Most accurate signal generator

[loop123]

I have 2 china made signal or function generators that are junk. It can't even tell the amplitude. What is the most accurate signal generator ever but also inexpensive? Range is audio range of 0 to 20000Hz and voltage from 0 to 5V or so. It has to be accurate in 1/100000th or output say 1.00001 V or has frequency accuracy of say 5000.00000 Hz and can output in rms or peak to peak. It has to be stand alone unit because I don't want to buy a $5000 oscilloscope just to use the function generator. What have you encountered or used? Thank you.

[Aldo22]

What do you mean by "inexpensive"?
I'm no expert, but I doubt that 10 microvolts of amplitude "accuracy" and "inexpensive" go together.

[HalFoster]

First, an $5K oscilloscope built in generator would not even be close.  The frequency accuracy would be met by most any OCXO, and by many of the better ones with a standard oscillator.  The output will be specified in dBm at 50R, not in volts, and would be around -87 dBm for .00001 VRMS.  A very good, affordable choice would be a HP 3335A.

[Antonio90]

10uV is inside the noise specs of really good linear PSUs. You cannot measure it with any reasonable certainty using cheap DMMs (ACV).
A Siglent SDG2042X (€475+VAT) will outperform any DSO's integrated AWG, and the specified amplitude accuracy is ±(1%+1mV), so 1V ± 0.02V (at 10KHz, and the uncertainty goes up with frequency). 1.00001V means 0.001% or 10ppm accuracy.
I don't think it's happening anytime soon. Although there might be audio analyzers with signal generators that reach those levels, a general purpose AWG will not. As a matter of fact, the resolution you asked for could not be resolved even with 16 bit ENOB, as that would be 65,536 steps, and around 15uV for a 1V peak to peak signal.

[jonpaul]

Audio Precision, GenRad, Prisim, TEK SG505

China junk is not to be trusted for any measurement

j

[ebastler]

It has to be accurate in 1/100000th or output say 1.00001 V or has frequency accuracy of say 5000.00000 Hz

You mean an amplitude accuracy of 10^-5, so 1 V +- 0.00001 V?
And a frequency accuracy of 2 * 10^-9, so 5000 Hz +- 0.00001 Hz?

I am not sure which commercial instruments would offer that. Seeing you mention "inexpensive", I am quite sure you would not want to pay for them, if they exist. And frankly, I would be very surprised if you need these specs. What is the application which requires that level of accuracy?

Edit: You might be confusing accuracy (to what extent can you trust the exact value?) with resolution (what are the smallest relative changes the display shows you?). And even when talking about resolution, you probably don't need the values you mention. 0.00001 Hz is one oscillation every 100 000 seconds, i.e. 27 hours! And 0.00001 V = 10 µV is quite challenging to control and measure on its own -- let alone when it sits on top of a 1V signal.

[themadhippy]

Most accurate signal generator

Brian,the blind piano tuner i used to know.

[DimitriP]

Most accurate signal generator

Brian,the blind piano tuner i used to know.

That would be a frequency counter....not a generator

[DimitriP]

What have you encountered or used?

For audio, using a USB audio interface and software will be "cheaper" than buying stand alone instruments.

But more importantly, what are you trying to get done?

[Antonio90]

Most accurate signal generator

Brian,the blind piano tuner i used to know.

That would be a frequency counter....not a generator

Maybe he sang really really in tune.

[Fungus]

Signal generators aren't cheap. Those Aliexpress gadgets are toys, as you've seen, they output waves but that's about it.

I think the cheapest signal generator worth owning is the Unit-T UTG932e. That's your baseline for price.

It has to be accurate in 1/100000th or output say 1.00001 V

Maybe you mean the smallest change you can make in the output, not "accuracy"?

1/100000th is approx. 17 bits so you'd need a generator with 18 bits (or more) to achieve that.

If you really meant "accuracy" then I don't think that exists in a signal generator. If it does, you won't want to pay for it.

PS: You'll definitely get a better answer if you say what you're trying to achieve.

[Fungus]

For audio, using a USB audio interface and software will be "cheaper" than buying stand alone instruments.

But getting an accurate output voltage won't be easy.

[Antonio90]

Signal generators aren't cheap. Those Aliexpress gadgets are toys, as you've seen, they output waves but that's about it.

I think the cheapest signal generator worth owning is the Unit-T UTG932e. That's your baseline for price.

It has to be accurate in 1/100000th or output say 1.00001 V

Maybe you mean the smallest change you can make in the output, not "accuracy"?

1/100000th is approx. 17 bits so you'd need a generator with 18 bits (or more) to achieve that.

