Author Topic: EEVblog #323 - Rigol Scratch'n'Sniff  (Read 20438 times)

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EEVblog #323 - Rigol Scratch'n'Sniff
« on: July 26, 2012, 11:01:10 pm »


Dave.
 

Offline nitro2k01

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #1 on: July 26, 2012, 11:20:07 pm »
The audio output seemed fairly noisy, and and a bit distorted. At the higher frequencies, it sounded a bit too distorted to be a sine. When you turned the frequency down, it sounded like the modulating wave was in itself modulated by a lower frequency wave. I wonder what's going on there.
And I was hoping to hear the voice waveform...
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Offline mikeselectricstuff

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #2 on: July 26, 2012, 11:27:59 pm »
I struggled to hear what that voice is saying, depending on sample rate it could be "Rigol" or "Help Me"..
Teardown here in case anyone missed it:

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Offline firewalker

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #3 on: July 26, 2012, 11:45:01 pm »
I struggled to hear what that voice is saying, depending on sample rate it could be "Rigol" or "Help Me"..

"Help me! Mike plays with my chips!"

 ;D ;D ;D

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Offline Architect_1077

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #4 on: July 27, 2012, 01:29:31 am »
Dave, something I'm wondering about:

Do you have to pay taxes and/or postage on things that companies send you for review?
 

Offline M. András

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #5 on: July 27, 2012, 03:29:09 am »
i seriously doubt when they quote 100usd for each unit, as for a demo unit its already used so they cant complain about that, they wont send you a 4k series rigol? i would love to see the comparsion to the x3k series agilent
 

Offline tnt

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #6 on: July 27, 2012, 03:42:09 am »
@Dave: When reviewing them, could you use the spectrum analyzer to check the phase noise of the arb sig gen ? I'm curious to know how good it is.
 

Offline Chet T16

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #7 on: July 27, 2012, 04:07:00 am »
The DG1022 has the pulsing power button too and that's quite old now. I kind of like it but I just know if I had another bit of rigol gear the unsynced pulsing would blow my OCD fuse
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Offline TheWelly888

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #8 on: July 27, 2012, 04:20:34 am »
Somehow I find the pulsing flashing standby light rather creepy - I suppose I have been watching too many sci-fi horror flicks!  ;D

Seriously I was very impressed with the build quality of the signal generator that Mike took apart.
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Offline chrome

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #9 on: July 27, 2012, 04:28:12 am »
I find the flashing light not to be a problem at all (don't know about power consumption though) but the light is so dim, it's in my room and I don't even notice it and I face the device when sleeping.
 

Offline Zad

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #10 on: July 27, 2012, 04:35:58 am »
If a unit is sent out on loan for review, rather than being given to the recipient, $100 is not an unreasonable nominal fee. There should be no tax to pay on it.

The modulated output sounded much more like a square wave. Very harsh at the lower frequencies with lots of overtones. Maybe it was fooling the AGC and clipping the input gain.

One thing that still amazes me when people un-box stuff, they try to lift a comparatively heavy item out of a cardboard box. This means you have to struggle clamp the box between your feet or get someone to hold it, wobble the item around and risk dropping it or falling over. Far easier to fold the flaps back, rotate the package onto the side, then onto what was the top. Lift the cardboard box off. Done. Obviously don't be a twonk and do this on a floor strewn with gravel and an unprotected item (very rare nowadays).
« Last Edit: July 27, 2012, 04:50:08 am by Zad »
 

Offline Alexei.Polkhanov

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #11 on: July 27, 2012, 07:04:33 am »
This is it, I am going to start my rant here :-)

Second review for Rigol function gen I am watching in last week. what I am hearing is "It is heavy", "Nice solid design", "have quality appearance". Mikeelectricsfuff did first review - same thing. "it is heavy". WTF guys! Let's not be like house wives reviewing dish washing machines. 

