LeCroy Waverunner LT224 Review, (partial) teardown and wfm/s measurement

[Wuerstchenhund]

Ok, this is my first review, so please be patient

Recently I acquired what is my first own LeCroy oscilloscope. I have used other LeCroys on various occasions but I always wanted to have my own. Why? Because they are still considered to be the Mercedes of scopes, due to their very advanced signal analysis capabilities. Unlike other scope manufacturers which target primarily electronics design/development/service, LeCroy comes from the physics and sciences corner and therefore has taken a somewhat different approach to their scopes, putting much more weight on the analysis tools. Especially older LeCroy scopes are also known for a somewhat awkward user interface, at least if one is used to the standard layout that is common amongst most analog and digital scopes (it's usually less a problem for physicists, mathematicians and other scientists).

However, while I always wanted my own LeCroy, I didn't want one of the old 9300 Series (the one that is shown in Dave's repair video) as they have become a bit long in the tooth with their slow 68k processors and monochrome CRT. I wanted something a bit more modern (1999 to 2000 vintage) and with color screen. That means either a LC Series scope (LC3xx/5xx aka with color CRT, LC6xx with LCD monitor, with bandwidths from 500MHz to 1.5GHz) which succeeded the 9300 Series in the highend market in 1998, or one of the new (at that time) midrange series called 'Waverunner LT' (200MHz to 500MHz). And finally, when the chance came up to get a Waverunner at a reasonable price, I just couldn't resist.

So what follows is a short introduction to the Waverunner LT, a short review of my particular scope and a semi-teardown of my 'new' LeCroy Waverunner LT224.

If you have comments or questions, let me know!


UPDATE 15/05/2013: I was finally able to measure the waveform update rate (trigger rate) of this scope, and have updated this threads with the results.

[Wuerstchenhund]

The Hardware:

The LT Series is the first generation of LeCroy's midrange oscilloscope series called 'Waverunner' which was introduced in 1998. The Waverunner LT scopes were produced by Iwatsu in Japan, however the technology and the software came from LeCroy, with Iwatsu merely serving as manufacturer (so it's not just a rebadging job like LeCroy did with the craptastic WaveAce Series made by Siglent).

The Waverunner LTs are compact bench scopes in a white casing, available in two-channel (LTxx2) or four-channel (LTxx4) configuration, with analog bandwidths between 200MHz and 500MHz and single-shot sample rates between 200MSa/s and 1GSa/s. They were later succeeded by the Waverunner 2 Series which was essentially a refresh of the first gen Waverunners with faster processing (same as the WavePro 900) and new aquisition systems which came in a blue casing. Both generations use the same firmware/OS package, built on Windriver's VxWorks, a dedicated Real Time Operating System (RTOS).

The successor of the Waverunner 2 is the Waverunner 6000 which runs Microsoft Windows and is based on LeCroy's XStream architecture and MAUI touch screen interface.

The Waverunner 1 LT uses a 96MHz MPC603e PowerPC processor and Enhanced Data Output (EDO) memory in 72pin PS/2 format (it can use Fast Page Mode (FPM) memory, too, albeit not officially supported by LeCroy). There are two memory slots. Basic Waverunner LT models come with 16MB or 32MB RAM (1x 16MB), which can be upgraded to 128MB (2x 64MB). Other components like the GPU (Chips & Technologies 65545 with 1MB DRAM) are connected via VESA Localbus (VLB) to the core chipset. The screen is a 8.4" 640x480 LCD displaying 256 colors out of a palette of 4096 colors.

The digitizer frontend comes with two (2Ch models, LTxx2) or four (4Ch models, LTxx4) 8bit ADCs with local sample memory, which sits on proprietary memory modules (HMM, Hybrid Memory Module) and can be upgraded with up to four modules (if you manage to get hold of the modules, that is). Basic configurations come with 100k or 250k of sample memory, which could be expanded up to 8M (4M per channel). The BNC inputs on the front also have a smaller connector with an I2C bus, which serves for communicating with the more advanced LeCroy probes. It's the same system as used on the 9300 Series and the LC up to the latest LeCroy scopes.

