Author Topic: EEVblog #323 - Rigol Scratch'n'Sniff  (Read 20521 times)

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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?

They always hiding their EVIL IN DETAILS :-)

 

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.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!
 

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. :(
 

Offline EEVblog

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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?
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!
 

Offline EEVblog

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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
Chet
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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.
 

Offline EEVblog

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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

Dave.
 

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.


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