Anyone will ever bother looking at data sheet? This thing has jitter 500ps (Agilent is <40ps), amplitude accuracy ... I am not an expert in function generators at all, but first time I tried one - rise time and jitter were so bad it was useless for me and I am not doing anything complicated.

Some good practical advice on how to choose function gen for project would have helped enormously.
 

Offline KTP

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #12 on: July 27, 2012, 07:16:19 am »

Anyone will ever bother looking at data sheet? This thing has jitter 500ps (Agilent is <40ps), amplitude accuracy ... I am not an expert in function generators at all, but first time I tried one - rise time and jitter were so bad it was useless for me and I am not doing anything complicated.


But but, it is heavy!    ;D
 

Offline firewalker

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #13 on: July 27, 2012, 07:48:36 am »
I believe that the "heavy" part has to do with the physical construction. The first impression will be good if you pick up something solid, stiff and heavy. I don't recall Mike saying that it is heavy thus it is good as a function generator.

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Offline dda

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #14 on: July 27, 2012, 08:05:31 am »
What is the difference between a 'real' counter and not one?
 

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #15 on: July 27, 2012, 08:30:11 am »
Do you have to pay taxes and/or postage on things that companies send you for review?

No. In this case they were invoice marked as demo units, with a value of $100. Customs limit in Oz is a generous $1000.

Dave.
 

Offline Zad

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #16 on: July 27, 2012, 09:09:18 am »
This is it, I am going to start my rant here :-)

Second review for Rigol function gen I am watching in last week.

No you didn't. You watched 1 unboxing (Dave's) and 1 teardown (Mike's). Both explicitly said they weren't reviews.

I imagine the jitter clears up massively with an external clock source, which as we all know can be obtained very cheaply from Ebay.

Offline mikeselectricstuff

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #17 on: July 27, 2012, 09:13:18 am »
What is the difference between a 'real' counter and not one?
On a scope, it can either have dedicated counter hardware (usually as part of the  FPGA) , or it can measure frequency from samples in the acquistion memory. The latter has limitations, in particular counter resolution is tied to sample rate, and the upper end is limited.
 
The Rigol DG has a hardware frequency counter, but it is IMO badly implemented as it uses gate times which are power-of-2 multiples of the 500MHz clock, instead of powers of ten, so if you measure 10.000 000 MHz you get a reading that flips between 2 odd-looking values (neither of which are 10.000 000 at faster gate times) due to non-decimal rounding issues. It also displays far more digits than can possibly be meaningful at the selected gate time.

 
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Offline Alexei.Polkhanov

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #18 on: July 27, 2012, 10:10:44 am »
I imagine the jitter clears up massively with an external clock source, which as we all know can be obtained very cheaply from Ebay.

Well yes, kind of. If we look at jitter closely - we have 3 kinds, absolute jitter, period jitter and cycle-to-cycle jitter. Plugging in rubidium clock source into 10MHz external clock input affects only cycle-to-cycle jitter. This kind of "fix" was first thing that came to my mind :-) It did not help, not significantly.
I noticed that there are different lines on datasheet for these things one expressed in ppm another in ps. It is not clear to me if picosecond value refers to period or absolute, but ppm shows value for cycle-to-cycle jitter.
 

Offline RRobot

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #19 on: July 27, 2012, 12:37:16 pm »
This is it, I am going to start my rant here :-)

Second review for Rigol function gen I am watching in last week. what I am hearing is "It is heavy", "Nice solid design", "have quality appearance". Mikeelectricsfuff did first review - same thing. "it is heavy". WTF guys! Let's not be like house wives reviewing dish washing machines. 

Anyone will ever bother looking at data sheet? This thing has jitter 500ps (Agilent is <40ps), amplitude accuracy ... I am not an expert in function generators at all, but first time I tried one - rise time and jitter were so bad it was useless for me and I am not doing anything complicated.

Some good practical advice on how to choose function gen for project would have helped enormously.