The Waverunner also has an PCMCIA Type II/III slot on the rear which can take a PCMCIA hard drive (up to 512MB) or one of the antique SRAM memory cards that were more common on the 9300 Series, which then serves as local mass storage. Unfortunately the slot is inactive unless activated through the HD01 or HDS software options. There also is a 1.44MB 3.5" floppy drive (Citizen W1D) which is prone to malfunction as the drive belt (yes, this thing doesn't have direct drive) tends to dissolve itself, which can be fixed by either replacing the drive (some old Compaq laptops used a similar floppy drive) or the belt. Considering how useful 1.44MB of storage are in these days, it as well can remain unfixed.

Connectivity consists of GPIB (scope control), RS-232 (scope control or printer) and parallel port (printer). There is also a slot for an optional 10Mbps Ethernet network card which is basically unobtainium. And of course, like other LeCroy scopes of that era, an optional graphics printer was available, too.

The scope is cooled by a single fan only.

The build quality, probably thanks to Iwatsu, is very high, and in several areas a lot  better than on the 9300 Series or the LC models.

[Wuerstchenhund]

The software:

The Waverunner 1 LT was LeCroy's first scope running Windriver's VxWorks embedded RTOS (9300 and LC Series use a LeCroy proprietary OS), which is used in many other applications as well. The user interface of the Waverunner LT is similar to that of the LC Series and the 9300 Series. In terms of features it's well equipped. From persistence mode (either color-graded or analog CRT-like), advanced triggering modes (SMART triggering, edge/slope/signal pulse width/signal interval/state or edge qualified/dropout/TV), zoom, segmented memory, ERES (Extended Resolution, something along the lines of Tek's HiRes mode, just a bit more sophisticated) and many other things one would expect from a modern DSO.

As with other LeCroy models, the scope functionality can be upgraded by software unlock codes. All Waverunner LTs already come with standard math, statistics and FFT packages which on the 9300 and LC Series were paid-for options (WP02, WP03) and which already exceed what is available on most other scopes (even modern ones). If this is not enough then there are several software options available: Enhanced Measurements and Math (EMM), WaveAnalyzer (WAVA), Jitter and Timing Analysis (JTA),  digital filter package (DFP), Advanced Trigger (ATP), PolyMask Testing (PMSK), Power Measure Analysis (PMA1), as well as the specialist Surface Map Analysis (SMAP) and Disk Drive Measurement (DMM) for those working with hard drive internals (there's also ODM which is the same but for optical drives). Thanks to the faster processor, the Waverunner LT is much quicker in advanced analysis or math modes than the old 9300 Series, and is as fast as the highend LC Series.

LeCroy also offers a choice of free Windows applications for using the scope with a PC. ScopeExplorer can remote control a LeCroy scope, it can access the scope's mass storage (hard drive, floppy drive) and transfer files between scope and PC, and can update the firmware directly over the internet. ActiveDSO is an ActiveX control for controlling the scope within other applications like Office and VisualBasic. DSOFilter is another ActiveX control for designing custom digital filters. MaskMaker is a too for creating masks for using with the PolyMask software option. The programs that actively control a scope can do so via GPIB, serial interface or network interface. And albeit only NI GPIB adapters are officially supported, the programs work fine with an Agilent 82357 or the Beiming 82357 clones in NI.488 mode.

[Wuerstchenhund]

My Waverunner LT 224:

The scope I got is a Waverunner LT 224. It's a 4-channel 200MHz scope with 200MSa/s single-shot sampling rate and 10GSa/s repetitive sampling rate. It also 100k of sample memory per channel and came with 16MB RAM. It doesn't have the optional printer, but since I wouldn't have any use for it it's actually a good thing.

The scope arrived in very good condition, but like most LeCroy scopes of that era it also suffered from a well known LeCroy illness: missing knobs. The knobs LeCroy used on these scopes tend to loose their grip on the encoder shaft after a while and become loose quickly, resulting in some of the knobs going missing sooner or later. My scope has lost the know for vertical deflection and time base, but I could replace them with standard cheap grey plastics knobs for little money. The floppy doesn't work as it suffers from the above mentioned belt problem (not sure if I can be bothered to fix it). The acoustic noise level the single fan creates is, in my opinion, acceptable, albeit it's no silent unit. At the moments I have no plans to replace it, though.

