Rigol DSG815 - testing feedback and comments - Page 1
Forum section: electronics / testgear

author: noreply
author_rank: Frequent Contributor
timestamp: July 06, 2020, 04:21:02 pm
content: I have been fortunate to have a NEWRigol DSG815made available to me for testing purposesI want to take this opportunity to invite any forum members who are interested inRF Signal Generators- to make some 'testing' suggestions while I am reviewing this unit.From my experience - there have been very little comments on the forum regarding the actual performance / use of the DSG815The only 'hands-on' has been Dave's brilliant teardown on the 815 some time agoI was very impresses at the 'clean' build quality and clever RF design as Dave highlighted so well - it looked like a extremely high quality unit, and this was my inspiration in looking deeper to evaluate the actual 'use / performance' of this device before making a purchasing decision (the SSG2030x as the alternative).So here we are ...So far I am impressed at the build quality - and initial testing has shown solid results - well within the published specifications.If anybody has some testing which they would like me to do - then please make a suggestionKeeping in mind I can only do some simple things at this moment in time.I have a SVA1032x and a Rigol MSO5350 at my disposal to complement the testing.As I make some of my own testing - I will post my results hereHope everyone interested in purchasing a new RF Signal Generator will find this thread useful

author: noreply
author_rank: Frequent Contributor
timestamp: July 06, 2020, 08:51:51 pm
content: TestingFrequency / Amplitude / HarmonicsThe specifications for the Rigol DSG815 are …FrequencyStability with internal oscillator is <2ppMSo, @100Mhz we should not have a frequency deviation of < 200HzSo, @500Mhz we should not have a frequency deviation of < 1KHzSo, @1000Mhz we should not have a frequency deviation of < 2KHzSo, @1500Mhz we should not have a frequency deviation of < 3KHzAmplitudeAbsolute Level UncertaintyTemperature range: 20℃ to 30℃For Amplitude range between +13 dBm to -60 dBmAt a frequency Range between 100 kHz ≤ f ≤ 3.6 GHzThe Amplitude can deviate by ≤ 0.9 dB, ≤ 0.5 (typ.)For an Amplitude Range between -60 dBm to -110 dBmAt a frequency Range between 100 kHz ≤ f ≤ 3.6 GHzThe Amplitude can deviate by ≤ 1.1 dB, ≤ 0.7 (typ.)HarmonicsCW modeFor Frequency range of 1 MHz ≤ f ≤ 3.6 GHzAt an Amplitude level of ≤ +13 dBmThe Harmonics should be < -30 dBcMy Test FindingsUsing a direct connection from DSG815 to SVA1032x with > 6GHZ low loss cableAt 100MHz , 20dBm Amplitude (DSG815)(this is OUTSIDE PUBLISHED SPECIFICATIONS which are limited to <13dBm)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =19.63dBmSpecification states typical < 0.5dBm errorConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic-20.14dBmThis is outside the specifications of < 30dBmBUT keep in mind we are operating at 20dBm Amplitude settingwhich is outside the < 13dBm SpecificationAt 100MHz , 13dBm Amplitude (See 13dbm.png)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =12.66dBmDeviation was -0.34dBmSpecification states typical < 0.5dBm errorConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic-34.13dBmThis is inside the specifications of < 30dBcAt 100MHz , 0dBm Amplitude (See 0dbm.png)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =-0.27dBmDeviation was -0.27dBmSpecification states typical < 0.5dBm errorConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic-47.08dBmThis is inside the specifications of < 30dBcAt 100MHz , -10dBm Amplitude (See -10dbm.png)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =-10.35dBmDeviation was -0.35dBmSpecification states typical < 0.5dBm errorConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic-52.94dBmThis is well inside the specifications of < 30dBcAt 100MHz , -20dBm Amplitude (See -20dbm.png)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =-20.31dBmDeviation was -0.31dBmSpecification states typical < 0.5dBm errorConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic-53.19dBmThis is inside the specifications of < 30dBcAt 100MHz , -110dBm Amplitude (See -110dbm.png)SVA1032x Resultant measurements areFrequency =100MHzWithin Specifications (spot-on)Amplitude =-110.56dBmDeviation was -0.56dBmSpecification states typical < 0.5dBm error but can be <0.9dBmConclusion DSG815 well within SpecificationsHarmonics1st2nd Harmonic –it’s below the noise floor of the SVA at -142.79dBmA tribute to the Siglent SVS1032x – and its low noise floor of -142dBm well done!This is inside the specifications of < 30dBcOK , without going through ALL of the individual results here is summary for other frequencies …10dbm at 500Mhz (see 500mhz @ 10dbm.png)Frequency 500.2666667MHzDeviation is 2.66KHz – acceptable limit is 1KHz (I strongly suspect the SVA in error here because of the LARGE frequency span in measurement)Amplitude = 9.65dbm – well within spec1st2nd Harmonic = -31.25dbm – well within spec0dbm at 500MHz (see 500mhz @ 0dbm.png)Frequency 499.536667MHzDeviation is 4.633kHz – acceptable limit is 1KHz (I strongly suspect the SVA in error here because of the LARGE frequency span in measurement)Amplitude = -0.31dbm – well within spec1st2nd Harmonic = -40.86dbm – well within spec-110dbm at 500MHz (see 500mhz @ -110dbm.png)Frequency 500MHzDeviation is 0kHz – acceptable limit is 1KHzAmplitude = -110.64dbm – well within spec1st2nd Harmonic – it’s below the measured noise floor of the SVA at -135.36dBmSee1ghz @ 10dbm.png(results are once again well within specs)See1ghz @ 0dbm.png(results are once again well within specs)See1ghz @ -110dbm.png(results are once again well within specs)See1.5ghz @ 10dbm.png(results are once again well within specs)See1.5ghz @ 0dbm.png(results are once again well within specs)See1.5ghz @ -110dbm.png(results are once again well within specs)ConclusionThere was a consistent error of approx. 0.3dbm (well within the specifications) in the Amplitude at 100MHz measurements – this is most likely the ‘loss’ in the cable.All othermeasurements are well within the specificationsof both instrumentsSo the RigolDSG815 is true to its specificationswith regard toFrequency / Amplitude / HarmonicsMore Testing to follow soon ...

author: TurboTom
author_rank: Super Contributor
timestamp: July 06, 2020, 08:59:17 pm
content: Seems like you're mixing up dBm and dBc in your harmonics tests.@ 100MHz 20dBm, a harmonics level of -20dBm is still within Rigol's specs of better than -30dBc, namely -40dBc.Anyway, interesting tests that you're doing there, I wish I had an excuse for spending the money on such a generator...