If you really meant "accuracy" then I don't think that exists in a signal generator. If it does, you won't want to pay for it.

PS: You'll definitely get a better answer if you say what you're trying to achieve.

17 bits ENOB looks to me more like 22-24 bits. Cheap audio interfaces can do that resolution-wise, but not accuracy-wise. It would need high frequency stability, so some kind of hacked-in OCXO or TCXO, and then a low noise amplifier to get the 5Vpp.

[loop123]

Signal generators aren't cheap. Those Aliexpress gadgets are toys, as you've seen, they output waves but that's about it.

I think the cheapest signal generator worth owning is the Unit-T UTG932e. That's your baseline for price.

It has to be accurate in 1/100000th or output say 1.00001 V

Maybe you mean the smallest change you can make in the output, not "accuracy"?

1/100000th is approx. 17 bits so you'd need a generator with 18 bits (or more) to achieve that.

If you really meant "accuracy" then I don't think that exists in a signal generator. If it does, you won't want to pay for it.

PS: You'll definitely get a better answer if you say what you're trying to achieve.

Since Im not even sure what amplitude my 2 china signal generator is outputting. I just want something where you can input the voltage and frequency in the led and it would produce accurate output. Just accuracy, not about resolution. For general use for example testing any amplifier or ADC. So what sub $200 is accurate enough?

[ebastler]

So what sub $200 is accurate enough?

Accurate enough for what? What do you want to do with the generator? You mention amplifiers and ADCs -- are these just for audio use, or something more specialised? Do you want to develop audio amplifiers, or repair them? What specifications do these amplifiers have, or what do you have in mind? etc.

As a general comment: It's not "just accuracy". Accuracy is harder to achieve than resolution. E.g. my 3 meter tape measure easily has 1 mm resolution -- I can clearly see the scale lines every mm. But is it accurate to 1 mm? Maybe not; it might actually be 3.002 meters long instead of 3 meters.

[Fungus]

For general use for example testing any amplifier or ADC. So what sub $200 is accurate enough?

For Audio amplifiers? The Unit-T UTG932e is plenty accurate enough.

(and it's the only sub-$200 generator worth considering, so if that's your budget then...  )

[radiolistener]

I think SDG6022X signal accuracy should be good enough for amateur needs.
https://siglentna.com/product/sdg6022x/

But its performance is not the best. So, if you want better performance, there is may be a sense to look for some specialized signal generator for your needs?

What do you mean when talking "most accurate"? Less noise / less spurs / high dynamic range? 

If you're interested in precise amplitude, then there is a sense to look for RF generator. They have pretty clean sine output and allows to setup calibrated amplitude. But note, all signal generators have fixed output impedance, usually 50 Ω (sometimes there is a switch between 50 Ω and 600 Ω). And if your load is not 50 Ω, then you're needs to recalculate amplitude, that is normal and expected behavior.

[PA0PBZ]

Get yourself a 2nd hand Wavetek 98, 8 digits frequency resolution, 4 digits amplitude, can be had for $100.

https://www.testmart.com/webdata/mfr_pdfs/FLUPR/WAV_98.pdf

[Electro Fan]

Signal generators aren't cheap. Those Aliexpress gadgets are toys, as you've seen, they output waves but that's about it.

I think the cheapest signal generator worth owning is the Unit-T UTG932e. That's your baseline for price.

It has to be accurate in 1/100000th or output say 1.00001 V

Maybe you mean the smallest change you can make in the output, not "accuracy"?

1/100000th is approx. 17 bits so you'd need a generator with 18 bits (or more) to achieve that.

If you really meant "accuracy" then I don't think that exists in a signal generator. If it does, you won't want to pay for it.

PS: You'll definitely get a better answer if you say what you're trying to achieve.

Since Im not even sure what amplitude my 2 china signal generator is outputting. I just want something where you can input the voltage and frequency in the led and it would produce accurate output. Just accuracy, not about resolution. For general use for example testing any amplifier or ADC. So what sub $200 is accurate enough?

