Lecroy HDO 4000 12 Bit Scope

[Martin72]

The 12bit is not just a wank, it does make a difference to how clean your waveform looks, especially on a large screen.

Yes, the difference was clear to see, I´ll take a picture from this.

[0xdeadbeef]

Also if you're looking at the HDO6000A you'll find it to be similar to the HDO4000A, but be careful when they start pointing out 10GS/s on all channels, you'll find the slope is slippery when they start comparing artificial sample points to real acquisition hardware. Those systems only provide 2.5GS/s hardware then apply sinx/x interpolation to boost it to 10GS/s. 

Both, the HD4000 and HD6000 series clearly state a sample rate of 2.5GS/s. There is no hint about claiming 10GS/s in the datasheet. Actually 2.5GS/s appears on the front panel. So that accusation seems to lack any foundation.
The only argument that I could agree is that 2.5GS/s isn't that much for scopes going up to 1GHz. I guess this might the price to pay for the 12bit sampling. E.g. the cheaper Waverunner 510 features 10GS/s but is limited to 8bit.

Anyway, LeCroy seems to be much more honest in this aspect than Tektronix as the Tek 5's maximum sample rate of 6.25GS/s limits the ADC resolution to 8bit. The 12bit resolution is only available up to 3.125GS/s - which is a bit better than 2.5GS/s but not something to brag about. E.g. the much cheaper R&S RTM3000 allows 10bit sampling at 5GS/s - admittedly interleaved (i.e. only on two channels) but it doesn't drop to 8bit.
Besides, at least the 2GHz models of the series 5 seem to have bandwidth limitations for the low voltage ranges (<=5mv/div). There seems to be an error in the datasheet btw.(the footnotes mention always 1mv/div but refer to 2mV/div and 5mV/div as well).

[Martin72]

In the data sheet, it´s 10GS/s with "enhanced sample rate" - whatever this means...

[nctnico]

I think the enhanced samplerate is a elegant term for sin x/x signal reconstruction. This doesn't need to be bad perse but it depends on the front-end filter. These is probably some signal processing going on.

[0xdeadbeef]

Anyway, this was obviously added in the specs for the "A" models. I had a look in the original HDO4000/6000 datasheets and they clearly stated 2.5GS/s.
Boy, I miss the time when a Lecroy 6Zi had (real) 20GS/s for 600MHz and even 40GS/s for >=2GHz or so.

[Martin72]

Our new waverunner got 20Gs/s (2Ch) or 10GS/s(4Ch). The "M" versions from it got it double.

[BrianH_Tektronix]

Anyway, this was obviously added in the specs for the "A" models. I had a look in the original HDO4000/6000 datasheets and they clearly stated 2.5GS/s.
Boy, I miss the time when a Lecroy 6Zi had (real) 20GS/s for 600MHz and even 40GS/s for >=2GHz or so.

Yes I was referring to the HDO-A models when stating the 10GS/s is interpolation. That is independent of Sinx/x or linear interpolation which can be applied on standard sampling. Interpolation is best estimated points between real sample points, fyi its extra math. It can not help with nyquist bandwidth improvements. Be careful and always compare HW sample rate to HW sample rate...

On your other statement, the Tek scopes provide industry leading 6.25GS/s on all 8 channels. Regardless of 8 or 12-bits, thats a lot of sample rate in a single box. You'll only benefit from 12-bits if the noise is low enough, and to be honest most 2GHz scopes have ENOB below 8-bits because of the noise limitation. As have been noted in lots of previous threads, Tek at 6.25GS/s on the 5 Series and 25GS/s on the 6 Series can transfer 8-bits to memory at max sample rate, and the ADC is always capturing at 12-bits. There is a memory throughput maximum of 25GB/s from the chipset. So you need to 1/2 the sample rate to go into 16-bit data transfer mode. You can easily press the High Res button on the front panel too. As it will drop the sample rate and apply extra filtering to optimize the scope for best vertical resolution viewing.

[0xdeadbeef]

On your other statement, the Tek scopes provide industry leading 6.25GS/s on all 8 channels. Regardless of 8 or 12-bits, thats a lot of sample rate in a single box.

If at all, 6.25GS/s on 8 channels may be somewhat unique. I'm actually not even sure it is, but am just too lazy to investigate further.
As 6.25GS/s can be only used with 8bit, that's not even close to "industry leading". E.g. a WaveRunner 9254M has 20GS/s on 4 channels and 40GS/s on 2.
And of course this isn't the bleeding edge yet, but everything above that is more in the "investment" league.

As have been noted in lots of previous threads, Tek at 6.25GS/s on the 5 Series and 25GS/s on the 6 Series can transfer 8-bits to memory at max sample rate, and the ADC is always capturing at 12-bits. There is a memory throughput maximum of 25GB/s from the chipset. So you need to 1/2 the sample rate to go into 16-bit data transfer mode. You can easily press the High Res button on the front panel too. As it will drop the sample rate and apply extra filtering to optimize the scope for best vertical resolution viewing.