author: noreply
author_rank: Frequent Contributor
timestamp: July 06, 2020, 09:55:42 pm
content: Quote from: TurboTom on July 06, 2020, 08:59:17 pmYes you are correct about my mix-up with dBc(I mode the correction in the post)I made so many measurements in the process - part of getting to know how to drive the equipment - that when it came to present the results - it became even more workI wanted to make a table - but that's not easy...So decided to do itverbose- by simply stating the results as seen on the screen shots.After doing the 100MHz , it was easier to simply refer to the screen shots - so those who are interested can interpret their own.Yeah .. this is a nice bit of kit (as are other RF signal generators I am sure - waiting to get my hands on the Siglent SSG3021x soonI found some really novel (for me at least) ways to use this device for testing radios and antenna systemsWith Radios - its really simple ...I connect the SG to an antenna (not really legal - but at the power level I use I think it is??) and then set the LEVEL to -110dbm - tune the receiver to the test frequency - and then modulate the SG with a 1KHz sine wave (tone) - now slowly increase the output level - until the receiver 'hears' the tone - it gives a good approximation to the RF sensitivity of the receiver.Similarly by doing same with and without 'tuned' antenna - you can get approximation of the antenna gainThe great feature of the RF Signal Generators is the external input for modulation - you can use different things here.Again for testing purposes - I have a stereo encoder and RDS encoder - this can be connected to the modulation input of the SG and we have a well-conditioned FM signal with the 19KHz stereo pilot and RDS pilot - ready to test any FM receiver for sensitivity and signal quality.With a suitable SDR and GNU Radio - you can generate complex modulation - like DVB-T signals for testing digital TV tuners ...With RF design and testing the possibilities are endlessFor me the most important aspect of the RF signal generator is to trust its output characteristics.I am not too bothered with the frequency stability - as I will be using a GPSDO 10MHz reference (picture attached - lots of reviews on youtube on this device) - but having a trusted signal amplitude response is very important as you simply want to 'dial-up' the required LEVEL - without using another instrument in the loop to check if this is indeed correctFinally, you are once again correct - the RF SG's are not cheap - they cost more than some SA’s - so you really need to have a good reason for getting one

author: noreply
author_rank: Frequent Contributor
timestamp: July 09, 2020, 09:26:08 pm
content: TestingModulation / FM modulationSome more tests with 1GHz -20dBm with FM modulation at 1Khz and 10KhzUnfortunately - there appears to be no screen capture possible (or I simply don't know how at this moment in time) on the Rigol DSG815So I took some .jpg pics to show the settingsPlease see the images below