In my opinion so long as Rigol documented the specs of their AWG accurately its up to you to study them before buying.  Yes the 33521A has <40 ps jitter, but is worse (and in a few things better) then the Rigol in other specs and it also costs more ($2000). Also rise time on the Agilent (8.4ns) seems comparable to the Rigol (8-12 ns depending on the model). If you want something with a much lower rise time your looking at a lot more money, something like the PFANG.


« Last Edit: July 27, 2012, 12:42:07 pm by RRobot »
 

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #20 on: July 27, 2012, 12:40:48 pm »
In my opinion so long as Rigol documented the specs of their AWG accurately its up to you to study them before buying.  Yes the 33521A has <40 ps jitter, but is worse (and better) then the Rigol in other specs and it also costs more ($2000). Also rise time on the Agilent (8.4ns) seems comparable to the Rigol (8-12 ns depending on the model). If you want something with a lower higher rise time your looking at a lot more money, something like the PFANG.

Yes, this is designed as a sub $1K class instrument. The high end model is more, but you aren't really paying for the extra design effort there.

Dave.
 

Offline free_electron

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #21 on: July 27, 2012, 01:30:07 pm »
mailbag monday  : where dave opens his maul
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Offline KTP

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #22 on: July 27, 2012, 01:48:00 pm »
frying fridays  : where dave blows up stuff

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Offline ivan747

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #23 on: July 27, 2012, 02:17:34 pm »
The audio output seemed fairly noisy, and and a bit distorted. At the higher frequencies, it sounded a bit too distorted to be a sine. When you turned the frequency down, it sounded like the modulating wave was in itself modulated by a lower frequency wave. I wonder what's going on there.
And I was hoping to hear the voice waveform...

Maybe what you are hearing are the effects of audio compression.
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Offline ivan747

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #24 on: July 27, 2012, 02:20:12 pm »
What is the difference between a 'real' counter and not one?

This one is heavy.

 ;D
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Offline Zad

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #25 on: July 27, 2012, 02:36:38 pm »
If you want a source with longer term tau stability, constrain an OCXO to a GPS signal. Plenty of radio amateurs have hacked together systems that do this with great success and little outlay. If that isn't good enough then you need to be purchasing equipment with another digit (or two) in the price tag!

Offline Kozmyk

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #26 on: July 27, 2012, 03:35:36 pm »
I was waiting for you to modulate the 1MHz with the Voice wave, but no ...
I'll just have to wait for the review I guess.  ;)
 

Offline Alexei.Polkhanov

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #27 on: July 27, 2012, 03:38:04 pm »
Also rise time on the Agilent (8.4ns) seems comparable to the Rigol (8-12 ns depending on the model). If you want something with a much lower rise time your looking at a lot more money, something like the PFANG.
This is where I feel stupid - "1V" in Rigol datasheet versus "(nom)" in Agilent's, in other words 8.4ns (1V) is pretty clear to me, but "Nom"? Well if "nom" is more than 1V then it is better, if not then it is just as good. Looking at pulse signal I can see 100 ps resolution on Agilent, not mentioned for Rigol. I cannot see how I can have two pulses 100ps apart if jitter is 500ps. Ramp linearity - "<1%", 0.05%, BUT for 5-to-95% range. They definitely not making it easy to compare, not sure if it is Agilent's or Rigol's  fault, but still 1% on average sounds like way above 0.05% even if we adjust it for full range. Lecroy has 0.1% peak topeak, BUT then only in 1V range.

Here is the linearity parameters as they appear on datasheets for function generators in < $3000 range. Please vote which one sounds better and which one is actually better:

Rigol (160MHz): 1% peak-to-peak
Agilent (35 MHz): 0.05% 5 to 95% (not just 1V)
Lecroy (25MHz): 0.1% peak to peak, 1V range.
Hameg (50MHz) : 0.1% for f< 250KHz or < 2% for f>250kHz peak to peak

I need 0.5% for 0-10V. Which one should I choose?