I also noticed two constant bright pixels on the LCD screen, but luckily they are both in a corner outside the scale. The overall screen brightness is fine and much better as it appears on the images. There is also a 'screen saver' which, if enabled in the settings, switches the monitor off after 15mins. In addition, there is a VGA output on the rear to connect an external monitor or projector.

My scope already came with the Wave Analyzer, Enhanced Math, Jitter and Timing Analysis and Digital Filter software options, and it also has the HD01 option which enables the PCMCIA slot. So I did some tests to make sure everything works fine, connected my Beiming F82357 GPIB adapter to it and upgraded the firmware via ScopeExplorer to the latest version (9.3.0) which went fine. I then opened it remove the accumulated dust inside, and to replace the single 16MB EDO memory module with two 32MB FPM modules to increase RAM to 64MB. Last but not least I put a 512MB CF card in a PCMCIA adapter and inserted it in the rear PCMCIA slot as 'hard drive' (it's more like a slow SSD).

The scope does an automatic ~5s long recalibration from time to time, during which all operations are blocked. The recalibration happens more often within the first 10 minutes after switching on until the internal temperatures have stabilized, after that the interval between recalibrations is increased noticeably. In case this is a problem (i.e. because it would interrupt a critical measurement), the automatic recalibration can be disabled in the settings.

As at the moment my only signal source is a shitty Siglent SDG1020 20MHz AWG which suffers from a terrible jitter problem (a design flaw) on anything except sine wave mode and pulse mode, so I used this for a very quick play with some of the Waverunner's goodies. The jitter of the Siglent is really bad when the generator is set at around 10kHz, so I used signals between 10kHz and 20MHz to get a nice jittery signal (which is no problem for the Siglent). I created some screenshots which are posted below to show some of the functionality.

The user interface takes a bit getting used to, but it wasn't worse than moving say from a HP 54510A to an Agilent Infiniium. The scope reacted quick to user inputs, with a very slight lag only when lots of analysis functions were active. Signal reproduction is quite good, considering this thing does only 200MSa/s. I tried to measure the waveform/s performance, but my other scope is down at the moment and the only counter I have is the one that is in this crappy Siglent generator, so this will have to wait. Maybe someone else who has access to a Waverunner LT or even a LC Series scope (as the LC's signal processing part is essentially the same as the one in the LT) and some proper equipment can chime in.

All in all, I'm quite impressed by what this scope can do.

[Wuerstchenhund]

Here are a few images from the inside of a Waverunner LT.

[Hydrawerk]

200MSa/s... Well, not much. 

[jpb]

Thanks for posting this.

I don't know if you've already found it, but the service manual is at:

http://www.ko4bb.com/Manuals/LeCroy/LeCroy_LTXXX_WaveRunner1_Digital_Storage_Oscilloscope_Service_Manual.pdf

I have just bought a WaveJet also made by Iwatsu and I am favourably impressed by the build quality. I would like to get hold of the service manual which is sold in the States but the postage is as much as the manual ($120 for the manual, $110 for postage) which makes it rather unaffordable. Especially as it is still under warranty so I don't want to take it apart just yet.

[Wuerstchenhund]

200MSa/s... Well, not much. 

No, but depending on what you want to do it may well be enough. It would be way too slow for what I do at work (where we mostly have Agilent and Tek stuff), but for the simple things I do in my sparsely equipped home lab, it's good enough (and if not, I also have a 2GSa/s 500Mhz 4Ch HP 54542A, albeit with at the moment defective PSU).

This aside, I got the scope quite cheap, and I bought it more out of curiosity than anything else. But despite the low sample rate, the features are great, and what it has done so far is to convince me to look out for a reasonably priced 500MHz or 1GHz Waverunner 2 (or maybe even a Waverunner 6000?) for my home lab in the future.

[Wuerstchenhund]

I don't know if you've already found it, but the service manual is at:

Thanks, I already have the Service Manual (I actually had it before it has been posted on KO4BB).

I have just bought a WaveJet also made by Iwatsu and I am favourably impressed by the build quality. I would like to get hold of the service manual which is sold in the States but the postage is as much as the manual ($120 for the manual, $110 for postage) which makes it rather unaffordable. Especially as it is still under warranty so I don't want to take it apart just yet.