author: noreply
author_rank: Frequent Contributor
timestamp: July 21, 2020, 02:27:27 am
content: I recently acquired a GPSDO (a BG7TBL design)– its capable of producing a 10MHz reference sine wave signal accurate to 10E-14– when stabilized over a prolonged period of time– not moved or touched in any way in an isolated position (because of its high time accuracy– we can ‘see’ gravitational influence by nearby objects and movement of the device.For now– in the few days I have been running it– it is most likely accurate to at least 10E-12– but how can you measure this device– unless you have some reference with even ‘better’ accuracy.This is the beginning of the ‘time standard or GPSDO and Rubidium’ rabbit hole –BE WARNED!There is no end – so for now I simply accept that the GPSDO I have is accurate to at least 10E-11Great!So what can we do with it?Well, I have a really good RF signal Generator which I am reviewing – the Rigol DSG815 – it ALSO has an accurate frequency generation mechanism – after all this is VERY important for a RF Signal Generator.So why not compare the 10MHz signal – a pure sine wave – to the GPSDO’s 10MHz pure sine wave – which we assume is (it most likely is) accurate to 10E-11So how do we do this – I don’t have a frequency counter – capable of 10E-11 accuracy @ 10MHz – but I do have a MSO5000 capable of plotting x-y for respective CH1 and CH2 inputs.X-Y plotting on a Oscilloscope – generates interesting Lissajous figures – and if you understand how these are generated – then it’s VERY easy to ‘compare’ any two frequencies to determine how many Hz they are apart – or if indeed they are totally in-synch.Here is how you do your measurements / testing;-Connect your oscilloscope’s CH1 to your KNOW (the accurate reference frequency) frequency.Connect your oscilloscope’s CH2 to the source of the frequency you are trying to measure – the deviation from the KNOWN source.If you trigger your scope on the CH1 sine wave, you will see a rock steady sine wave (CH1) and a ‘moving’ sine wave on CH2.The rate – or speed of the CH2 sine wave as it moves out of phase and repeats this continuously – is in essence the time period of the frequency deviation from the CH1 frequency.Bu simply ‘looking’ at the moving waveform – we cannot tell how much the frequency of CH2 is deviated from the reference Frequency of CH1BUTIf we now enable X-Y mode – we will see a spinning circle – our Lissajous figure.The spinning circle represents the phase difference of the two sine waves.¼ of a ‘spin’ of the circle represents 90 degrees,½ of a ‘spin’ of the circle represents 180 degrees,¾ of a ‘spin’ of a circle represents 270 degrees,1 full ‘spin’ of a circle represents 360 degrees.Remember because we see the circle in 2 dimensions – when it spins onto itself – it actually has made ½ of a revolution, so it needs to spin onto itself TWO times for a full revolution.To understand this is very important.NOW, if we assume that CH1 frequency is rock solid (the time reference) – then any deviation will be in the frequency we are testing – CH2 in our case.The Rigol DSG815 – was set to be ‘spot-on’ its internal 10.000 000 00 MHzIts capable of displaying 8 significant digits – this means it can be programmed to produce .01 Hz resolution.The GPSDO is capable to producing ACCURATE resolution to 10.000 000 00000 MHzSo let’s look at this side-by-side10.000 0000010.000 00000000So we can now resolve0.00001 Hz– that’s incredible for a $100 device!Back to the ‘spinning circle’ – the rate of the ‘spin’ is an indication of how much deviation in Hz there is between the two frequencies.So, we nor go to the control panel on the DSG815 – and simply vary the least significant figure – to adjust the output frequency.As we ‘turn the know’ we are either increasing or decreasing (your choice) the signal generators output frequency – to try to match it as close as possible to the GPSDO reference frequency.As if you increase the frequency and the circle starts to spin faster – then we are going the wrong way – the sig gen frequency is already too high – we must reduce it.So if we now reduce the frequency the circle should start to slow down – we keep decreasing the frequency until we can ‘stop’ the spinning circle COMPLETELY.Unfortunately you will not be able to stop the spin completely – the Rigol DSG815 simply does not have such an accurate clock that it can match the GPSDO.BUTWe can virtually stop the ‘spin’You will be able to go down to 0.01Hz increment on the DSG815 and you will find that if you step this ‘up’ by 1 or ‘down’ by 1 this will be your final limit.When the DSG815 has been ‘warmed-up’ so its internal frequency source becomes stable – you will reach a point where the circle will still spin but VERY slowly – either left or right – depending on the last significant digit you dial.Now what?When you reach this stage – get your stop watch out and get ready.Now we are going to calculate the exact frequency ‘drift’ from the GPSDO reference frequency.Look at the circle – and wait until it becomes a ‘straight line’ – start your stopwatch.Wait until the ‘circle’ spins an entire revolution and becomes a ‘line’ again – remember this is only ½ turn because we are viewing in 2D – then wait for another revolution until it becomes a ‘line’ again – now STOP the stopwatch!VOILÀ!We have completed the measurements – congratulate yourself if you are still with meWARNING– the above ‘stop watch process could take a long time – especially if your signal generator is very close to the 10MHz frequency.To calculate how much ‘off frequency in Hz’ we are from the reference frequency we do the following;-In my case with the Rigol DSG815 – it took 172 seconds to make a FULL 360 degree turn of the circle.If we divide 1 by 172 – we will get the frequency offsetIn my case this was 1/172 which is 0.0051813953 HzIf we round this off to the GPSDO resolution it then becomes;-0.00581 HzPretty Good frequency accuracy for the Rigol DSG815(I am looking forward to performing same test on the Siglent SSG2032X soon)So what does this mean in relation to the DSG815’s ability to set ‘exact’ frequency?My offset for the 815 was 0.071 HzI could only change the last significant figureSo, can dial either 0.072 – circle still spinningORI can dial 0.070 – circle still spinning – in opposite directionBecause I need to ‘dial’ 0.71581But since I cannot – because I only have 0.00 Hz resolution and not the required 0.00000 Hz resolution offered by the GPSDO – this is why with the use of the GPSDO reference frequency – I can calculate the ‘exact’ difference needed to have a precise ‘lock’ to the 10MHz.In my case the Rigol DSG815 was 0.71581 Hz ‘higher’ in frequency than the exact 10.000 000 00 MHz dialed on the control panel.Interesting that the Rigol DSG800 series specification states a ‘frequency stability’ and not ‘frequency accuracy’– I don’t think manufacturers like to specify accuracy– because it can be way off.See detailed specifications / data sheet on the DSG800 series herehttp://telonic.co.uk/v/pdf/rigol/Rigol-DSG800-Signal-Generator-Datasheet.pdfWe just measured – frequencyaccuracy– something NOT specified in the data – but good to know.The STABILITY of the frequency – is specified in the data – referenced to 25 deg CelsiusWithin the range of 0 to 50 degrees Celsius.So if the instrument has ‘warmed-up’ and the room temperature where the instrument is operating is within the 0 to 50 degrees Celsius, Rigol specifies that the deviation in frequency will be less than 2ppmTo understand this better– visually it can be seen as thisEither09.999 999 90OR10.000 000 10Remember – Rigol only specifies STABILITY – not accuracySo we determined theaccuracy to be within 0.71581 HzAnd theSTABILITY within 0.2 Hz– at least around my room temp which was 21 degrees Celsius.The frequency did not drift more than0.00581Hzfor over 10 minutes – when instrument was warmed up.These are certainly impressive figures for a ‘cheap’ (non Agilent or Keysight) instrument.I did not stress the temperature stability to the entire range from 0 to 50 degrees Celsius unfortunately.ConclusionI have demonstrated how a GPSDO is a very useful instrument to have in your laboratory.With this device and a simple oscilloscope – capable of X-Y plot – we can measure the frequency accuracy of an instrument under test, and consequently its stability with respect to temperature.The Rigol DGS815 RF Signal Generator proved to be well within its published specifications.See attached screen captures.It’s not possible to ‘see’ spinning circle in the screen shots – so I tried to ‘capture’ as it was moving from straight line – to indicate its movement.Hope the above – rather detailed explanation of this simple testing process is useful for application to other devices under test.

author: noreply
author_rank: Frequent Contributor
timestamp: August 10, 2020, 11:23:31 pm
content: Today I had access to a IRF 2025 (old Marconi Instruments RF Signal Generator) which has exceptional specifications for a 20 year old design device.Its phase noise which has a specification of-121 dBc/Hz at 1GHz (20KHz offset)This is considerably better than the only 5 year old design of the DSG815– which has a phase noise figure of-105 dBc/Hz (typ.) at 1GHz (20KHz offset)So this was a good opportunity to see if the DSG815 did indeed have a better phase noise than the SVA1032X and if the ‘oldie’ IFR2025 was still as good as it was in its specified phase noise figures.Since the SVA1032X claims to have a-98 dBc/Hz Phase Noise @ 10 kHz offset (1 GHz, Typ.), then it will most likely be the LIMITING instrument when measuring the phase noise.Remember you cannot measure phase noise of an instrument which has a BETTER phase noise response than the phase noise of the device generating the signal for the phase noise measurement.Well if you look at the respective plots shown below ;-SVA1032X phase noise using DSG815 source 0dBm 1GHz (10KHz offset) - 30Khz spanWe can see that the SVA1032Xdoes notmeet its published phase noise specifications of -98 dBc/Hz @10 kHz offset at 1GHz – or at least my respective device did not match this figure.SVA phase noise is reported as-87.89dBc/HzOf cause – what could cause this specification not being attained - is thatthe inherent phase noise of the DGS815 could be HIGHER (worse) than the -98dBc/Hz of the SVASo I did another testI ran the same test with the IFR2025 and the results are shown in the following plot ;-SVA1032X phase noise using IFR2025 source 0dBm 1GHz (10KHz offset) - 30Khz spanHere we can see that the SVA phase noise is reported as-89.42dBc/HzSince this figure is not same as the DSG815 – in fact its considerably better but NOT close to the SVA specification – this means that BOTH of the RF Signal generators had worse phase noise figures than the SVA at the 10KHz offset of the 1GHz carrier at 0dBmI wonder why Siglent specified the 10KHz offset in the specifications?My guess is because this small offset makes it much harder to attain the phase noise figure – as most Sig Gen will have WORSE figures at this small offset.So I decided to run some more test plots but this time at 100KHz offset.This offset should produce much lower noise figures from the Signal Generators– so now we can see if the figures at this offset (100KHz) will match the specified 98 dBc/Hz @10 kHz offset at 1GHz of the SVASee plotsSVA1032X phase noise using IFR2025 source 0dBm 1GHz (100Khz offset) - 2mhz spanSVA1032X phase noise using DSG815 source 0dBm 1GHz (100Khz offset) - 2mhz spanThe tighter ‘span’ produced better noise figures – I suspect this is the inherent SVA processing – with tighter span there is better resolution.SVA1032X phase noise using DSG815 source 0dBm 1GHz (100Khz offset) - 0.5mhz spanSVA1032X phase noise using IFR2025 source 0dBm 1GHz (100Khz offset) - 0.5mhz spanUnfortunately BOTH of the Signal Generators - even at the 100KHz offset - could not attain the -98dBc/Hz noise figure - which was specified at a 10KHz offset.Homework- for someone willing to undertake some testing ...If you have an exceptional RF Signal Generator with much better noise figures banded about in the above testingANDYou happen to have a SSA3000X or SVA1032X- then you could perform a phase noise test at 1GHz carrier with a 10KHz offset- and see if you get your SSA or SVA report close to or better than the specified -98dBc/Hz noise figure.