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Offline tom66

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #28 on: July 27, 2012, 04:23:42 pm »
They look like pretty nice instruments. Very competitively priced. Now we need to wait for the other manufacturers (Agilent, etc.) to up the competition and lower their prices.
 

Offline nitro2k01

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #29 on: July 27, 2012, 05:18:04 pm »
The audio output seemed fairly noisy, and and a bit distorted. At the higher frequencies, it sounded a bit too distorted to be a sine. When you turned the frequency down, it sounded like the modulating wave was in itself modulated by a lower frequency wave. I wonder what's going on there.
And I was hoping to hear the voice waveform...

Maybe what you are hearing are the effects of audio compression.
No.
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Offline Architect_1077

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #30 on: July 27, 2012, 08:32:31 pm »
No. In this case they were invoice marked as demo units, with a value of $100. Customs limit in Oz is a generous $1000.

Dave.

Yeah... the customs limit here in Portugal is a ridiculous $50 or something. Living in Europe sucks big time. :(
 

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #31 on: July 27, 2012, 09:04:04 pm »
Yeah... the customs limit here in Portugal is a ridiculous $50 or something. Living in Europe sucks big time. :(

It used to be much lower here. IIRC it was $300 at one point. Not sure why they increased it.

Dave.
 

Offline nitro2k01

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #32 on: July 27, 2012, 09:05:43 pm »
Dave, is that per item or accumulated over a year?
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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #33 on: July 27, 2012, 09:20:25 pm »
Dave, is that per item or accumulated over a year?

That's per shipment.
So the usual drill here is to spread your Digikey/Mouser orders into $900 chunks.
You aren't technically supposed to do that though of course, but everyone does  ;D

Dave.
 

Offline Chet T16

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #34 on: July 27, 2012, 09:38:46 pm »
I do that with deal extreme, just order everything separately
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Offline somlioy

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #35 on: July 27, 2012, 10:58:06 pm »
1000 bucks limit. :o I'd go crazy buying stuff. Only 200NOK (about 27EUR) in norway. Which will add 25% tax on item cost and shipping.
 

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #36 on: July 27, 2012, 11:48:08 pm »
1000 bucks limit. :o I'd go crazy buying stuff. Only 200NOK (about 27EUR) in norway. Which will add 25% tax on item cost and shipping.

27EUR ?
That buys you like one connector from Farnell's  ;D

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Offline baljemmett

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #37 on: July 28, 2012, 12:01:15 am »
27EUR ?
That buys you like one connector from Farnell's  ;D

Here in Astonishingly Good Value Britain (::)) VAT is due on any consignment worth (including shipping) over £15 (~20EUR).  Import duty kicks in at £135, but is waived if the total duty calculated is less than £9.

Digikey's $30 shipping charge for orders under $100 works out to be £20 at the moment, and of course last time I received a Digikey package the UPS extortion/paperwork charge came to twice the VAT due...  I've decided I'll need a good reason to try that again; maybe when I can rack up > $100 in those little bits and pieces I can't get from Farnell but would like to evaluate for my crazy CPU project!
 

Offline SeanB

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #38 on: July 28, 2012, 01:06:11 am »
Here it is a guesstimate. good thing I am on good terms with the local customs guys, nice lot who do a good job with all my orders.
 

Offline mikeselectricstuff

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #39 on: July 28, 2012, 02:04:33 am »
[quote author=baljemmett link=topic=9785.msg132618#msg132618
Digikey's $30 shipping charge for orders under $100 works out to be £20 at the moment, and of course last time I received a Digikey package the UPS extortion/paperwork charge came to twice the VAT due...  I've decided I'll need a good reason to try that again; maybe when I can rack up > $100 in those little bits and pieces I can't get from Farnell but would like to evaluate for my crazy CPU project!
[/quote]
UPS do not charge additional brokerage fees on UK digikey orders over the £50 'free delivery' threshold, but VAT is charged on the goods total plus the nominal value of the "Free" shipping.
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Offline baljemmett

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #40 on: July 28, 2012, 02:20:27 am »
UPS do not charge additional brokerage fees on UK digikey orders over the £50 'free delivery' threshold, but VAT is charged on the goods total plus the nominal value of the "Free" shipping.

