaneous bandwidth and a frequency range of about 30 MHz to about 6 GHz.One thing to note, all of these USB devices are no substitute for a real spectrum analyser as they are un-calibrated for power. For any real quantitative EMC testing this is a must. That said a lot can be learned by just relative energy of emission, ie what you are doing with the RTL DVB-T device. Take away is when needing to measure power versus frequency in an absolute way a traditional spectrum analyser is what is needed, but for some qualitative investigation any of these devices should work. I will say the HackRF can be made to work with any software you are using for the RTL DVB-T devices. Also there is a very good python wrapping of hackRF with GNURadio that could be used to automate some of the measurements.QuoteThis is a big area, it really depends on the type of measurement you are trying to do. A common antenna or test apparatus is the TEM cell.http://www.atmel.com/Images/Article_AC10_Open-TEM-Cells.pdfThis could easily be constructed with a pair of N-type connectors and copper clad board. Most are constructed to be system impedance of 50 or 75 ohms. There are formulas out there for the impedance of the parallel plate type transmission line. Just follow these to get the width versus the height of the center section of the cell. Then just do a linear taper to the N-type connectors at each end.Not sure if any of that is what you are looking for, but just know that EMC testing can get complex requiring anechoic chambers and other expensive equipment. Now for some simple qualitative investigation just a small look made of the center conductor of a piece of coax will take you a long ways.Really look at the standards you are trying to meet and see what they require you to use.Best,Wylie

author: davorin
author_rank: Unknown
timestamp: May 09, 2015, 07:47:12 pm
content: Thanks for the clarifications :-)Remember the HackRF One....but never saw it in combination with spectrum analyzer software as the RTL DVB-T sticks, where RTLSDR scanner is the preferred software for scanning between 30MHz and up to 1.8GHz with R820T tuner...I'm not sure if the HackRF one could do a spectrum plot with power levels differences up to 100dB due to its 8 bit ADC or not....but I don't think a cheapo RTL stick has a better ADC inside (o;My purpose is to use such a device to compare spectrum plots before and after some modifications electrically or mechanically....having a pre EMC plot from an university lab upfront...but it seems the HackRF one seems to be software wise be supported for radio applications only...Just found this one:http://airspy.comWith better ADC...but lower frequency range....but still enough for EMC between 30MHz and 1GHz.

author: davorin
author_rank: Unknown
timestamp: May 09, 2015, 08:54:36 pm
content: Okay...seems the Airspy is also just a pimped up DVB-T with R820T2 tuner inside (o;Maybe I should save some money and go for a Signal Hound @ US$ 919?

author: thewyliestcoyote
author_rank: Regular Contributor
timestamp: May 09, 2015, 11:42:23 pm
content: QuoteWow, ok that is a big range,Sounds like what you need is a real standalone spectrum analyser. The ADC in the RTL is 6 bit IQ. This is to meet the USB 2. full speed spec.QuoteOk that makes more sense,I dont use it, but SDRsharp maybe can help with that, else you are stuck writing your own scripts. Not a bad why of doing it if you don't mind the little big of programming.QuoteYeah for the kind of dynamic range you are talking about something more like a traditional spectrum analyser is a good choice. There is a lot of automatic gain and attenuation in a traditional spectrum analyser to handle this kind of thing. Else they would all be the size of a small USB device. There are other options like the Ettus B200 or the Nxxx. They are more expensive and are still SDR's and have higher resolution ADC's.These do not sounds like what you need. A traditional sweep spectrum analyser is going to far outperform any SDR topology device.I sounds like you know this but I will say it anyways. There are 2 figures of merit here. First is the instantaneous dynamic range, this is a function of the ADC and the front end. Second is the total dynamic range, or the range largest signal to the smallest signal that can be measured. This factor is all about the gain, linearity, and out of band rejection of the system. This is why you can feed a signal at 10 dBm at 3 GHz into a spectrum analyser and still see a signal at 2 GHz at -80dBm. They don't need an ADC that is 16 or 20 bits.

author: thewyliestcoyote
author_rank: Regular Contributor
timestamp: May 09, 2015, 11:58:27 pm
content: QuoteThanks for the link to the app. I have application to link a hackrf to a smartphone, and this is a big help.QuoteHere is the list official list:http://greatscottgadgets.com/hackrf/The cost is about $300 to $330ish. Sparkfun I know has a couple right now. I am not sure if this helps you where you live.https://www.sparkfun.com/products/13001

author: davorin
author_rank: Unknown
timestamp: May 11, 2015, 06:00:14 pm
content: Okay...a regular DVB-T stick based on RTL is absolutely a no-go (o;Just did a frequency scan between 100Mhz and 200MHz and it shows harmonics from the internal 28.8MHz clock....If anyone has another USB device.....a frequency plot with no input signal, or better, ground with 50 Ohm, would be nice (o;

author: kripton2035
author_rank: Super Contributor
timestamp: May 11, 2015, 06:34:30 pm
content: rf explorer ?http://rfexplorer.com/

author: pascal_sweden
author_rank: Super Contributor
timestamp: May 11, 2015, 08:33:49 pm
content: Why is the HackRF One not a good spectrum analyzer?Is it not sensitive enough for measuring the power strength of a signal peek?Isn't everything controllable from software, given that it is Software Defined Radio? =)

author: davorin
author_rank: Unknown
timestamp: May 11, 2015, 08:55:41 pm
content: I don't own a HackRF one....nor have I've seen that anyone uses it as a spectrum analyzer...Also not sure if it is really supported by the Python RTLSDR Scanner software for frequency scans/plots...Just to spend US$ 330 just to find out it is of no use either hardware or software support wise...dunno (o;Would love to have some feedback from people having one :-)

author: Mr Simpleton
author_rank: Unknown
timestamp: May 11, 2015, 08:58:12 pm
content: There are a *few*problems with the simple "thumb-drive" SA's...Sweeptime... the receiver is not optimized for fast frequency change, and this means s-l-o-w sweeps (i.e. steps). Trying to capture a dynamic signal is no fun at all!Dynamic range. Most SA's do have a proper switchable attenuator, to improve dynamic range. The sticks only adjust internal gain and tries to survive.Most are not calibrated and will only show the rough amplitud...Spurs....There are other shortcomings too, but I agree that for a *very* tight budget these little devices can, and will, allow the user to get a simple overview over RF spectrum. Maybe better than nothing if you really need an RF-indicator rather than a full blown SA.I would go cracy using one for my RF needs though!

author: slurry
author_rank: Regular Contributor
timestamp: May 11, 2015, 08:59:02 pm
content: I have a HackRF, not been using it as a spectrum analyzer in that sense but it sure is impressive with its 20MHz bandwidthwith HackRF and a noisesource i adjusted a UHF bandpassfilter without any problems.

author: davorin
author_rank: Unknown
timestamp: May 11, 2015, 09:05:47 pm
content: Ah...finally someone using it :-)Can it be really used with almost any software which also support the regular RTL DVB-T sticks?