The WaveJets look like nice scopes. I've never come across one but the build quality of stuff made by Iwatsu is generally very good, so I wouldn't be surprised if the WaveJet's is as well. The only drawback with LeCroy is that unlike other T&M vendors they don't offer Service Manuals for download on their website. If I were you I'd just wait until warranty runs out, by which I would think the WaveJet will be EOL anyways. And once a LeCroy scope is EOL, it's a bit easier to get the Service Manuals.

If you have the time and motivation, maybe you can do a review of the WaveJet? I guess I'm not the only one who would be interested in one.

[jpb]

If you have the time and motivation, maybe you can do a review of the WaveJet? I guess I'm not the only one who would be interested in one.

I am planning to do this, but at present I don't have much to show as I've not yet acquired a signal generator.

I took the plastic back off and found it very well shielded and didn't want to go any further while it is under warranty.

I measured the dc gain and found it well within spec, in very good agreement with my 5 1/2 digit dvm:

DVM                  WaveJet
96.199mV         96.5mV
494.17mV         494mV
0.99643V          997mV
1.9948V            1.99V
4.9936V            4.99V
9.9903V            9.99V
14.9865V         15.0V
19.9905V          20.0V
29.9852V          30.0V

I measured the calibration signal on my meter and the oscilloscope:
meter                               WaveJet
299.16mV average          302mV average
423.1mV AC+DC rms       428mV  rms

I measured the time base using the 1pps signal from a gps module and it measured it at 999.998 mHz on the built in frequency counter so the time base seems to be ok to within 2 ppm (the spec is 10 ppm I think).


I measured the impedance of the ports in both 1M and 50ohm modes (using the 4wire measurement on the meter) and they were also good:

Port              1Mohm impedance  (kohm)      50ohm impedance (ohm)
1                   999.4                                       49.8
2                   999.7                                       49.8
3                   999.6                                       49.83
4                  1000.0                                      49.9
trigger          999.3

Bear in mind that the instrument was calibrated in 2006 (I bought it "new" but old stock - it had been sitting in stock for 6 1/2 years but I did get it cheap).

I've also looked at the signal from a 10MHz ocxo that I bought and the waveform looked nice and the frequency was at 10MHz (depending on the voltage applied) but
as I don't have independent confirmation of this I don't know if it is exactly 10MHz or not.

I measured the noise and the level was about the same or better than Agilent and Tektronix results I found in an Agilent app note but I don't have the results to hand.

[bingo600]

@WH

I have a Beiming GPIB adapter , still unused ....

What driver/libs did you use , the ones from the CD ?

/Bingo

[Wuerstchenhund]

I have a Beiming GPIB adapter , still unused ....

What driver/libs did you use , the ones from the CD ?

No, the latest Agilent IO Libraries Suite from the Agilent website.

Don't forget that this thing looks like a true Agilent 82357A (Beiming S82357) or Agilent 82357B (Beiming F82357) to your computer.

[digsys]

Thanks for the write up, good to see others out there that appreciate an awesome scope. Even though I've never had a problem
with my 3x 93XX LeCroys in 20 yrs, you're forcing me to purchase an LT6XX :-)  Seem to be quite a few LT/LCs available.
As far as CRT screen burn / monochrome go .. there used to be a seller who had new CRTs for ~$100 (I should have bought more).
In many instances, I don't mind mono at all ... I do like the razor sharp CRT screen. Once again, great job.

[Wuerstchenhund]

Thanks for the write up, good to see others out there that appreciate an awesome scope.

Thanks. Unfortunately in my field of work LeCroy is a rare occurrence, which I think is undeserved. They really do make great scopes.

Even though I've never had a problem with my 3x 93XX LeCroys in 20 yrs, you're forcing me to purchase an LT6XX :-)

I guess you mean a LT 5xx or a LC 6xx  Unless you need more than 500MHz of bandwidth I'd go with the LT Series, as they offer exactly the same processing power as the highend LC models, and already come with the PCMCIA hardware as standard which was a (rare) option on the LC Series.

As far as CRT screen burn / monochrome go .. there used to be a seller who had new CRTs for ~$100 (I should have bought more).