Ah, that's good to know, cheers.  The package that landed me with a UPS invoice was actually a competition prize rather than an order -- they apologised for sending it with the wrong brokerage terms and issued credit in the amount I'd paid, so I need to find some bits and pieces to order to soak that up sometime.  Hadn't looked at the shipping details from the UK site, to be honest!
 

Offline Nirios

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #41 on: July 28, 2012, 07:55:01 am »


Dave.

PEBKAC - Love it.  Have not heard too many people use that term recently.
 

Offline JackOfVA

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #42 on: July 28, 2012, 09:44:08 am »
I have the 100 MHz version of Rigol's arbitrary generator, model 4102. It's quite useful in cases where the standard signal generators (HP8657A) won't deliver the output power available from the Rigol.

Originally, I thought the dual output 4102 would permit two-tone intermodulation testing. However, it seems that the 4102 generates some internal intermodulation products, albeit at rather low levels, but still strong enough to be a problem when measuring high performance RF amplifiers. A work-around is to use external bandpass filters for the desired test tones, although this fails if the two test tones are close spaced such that individual tone bandpass filters become impractical.

Looking at Rigol's spectrum analyzer specs, it seems the major weak point is phase noise. Many tens of dB worse than the HP 8568B I use for bench work. The other specs seem quite decent, 10 Hz RBW is useful.

I did not see a spec on Rigol's internal intermodulation performance. This is generally a problem only where looking at high performance amplifiers and the work around is a band stop filter to reject the test tones, thereby improving the spectrum analyzer's performance.
 

Offline nanofrog

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #43 on: July 28, 2012, 11:57:35 am »
A bit OT, but for those in the UK:

If you know someone in the US that's willing, is it possible to get that person to re-box say a digikey order as a gift to a UK resident as a means of reducing, if not eliminating the VAT and other fees/taxes?

Done this for a friend in Australia for a smallish order once, and it worked (was a real gift, as it was my stock), so I'm curious.
 

Offline SeanB

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #44 on: July 28, 2012, 09:18:19 pm »
I have the same problem with moulded IEC plug leads, but I have a surplus of AUS plugs that I cannot use at all. The adaptors cost more than the leads did ( came from my ISP as he got a whole lot of switches and rack mount equipment with AUS plug IEC leads) and are moulded on. I have been using them as plain cable after cutting the ends off ( 2m long, perfect for certain jobs) and some i just put a standard plugtop on.

i wonder if it would be possible to take 2 or 3 of the signal generators and make a stereo FM transmitter from them. Probably would need only a sum and a difference amplifier and 2 mixers to get the composite signal, then feed to a third as a RF unit. Would be a pretty expensive transmitter though.
 

Offline hobbs

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #45 on: July 29, 2012, 02:48:11 am »
This is it, I am going to start my rant here :-)

Second review for Rigol function gen I am watching in last week. what I am hearing is "It is heavy", "Nice solid design", "have quality appearance". Mikeelectricsfuff did first review - same thing. "it is heavy". WTF guys! Let's not be like house wives reviewing dish washing machines. 

Anyone will ever bother looking at data sheet? This thing has jitter 500ps (Agilent is <40ps), amplitude accuracy ... I am not an expert in function generators at all, but first time I tried one - rise time and jitter were so bad it was useless for me and I am not doing anything complicated.

Some good practical advice on how to choose function gen for project would have helped enormously.