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: May 11, 2015, 09:30:11 pm
content: I've been looking at most of these , with no need to transmit .Just for field testing for possible sources of RF that may affect other equipment and then may check transmitters with out the need for the accuracy of a bench Spec analyzer [ ham radio gear ] .As an example , lower frequency at least down to 40 mhz [ I would prefer down to 2 mhz ] 40 and up for broadcast TV getting too much local RF into tuner [ right now I helping someone with the TV blanking as cars drive by , reflecting the source ] and then the same place is having issues with WiFi getting interfered with by possible RF in area , lots of drop outs , freeze ups etc. , so 2 gig & 5 gig .

author: pascal_sweden
author_rank: Super Contributor
timestamp: May 11, 2015, 10:06:28 pm
content: What about this solution?http://www.saankhyalabs.com/sites/default/files/avtar_1.pdf

author: davorin
author_rank: Unknown
timestamp: May 12, 2015, 07:14:48 pm
content: Got some feedback on the hackrf dev mailing list....seems this device is noise wise even worse than regular USB sticks (o;So leaves only the signal hound as a solution.....The pocket device seems nice...but I would like to have a device that is also open in terms of open source software support...

author: pascal_sweden
author_rank: Super Contributor
timestamp: May 12, 2015, 08:00:10 pm
content: Why can't any company get the noise level right, and make sure that power measurements are accurate?I want a USB stick that can be used as a decent spectrum analyzer.Believe that this is very feasible, but it just is not there today, because of the wrong people working on it, and the big companies that already launch their overpriced spectrum analyzers doing lobbying against something that can revolutionize the way people do frequency measurementsI know about the Signal Hound, but believe that it is overpriced, if you compare what you get for that money in the Rigol DSA800 series.

author: davorin
author_rank: Unknown
timestamp: May 14, 2015, 08:41:17 pm
content: I've ordered now some newer DVB-T sticks with the newer R820T2 tuner....few dB better than the original....Airspy doesn't seem to be a good device for spectrum analyzer...though it should be better than a regular RTL stick....but apparently RBW can't be set....whatever RBW is (o;I'm really considering going this way:http://www.scottyspectrumanalyzer.comhttp://lea.hamradio.si/~s53mv/spectana/sa.html

author: davorin
author_rank: Unknown
timestamp: May 14, 2015, 09:49:11 pm
content: Okay...asking in the airspy forum if this device is suitable as spectrum analyzer I got the reply that I should ask this question somewhere else...seems their forum os only for users who bought the airspy already (o;Let's see what the guys/girls from RF explorer will send a reply....First I'm gonna try their software on an existing RTL stick...which supposedly it supports as well....But the export capabilities are very limited...and I have no clue why all software never have the options to display a logarithmic frequency scale as it is used in EMC testing...making comparison a manual task...

author: Fraser
author_rank: Super Contributor
timestamp: May 14, 2015, 11:07:30 pm
content: I own two RF Explorers for quick checks of various frequencies etc. The unit was originally designed as an affordable spectrum monitor for radio remote control interference investigations etc. The Radio Control toy fraternity like it for this reason. From memory the amplitude measurement is based only on the receiver modules RSSI output and so is not the most accurate of of measurement systems. Relative levels are clearly visible however. It is also well supported and most of the the schematics are published. I even obtained the 'commercial sensitive' schematics after signing a simple NDA with Ariel.The RF Explorer is, IMHO, a very useful spectrum monitor and is quite powerful fro such when connected to a PC and one of the available software packages run. I certainly like mine and I own full size professional Spectrum Analysers so it isn't junk.The designer is both very friendly and approachable. Ariel has come up with a very neat, polished and affordable RF spectrum monitoring product for the masses.http://www.techrepublic.com/article/rf-explorer-a-good-inexpensive-rf-spectrum-analyzer/BUT, and it is a big BUT....... the RF Explorer is not, IMHO, a serious contender against, or alternative to, a lab type spectrum analyser. It has neither the accuracy not the scan speed of such.A close friend tested the Signal Hound and was impressed with its capabilities. It is apparently well thought of in the EMC fraternity. It does have its issues though so you are advised to do your research. Its frequency coverage is apparently good value for money when compared to the equivalent conventional bench spectrum analyser. I believe it is quite a slow sweep rate though. The optional software is also good but no idea about its cost. I would have a signal hound as well as my bench SA's if I could justify it. The RF explorer meets my 'quick and dirty' carrier and interference check need though.Aurora

author: fake-name
author_rank: Regular Contributor
timestamp: May 15, 2015, 04:47:31 am
content: I can't speak to the USB-SA44B, but I did a fair bit of software work with the BB60C from signalhound. It's quite the nice instrument.I also wrote a pretty comprehensive python wrapper for it's API:https://github.com/fake-name/pySignalHoundIt hasn't been tested with anything other then the BB60C, but IIRC they have one API for all their products, so it should be pretty straight forward to patch to support other models.

author: davorin
author_rank: Unknown
timestamp: May 15, 2015, 07:40:29 am
content: Maybe someone can tell more about the "slow sweep" rate of the Signal Hound?Are we talking here several tens of senconds or few minutes for doing a 30MHz - 1000MHz scan?

author: Gribo
author_rank: Frequent Contributor
timestamp: May 15, 2015, 08:00:15 am
content: I have several SA44B at work, 30M to 1G takes about a second, at the default RBW (30KHz if I am not mistaken). I will measure it when I get back to the office.I wrote a Labview driver for it, and their new API (3.x) is much better than the old one.

author: davorin
author_rank: Unknown
timestamp: May 15, 2015, 08:44:19 am
content: Hi GriboThat's quick in my opinion ;-)So you would definitively recommend this model for pre-EMC/after-EMC measurements to see what influence a change in electronics/mechanic can have?Can their software do a spectrum plot with logarhitmic frequency scale any maybe even define an overlay boundary region?

author: davorin
author_rank: Unknown
timestamp: May 15, 2015, 11:42:54 am
content: Playing around with RF explorers Touchstone software, as it support regular RTL dongles as well....Spectrum scan stops around 90% and hangs forever, when an antenna is connected....And I can't do a spectrum scan wider than 300MHz.....dunno if that's a limit of the RTL driver or the software itself...

author: Gribo
author_rank: Frequent Contributor
timestamp: May 17, 2015, 07:48:14 am
content: Ok, here is my actual measurement data:30MHz to 1GHz, at 100KHz RBW takes 4 seconds, for 33950 data points on my machine (Windows 8, Core i5 4460). I use this unit mainly in ATE, so I don't really care for this.There is no logarithmic frequency view, however, in LV it is quite easy to set your plot X axis to logarithmic.Regarding EMC precomliance - It is as good as any low range spectrum analyzer. It is not an EMC analyzer, with all the limits, masks and pre amplifiers, but that is not the scope of this device.Also, take into account that the SA44B gets up to 4.4GHz vs 3GHz for most low end analyzers.

author: davorin
author_rank: Unknown
timestamp: May 17, 2015, 09:09:08 am
content: Hi GriboAh great...thanks for the feedback....Have you used the new Spike software? Can you maybe post the 30MHz - 1GHz plot with no input signal here?Well...I'm already saving money for a SA44B now...the TG44 comes later.....might come handy also doing repairs of old radios :-)Sad the TG44A can't be used as a signal generator with AM/FM modulation....thanks in advancerichard

author: Gribo
author_rank: Frequent Contributor
timestamp: May 17, 2015, 02:07:45 pm
content: Here you go. I don't know what that dip around 150MHz is, it exists also in a lower span. This is without anything connected to the input.

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 02:20:41 pm
content: Something worth checking on the SignalHound and being aware of, IIRC it has a DC coupled inputfrom memory the signal passed straight into the first active stage without decent protection. this avoids issues with the input protection degrading the frequency response but it carries risk with it.Forgive me if this is duff information, I looked at the design a long time ago and I may have it confused with another USB spectrum analyser. I did photograph the whole input stage though and will have to see if I can find the images. Worth checking though as I know my friend fried his SignalHound input on more than one occasion. If it is DC coupled, I strongly recommend the use of a DC block on the input port.Aurora

author: Mr Simpleton
author_rank: Unknown
timestamp: May 17, 2015, 02:24:18 pm
content: The dip you see, is due to internal band switching, signals do have an alternative path inside, below 150 MHz.Now the SA44B do have a 250 kHz wide IF where it does its sampling, i.e. one have a real time spectrum which is up to 250 kHz wide. If one want to sweep wider, the SA44B is stepped, which accounts for the slightly long sweep times vs "normal" spectrum analyzers. The new software "Spike" has improved the UI and sweeptimes so its almost like a new instrument. Having used simple TV dongles and the similar Fun Cube and they are not in the same class as the Signal Hound.As far as I know the Signal Hound offers a 30 day money back... and they do have an european dealer so this might be a way to try it out!I find that the Signal Hound compliments rather than tries to replace my big HP analyzer, at sweeps less than 250 kHz it is a lot faster than any of my HP analyzers... especially when having very narrow RBW.And the SA44B is calibrated and offers traceability to NIST....