I saw the offer for the new CRTs, but for me it just wasn't worth it getting a 9300 scope. Aside from the screen burn-in, most 9300 scopes were either overly expensive, completely beaten down, or (most cases) both. This would have meant to not only buy the scope (which would have cost me more than my LT 224), but also to buy a new CRT and all the other parts, and then spend time to rebuild it just to end up with something with much slower processing power and less capable analysis tools.

Don't get me wrong, the 9300 Series was way ahead of what other manufacturers offered when it came out, and they are still good scopes. But they also are now 18 to 20 years old, which does show on most 9300 Series scopes in one way or another.

In many instances, I don't mind mono at all ... I do like the razor sharp CRT screen.

I generally don't mind monochrome, too (but I prefer green over amber), and I'd rather have a scope with mono CRT than with color CRT due to the nasty issues re convergence that color CRTs come with. But a color display helps tremendously when using the various analysis functions

[saturation]

Nice review and excellent build quality for a c1990s scope, when LeCroy was at its prime.   200Ms/s, ~ 20 MHz,  4 channels can still be quite useful, it all comes down to how much it cost for this older technology, particularly since LeCroy excel in waveform analysis.

[Wuerstchenhund]

I finally had the chance to measure the waveform update rate of my LeCroy Waverunner LT224. Here are the results:

Time Base Setting	Sampling Rate	Single Channel (wfm/s)	Dual Channel (wfm/s)	Persistence, color graded, infinite (wfm/s)	RIS Sampling Rate	RIS Single Channel (wfm/s)	RIS Persistence (wfm/s)
1ns	200 MSa/s	58.7-60.2	58.7-60.2	367-375	10 GSa/s	23k-25k	23k-25k
2ns	200 MSa/s	58.7-60.2	58.7-60.2	364-373	10 GSa/s	23k-25k	23k-25k
5ns	200 MSa/s	58.7-60.2	58.7-60.2	363-373	10 GSa/s	23k-25k	23k-25k
10ns	200 MSa/s	58.7-60.2	58.7-60.2	363-373	10 GSa/s	23k-25k	23k-25k
20ns	200 MSa/s	58.7-60.2	58.7-60.2	356-364	10 GSa/s	23k-25k	23k-25k
50ns	200 MSa/s	58.7-60.2	58.7-60.2	346-353	10 GSa/s	20k-24k	20k-24k
0.1us	200 MSa/s	58.7-60.2	58.7-60.2	334-336	10 GSa/s	20k-24k	20k-24k
0.2us	200 MSa/s	59.7-60.6	59.7-60.6	316-322	10 GSa/s	20k-24k	20k-24k
0.5us	200 MSa/s	59.7-60.6	59.7-60.6	260-269	10 GSa/s	20k-24k	20k-24k
1us	200 MSa/s	59.7-60.6	59.7-60.6	223-227	4 GSa/s	20k-22k	19k-20k
2us	200 MSa/s	59.7-60.6	59.7-60.6	155-170	2 GSa/s	16k-17k	16k-17k
5us	200 MSa/s	56.7-58.7	56.7-58.7	92.9-93.9	1 GSa/s	10k-11k	10k-11k
10us	200 MSa/s	45.9-47.9	45.9-47.9	53.8-54.8	400 MSa/s	6k-7k	6k-7k
20us	200 MSa/s	29.3-30.3	22.7-24.3	27.3-28.4	---	---	---
50us	200 MSa/s	14.7-15.7	11.7-12.7	11.7-12.7	---	---	---
0.1ms	100 MSa/s	14.7-15.7	11.7-12.7	11.7-12.7	---	---	---
0.2ms	50 MSa/s	14.7-15.7	11.7-12.7	11.7-12.7	---	---	---
0.5ms	20 MSa/s	14.7-15.7	11.7-12.7	11.7-12.7	---	---	---
1ms	10 MSa/s	14.7-15.7	11.7-12.7	11.7-12.7	---	---	---
2ms	5 MSa/s	13.7-14.7	11.7-12.7	11.7-12.7	---	---	---
5ms	2 MSa/s	9.7-10.1	9.7-10.1	9.7-10.1	---	---	---
10ms	1 MSa/s	6.4-6.7	6.4-6.7	6.1-7	---	---	---
20ms	500kSa/s	4	4	3.6-4.1	---	---	---
0.1s	200kSa/s	1.8	1.8	1.9	---	---	---
0.2s	100kSa/s	0.9	0.9	0.9	---	---	---

Measurement conditions: Siglent SDG1020 generator, set to sine wave, 20MHz, 3Vpp, 0V offset, 50 Ohms termination, into Waverunner EXT input (50 Ohms terminated); trigger set to EXT; rear output set to TRIG OUT, into Siglent SDS1102CNL scope 1 MOhms CH1 input.