Yup.  The spectrum analyzer's phase noise is the pits as well--the spec is -80 dBc/Hz at 10 kHz, _typical_.    My HP8568B boat anchor's phase noise is as low as that at a 200 Hz offset, even at 1.5 GHz, and gets down to about -110 dBc at 30 kHz, i.e. a good 20-30 dB better than the Rigol, for about the same money.  Score one for the antiquated  CRT-based analyzers from eBay!

The Rigol is fine as long as you realize that its performance is strictly entry-level.

Cheers

Phil Hobbs
 

Offline JackOfVA

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #46 on: July 29, 2012, 05:19:45 am »
Out of curiosity, I looked at the noise spectrum of my Rigol 4102 arbitrary waveform generator.

Test setup is to set the 4102 to 10.050 MHz, 0 dBm sine and feed it to a MiniCircuits connectorized double balanced mixer. The other RF input port to the mixer connects to the 10 MHz reference output of an HP 3816A GPS disciplined oscillator. Mixer output is centered at 50 KHz and connects to an HP3562A dynamic signal analyzer with a 50 ohm coaxial through termination at the 3562A input.

The 3562A is set for 50 KHz nominally, 20 Hz span, so each horizontal division represents 2 Hz.

Test 1 is the  Rigol with internal time base and test 2 is with the Rigol locked to the HP 3816A time base through a distribution amplifier.

There's a huge difference between the two as seen in the plots. With the external time base, it's hard to expect any generator to do better. With the internal time base, it has a lot of close in noise which apparently comes from the 4102's master time base. 

The 3652A is in average mode and each image is the result of 16 sweeps averaged.
« Last Edit: July 29, 2012, 05:22:47 am by JackOfVA »
 

Offline hobbs

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #47 on: July 30, 2012, 11:36:24 pm »
Wow, that's the noise at _ten megahertz_?  Eeeewwwww.  (How's that for a sober engineering evaluation?)

Thanks for posting this.

It looks like they used the internal clock of their micro as the timebase, or maybe one of those little clock oscillators that has a synth inside.  It would take serious talent to make a plain crystal oscillator that bad.

Nice that it cleaned up with an external reference, but going to 1.5 GHz from 10 MHz lifts the reference noise by 43 dB, so we still can't tell how good it would eventually get.

But those noise sidebands.  Wow.  Just wow.

Cheers

Phil Hobbs
 

Offline JackOfVA

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #48 on: July 31, 2012, 06:37:07 am »
The 4102 is a generator, max frequency is 100 MHz, not the spectrum analyzer.

My thought matches yours, a "synthesizer in a can" time base may be used in the 4102. Those are pretty bad in terms of noise.

Jack
 

Offline Zad

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #49 on: July 31, 2012, 06:43:14 am »
It wouldn't be the first time a decent piece of equipment has been crippled by using a horrible cheap noisy oscillator. Even high end ultra expensive audio gear can often be upgraded by fitting a good oscillator with a correctly cut crystal rather than a jelly bean synthesised one.

Offline mikeselectricstuff

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #50 on: July 31, 2012, 10:07:32 am »
Wow, that's the noise at _ten megahertz_?  Eeeewwwww.  (How's that for a sober engineering evaluation?)

Thanks for posting this.

It looks like they used the internal clock of their micro as the timebase, or maybe one of those little clock oscillators that has a synth inside.  It would take serious talent to make a plain crystal oscillator that bad.

Nice that it cleaned up with an external reference, but going to 1.5 GHz from 10 MHz lifts the reference noise by 43 dB, so we still can't tell how good it would eventually get.

But those noise sidebands.  Wow.  Just wow.