author: Mr Simpleton
author_rank: Unknown
timestamp: May 17, 2015, 02:27:24 pm
content: 1 Hz to 4.4GHz, max +20dBm and 0 VDC.... Have been lucky and my input stages are still unharmed!Agree a DC block do come in handy... and watch the RF input level too

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 02:30:24 pm
content: Yep, just found a pic of warning on unit...... Unusual and some users are used to <=25V DC offset capability on conventional analysers so kill their new toy with a DC offsetA case of RFMAurora

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 02:32:33 pm
content: Also BB60 front end block diagram may be of interest. I will see if I can find the exact one for the '44'

author: Mr Simpleton
author_rank: Unknown
timestamp: May 17, 2015, 02:40:10 pm
content: This is from the manual, a very simplistic block diagram. I remember someone in Russia tearing the analyzer apart... see if I can find the thread. It was all in russian though

author: Fraser
author_rank: Super Contributor
timestamp: May 17, 2015, 02:51:58 pm
content: I took one apart as well. From memory I was impressed with the unit (apart from the lack of front end resilience) When it came down to it, it was a SDR with wide window sweep and it performed as such. i.e very much dependant upon the capabilities of the software. This was seen by me as a positive as the software provided was Ok and there was room for greater capabilities in the future without a hardware change. I was not a great fan of SDR technology as it often had a limited data window width and less than great dynamic range. Tektronix were proud of a 64Khz window when I checked out one of their new oscilloscopes. SDR is likely the future though and the Signal Hound is definitely a respectable attempt at a USB based SDR spectrum analyser. Capabilities are getting better all the time as hardware and software improve.Will a USB based spectrum analyser ever replace the bench top conventional designs ? No idea but it may well be the future of such test equipment. Imagine having a single smallish box that contains all your test equipment and that has great capabilities that may be upgraded through just a software update. Multimeter + LCR meter + ESR meter + DSO + LA + SA + ? ..... sounds nice if it can be done at an affordable priceAurora

author: Mr Simpleton
author_rank: Unknown
timestamp: May 17, 2015, 03:13:38 pm
content: Unable to find any pics from a dismembered SA44B, but the SA12B...http://forum.vhfdx.ru/izmeritelnaya-apparatura/analizator-spektra-signal-hound-usb-sa44b/?action=dlattach;attach=45656;imageSee if I can find the guts to pluck mine open

author: davorin
author_rank: Unknown
timestamp: May 17, 2015, 04:12:27 pm
content: Thanks for the print screen :-)Yes I saw somewhere in the datasheet that it has two frequency ranges with a switch at 150MHz...Also remembering that the input is DC coupled and has a limit of +/- 0.2V....but the European distributor sells a kit for Euro 40 also including a DC blocker...But also according to the datasheet...theoretically I could also do a spectrum plot in the audio range....Have to put now some more stuff on ebay to get my Signalhound SA44b sooner ;-)

author: davorin
author_rank: Unknown
timestamp: May 17, 2015, 09:00:42 pm
content: Okay...regarding the few replies that the Signalhound SA44B can't replace a real HP spectrum analyzer....Which HP analyzer would you recommend to have a look out on Ebay then? And which wouldn't kill my budget/wallet? (o;

author: Mr Simpleton
author_rank: Unknown
timestamp: May 18, 2015, 07:24:26 am
content: B4 we can give a definite answer... You need to clarify your needs!What freqency range?Portable or bench?Size matters?Saving data on computer?Warranty vs fixing your self when breaks down?There have been numerous discussions on this very topic lately on the forum... just search for spectrum analyzer.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 18, 2015, 08:44:24 am
content: Quote from: davorin on May 17, 2015, 09:00:42 pmDoesn't have to be HP. Another option might be a Rohde & Schwarz CRTU-RU (a Wireless tester containing a Spectrum Analyzer, RF generator, RF Analyzer with 11(?)digit frequency counter, and Power Meter).There recently was a huge surplus auction in Finland where lots of CRTU-RUs from some big cell phone manufacturer were sold for peanuts, and they now show up on eBay in Europe (and prices will probably drop further). Some forum members also bought several of these things and might sell you one for a reasonable price.The SA in the CRTU is pretty good, with a bandwidth of 10MHz to 2.7GHz. Not as good as a high end SA like the HP 8566 Series of course, but the CRTU holds up quite well against the current crop of entry level SAs, and in some cases even against my lab grade R&S FSP7. It also has the advantage that the CRTUs from that auction are only around 7-8 years old and not ~30yrs as most HP SAs, and CRTUs don't suck as much power and produce as much noise as the HP boat anchors.Depending on what you need, this could be a viable option.

author: Mr Simpleton
author_rank: Unknown
timestamp: May 18, 2015, 05:39:32 pm
content: Just had a quick look at e-bay, but cannot really say the marked is flooded with cheap CRTU's... prices runs from $2k for non-working units up to $20kGuess those Nokia units still have to show up and kill the market

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 18, 2015, 09:38:19 pm
content: Quote from: Mr Simpleton on May 18, 2015, 05:39:32 pmI guess you checked ebay US (which in term of CRTUs doesn't have much and what's on offer is mostly way overpriced) but there are some on ebay in Europe:www.ebay.co.uk/itm/Rohde-Schwarz-CRTU-RU-1138-4000-83-Universal-Protocol-Tester-RefRUS-/171760548301www.ebay.co.uk/itm/Rohde-Schwarz-CRTU-RU-1138-4000-82-Universal-Protocol-Tester-Ref1693-/171760535938www.ebay.co.uk/itm/Rohde-Schwarz-CRTU-RU-1138-4000-82-Universal-Protocol-Tester-Ref1695-/171760521674As far as I know Nokia wasn't the only one off-loading CRTUs, companies like Broadcom have as well as the CRTU doesn't support 4G (LTE) and is now successively replaced with CMWs. Which means prices will fall even more.

author: G0HZU
author_rank: Super Contributor
timestamp: May 18, 2015, 11:39:26 pm
content: If you just want to use an analyser for casual EMC testing then the SignalHound is going to be worth considering.It is a very unconventional analyser (in terms of block diagram and how it tries to get a decent image rejection) so it will be compromised in some areas of its performance and also in some parts of its frequency range. I've not used one myself though... I'm sure if I had one here to review I'd find quite a few glaring limitations in its performance.But I think as long as it is used with a degree of sympathy wrt these limitations it should be a lot better than the typical USB dongle type analysers and it will be capable of more than respectable performance in some areas even when compared to some classic old lab analysers.However, I suspect that the 'spectrum analyser' in the R&S CRTU and CMU200 models will be pretty ropey if you want a decent spurious free dynamic range. R&S seem to offer very little info on the hardware used in the receiver section and I suspect this is because it would make it obvious how limited they are in terms of performance. The spec sheets offer a few clues that the RF performance of the receiver/downconverter section will be pretty dire compared to a conventional lab analyser. Despite the fact that they are made by R&S I'm not so sure the analyser in these instruments is quite as good as it may appear to some people.

author: Electro Fan
author_rank: Super Contributor
timestamp: May 19, 2015, 12:13:34 am
content: Quote from: davorin on May 17, 2015, 09:00:42 pmOklahoma is not exactly right next door to Switzerland (and I don't know anything about this unit or this seller), but a HP 8560E seems like a worthy candidate:http://www.ebay.com/itm/48-HOUR-PRICE-DROP-HP-8560E-SPECTRUM-ANALYZER-OPT-07-MASS-MEMORY-MODULE-/111672894396?pt=LH_DefaultDomain_0&hash=item1a003923bc

author: Mr Simpleton
author_rank: Unknown
timestamp: May 19, 2015, 02:14:02 pm
content: And the seller seems very keen on selling to within US... Still price is very very good for a working 8560E!

author: davorin
author_rank: Unknown
timestamp: May 19, 2015, 08:09:03 pm
content: Well...at least I know now the model names which would fit my purpose...But for a start I still go with the SA44B...almost got my Paypal account filled up to order (o;Not only that I work 3 days at home and 2 days in the office...so taking this device with me is a great plus...But also the fact it is based on SDR and their API allows to read out Q/I directly or do custom sweeps is a benefit....And sure I will order a DC blocker, attenuator and the like....not sure if their passive probe comes handy....not expensive for 2GHz bandwidth probe...