The Uni-T UTG generator models are good baseline models to consider as you look at your options.

https://storage.googleapis.com/uni-tdocuments/UTG900E_Series_User_Manual_REV2.pdf

Not 100% sure about your objectives but if you want to build something that is still more accurate and flexible you might consider finding a solid signal generator that has a 10 MHz Reference Input, such as the Siglent SDG1032X, but this alone will set you back about $350.

https://siglentna.com/wp-content/uploads/dlm_uploads/2022/06/SDG1000X_UserManual_UM0201X-E01E.pdf
See on page 4:  10 MHz Clock Input/Output

Then, for about $100-200 you can add a GPSDO, such as some model made by BG7TBL on eBay.

https://www.ebay.com/itm/296236063029?itmmeta=01HSTZB4K00HP2PPEAZA5PW64B&hash=item44f90b9935:g:VRcAAOSw~dFl1E5q&itmprp=enc%3AAQAJAAAA4MtrtctaRljoQ7FmzGN3WVi2l6pgv1PrjLbi0NuhSM6pql7j7%2FqoyB89uRCzMNoK1x7q2qqF8jDl6XJbPSmvasas2NC%2FLGC0n8zpFPfTsgCcPsqYTXZkGMCqsiPEnaxCA5%2BNPzBLAqu7SsAm6%2BedWsAY9%2Ftwa2Rs8%2BCBJDfSr7q5nGRd2PczloEG%2FdH%2BnABJG0aix8aCPaSfPNyhsqMeVzFRv4IjEnkS3XXZtPivapJnUvtBKsPFXodPxHLgBkeH8I%2Bih7gUaWTsOl1YSwDAFR%2F3%2BbmvOOXwfYo4aadWujoH%7Ctkp%3ABk9SR8bJrN_OYw

The GPSDO 10 MHz output connects to the 10 MHz input on the back of the Siglent generator.

Altogether this will set you back about $550 but you should be good to go on flexible and accurate signal frequency management.

Or you could start with the Siglent and see if you want/need the GPSDO.

Hint:  what you are looking for is something with a good clock source.
Maybe study oscillators:
https://blog.bliley.com/quartz-crystal-oscillators-guide-ocxo-tcxo-vcxo-clocks

[radiolistener]

It has to be accurate in 1/100000th or output say 1.00001 V or has

if you want to setup 1 V or 0.00001 V, RF generator can do that, it can even do 0.000001 V or 0.0000001 V.
But it doing it with logarithmic scale, while 1.00001 V requires linear scale with 0.00001 V resolution.
I didn't hear that such generators exists.

frequency accuracy of say 5000.00000 Hz

That is 0.002 ppm. Using rubidium frequency standard it can be possible.

But I'm not sure what is the use case for so precise signal? 

[bdunham7]

Since Im not even sure what amplitude my 2 china signal generator is outputting. I just want something where you can input the voltage and frequency in the led and it would produce accurate output. Just accuracy, not about resolution. For general use for example testing any amplifier or ADC. So what sub $200 is accurate enough?

Any reasonable DDS-based AWG (arbitrary waveform generator) is probably what you are looking for, but your stated accuracy requirements are not as easily achieved.  I'd suggest not just randomly picking numbers when you make a request like that and instead figure out what accuracy you really need.  For testing an audio amplifier a 0.3dB accuracy, which corresponds to about 3% voltage error, should be good enough and is easily achievable by inexpensive AWGs.  For testing an ADC, that depends on exactly what testing you are doing.  For frequency accuracy with a sine wave, it should be easy to achieve <50ppm error, but you seem to be implying that you want an accuracy of better than 1 in 500 million, or 2ppb, which would be unreasonably difficult for an inexpensive AWG.

IDK about under $200, but the Siglent SDG810 is $239 and seems to do what you need (but not what you stated originally).

https://siglentna.com/wp-content/uploads/dlm_uploads/2017/10/SDG800_DataSheet_DS02008-E02D.pdf

Other more expensive AWGs may have better specs if you actually need them.  The Siglent SDG2042X that I have is roughly 1ppm and 0.1dB.  Getting better than that starts to cost real money.
 

[voltsandjolts]

But I'm not sure what is the use case for so precise signal? 

The OP is "experimenting" in electrical signals of the human body, see other nonsense threads.

[nctnico]

Cheap and super accurate don't go well together. When you need accuracy, you'll need a levelled signal generator like the ones being used to calibrate oscilloscopes. There is an HP / Agilent generator model with accurate outputs but I can't remember the model number.

[switchabl]

There is an HP / Agilent generator model with accurate outputs but I can't remember the model number.

You may be thinking of the 3245A Universal Source. The headline spec for AC amplitude accuracy is 0.4% which would be roughly on par with an APx555.

The prize for actual "most accurate signal generator" probably goes to one of the JAWS (Josephson Arbitrary Waveform Synthesizer) developed by several national metrology institutes.

[Fungus]

The OP is "experimenting" in electrical signals of the human body, see other nonsense threads.

Oh... I did wonder about somebody posting those requirements along with a picture of a FNIRSI.