Cheers

Phil Hobbs
It uses an ADF4360 synth, driven by what looks like a standard osc module. The frequency was surprisingly accurate - ISTR less than 0.5ppm off my rubidium standard
Youtube channel:Taking wierd stuff apart. Very apart.
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Offline JackOfVA

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #51 on: July 31, 2012, 10:23:58 am »
It uses an ADF4360 synth, driven by what looks like a standard osc module. The frequency was surprisingly accurate - ISTR less than 0.5ppm off my rubidium standard


Mine was also quite good for accuracy and stability, compared against GPS standard. Plot below shows 4 days or so worth of stability as measured against an HP3816A GPS frequency standard. You can see the day/night temperature change in my basement lab. Not sure what caused the abrupt shift on the right hand side of the plot - GPS may have had a lock interruption.

 

Offline northlondonsage

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #52 on: August 11, 2012, 03:01:06 am »
Is it ok to admit that I am realy jealous of Dave getting this stuff free in the mail...


There, I feel better for that....

 

Offline KTP

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #53 on: August 11, 2012, 03:22:31 am »
Is it ok to admit that I am realy jealous of Dave getting this stuff free in the mail...


There, I feel better for that....

don't be jealous...he is doing it as a full time job now.

If you put the same effort he probably does into making these video reviews into a regular engineering job, you also could have these wonderful toys.  The only difference would be you have to send Agilent or Rigol these little pieces of paper you obtained from the job before they send you the toys.  The papers normally have pictures of famous people on them.

I do wonder if Australia makes Dave deduct the value of these from his income taxes...actually I have no idea how Australia does taxes...maybe they have so much gold they don't even bother taxing people.   ;D
 

Offline tnt

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #54 on: August 11, 2012, 03:46:02 am »
I have an engineering job and I'm nowhere close to getting a 140k$ scope.
 

Offline pickle9000

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #55 on: August 11, 2012, 04:00:43 am »
The expensive gear is only on loan I'm sure.

 

Offline KTP

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #56 on: August 11, 2012, 04:02:54 am »
I have an engineering job and I'm nowhere close to getting a 140k$ scope.

He doesn't get to keep the 140K scope, so it is the same thing as you getting to use stuff at work.

I worked a long time ago as a student intern for a government entity and was building and testing semi-rigid cable on a $100,000 HP network analyzer....and this was in the 1980s...that would be like $250K today.
 

Offline olsenn

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #57 on: August 11, 2012, 04:31:14 am »
What's with the comments about the noise floor being bad on the Rigol spectrum analyzer? Of course I have nothing to compare it too, but I never notice the noise floor on mine to be bad at all... especially with the built in preamplifier.
 

Offline Rufus

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #58 on: August 11, 2012, 07:21:46 am »
What's with the comments about the noise floor being bad on the Rigol spectrum analyzer? Of course I have nothing to compare it too, but I never notice the noise floor on mine to be bad at all... especially with the built in preamplifier.

There are no comments about noise floor. The comments are about phase noise.
 

Offline mortos360

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #59 on: August 13, 2012, 07:08:26 pm »
When is the review video coming?
 

Online EEVblog

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #60 on: August 13, 2012, 07:13:33 pm »
The expensive gear is only on loan I'm sure.

The $140K 90000 scope and PFANG are only on loan.
You can get loans of them too at work, just ask Agilent. Most other companies or local suppliers have loaners too.

Dave.
 

Offline tnt

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Re: EEVblog #323 - Rigol Scratch'n'Sniff
« Reply #61 on: August 13, 2012, 07:35:16 pm »
Test setup is to set the 4102 to 10.050 MHz, 0 dBm sine and feed it to a MiniCircuits connectorized double balanced mixer. The other RF input port to the mixer connects to the 10 MHz reference output of an HP 3816A GPS disciplined oscillator. Mixer output is centered at 50 KHz and connects to an HP3562A dynamic signal analyzer with a 50 ohm coaxial through termination at the 3562A input.

I think that setup is a bit unfair to the internal timebase.

Since you use the same 10 MHz source for the mixer as the one you feed to the Rigol, any noise on the source would just not appear at all (since it's the same noise on both side of the mixer).

But at least it shows the ADF itself doesn't add too much noise.
 


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