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 20, 2015, 05:48:01 am
content: Quote from: G0HZU on May 18, 2015, 11:39:26 pmThere's quite a lot of information on how these units work available in the Service Manual (I can see if I find a link).Not sure why you put spectrum analyzer in quotas, as the CRTU doesn't work any different than most newer standalone SAs. The platform the CRTU and CMU200 is built on is the same platform that R&S had built their previous generation of mid-range and high-end standalone SAs. We're also not talking about cheap basic GSM testers here, a CRTU with a few options did cost in excess of $100k.I'd say that specs like a SSB phase noise of -110dBc to -118dBc and a frequency stability of+5 * 10E-09 aren't too shabby when we are talking about cases where the alternative is to use some Realtek-based TV receiver as software SA. The CRTU also has a pretty flat response over the whole bandwidth (20MHz to 2.7GHz).QuoteReally, get over yourself. It' has already become obvious that anything that performs worse than a HP 856x is too inferior for you to just even look at and therefore must be crap. Don't worry, I get that.Reality is however that not everyone needs a high end lab SA just for doing RF work, in a similar way as not every EE needs a 20+GHz scope. Again, the OP was considering using USB TV receivers. You really believe they would give a better RF performance than a lab-grade communications test platform?BTW, my old CMU200 is at the moment sitting in an EMI lab to do simpler pre-compliance testing. Seems to be non-"ropey" enough for the task.

author: Mr Simpleton
author_rank: Unknown
timestamp: May 20, 2015, 07:25:08 am
content: If I understand correctly the CMU-family do have a 10 MHz sampling bandwith... how fast does it manage to step through say 1 GHz sweep?Can you choose RBW ?And how easy is it to replace/service the Win2000 image? Just a matter of cloning disks? Are there any calibration constants that may be lost and make life miserable?It sure looks like a sweet box and at prices shown i.e. £500 it looks even better!

author: jadew
author_rank: Frequent Contributor
timestamp: May 20, 2015, 09:00:05 am
content: Don't bother with USB sticks, they all suck in one way or another. Even the new Tek RSA toy fails miserably with those spurs that get mixed in with the signal.I have the HackRF and its sensitivity is worse than the RTL dongles and on top of that, it has lot more spurs.My suggestion is to save up and get a real SA. If you decide to go for a signal analyzer instead, make sure it's one that can do a full sweep and doesn't take a million years to do it. Also make sure that it doesn't suffer from the same issues that the USB dongles have, since signal analyzers are nothing more than SDRs and their primary goals are very different than those of SAs.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 20, 2015, 09:10:21 am
content: Quote from: Mr Simpleton on May 20, 2015, 07:25:08 amBoth CMU200 and CRTU do a frequency span from 0 to 2.98Ghz bandwith (so are not limited to just in 10MHz as the Agilent E4406A Comms Tester). The RBW can be set automatically and manually between 10Hz and 1MHz in 1-2-5 steps.The fastest sweep time for the full bandwidth (20MHz to 2.7GHz) is approx 100ms, but the sweep time of course depends on the RBW.QuoteYes, exactly. Both CMU200 and CRTU use 2.5" IDE hard disks (with depending on age of the device between 40GB and 80GB of capacity). Simple to clone.Some words about the software:The CMU200 comes with a MsDOS partion only, as the user interface software is based on MsDOS. The hard drive can be cloned easily to a 4GB CF card with plenty of spare sectors for wear leveling.The CRTU comes with three partitions, one with Windows 2000, one with MsDOS, and one restore partition with Norton Ghost. The DOS partition is essentially the same as the one on the CMU200, and the DOS software is what one would use for using the CRTU as a normal test instrument, The Windows 2000 partition does not contain software that can be manually used for testing but an application suite for automated cell phone testing, which for general use is worthless.However, it also comes with Windows drivers for all the hardware and Microsoft Visual C++ 2003/2005, which means someone with the necessary time and skills could write his own Windows test applications to make the CRTU in whatever he wants it to be.QuoteNo. Unlike many old kit like the mentioned HP analyzers which store all calibration data in a single (often volatile) memory, or newer kit which stores cal data on the hard drive, R&S uses a different approach where each individual module contains a NVRAM with the module's calibration data. That means should your CMU200/CRTU hard drive dies you can get another one from a different unit and use it without having to worry about calibration. It also means that if you replace a module that you won't have to recalibrate the whole unit. Just plug in the replacement module, initiate a firmware update from the File Manager, and done.QuoteThe CMU200 is still somewhat in demand and therefore still pretty expensive (but then it offers some options that are not available on the CRTU), but the CRTU is certainly a lot of value for the money, and even more so if you want to experiment with your own software.I haven't had much time to play around with mine but I might do some review in the near future, and if you or anyone else has questions or wants to see some screenshots then let me know.

author: tmbinc
author_rank: Frequent Contributor
timestamp: May 20, 2015, 10:16:11 am
content: The measurement bandwidth of the CRTU is limited by the IF bandwidth (~8MHz centered around 10.7MHz), and then further limited by the Digital Down-Converter ASIC (the only ASIC in the whole thing, the rest are mostly off-the-shelf FPGAs and DSPs, of course with application-specific bitstreams/firmware). I haven't yet figured out the maximum output rate of the DDC, but I think it's not much more than 4 MS/s (i.e. 4MHz since it's I/Q). RBW max. is 1MHz.The Windows software is very specific to the GSM needs. It makes use of the integrated signalling units (DSP+FPGA+microprocessor), and with reasonable effort (once you understand the software design, and maybe have the chance to look at a few samples) it's possible to build dedicated GSM tests - included corner cases like "there's three cells, one of them is losing signal power, so the phone attempts to switch over to the next-strongest, but it refuses with a specific reason, so the phone is supposed to try the third one" etc. (You actually need multiple CRTUs for most of these scenarios).The Windows part unfortunately doesn't do any of the fancy RF things. It can mostly tune to a frequency for each of the 2 RX and 2 TX channels, set/measure power, and that's it. (And then of course there's all the GSM-specific stuff on top of it).The DOS-based software (actually 32-bit), which is mostly there for servicing the unit (I think it's mostly a "free" leftover due to the CMU200-based design), however is written in a very modular way, with different "Function Groups" that are loaded at runtime, and is scriptable via GPIB and serial port (and apparently network, in more recent versions). For further processing, you can use the IF (or I/Q if you have the option installed), but again it's limited by the ~8MHz IF bandwidth. I used SignalVu on my scope (via the IF output), and it worked reasonably well.

author: G0HZU
author_rank: Super Contributor
timestamp: May 20, 2015, 04:24:29 pm
content: QuoteRead what I said again... I warned that the R&S CMU200 and the CRTU are probably going to show very limited spurious free dynamic range. So if someone buys one of these and tries to do some basic linearity or spurious checking then these analysers may prove to be much, much worse than a conventional mid range spectrum analyser. Even compared to an oldschool midrange analyser from 30 years ago that fw people would want and can be purchased for sub $200.QuoteI doubt that the RF platform/section is the same as a conventional high end analyser. I think you need to realise that 'cost' does not always guarantee that a test set will have a spectrum analyser in it with better than 'ropey' spurious free dynamic range. Even if it costs $250k new, let alone $100k.But maybe you know something I don't... Can you share your knowledge and tell me the basic frequency plan of the CMU200 RF section. I assume you know this because you own one and you made the platform claims above and have access to the service manual.

