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snoopy:

--- Quote from: Sighound36 on May 08, 2020, 06:57:18 pm ---
--- Quote from: snoopy on May 08, 2020, 12:20:42 am ---
Nope ! It's a 1GHz bandwidth scope that can't display 1GHz and that has an ENOB of 8 bits or less even though it claims 12 bits !

If it was a Tek scope a few of them on here would be all over it bagging the crap out of it !

--- End quote ---

Hi Snoopy

I do agree with you so to keep things in perspective an image of the LeCroy Wavepro 254 meeting its 2.5Ghz bandwidth @ -3db with the 12 bits and no high resolution filter added.


--- End quote ---

Because I'm not one to continuously bash a particular test equipment vendor because of preconceived biases, in fairness to Lecroy, later on they did bring out the HDO4000A scope with higher sampling rate (from 2.5Gs/s to 10GG/s probably by combining all 4 ADC's) although this particular 4000 series scope does have equivalent or repetitive time sampling up to 125 Gs/s so it should have been able to display a 1GHz sinewave if it was switched on that is, or did the Keysight dude conveniently switch it off ?

Lecroy HDO4000 datasheet

http://cdn.teledynelecroy.com/files/pdf/hdo4000_oscilloscope_datasheet.pdf

Lecroy HDO4000A datasheet

http://cdn.teledynelecroy.com/files/pdf/hdo4000a-oscilloscopes-datasheet.pdf

cheers

0xdeadbeef:
I hate to say this, but the "enhanced sampling rate" in the HDO4000A is a marketing ruse as well:
http://cdn.teledynelecroy.com/files/whitepapers/enhanced-sample-rate-whitepaper.pdf
I understand the HDO4000A still uses 2.5GSa/s (5GSa/s interleaved) but interpolates samples inbetween to "enhance" the sample rate.

About the Keysight video: as far as I could see, there is only one channel active, so I guess interleaved 5GSa/s were used.
Still, when comparing a 5GSa/s scope with a 20GSa/s scope you will easily find cases where the one with the four times lower sampling rate shows its limits.
snoopy:

--- Quote from: 0xdeadbeef on May 09, 2020, 11:03:59 am ---I hate to say this, but the "enhanced sampling rate" in the HDO4000A is a marketing ruse as well:
http://cdn.teledynelecroy.com/files/whitepapers/enhanced-sample-rate-whitepaper.pdf
I understand the HDO4000A still uses 2.5GSa/s (5GSa/s interleaved) but interpolates samples inbetween to "enhance" the sample rate.

About the Keysight video: as far as I could see, there is only one channel active, so I guess interleaved 5GSa/s were used.
Still, when comparing a 5GSa/s scope with a 20GSa/s scope you will easily find cases where the one with the four times lower sampling rate shows its limits.

--- End quote ---

Regarding the HDO4000, Lecroy should have really band-limited this scope to 500MHz and not 1Ghz ie 1/5th the max ADC sample rate ;)

cheers
0xdeadbeef:
5GSa/s interleaved is not totally uncommon for 1GHz scopes but yeah, personally I'd rather have 10GSa/s or so. Again, Keysight could have chosen a scope in the same price/performance league or selected test scenarios where the the LeCroy would have looked much better (even better than the Keysight in certain cases). Besides, the ENOB comparison looks like BS. I guess they compared measured system values of the LeCroy with theoretical ADC (not system) values fo the Keysight.
egonotto:
Hello,

snoopy wrote: "Regarding the HDO4000, Lecroy should have really band-limited this scope to 500MHz and not 1Ghz ie 1/5th the max ADC sample rate"

As I remember right, a staff of Pico Technology mean that the better rise time is the reason.

And that convinced me.

Best regards
egonotto


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