author: rdsi
author_rank: Contributor
timestamp: August 11, 2020, 12:49:55 am
content: Yeah, I got the DSG821A & have been happy with it so far. One area I was disappointed with was the internal IQ generator. Although I purchased this with intent of using an external IQ source the internal generator is only usable by loading an arb file. This file can be generated using MathLAB and Rigol Ultra IQ Station in conjunction with Ultra Sigma.I contacted Rigol about the format of this file so I could perhaps use a spreadsheet to develop my data then convert it to the arb file format,but, they just kept pointing me to their MathLAB solution. So I tried their solution but there seems to be no support for the 821?Anyway, when I get dual a arb generator I'll be able to test out the IQ modulation.I have found some arb file formats for Rigol signal generators but they are just for 1 channel. The file format for the 821 must somehow encode both the I & Q channels.If someone has the Rigol MathLAB solution could you post a file so I could decipher the format?Thanks

author: noreply
author_rank: Frequent Contributor
timestamp: August 11, 2020, 01:25:36 am
content: @rdsiThanks for the feedback on the 821AYes apparently most (at least the SSG range - Siglent's offering) IQ enabled Sig Gens need the IQ data to be prepared via an external device.There is quite a bit of 'crunching' required to generate the IQ data -my guess is that the processors in the devices are not equipped to do this effectively - so unless you have a Keysight or R&S device - its most likely going to have to use a 3rd party source for the data.It can however be set-up to be seamless if it is well specified and has the correct interface - i.e. use the network connections and load the data automatically.Not sure if you are aware that there is another much older thread on the DSG800 serieshttps://www.eevblog.com/forum/testgear/upcoming-rigol-dsg815830/There are several other forum members who have the 800 series - but not sure if they have the IQ 'A' variant(s)I had a quick look at the RigolUltra IQ Stationsoftware some time ago - but don't have the appropriate HW to take if further.Not sure if you tried - screen shots attached for you to seeGood Luck

author: tautech
author_rank: Super Contributor
timestamp: August 11, 2020, 02:43:32 am
content: Phase Noise check of SVA1032X using my old tired HP 8654B that drifts like a SOB.Frequency adjustment mechanism is unreliable and sticky so ~474 MHz out of 520 MHz is all I got for you..... moreView was needed to catch the below screenshot and even then the fundamental peak had drifted from CF despite the HP's hour long warm up.Clues of how to meet the datasheet spec are in the datasheet itself with an image of the settings used.