author: tmbinc
author_rank: Frequent Contributor
timestamp: May 20, 2015, 06:10:34 pm
content: Here's the service manual for the CMU200:https://www.ntecusa.com/docs/RS_CMU200_CMU300_other.pdfI also have the service manual for the CRTU-RU, but the RF part (and likely a lot more) is identical.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 21, 2015, 02:27:22 am
content: "On the receiver side (RX), the RF signal is fed in at the SMA connector RFRX1 (bottom of module) of the RXTX BOARD1 which is provided by the RF FRONTEND.On the RXTX BOARD1, this signal is taken via a switchable attenuator with fine stepping and large attenuation range in order to match the level according to the level applied.Subsequently, this signal is converted to an IF frequency of 10.7 MHz by means of triple signal conversion (IF1, IF2, IF3) and several filter and amplifier stages and provided at the MMCX connector IF3RX1 (top of module) for the DIGITAL BOARD.This procedure is necessary to achieve a high image-frequency rejection and a high dynamic range with a simultaneously high intermodulation suppression. For the receiver side, an extra LO1RX (local oscillator) is provided with a large tuning range and a very fine frequency resolution used for setting the receive frequency, an LO2 fixed-frequency oscillator shared with the transmitter and an extra LO3RX with a very small tuning range.All LOs are synchronized by the MMCX connector 110.8 MHz at the bottom of the module with the reference frequency from the REFERENCE BOARD."-Synchronized triple conversion to enhance image (spurious) rejection, this could be a problem for using the CMU as a general purpose wide band spectrum analyzer. Typically dedicated spectrum analyzers have a YIG filter or similar device to improve image (spurious) rejection. For general RF and microwave work, it is extremely important to know if what one is viewing is real or not.*Now I'm curious to see what is actually inside the RF front end box.The other item that does does not impress me too much is the system package layout. All that noisy front panel digital stuff including the hard drive is directly next to the RF input section. Shielding might help, but the better way is to simply not have that stuff any where near the sensitive RF front end.It is clear this device has rather powerful computer driven test system capabilities. Kinda like a computer driven RF test system in a single box.CMU-200 ad sheet:http://www.upc.edu/sct/documents_equipament/d_175_id-448.pdfCMU-300 ad sheet:https://d3fdwrtpsinh7j.cloudfront.net/Docs/datasheet/12350.pdfInherent spurious response:<-50 dBLow distortion mode, 20 MHz to 2200 MHz, except 1816.115 MHzInherent harmonics:(f0 =50MHz to 2200MHz, upto 7GHz)RF1, RF2, RF4IN: <-30 dBRF4IN: <-20 dBBerniceQuote from: tmbinc on May 20, 2015, 06:10:34 pm

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 21, 2015, 10:54:07 am
content: Quote from: G0HZU on May 20, 2015, 04:24:29 pmI suggest you read again what I wrote. The CRTU as suggested as an alternative to the various USB TV tuners and USB analyzers, which is what the OP was asking, remember?We know you prefer gold-plated solutions, but I think you need a thorough reality check and realize that not everyone needs a high end SA to solve a problem, and that every day engineers have no problems getting work done with devices that I'm sure wouldn't get your blessing.Again, this was about using USB TV tuners as SAs, remember? And I bet that most of these USB devices will perform worse than a CRTU.QuoteMaybe, maybe not. Unless you're really lucky then I doubt you will find anything in the sub $200 class that offers better specs in terms of linearity, spurs or frequency stability than the CRTU, so I'm really curious what devices that might be as I'm sure you can name several in an instant.QuoteReading comprehension is obviously not your strongest point, as I said "platform" not "RF platform". I never suggested that the RF section of a R&S high end lab SA would be the same as the one in the CRTU, that's your imagination. But the platform (i.e. chassis, controllers, architecture etc) *is* the same between CRTU and older standalone SAs like the FSU.QuoteI never said that cost gurantees good performance. The reason I meantioned the price is because you seem to believe (reflected in your attitude) that everything that is used for cell phone testing must have cheap-ass components in it to produce a cheap tester, which is nonsense. In fact, these days any lab grade standalone mid-range or high-end SA comes with cell phone/wireless test and measurement applications, simply because this is the largest market for SAs.QuoteYes, I have one (actually only a CRTU, as the CMU200 has gone), but as my device is registered on my R&S GLORIS account and I got the SM via that account so I'm a bit reluctant to publish large sections of any manual provided there.However, it seems tmbinc has already provided a link to the CMU200 manual anyways.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 21, 2015, 11:08:21 am
content: Quote from: tmbinc on May 20, 2015, 10:16:11 amNo, it doesn't do anything fancy, but I think the real value is in the Windows drivers, which can control the full capability of the hardware, and which would allow someone to write his own Windows applications.I agree that the test software itself is worthless, but it could be useful for finding out how to control the hardware in these boxes.QuoteThat's incorrect. This is plain 16bit MsDOS 6.2 with a proprietary 32bit memory extender (which provides page switching for the 16bit DOS applications).QuoteThere is no control over the network. The optional LAN ports are merely to provide data streams to the UUT (i.e. cell phone) from an external server, but can not be used for remote controlling the CMU200/CRTU (obviously on the CRTU it can under Windows, but not DOS).BTW: the CMU300 is actually a CMU200 without the signalling test capability, and was mean as a simple production tester while the CMU200 was more designed for development activities. While the CMU200 was equally useable as production tester as the CMU300, the CMU300 was noticably cheaper. The CMU300 moniker was dropped pretty quickly, and both devices were later marketed under the CMU200 moniker.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 21, 2015, 11:17:10 am
content: Quote from: Rupunzell on May 21, 2015, 02:27:22 amI can't see the problem. The FMR (controller PC) is pretty well shielded in these boxes, as are all the modules. The bus that is used to communicate is 16bit ISA (slow 8MHz clock) and serial ports, which aren't as critical in terms of emissions as high speed buses.The same layout and architecture is also used in the R&S FSU standalone high-end lab SA (up to 67GHz), and despite its higher sensitivity isn't a problem there either.

author: mzzj
author_rank: Super Contributor
timestamp: May 21, 2015, 11:58:11 am
content: Quote from: Wuerstchenhund on May 21, 2015, 11:17:10 amYou should know already that for rupunzell&co anything else than old HP boat anchor is not any good.And of course they expect that everyone is able to get HP 8560E or similar for less than 100 bucks since they happen to get amazing deal once in century

author: jadew
author_rank: Frequent Contributor
timestamp: May 21, 2015, 01:21:49 pm
content: Quote from: Rupunzell on May 21, 2015, 02:27:22 amThis is what I was worried about.Anyway, I'd like to add that you don't need a gold plated HP SA, if you can't afford it. Cheap Advantest ones can be had for ~$300-$500 (within the OPs budget).

author: Fraser
author_rank: Super Contributor
timestamp: May 21, 2015, 01:34:38 pm
content: And there is absolutely nothing wrong with Advantest kitThat is why R&S partnered with themI have several Advantest SA's and I like them all.Aurora

author: G0HZU
author_rank: Super Contributor
timestamp: May 21, 2015, 03:47:18 pm
content: Quote from: jadew on May 21, 2015, 01:21:49 pmYes, I tried to highlight the spurious limitations of these test sets when making comparisons against other conventional spectrum analysers that might be considered as alternatives for the OP. There are various spec limits for -20dBc or -30dBc spurious terms for the CMU200.At work, the nearest thing I can find to the CMU200 or CRTU is the newer LTE/OFDM '500' version and this also suffers from poor spurious performance. The other comment I would make about it would be that the user interface is very much designed for automated use and the analyser interface is a bit unconventional if you try and use the front panel interface manually. It's very much a softkey/mouse affair and some aspects of the analyser control are very strange if you are used to a conventional analyser. Obviously, the 500 version is staggeringly expensive to buy but my point is that if the CMU200/CRTU has a similar interface then it's worth the OP checking that they would be happy using it.I thought the whole point of the thread was to discuss good/bad points of analysers within the OP's budget. I'm just offering my professional experience/knowledge/opinion and ultimately, it's up to the OP which analyser to choose.