So OK, it's a chipset bandwidth limitation that doesn't allow to use 12bit at 6.25GS/s. Understandable, maybe not a real world issue for high frequencies, but still a limitation worth noting when comparing sample rates.

[Berni]

I think the industry leading part is "having 8 channels at 6.25GS/s", id say that's pretty impressive for the category this scope is aimed at.

The datasheet for the Tektronix 5 series does clearly state:
8 bits @ 6.25 GS/s
12 bits @ 3.125 GS/s
13 bits @ 1.25 GS/s (High Res)
14 bits @ 625 MS/s (High Res)
15 bits @ 312.5 MS/s (High Res)
16 bits @ ≤125 MS/s (High Res)

But yeah it is a bit misleading calling it a 12bit scope (And it does have a 12bit converter in it) and then also slapping on the 6.25GS/s number.

The Tektronix 5 series datasheet does appear to downplay the RMS noise performance of it (If not, then the AFE in this scope is quite a noisy one):

All of this claims to be in High Res mode. Keep in mind that the values for < 10mV/div 50Ohm on the 2GHz model start dropping off in bandwidth down to only 175MHz (1mV/div) even tho the column is labeled 1GHz

Compared to the Keysight Infiniium 9000 series that is about 10 years old (the 9014A is the 1GHz model):

Where no special high res mode is used on this scope, while only having a 8bit ADC (I did check on my scope, the table matches when running in 50Ohm, Normal mode 20GS/s). The numbers look pretty similar to the Tek with its 12bit ADC.

However the Infiniium 9000 does also have a high resolution mode that can be turned on on top of this, but when it is turned all the way up to 12bit the sample rate drops off to only 2.5GS/s and the channels bandwidth drops to 550MHz but it also results in a RMS(AC) noise of 99uV on the 10mV/div range. Dialing it back to 11bit in order to get us to a more Tek comparable 5GS/s 1.12 GHz of bandwidth and a RMS noise of 150uV. So significantly better than the 12bit Tek

Infact looking up the LeCroy HDO6000 (Another true 12bit ADC scope) the RMS noise spec for 1GHz 10mV/div is 155uV. This is 5uV worse than my Keysight 9000 that is pretending to be 12bit on its old 8bit ADC.

As you see having a 12bit ADC might not be as big of a advantage as it sounds.

[Berni]

And to put money where my mouth is here are screenshots of a RMS(AC) noise test on a Keysight Infiniium MSO9254

EDIT: For the sake of completeness also added a 20MHz bandwidth limited screenshot (Tho unlike the 12bit high res mode this bandwidth limit does not happen inside the acquisition ASIC but is done in software so its a significant speed penalty)

[Martin72]

While the hdo6034 looks the same as the 4024a, I was shocked after unpackaging the waverunner - Boy, what a beast….

Two pics, hdo6034a vs wafesurfer 3024, 12" vs. 10" Display.
And then the wr9054....

[tautech]

Interesting, multiplexed vertical controls in this class of instrument.

Do they annoy you much ?

[Martin72]

Hi,
I´ve been "growing up" in the last 16yrs with lecroy scopes, especially waverunners (LT series) and they all have no separate vertical controls.
So it annoying me not much, but sometimes….
When you work with all channels displaying it´s not comfortable to select the channel first, then move it.
But I could live with it.
What´s impressing is the fast response of both scopes, comparing to the ws3024, ok a little bit unfair.
The ws3024 was a try to establish a new general purpose scope for simply testing and service.
Our new scopes (hdo and waverunner) will be used for advanced tasks, nevertheless we´re still looking for a pricy but good enough scope for the daily work.
Because the ws3024 was a disappointment in nearly every case.
Plus the still available bugs…
They promised to fixed them, but after over a year nothing happens.
The SDS5000 could be the better choice, but there is the problem not to get the special lecroy stuff connecting to it  (current probes).
And one point on the hdo/wr is really annoying for us….
The tracking function for the measure gate, known from the old waverunners but also known from rigol/siglent scopes, is missing on both new scopes.

[tautech]

The SDS5000 could be the better choice, but there is the problem not to get the special lecroy stuff connecting to it  (current probes).

Adapters for LeCroy active probes are coming and before years end according to the factory.

And one point on the hdo/wr is really annoying for us….
The tracking function for the measure gate, known from the old waverunners but also known from rigol/siglent scopes, is missing on both new scopes.

OK later when I get some time I'll grab a screenshot from my SDS5104X  SDS5054X...other things to do this morning.

[Martin72]

Adapters for LeCroy active probes are coming and before years end according to the factory.

Ahh….
This could be a real game changer.