author: noreply
author_rank: Frequent Contributor
timestamp: August 12, 2020, 01:26:54 am
content: @tautechFirst of allTHANK YOUfor being the only person (so far) to attempt to do the HOMEWORKHowever– despite your effort of doing the work (10/10 for this part)– I think you failed to fully understand the basics of Phase Noise (PN) and more importantly how PN is actually specified thereby allowing a meaningful measurement to take place.I found an excellent tutorial on The Signal Path (YouTube) episode TSP #162The graphics used for this presentation are available here …https://www.keysight.com/upload/cmc_upload/All/20180720_KEE7_PhaseNoise.pdfThis is a much more in-depth presentation– probably great to review later– but for the scope of my post here I have just ‘lifted’ some screenshots based on the above slides from TSP #168 (thank You Shahriar for doing this video).In short, phase noiseMUST be definedfor any given instrument as shown in the following slide ;-what is phase noise - TSP #162 @8.03.JPGOnce defined as a specific‘offset’ and carrier frequency– when making measurementsIT MUSTalso be measured as theSAME carrier frequency and ‘offset’For the SVA1032X– as shown in Siglent’s specifications data for this device – this is-99 dBc/Hz @10 kHz Offset Phase Noise (1 GHz, Typ.)So making a PN measurement with a carrier frequency not precisely at 1GHz and an 'offset' frequency not exactly at 10KHz –IS TOTALLY MEANINGLESS- when comparing this to Siglent's published PN specification.– It’s like me posting a picture of a NFL football and saying it’s the ‘ball’ used by the UK premier league to play soccer with– when I really should have posted a picture of a SOCKER ball instead.(sorry for the football analogy - but ANY similar analogy or a ridiculous comparison would suffice)When working with PN specifications and measurements–the OFFSET and CW frequencies at which phase noise is measured areCRUCIALto meaningful measurements,as is also the relative power level of the Carrier.If you have a look at the following slide ;-phase noise related to bessel functions - further away from carrier the lower the PN - TSP #162 @11.14.JPGYou will see that the Phase Noise is related to the Bessel functions– and again, in short,- the further we move from the carrier frequency – the ‘offset’ – the BETTER the resultant phase noise measurement becomes.So if Siglent (or anyone else) specifies a phase noise of-99 dBc/Hz @10 kHz Offset Phase Noise (1 GHz, Typ.)This means you MUST measure it with an offset of 10KHz and not 948Hz AND at 1GHz Carrier Frequency and not 474 MHzBecause of the shape of the Bessel function– the closer you are to the Carrier Frequency (the smaller the offset frequency)– then it becomes far more challengeable to get low PN figures.Even Keysight and R&S will be challenged to have great PN figures at small ‘offsets’Now,lets have a look,specifically at the Siglent SVA1032X phase noise responsePlease have a look at the following slide ;-SVA1032X phase noise plot from 100Hz to 100MHz - using Signal Hound Low Phase Noise Generator - TSP #162 @34.05.JPGWe can see that it becomes relatively ‘flat’ from about 10KHz to 100KHzSo when, Shahriar Shahramian made the above phase noise measurement of the Siglent SVA using his low phase noise source (the Signal Hound PNCS-1) and the Agilent 26GHz SSA which has a ‘built-in’ phase noise function, he mistakenly specified his noise marker at 100KHz, whereas it should have been specified at 10KHz.BUTBecause the phase noise response in that region (from 10KHz to 100KHz) is ‘flat’ the resultant noise figure is pretty close to what it would read at the correct 10KHz offset frequency.I hope the above theory and slides from Keysight’s Bob Nelson and Shahriar’s great video are sufficient to clarify how proper PN measurements should be made.So for the actual measurement data part of your HOMEWORK– you score 0/10– because you TOTALLY failed to see the significance of how PN is defined and more importantly how it should be measuredAs a bonus – for Siglent SVAI once again decided to make some PN measurements using the DSG815 as the source of my PN measurements.The DSG815 is specified to have a ‘better’ PN than the SVA – so should not ‘limit’ the measurement.See plots belowSVA1032X phase noise using DSG815 source 0dBm 1GHz (10KHz offset) - 100Hz RBW - 30Hz VBW .pngSVA1032X phase noise using DSG815 source 0dBm 1GHz (10KHz offset) - 1Hz RBW - 30Hz VBW .pngHere we can see different PN measurement RESULTS based on different RBW and VBW values ONLYOK you would think that ‘tighter’ RBW and VBW will give more ‘tuned’ result – but in fact it reports a worse PN figure.What is important is to know precisely what RBW and VBW figures for the respective measurement should be usedI repeated the same measurement– but used different RBW and VBW figures– both set at 1KHz with a span of 250KHzUsing these values– the PN of the SVA was very close to the specified PN by Siglent.PLEASE NOTEI repeated the measurement at Both 10KHz and 100KHz offsetsSVA1032X phase noise using DSG815 source 0dBm 1GHz (10KHz offset) - 1KHz RBW - 1KHz VBW .pngSVA1032X phase noise using DSG815 source 0dBm 1GHz (100KHz offset) - 1KHz RBW - 1KHz VBW .png– because the SVA phase Noise response is fairly linear in this range– as demonstrated by Shahriar’s plot and shown in thisSVA1032X phase noise plot from 100Hz to 100MHz - using Signal Hound Low Phase Noise Generator - TSP #162 @34.05.JPGPlotIn fact Siglent somehow managed to ‘dip’ the PN response precisely at the 10KHz offset – resulting in ameasured response of -100dBc/Hz@tautech,I want you to know that about 2 weeks ago - I was a TOTAL noob - and thoughtI was making meaningful PN measurements myselfwhen posting my analysis plotsBut sadly I was notIt was not until studying and trying to understand the concepts of PN and how its defined together with how to make meaningful measurements (thank you Shahriar and Bob Nelson) that I can finally feel confident in making PN measurements.I am sure that MANY others on this forum will fall fowl at mastering PN measurements.I hope this short overview will help those who do.. BTWPlease be rest assured that theSVA passes Siglent's published Specifications for the PN

author: tautech
author_rank: Super Contributor
timestamp: August 12, 2020, 02:15:56 am
content: And another I prepared yesterday half expecting some rejection of the ~500 MHz screenshot so to satisfy SVA/SSA myself will indeed meet its spec.SSG3021X @ 1 GHz 0 dB which as you probably know has specified PN: -110 dBc/Hz @1 GHz ,offset 20 kHz (typ.)So again, SVA/SSA PN will limit results.

author: rdsi
author_rank: Contributor
timestamp: August 12, 2020, 03:40:10 am
content: OK, I finally figure out how to get IQ station installed and managed to produce a file. I have yet to figure out how to transfer data via LAN to the instrument but was able to use a USB drive. The file loaded & I was able to produce some modulation with the internal generator - see below.So it's going to take some messing around to see how useful this is compared to an external modulation source. Unknown to me IQ station does include tools to load raw data files such as produced by a spreadsheet. So this is a plus.However, my initial feel for the RIGOL software is that it's pretty low quality. On my computer many of the screen functions are partly obscured so you're left to extrapolate their meaning and the color coding makes it difficult to discern clickable objects. Perhaps that's why the program title includes (Trial) in it?Anyway, I feel a little more hopeful that the internal IQ generator maybe useful after all.Having gotten time using the machine in this exercise I really noticed with the overhead lights on both the MOD & RF button LED's are useless. So unless your in the home screen where their status is shown you'll need to cup your hand over them to see if they're on or off!

author: noreply
author_rank: Frequent Contributor
timestamp: August 12, 2020, 12:02:31 pm
content: Quote from: tautech on August 12, 2020, 02:15:56 amWell done - we now have yet another who understands PN specifications and can make a meaningful measurementOne question that you could investigate ...Please do EXACTLY SAME analysis - but this time change the RBW and VBW to 1Hz - and see what happens?It would be nice to know what should be the 'best' settings for RBW and VBW to produce the most accurate result?

author: rdsi
author_rank: Contributor
timestamp: August 12, 2020, 07:07:02 pm
content: When I first got my DSG821A (last week) I checked out all the basics & found them to be within the data sheet specs. Although I planned to operate my unit using a GPSDO I did checkout the internal OSC because the data sheet spec indicated it was pretty darn good.After about an 1 1/2 hours the OSC stabilized from cold 9,999,999.6xx to 9,999,999.890 well within the 2 ppm specs.Over the next hour I collected the following statistics using my GPSDO based counter:

author: noreply
author_rank: Frequent Contributor
timestamp: August 12, 2020, 08:30:02 pm
content: @rdsiYeah ... considering that the standard unit does not come with the OCXO - but just a TCOX - its out-of-the-box frequency accuracy is pretty good.In fact my Rigol DSG815 was 0.71581 Hz ‘higher’ in frequency than the exact 10.000 000 00 MHz dialed on the control panel.If you have a GPSDO - use procedure posted above - with the use of an Oscilloscope with X-Y mode - you can get much higher precision measurement than your VERY NICE counter (I think?)Provided your room temperature where the DSG resides stays constant - the 'drift' is well within specifications.