author: SArepairman
author_rank: Frequent Contributor
timestamp: May 21, 2015, 03:49:28 pm
content: a flat wide band noise source can be used to calibrate the SA $$$$$$$$$

author: G0HZU
author_rank: Super Contributor
timestamp: May 21, 2015, 04:02:57 pm
content: QuoteBut the part of the analyser that severly limits the spurious free dynamic range is the RF/receiver section. The design of the receiver section of these analysers is compromised for various reasons. I'm merely raising this point for the benefit of the OP.Just because it is in the same type of chassis and has a similar controller (and it cost $100k) does NOTHING for the performance of the RF section.

author: _Wim_
author_rank: Super Contributor
timestamp: May 21, 2015, 05:51:58 pm
content: Quote from: Wuerstchenhund on May 21, 2015, 11:08:21 amMany thanks for the excellent info you posted already, much appreciated. This info is hard to come by on the net. I am seriously considering buying one of these, but I am hoping you are right and prices will drop even a little lower.To other posters, I would be excellent if you could also post ebay-links (or other sites) with SA’s actually on sale for low affordable prices (preferably <500€). I have been reading this forum a lot, and been following Ebay (German and Belgium site) for quite some time. So far I did not find anything affordable that goes up to 2GHz and is less than 20 years old. After recommendations here, I have been specifically looking for Advantest, but so far also without luck price wise. Wuerstchenhund posted the in my opinion the best available deal so far, but I am still doubting because of the following reasons:- Price is more then 500€- Looks a very complex unit for an RF-beginner like my…

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 21, 2015, 10:06:17 pm
content: Quote from: G0HZU on May 21, 2015, 03:47:18 pmThat would be the CMW500 then, which replaces both the CMU200 and the CRTU product lines.QuoteIt doesn't. The CMW Series is Windows only and uses a completely different software than the CRTU and the CMU200, both which are pretty easy to operate when running the DOS-based test applications.

author: davorin
author_rank: Unknown
timestamp: May 21, 2015, 10:20:15 pm
content: Wowowowoow....never thought I start a discussion like that....(o;But great forum and members here to read all their opinions and suggestions :-)Nevertheless I will start with the SA44B...as I get a new device for Euro 799.....I've also looked on ebay for along time for real SAs...but they are still too bloody expensive or just too old...I see the Signalhound as a starting device for me being a hobbyist...well...in the RF area....and maybe this device will help me to understand this new field better...and even build own devices above 1MHz (o;So far my field is only embedded hardware/software design and FPGA synthesis as well as PCB design....

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 21, 2015, 10:26:51 pm
content: Quote from: _Wim_ on May 21, 2015, 05:51:58 pmDon't hold your breath. If that works like similar discussions in the past then you might hear about some incredible deals by certain individuals, but unless you're at the right time at the right place and know the right people, these bargains of cheap high quality test gear for bottom basement prices are unlikely to materialize for the majority of people. That (as you probably found out already) mostly leaves the stuff you find on ebay & co., which in the lower price range usually consists of "untested" (i.e. guaranteed to be defective) or openly defective bangers from 25yrs ago, and even if you spend more you'll mostly get either some 20+yr old standalone SA (often the 75ohms variant) or working but spec-wise not perfect comms testers like the mentioned CRTU.SAs are pretty expensive, even used ones, and the smaller your budget is the larger the limitations (specs, age and therefore reliability, size, noise, features) you have to accept.QuoteI wouldn't worry about complexity, especially since any other SA will very likely be even more complex. The advantage of newer kit like the CRTU is that it is much more reliable than kit from 25+yrs ago, there's not much that needs adjustment, and thanks to the modular design repairs are pretty easy (and modules can often be found on ebay).Should you decide for a CRTU then offer EUR500 (and tell him that you know that the market is going to be swamped with these things), which I'm sure a sensible seller would gladly accept, considering that these things will only fall in value.

author: G0HZU
author_rank: Super Contributor
timestamp: May 21, 2015, 11:14:20 pm
content: QuoteDespite the above differences it looks very similar (to me) in terms of the analyser UI. I base this on having spent an hour playing with the 500 and also looking at various screenshots of the other two machines. The soft controls and menus and the analyser display look very similar to an onlooker.I certainly hope the 200 is nicer to use than the 500. However, I've only used the 500 for about an hour and I only used the analyser UI. It looks (to me at least) to be very similar to the screenshots and links you posted up earlier.It was a very odd analyser to drive and the whole experience was like using something written in Visual Basic by a comparative novice who probably never planned to use the interface themselves at any point in the future. Hence my concern that the 200 might be similar.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 22, 2015, 05:27:56 am
content: "Don't be a hammer that perceives everything is a nail that must be hammered. There are times when a claw-foot pry bar needs to be used to remove the nails revealing what is actually inside."*This is NOT a contest or competition of what is best, it should be a sharing of knowledge and learning.These test sets came to being when the communications industry needed a good high speed automated test system to deal with the sheer volume of techno-widgets (cell phones an such) streaming off the production line. These test sets can replace a rack of test gear and the problems related to integrating each instrument in the test rack into a automated test system. Considering these test sets can replace all these individual items of instrumentation makes then a very good value for what they are intended to do.Once these computer driven test systems are taken out of context or their original intent such as a lab / development / research / home hobby environment, their designed in strengths can become a significant dis-advantage. This does not make these test sets un-useable in these environments, their limitations must be considered and well understood before consideration for making meaningful measurements.Historically on this web forum there is much prejudice and distain for "old-obsolute and in the way of progress" test gear. Yet there are many historically significant and classic items of instrumentation that is never consider due to their age, lack of computer interface or fashion. These classic pieces of instrumentation can offer many lessons in design and technology and physics... all there for those who are willing to listen, learn of what they have to offer. All this for rather affordable cost.In the world of digital and computing, faster processing, more memory, the ability to crunch information often means greater measurable functionality and what a computer can achieve. The analog-RF-microwave and physics world does not work this way. Nature is what it is and individuals who endeavor into exploiting nature to create a technical widget is forced to make a compromise deal with this hash reality. This is one of the reasons why good spectrum analyzers and other properly designed and built analog instrumentation holds their value on the used market. Consider why the hp 8566 stayed in production for nearly two decades and continues to hold their value to this day. Then consider why a two decade old computer is not much more than a technical curiosity today.hp is NOT the only manufacture to make spectrum analyzers, others include Avantest, Anritus, Rohde & Schwarz, Tektronix and others. Historically Systron Donner, Ailtech-Eaton, Polarad, Cushman and others also once made SAs.Bernice