[tautech]

Adapters for LeCroy active probes are coming and before years end according to the factory.

Ahh….
This could be a real game changer.

Yep and TekProbe adapter coming early next year. 
Mentioned here:
https://www.eevblog.com/forum/testgear/at-last-siglent_s-sds5054x-touchscreen/msg2690724/#msg2690724

And one point on the hdo/wr is really annoying for us….
The tracking function for the measure gate, known from the old waverunners but also known from rigol/siglent scopes, is missing on both new scopes.

Had a quick play with 5 KHz sine sweeping over 4.5-5.5 KHz for 5s and tracking cursors but I got the Gate wrong and used Zone triggering not Measure gate. 

Measurements track fine on the Y axis but it seems the X axis is fixed 



I'll have a bit more investigation.........

OK, now with a measurement gate (white dotted lines) but it seems unrelated to tracking cursors.

[Performa01]

@tautech ... no need to struggle. The discussion about tracking gates is quite old and Martin72 is certainly aware of the capabilities in Siglent X-series DSOs - I believe he has access to an SDS1104X-E.

Furthermore, I've already demonstrated the gating options quite a while ago, see reply #202 here:

https://www.eevblog.com/forum/testgear/at-last-siglent_s-sds5054x-touchscreen/msg2418549/#msg2418549

[Martin72]

Hi,

OK, now with a measurement gate (white dotted lines) but it seems unrelated to tracking cursors.

Yep.
You can define a gate through the dotted lines and what´s inbetween would be measured.
Every modern scope got it, the new lecroys too.
But what they not got is the tracking function of the measurement gate ( of course, by cursors they got it)like older lecroys had it.
Example given:
We measure the loadstep behaviour of our Inverters. They got sinewave output.
We measure this sinewave for three cycles after the loadstep.
1st cycle XYZ Vrms, 2nd cycle, 3rd cycle…
So we define a gate which is one cycle wide and measure the voltage inbetween.
Then the next cycle and so on.
So if you have the tracking function, it´s an easy thing, once defined you could simply move this gate over the screen.
Now we must define the gate for every cycle new , that´s a little bit annoying 

[0xdeadbeef]

Wouldn't this something to use WaveScan for on a LeCroy? I'm not 100% sure that it will work for your case, but e.g. when I first wrote a SENT decoder in 2006 or so, I used WaveScan to analyze SENT patterns with period (falling edge to falling edge) measurements. So I had a list of periods in WaveScan which I could use to check instead of trying to trigger on a message start (CAL pulse) and measuring the periods after that with gating.
This kind of stuff is really missing in most other scopes.

[nctnico]

As you see having a 12bit ADC might not be as big of a advantage as it sounds.

At high samplerates you'll also run into another problem: the jitter on the clock for the ADC is becoming a major noise contributor. IIRC to get 10bits ENOB from an ADC clocked at 250MHz (250Ms/s) you'll need a clock with less than a ps of jitter. Now scale that up to 12 bit and several GHz. Something has to give. Still I think having more bits is beneficial for measuring lower frequency signals with more detail. Oversampling to get more bits doesn't make non-linearities in the ADC go away and without enough/good noise it can play nasty tricks. So in the end there is no substitute for real ADC resolution.

[Martin72]

Wouldn't this something to use WaveScan for on a LeCroy?

I told lecroy about the tracking thing and they answered me the same thing as at the first time when I´d "explore" the lacking of this feature on the ws3024.
We will forwarded this, but....

…Try to use the zoom function - you could define a measuring parameter on the zoom channel.
Yes, I could do this, but what is the problem to implement the tracking function, it´s only a software thing….

[Martin72]

Hmpf,

2 Month after buying the expensive hdo6000, lecroy launch their new 12bit entry level scope:



Sure it wouldn´t have the perfomance like the 6000, but chances are high, that this thing would be enough for us - too late…

Starting price about 7400 bucks.

[Martin72]

…Try to use the zoom function - you could define a measuring parameter on the zoom channel.
Yes, I could do this, but what is the problem to implement the tracking function, it´s only a software thing….

No chance, they told me, yes the tracking function was gone since we used windows as OS - Why, we don´t know.
Hope is weak that this feature will come back - I found it much more comfortable as the zoom Thing, but it seems we are the only customer who feel about it.
Apart from this the service is great:
I think I´ve found a bug on the new scopes, wrote an email - And on the other day they phone me up...
Describe the problem Sir, we got your model rigth now here to check it and so on....
It´s a difference if you spend 4000 or 14000 bucks…..
(They also told me clearly what the tracking function concerns, WHEN it wouldn´t be made also for our WS3024 because it´s too cheap)

[Martin72]

Hah, I think I´ve found a bug...
On both scopes ( hdo6034a and wr9054) you can´t compensate the probes completely.
You have always a little overshoot - reminds me of the problems some rigol mso5000 users got...