author: rf-loop
author_rank: Super Contributor
timestamp: August 13, 2020, 01:30:43 am
content: Quote from: noreply on July 06, 2020, 08:51:51 pmNitpick or notbut...One sidenote because when we talk physics I like we keep basic simple fundamentals right, as example how we name basic fundamental things - like example harmonics.Looks like this is not normal typemistake because it is repeated several times.Forum have full of readers with different level of knowledge etc. So it is perhaps good to try keep basics somehow right.Here is lot of total noobs what may learn wrong things what are then later difficult to reverse learn away and swap with right.1st harmonic == fundamental frequency!I believe you are talking about 2nd harmonics.It is nice if you have time for correct these in this quoted OP.Normally we set generator for some frequency, example tune it for produce 100 MHz sinewave.What are harmonics. 1st harmonic is 100 MHz! 2nd harmonic is 200 MHz, 3rd is 300MHz etc. Harmonic number is like multiplier.If you find some other information in www or irl they are just perfectly wrong (this mistake is not at all rare).But overall nice test, more these... with good accurate info how tests are made as here is...

author: tautech
author_rank: Super Contributor
timestamp: August 13, 2020, 01:57:38 am
content: Quote from: rf-loop on August 13, 2020, 01:30:43 amThank you.Like others I had harmonics understanding wrong also as I found out based even on a Wikipedia link:https://en.wikipedia.org/wiki/Harmonic

author: noreply
author_rank: Frequent Contributor
timestamp: August 13, 2020, 09:31:52 am
content: @rf-loop , @tautechThank you for pointing out this misleading interpretation by myself.I guess my professor who was teaching me (many years ago) the fundamentals of signals & networks (not computer networks – but signal processing RF networks) did not have the convenience of Wikipedia that he could refer his student to.We were taught 1st principal theories - so that once you understand the theory – you can always derive subsequent solutions.With sinusoid frequencies, when you have a fundamental frequency – it was considered ‘the fundamental frequency’ – subsequent harmonics (and the math says there will be harmonics) should start as 2nd, 3rd, 4th, etc, etc. where the fundamental frequency is the 1st in this progression.This sounds counterintuitive – because why would the fundamental frequency be called a harmonic?Unfortunately, it’s because of the math and the need to number a progression – so the fundamental is also the 1st harmonic.Nit-picking or not , from a definition point of view – you make a valid pointHowever I am also sure that most forum members would realize that the 1st harmonic (which is the fundamental frequency) cannot exhibit the SAME amplitude unless its the fundamental frequency.So in the context of the measurements above – it is by observation (not necessarily definition – which is wrong) that most people would realize that the 1st harmonic is really the 2nd harmonic – by definition.This however does not justify the incorrect use of the nomenclature.Thank you for bringing this to MY attention – and most likely to may othersOP corrected

author: tv84
author_rank: Super Contributor
timestamp: August 27, 2020, 10:29:24 am
content: @noreply,I don't know if you still have the DSG but here is the guide that Rigol uses to verify the equipment.

author: noreply
author_rank: Frequent Contributor
timestamp: August 27, 2020, 03:52:31 pm
content: NiceGreat now all we need is the 'test equipment' to test the 'test equipment'- I think one of the 'test equipment' cost considerably more than the other 'test equipment'Yes still have the DSG815Will be writing-up the final conclusion of the hands-on-testing VERY soon - just got too many distractions ATMPLUS a pleasant surprise for those who have access / ability to recalibrate the DSG815