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 22, 2015, 05:41:13 am
content: Quote from: G0HZU on May 21, 2015, 11:14:20 pmI have only had the chance to play with a CMW500 once, and that was for a few minutes only, but from a software point of view the CMW500 looked like a much more complex device than either CRTU or CMU200.QuoteThe basic control principle has shares some similarities but many functions and menus aren't available on the older devices.Using a CRTU/CMU200 as a SA (or RF generator, or power meter) is really dead simple, as unlike with other comms testers these functions are kept completely separate from the cell phone testing applications. Even a beginner should not have difficulties to start the SA without reading a manual. I can post some more screenshots if you want.I also have a lab-grade standalone SA from R&S (FSP7), and while overall its a very nice device, seriously, I wish the UI was more like the CMU/CRTU UI instead of structural mess that it is.QuoteAs I said, the basic idea behind the UI is roughly the same, but that's it. CMU200/CRTU are really dead simple.Can you post some screenshots of the CMW500 interface?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 22, 2015, 08:41:40 am
content: Quote from: Rupunzell on May 22, 2015, 05:27:56 amWhile as a general rule this is correct, you completely ignore that the CMU200 was actually designed and used as a standalone lab instrument for manual use by a human, not an automated test system. Of course, like other lab test kit intended for manual use (i.e. the HP 8566) it comes with a GPIB port and can be remotely controlled, but that was never the main purpose of the CMU200, which was sitting on a bench and being used by an engineer working on RF designs.The CRTU (which hardware-wise is mostly the same as the CMU200) actually *was* intended as automated test system, and this was done by adding a Windows 2000 partition which runs a dedicated test environment. However, the CRTU (which is a multi-boot device) comes with the same DOS software as the CMU200, and with that DOS software behaves exactly as a CMU200 (i.e. a standalone lab instrument).QuoteTrue, but that is no different to any other test instrument out there, no matter if automated or manually operated. Every test instrument lies to some extend, and a good engineer takes that into account.QuoteI disagree. I've been here a while but I have yet to see any "disdain", in fact, there's probably still a strong preference of older, analog instruments over their modern equivalent, probably resulting from the fact that a large part of forum members are hobbyists, and hobbyists tend to have small budgets which usually means older and simpler instruments.But its true that very old test instruments can often be had for little money these days. However, what you ignore is that in many areas even old high end kit performs worse than modern entry level equipment. In some areas (i.e. scopes) the change in technology is pretty significant, as what once was an instrument which didn't do much else than displaying (parts of) a waveform has now become full signal analyzers. Also, many of the techniques used with old kit no longer make sense or are even counter-productive with modern kit.You also forget the running costs. It's all fine and dnandy when you can get an old instrument for cheap, however when it's more than two and a half decades old the likelihood of failure increases dramatically, and often repair turns out difficult because parts are no longer available or are generally unobtainium (i.e. some ICs from Tek and HP), with a good chance rendering the investment into a complete loss.There's also the issue of size, noise and power consumption, all areas where old test instruments don't really shine. Many hobbyists are severely space constrained.QuoteNot really, no. Of course the physics behind hasn't changed, but the simple fact remains that analog instruments are severely limited in what you can do with them. For example, have a look at the HP 8566 Series, which by many engineers is considered to be the epithome of analog SAs. But all that huge box does is giving you a display and some markers, but in terms of measurements its pretty dire (even for basic stuff like OBW). You can compensate for some of that by connecting it to a computer, but the box itself is pretty basic. The FFT option is utterly basic, and again pretty useless without an external computer.It's even worse in other areas, i.e. scopes. Analog scopes give you a waveform display but that's about it. If you're lucky you get some primitive storage capability. Good luck trying to find out what the various frequency components of a square wave signal is, or how a pulse variies over time, or the recurring and intermittend jitter components, or anything else for that matter. The timebase of most analog scopes is pretty inaccurate, and the presence of certain by-products (i.e. noise) might not even be noticed by the operator as it might not even be visible due to insufficient brightness.You also completely ignore the change of what signals are measured today. In the good old days most hobbyists would probably be playing around with some amplifier, audio equipment, radio kit or other analog stuff. These days it's more like Arduino & Co, fast digital busses, digital transmissions, SDRs and other pretty complex things. Old analog test kit is simply insufficient to extract relevant measurement data from such signal environments.QuoteThe reason the 8566 was produced for that long is simply because there was no need for a replacement, Tek was pretty crap in producing SAs, and Tek and HP were essentially the to-go brands for most companies and government agencies around the world. It was also made in the US, which was (and still is) a big thing for the US government, a spender of extraordinary amounts of money for such kit. Also, high end SAs were a pretty small market, and for many manufacturers it simply wasn't worth (or they were simply incapable) to justify investing lots of money into it, as even if they did HP would still outsell them.That means, without any other major challengers, HP could continue selling the 8566 for a long time without having to invest much money into a product update. It also helped that government customers paid quite a lot of money for this device to be available to them for an extended period of time. HP was merely riding it out.The other thing is that before the end of the 90's available computing power was limited and simply insuficient to do advanced signal analysis. Only after computing power increased all the functionality that a modern SA is capable of became possible.The reasons the 8566 is still somewhat expensive as 2nd hand device are that the choice of old lab-grade high-end SAs is pretty limited for the reasons stated before (it was a small market after all), and that it carries the HP label, which is the same reason as to why primitive old Tek DSOs with awful specs still fetch insane prices. The name has a tremendous pull.However, as good as the 8566 is, these days, if I needed a reasonably priced high-end lab SA I'd rather hunt for a R&S FSIQ than a HP 8566. The FSIQ exists in various variants up to 26GHz and has similarly good specs as the HP, but is faster, smaller, less noisy, comes with a color TFT display instead of a green CRT, and offers tons of analysis capabilities you won't get with the HP. And often enough the 26GHz variant goes for around the same as a 8566B in decent condition. And as a bonus, the FSIQ can emulate various HP SAs including the 8566 on the GPIB bus.QuoteOlder Tek SAs suck (the 492P was the worst SA I've ever had to use). R&S did't produce many SAs before ~1999 and resold Advantek midrange SAs instead. Most of the Anritsu devices offered as "Spectrum Analyzer" on ebay are actually cell phone analyzers, many of which have pretty dire specs (worse than the CMU200/CRTU) while regularly costing much more.The others mentioned are pretty antique, some even come with valves and mechanical dials. Not sure that is a good investment for a hobby lab, these things are more suitable for collectors.

author: G0HZU
author_rank: Super Contributor
timestamp: May 22, 2015, 12:00:24 pm
content: QuoteI'll try and post up jpg 'prints' saved to USB when I get a chance. I'm not sure it's relevant to the thread though... The model we have is a CMW500 and it boots up in WinXP. So my guess is they tried to maintain a similar (looking) spectrum analyser UI for the 500 despite the move to Win XP.However, I've now got hold of a Tek RSA306 to play with which is going to prove a bit of a distraction.

author: G0HZU
author_rank: Super Contributor
timestamp: May 22, 2015, 01:00:20 pm
content: I took a few CMW500 screenshots and here is one of them.Note:I've edited the image to remove the SW revision number at the top in case this info is unique to us.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 22, 2015, 03:08:14 pm
content: Quote from: G0HZU on May 22, 2015, 01:00:20 pmThanks for the screenshot. Looks like what I remember, and I agree that the interface is a bit more complex.The CMU200/CRTU UI is much simpler. It shares the basic principle (selection of setting category on the right side, individual parameters at the bottom) with the CMW, but the layout is simpler, and different functions are not stacked on each other as on the CMW. Admittedly it's not as comfortable as having separate buttons for each function (Start/Stop/Span/RBW) but it's not rocket science to operate a CMU200/CRTU.

author: G0HZU
author_rank: Super Contributor
timestamp: May 22, 2015, 08:49:33 pm
content: The interface on the 500 is quite annoying to use IMO. Also the trace update rate is poor. Maybe I haven't configured it correctly but the UI was clearly not designed by (or for) an RF engineer.But I doubt anyone is going to buy a 500 cheaply on ebay for many years to come so I guess none of this matters

author: G0HZU
author_rank: Super Contributor
timestamp: May 22, 2015, 08:52:31 pm
content: Quote from: davorin on May 21, 2015, 10:20:15 pmMost users appear to be quite content with the SA44 now that there is a new suite of SW to control it. So I expect you will be OK

author: _Wim_
author_rank: Super Contributor
timestamp: May 23, 2015, 05:57:43 am
content: Quote from: Wuerstchenhund on May 21, 2015, 10:26:51 pmThanks, I will give that a try, and if the seller does not accept, I will include the CRTU in all my future ebay-searches

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 23, 2015, 06:12:46 am
content: Quote from: _Wim_ on May 23, 2015, 05:57:43 amYou could also try to ask for offers in the Buy & Sell section of this forum, as it seems a few forum members have bought several CRTUs from the recent auction in Finland, and by now are probably ready to sell some of their boxes on, and saves them the ever increasing ebay fees (so you might get a CRTU for even less than EUR500).BTW, should you buy one it would be great if you'd come back and report about your experience with the CRTU, as I'm sure this could help other beginners looking for a similar low-budget entry into RF.Also, don't forget to buy some proper RF cables and adapters. I'd avoid the noname China stuff and go for reputable brands (like Gore, Huber & Suhner, Amphenol etc) instead. Doesn't have to be expensive, brand name RF cables regularly can be found on ebay for little money.

author: davorin
author_rank: Unknown
timestamp: May 27, 2015, 06:23:57 am
content: I did both now...ordered a Signalhound SA44B with some adapters as also posted on the buy/sell forum if someone has a spare CRTU (o;The SA44B should arrive already on Friday or Monday as it is on stock in Netherland....

author: davorin
author_rank: Unknown
timestamp: May 27, 2015, 04:49:10 pm
content: So both are on the way...SA44B and CRTU (o;BTW: Anyone seen a service manual and operating manual for the CRTU? Especially interested in remote programming.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 27, 2015, 05:10:03 pm
content: Quote from: davorin on May 27, 2015, 04:49:10 pmNice. So youcoulddo some comparisonQuoteAll documentation (including Operating Manual, Quick Start Guide and Service Manual) should be in the Windows 2000 partition.

author: davorin
author_rank: Unknown
timestamp: May 27, 2015, 05:15:02 pm
content: Well sure I will compare them and post some pictures (o;Ah okay...and I assume the CMU200 service manual has some analogies to the CRTU as the CRTU is just a CMU200 with Win2K in the box...Also I read in another thread that the Win2k software is mainly for automated testing...but measurements can be done from within DOS....so basically it would be possible to drop Win2k completely and have it replaced with Linux? (just my wishful thinking ;o)

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 28, 2015, 05:29:55 am
content: Quote from: davorin on May 27, 2015, 05:15:02 pmNot quite. There are some hardware differences as well.QuoteNo, unless you write all the Linux hardware drivers for the various DSPs and proprietary signal processors yourself.What you could do is however to write your own Windows software, considering that the W2k partition already comes with the hardware drivers, and also with Microsoft Visual C++.

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 01:40:56 pm
content: Just picked up my CRTU from post office and fired it up...Amazing device with loads of buttons and connectors (o;Guess I have to do some heavy manual reading to get to know it....but at least it prompts to the RF spectrum display when powering up...

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 30, 2015, 02:14:20 pm
content: Quote from: davorin on May 30, 2015, 01:40:56 pmDon't worry, once you get around the somewhat quirky way R&S designs their UIs it's pretty easy to use. But don't rely on teh CRTU documentation as this mostly only covers the automated testing under Windows. Just read the CMU200 manual and you'll see how things work for manual testing.But the first thing I'd do is a full backup of the hard disk, as the disks in these devices quite often start getting bad sectors these days. Once you've a backup then you can just swap it for a new drive, or a SSD.

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 02:17:46 pm
content: What is the best way to do a backup? Install some backup software under Win2k?Or can I boot with some Linux USB stick with a backup tool?I see 3 partitions inside C, D and E...Definitively I will replace the drive anyway with a SSD soon...Does RAM upgrade bring some improvements as well?BTW: What was the original price of this device?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 30, 2015, 02:38:01 pm
content: Quote from: davorin on May 30, 2015, 02:17:46 pmYes, you can boot from a Linux USB stick (you might need an external monitor if the Linux tries to switch to a higher resolution than 640x480@60Hz).QuoteRAM upgrade won't bring much, at least not under DOS. If you plan to use the W2k partition then that's adifferent story, though. The FMR6 controller in the CRTU takes SODIMMs btw (PC133 SDRAM), but I'm not sure it supports 512MB modules.The SSD is a great update, I put a Transcend PSD330 in mine, which is quite noticable under W2k.QuoteDifficult to say but depending on the config somewhere between $100k and $180k.

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 06:43:26 pm
content: Just browsed through the documentation on the harddrive...Seems though the CRTU has a GPIB connector, it is not meant for controlling it, but the CRTU controls other devices....Is there no way controlling this device remotely to set start/stop/span rbw and so on and having a screen dump created?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 30, 2015, 07:57:18 pm
content: Quote from: davorin on May 30, 2015, 06:43:26 pmUnder Windows, the CRTU can act as GPIB controller or be remote-controlled by another device via GPIB. Under DOS, the CRTU can only be controlled via GPIB but not act as a controller itself.You can also control the CRTU via RS232 (DOS only), or via LAN (Windows only).

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 08:03:29 pm
content: Hmm...didn't saw anything in the documentation how to control the CRTU via GPIB...Also...didn't respond to *IDN? query to the preset address under DOS...well..tried under Linux with "ibterm" and a S82357 USB adapter...Is there no GPIB/SCPI programming manual like HP supplies?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 30, 2015, 09:23:03 pm
content: Quote from: davorin on May 30, 2015, 08:03:29 pmHave you checked the GPIB settings in the CRTU's software?QuoteIf you want to control it in DOS mode then you'd have to look in the CMU200 manuals, as the CRTU manuals mostly discuss the Windows software.

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 09:29:32 pm
content: Yes I checked it...default set to GPIB address 20....not sure what the slave address is good for....as they can be set for RF generator and different GSM modes...Ah right...the CMU200 is similar....but as I've read the CMU misses the spectrum analyzer? So those commands would be missing?Anyway...already late here in .ch...downloaded the operating manual and will read through tomorrow (o;

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 30, 2015, 09:32:15 pm
content: Quote from: davorin on May 30, 2015, 09:29:32 pmNo, the CMU200 also does have the spectrum analyzer. In fact, the DOS software between CMU and CRTU is identical.

author: davorin
author_rank: Unknown
timestamp: May 30, 2015, 09:40:32 pm
content: Ah great to know....Does R&S supply software/firmware updates for everyone or only through expensive support contract?Well...from the software point of view I intend to use the DOS version only....meaning the RF spectrum application....And if that's controllable remotely...than it's a perfect device...Not sure for what the TCP/IP setting is for...guess that's for the TFP automation only?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: May 31, 2015, 07:35:49 am
content: Quote from: davorin on May 30, 2015, 09:40:32 pmYou need an R&S GLORIS support account, with access to the CMU and CRTU areas, which is usually only provided to corporate customers.This is because access to firmware and compatibility module updates was regulated by support contracts.What version of the DOS software do you have (you can check in Version Manager, which you can get into by pressing a button during the loading phase when the CRTU splash screen is shown).QuoteIt's remote controllable via GPIB and serial.QuoteThe TCP/IP settings in the DOS application are for data transfers between a cell phone and an external server. This was used to test data transmission (i.e. mobile internet).Unfortunately the DOS application can't be controlled via network.

author: davorin
author_rank: Unknown
timestamp: May 31, 2015, 04:13:38 pm
content: It says software version 4.34...Took me a while as I was recabling my whole lab (o;

author: davorin
author_rank: Unknown
timestamp: May 31, 2015, 04:39:05 pm
content: Hmm...still no joy with GPIB and F82357 with linux-gpib...Not even answers to a simple *IDN? query....

author: jadew
author_rank: Frequent Contributor
timestamp: May 31, 2015, 06:32:21 pm
content: Congrats on the new acquisition!Any preliminary impressions on it?

author: davorin
author_rank: Unknown
timestamp: May 31, 2015, 06:37:49 pm
content: Apart from the fact I can't control it with GPIB....I'm really happy....Well...my main focus was to get a reasonable USB spectrum analyzer...I just played a little with the RF spectrum analyzer...not much more....people mentioned that it is not a perfect SA like a clumsy HP or any dedicated SA:..But it does sweeps really fast from 10MHz to 2.7GHz.It looks like almost unused...nice equipment...now the Fluke 606A/AN looks like stone-age in design...but that one gets replaced soon with a R&S signal generator (o;

author: Mr Simpleton
author_rank: Unknown
timestamp: June 01, 2015, 09:48:24 am
content: Have you received the SA44 yet? I am eagerly awaiting your put up against the CRTU

author: davorin
author_rank: Unknown
timestamp: June 01, 2015, 09:51:26 am
content: It should arrive today at the work place, where I am at tomorrow and Wednesday....and bringing it home then...so first comparison at Thursday first...I also can't wait to compare them ;-)BTW: Anyone use the tracking generator together with the SA44B?From the specs it should be possible to do a frequency plot of the audio spectrum as well?

author: Mr Simpleton
author_rank: Unknown
timestamp: June 01, 2015, 01:16:55 pm
content: I have both the SA44B and TG44A, but only used it in the MHz range...

author: davorin
author_rank: Unknown
timestamp: June 01, 2015, 01:58:56 pm
content: And is it worth the additional cost of the tracking generator?But definitively something to try out if I get a TG44A...