author: noreply
author_rank: Frequent Contributor
timestamp: September 05, 2020, 01:52:29 pm
content: It’s been a while since my last post in this thread.I started this thread because I had a great opportunity to review two RF Signal Generators – the Rigol DSG815 and the Siglent SSG3021X – before making a decision on which one I should buy.It’s not often that a test equipment distributor – who supplies BOTH brands of signal generators is welcoming in allowing their customer to decide which of the two signal generators best suits their needs.With an opportunity like this you simply do need to take advantage of this offer and make the most of it, not only for myself to find out which Signal generator best suits MY needs, but at the same time take all of the interested forum members for a ‘informative ride’ during this evaluation / test period.Well the evaluation time has come to an end and I do need to make my decision as to which of the two signal generators I will purchase.So here is MY rationale and findings during this evaluation period, what I discovered, what was important to me, and how the DSG815 performed – most importantly – did I decide to buy this unit and if so, why?OK, let’s start at the beginning.I have an interest in RF circuit design – in particular microwave frequencies and higher.Unfortunately it was not until now with covid-19 that I have had an opportunity to ‘learn’ as much as possible about this very interesting area RF circuit design.For those of you already working or exposed to this area of electronics, you will no doubt know that when your test equipment needs move into frequencies above 10GHz – the cost of this ‘kit’ becomes very serious $’sFor someone who currently does not have a ‘paying customer’ to fund their test equipment acquisition, my choices in selecting and purchasing test equipment (TE) were guided by various factors of which cost was one of the most critical.So exactly what TE do you need when you want to do RF circuit design?Since with RF we usually want to know about things in the frequency domain, first on the list is a Spectrum Analyser.At the time and after quite a deal of research, I decided to purchase the Siglent SSA3021X Plus.Sure it’s not a >10GHz Spectrum Analyser, but as a starting point it’s a good ‘low end’ device which with the help of the forum members here can be ‘enhanced’ to a good bang for buck device.To get the most out of any TE, I strongly believe that you must be familiar with each instrument’s limitations and theory of operation. It is only then that you can truly appreciate any measurements you make and more importantly how to meaningfully interpret them.The Siglent SA was my starting point.The second and very important TE for a RF circuit design lab is the Oscilloscope.Once again, keeping it ‘real’ I decided to get the best value your $ can buy – the Rigol 5074 MSO with the associated Logic probes. This is a fantastic bit of ‘kit’ – especially after it is ‘enhanced’ – it’s a device that cannot be beaten for price performance.We finally are now approaching to a VERY critical piece of TE which I believe is crucial to any RF Circuit design lab – the RF Signal Generator.Please note – I specifically am talking about an RF signal Generator – not a AWG or function generator – that can produce Sine and Square waves.What’s the difference?Big difference (outside the scope of this post for a detailed explanation) and you will note that for a high end AWG you can pay $1500, but for a high end RF Signal generator you will pay over $15,000 – a very big difference.In simple terms – it’s because there is a great deal of advanced RF circuit design ‘inside’ each and every good RF Signal generator – which is hard to engineer especially at a very low cost.In fact there is a little paradox here, in order for me to learn about RF Circuit design, I need an instrument – the RF Signal generator – which itself needs instruments like itself in order for the design engineer involved in its design can design a ‘clever’ and very functional instrument for a reasonable cost.When you are dealing with high frequencies – you are moving into a fascinating area where you are now faced with common ‘electrical’ concepts that no longer behave as one would expect – and more importantly there are now new areas of physics and quantum mechanics which govern the design and behaviour of these circuits and devices you are designing and manufacturing.If you have seen some of the teardown videos of RF Signal generators Dave made – you will see why he gets ‘excited’ when he peeks inside one of these units.In fact it was the teardown of the Rigol DSG815 (thank you Rigol for providing this to Dave all the way back in 2015 – a pity that Siglent did not do same when they released the SSG3000X range) that drew my attention to the DSG800 series.It is no doubt a VERY clever ‘clean’ and functional compact design – especially way back in 2015!It’s interesting, that in RF design – by simply looking at the circuit board and the remaining mechanical design – you can immediately ‘tell’ if the device has any merit and is likely to have a reasonable performance.The DSG800 series ‘layout’ just tells you this straight away.Was this because Rigol has very clever RF engineers?ORIs it more likely because R&S has some very clever RF engineers?I personally think it’s the latter.Why?Because it takes quite a few ‘iterations’ not to mention innovations in the circuit design to achieve a ‘ready to manufacture’ product.Since the DSG800 series was Rigol’s first entry in the RF Signal Generator marketplace (IMHO) – they entered the market at a very high level ‘good performance’ device – something virtually impossible to do in a short period of time without ‘significant help’ from looking at R&S and HP / Agilent offerings.As the saying goes – ‘don’t do the crime if you are not prepared to do the time’With RF design – it’s almost identical you can’t make a decent product – if you have not put a massive amount of engineering time to design / test and develop.Any company who introduces a complex high performance RF test equipment device - cannot do this as a single iteration.I guess this is further supported by the fact that Rigol has not ‘updated’ the DSG800 series for over 6 years – probably because in this specific market sector (cost vs performance of the DSG800 series) there are no ‘new’ R&S or HP / Agilent designs which could be used to ‘inspire’ Rigol with a revised, higher performance, release of a new RF Signal Generator.Enough of the ‘politics’ of product development.The main point I wanted to make is that RF signal generators are a ‘special breed’ of signal generators and should not be confused with AWG / function signal generators which have mainly DAC’s which ultimately produce the waveforms.So why did I choose the Rigol DSG815 as a contender to purchase?1. Price2. Size (it’s very small)3. Performance (yes it’s the 3rd choice – because if the other two fail – then performance will not be an issue)4. Future ‘enhancement’I did not want to pay more than GBP1500 + VATWith a reasonable discount from my distributor – this was possible.Before covid-19 I did considerable traveling – so being able to take the RF Signal Generator with me as cabin luggage on a flight is important.Since I have already invested in a Spectrum Analyser – which could be capable of 3.2GHz response , an RF Signal generator of AT LEAST the possibility of 3.2GHz Frequency response would be most welcome.The performance of the DSG815 is very good – it simply ‘does what’s written on the tin’ and then some – it does it extremely well!From all of the impromptu testing I did, the DSG815 operates well within its published specifications.One of the features which I really need for my design work and testing is the ability to have external modulation input.Both the Rigol DSG800 range and the Siglent SSG3000X range supports the external modulation input via a BNC connector.Having said that you should beBEWAREThat not all inputs are the same!I found out that the Siglent SSG range – including their more expensive 6000 range (in fact currently ALL of their RF signal generators currently sold, have a 50 Ohm – low impedance eternal modulation input.This is a terrible oversight by Siglent – who have simply removed themselves from my shortlist and possibly many others who need to use external signals which are ‘high impedance’ usually at least 600 ohms or more.On the other hand Rigol have included three options with regard to external modulation inputs on their RF signal generators.1. 50 Ohm2. 600 Ohm3. High Impedance (>600 Ohm)I guess when Rigol ‘designed’ their DSG800 series – they had not forgotten what R&S and HP / Agilent have used on their external modulation inputs.Sometimes trying to be ‘creative’ – especially when you are a young engineer and think you are doing something clever – you are in fact killing the product.Remember the R&S and HP / Agilent engineers took many years to design and ‘prove’ their products in the industry. If they support 600 Ohm and high impedance inputs – not just 50 ohm – then there is a VERY GOOD REASON for doing this.So if you are being influenced by these old masters when you design your equipment – don’t leave things out because they don’t make sense to you (the young engineer) – if they have included an interface with 600 Ohm impedance – then this is a VERY GOOD REASON for you to also make a 600 Ohm impedance interface.Well done to Rigol – for providing this very important feature!Siglent – you failed here – learn you lesson.Despite this I came up with a way for Siglent to recover from this design error.The suggestion was to make an external ‘interface box’ which will provide a 600 ohm or higher impedance input and simply convert it to a 50 ohm impedance. For this to work effectively – you will need an active circuit and not a balun alone which will be lossy.This ‘interface box’ will be put into circuit between your modulation source and the existing 50 Ohm external modulation BNC connector on the SSG range of devices.So far no official response from Siglent.Hopefully someone here on EEVblog forum who officially has links to Siglent Factory, can make this same suggestion.The DSG800 series has a relatively ‘old’ user interface and a SMALL LCD screen – not touch screen – like the SSG range from Siglent.Despite this being a letdown (who does not like a nice touch screen) from Rigol – its nevertheless very functional.It take a while to get used to the menu structure on the DSG815, but when you do – its simply a few button presses and you are good to go.Initially this was a negative for me, but after Siglent disqualified themselves from this head-to-head because of their total failure with regard to the 600 ohm external modulation input, I was forced to endure the ‘older’ Rigol UI until I finally realized it’s not that bad after all.So here we are, the DSG815 passes the first 3 main points important to me in my purchase decision.Now what happens with the final point – future ‘enhancement’As most of us in EEVblog forum – we all appreciate including Dave (with open support from Rigol and Siglent) – the ability that BOTH Rigol and Siglent leave in their instruments the ability for potential software ‘enhancement’.Basically, the ‘door is open’ to enhance your product to a higher specified and more expensive model.This is why I have chosen the ‘base model’ DSG815Having said this – currently there is no ‘official’ (publicly available) method of ‘enhancing’ the DSG800 series.Despite this – by understanding the architecture of previous Rigol products and their design methodology with regard to software functionality – there are some very clever people here on this forum who love to ‘tinker’ at finding ways to ‘enhance’ products via software – via official but undocumented techniques, that they happen to work out how to do it exactly – because of the time and effort and ‘brain power’ they put into this challenge.We, who are less fortunate wizards at software reverse engineering, simply benefit from the work these guys put into discovering ways to ‘enhance’ products.At first, I got alarmed at even contemplating a possible ‘enhancement’ of a product using these techniques. But after a while and especially after reading lots of various posts here in EEVblog and seeing videos Dave made with the blessing of BOTH Riglo and Siglent – I came to the conclusion that BOTH manufacturers are very aware of the ‘enhancement’ of their products.Do they care?Probably not – because we are not the ‘regular customer’ from who they make the majority of their $’sI guess members of EEVblog are a select group and significant enough to possibly increase BOTH of the manufacturers sales well in the 100’s possibly 1000’s of units – BUT - we are no means their ‘bread and butter’ business.So any incremental sales to me and you – with the possibility of a future enhancement – is no big deal to Rigol and Siglent (IMHO)So despite the fact that currently the DSG800 series has no official ‘enhancement’ and the Siglent SSG3000X series does have a way which was made public, I nevertheless have faith that very soon, the DSG800 series ‘enhancement’ procedure will be made public as well – allowing both of the competing RF Signal Generators to be enhanced in the future if so desired by their respective owners.If you are still reading this post and reached this point – the next question is where do we go from here?After reviewing the DSG815 and coming to the conclusion that it’s a capable RF Signal generator which clearly meets its published specifications – do you still want to ‘buy’ this device?In the context of the review – in essence there were two contenders – the DSG815 and the SSG3021X, for my immediate needs – I believe that the DSG815 is a better device and has a better potential if ‘enhanced’ in the future. The HW of the DSG800 series is capable of a 3.6GHz frequency at the top end – significantly higher than the SSG3000’s top end of 3.2GHz.The DSG815 is also a very compact unit – at least 30% smaller than the SSG3000 form factor.The DSG815 also has a slightly better phase noise than the SSG3000 range.The DSG815 does have a ‘functional’ External modulation input unlike ALL of the SSG’s range which only supports 50 Ohm impedance External Modulation Input (BEWARE of this if you will be using the External modulation input in your work).The DSG815 is slightly less cost than the SSG3021XSo from a direct comparison point of view – the DSG815 ‘wins’ for my immediate needs.But, is this it?Or are there some ‘other’ alternatives which I (and possibly some of you reading this post) could explore before buying the Rigol or Siglent RF Signal generator offerings?What are the alternatives you might ask?Surely not the R&S and HP / Agilent offerings which are in a totally different price league?No not at allThe alternatives are some of the ‘oldies’ – yes USED equipment – which is still serviceable today.From the variety of ‘oldies’ available the most prevalent are the HP devices and more recently the Marconi Instruments (Now IFR) 2025 range.The HP devices are extremely well engineered – but they are a ‘beast’ of a unit – large and power hungry. You also have to be extremely lucky to be able to pick-up a ‘decent’ fully functional unit.On the other hand the IFR 2025 devices are currently more prevalent – mainly due to the UK ministry of defence (MOD) taking all of them out of service and dumping them to various surplus TE dealers.Some of the IFR2025’s have only 100 hours on their ‘clock’ – that’s less than 5 days of continuous use during the last 15 years! Mainly due to the ‘redundancy’ policy of the MOD – to have available TE in stores for critical situations where higher than expected deployment is required.Basically, if there is a ‘war’ and the UK government is getting hammered and their air force assets are in need of servicing – they will have enough ‘reserve’ capacity to do this – rather than put out an order to purchase another 100 IFR2025’s which will not be delivered until well after the ‘war’.So, if you live in the UK and know someone who had access to this surplus MOD supply of TE – then you could be lucky and pick-up a 100 hour old IFR2025 for about GBP1500 – a bargain!Despite the IFR2025 being over 15 years old (they still sell them today new so I am told) – they have a great specification and a much lower phase noise than BOTH the Rigol and Siglent offerings.You also have FULL access to a detailed service manual – where you can perform your own ‘calibration’ if required – to the specific instructions and specifications as detailed in the factory service manuals.I guess Marconi Instruments was not afraid to release the FULL schematics and BOM of these devices – simply because they have nothing to hide – the did totally design these units and did an amazingly good job.I was fortunate enough to ‘sample’ one of these ex MOD units – it had 240 hours on the clock.It was a IFR2025 with a high power option – this gave it 25dBm output at its maximum frequency of 2.51GHzIt also had a -140dBm attenuation level well beyond the Rigol & Siglents -110dBm levels.The other most interesting observation – was that this device which was last calibrated in 2013 – was perfectly in spec (at least as could be measured on my Siglent SSA) with respect to the attenuation and power levels across its entire operating frequency range – not bad at all!Part of me wants to buy one of these ‘100 hour’ IFR2025’s – but they are not easy to find and then the sellers want about same price as a new DSG815Is the IFR2025 better than the DSG815?Probably yes without doubt in terms of sheer performance and specifications.BUTIt’s an old device and not as portable as the DSG800 series.For me – I love the ‘oldies’ – if you can find a good one – they are a worthy investment.I wanted to discuss the above – simply to let everyone know that if you are on a budget, have plenty of time (to find a good specimen) and are prepared to ‘tinker’ (possible calibration required) – then don’t rule out getting an ‘oldie’ as an alternative to today’s RF Signal Generator offerings from China.I hope that this rather long ramble as a conclusion to my impromptu review and findings on the DSG815 have been helpful to anyone interested in purchasing a new RF Signal Generator.I don’t like to promote and blow ‘sales’ related stuff in my forum postsHoweverThe DSG815 (and SSG3021X) review would not be possible if my Rigol & Siglent Distributor (telonic.co.uk) was not accommodating to allow me to do this.For this I must thank them and give them credit insupporting this forum communityby allowing me to do these reviewsIf you do decide to purchase either a DSG815 or the SSG3021X – please give them a try and tell them about this forum post – I’m sure you will get a significant discount.If you found this DSG815 review useful, that’s great.If you did not, then I'm sorryHopefully in the very near future I will publish one of my projects – on how to create a FM radio ‘test box’ which you can add to an existing RF Signal Generator that has an External modulation input (600 Ohms or Higher impedance).With this device you will be able to ‘tune’ FM receives – for the stereo separation and modulation parameters as well as testing the RDS decoding system of the receiver