The result table is also enclosed as pdf file.

[digsys]

Interesting and confusing results. What do you make of the wfm/s difference in Single mode c/w RIS ??
~60 seems quite low, even though I can't recall really having problems triggering on spurious pulses ??
Any thoughts ?

[Wuerstchenhund]

Interesting and confusing results. What do you make of the wfm/s difference in Single mode c/w RIS ??
~60 seems quite low, even though I can't recall really having problems triggering on spurious pulses ??
Any thoughts ?

Yes, the results are indeed a bit odd. But simply measuring the trigger rate doesn't shows the whole picture anyways.

Most DSOs simply throw away sample data when scaling their sample points down to display resolution. That's how they reach their high waveform update rate. As a consequence, since they throw away data, they often throw away signal information that is important (i.e. small glitches you never see or only see occasionally when they are eventually captured).

These LeCroy scopes however use a different process where no data points are thrown away (every data point is actually displayed on the screen), so you don't need a high waveform rate to capture even small glitches.

[elecBlu]

my question is not about LT 224, but again some waveforms/s measurement at LeCroy Waverunner Scopes:
I got a used Waverunner, 6000A Series, some years newer than LT224. It says in manual (page 11) there are 125.000 waveforms/ second trigger rate. http://www.teknetelectronics.com/DataSheet/LECROY/LECRO_6200a101825.pdf
I tried to verify that, using my Sinewave generator, 20mhz signal, trig out at back connected to frequency counter. My result was something between 80 and 220 Hz, depended on timebase, channels... In the RIS (Random Sampling) Mode (200GSa/s) i noticed a maximum of about 20kHz.
But far away from 125kHz?  Even with that different way how LeCroy Scopes handle that trigger thing, ther should be a way to get the value of spec sheet out of this scope. Any ideas?

Ben

[jpb]

For the 1ns results for instance, at 200MS/s there would be a sample every 5 nsecs which would mean that there would only be 2 or 3 actual sample points on the screen. I assume therefore that it does a lot of interpolation (sinc x I guess) which presumably is processor intensive and accounts for the slow update rate.

The rate is perhaps much higher in RIS mode because it is not doing such interpolation (the points themselves provide the interpolation) so it triggers much more frequently but because it is building up to 10GS/s from its natural maximum rate of 200MS/s it is grabbing 50 triggers worth for each screen that is shown and perhaps just doing linear interpolation or no interpolation.

[elecBlu]

as i said, my scope is 6000A series which brings 5GS, and even when i go to slower timebase this not increasing waveform/s rate. there is no interpolation, so nope, thats not the reason at all (with my scope).
It seems to be true, LeCroys "trigger rate" has nothing to do with "waveform update rate" or "waveforms/second" as they were measured in this form.

[Wuerstchenhund]

my question is not about LT 224, but again some waveforms/s measurement at LeCroy Waverunner Scopes:
I got a used Waverunner, 6000A Series

Nice scope! Which model do you have? I was thinking of getting a 6050A myself, if I find one at a good price.

I tried to verify that, using my Sinewave generator, 20mhz signal, trig out at back connected to frequency counter. My result was something between 80 and 220 Hz, depended on timebase, channels... In the RIS (Random Sampling) Mode (200GSa/s) i noticed a maximum of about 20kHz.
But far away from 125kHz?  Even with that different way how LeCroy Scopes handle that trigger thing, ther should be a way to get the value of spec sheet out of this scope. Any ideas?

It may sound stupid, but have you set the Auxiliary Output at the rear to Trigger Out mode? Just mentioning as I have been caught out a few times by this with the WR LT.

Other than that, can you give a few more details about the test parameters (i.e. scope settings)? Is any software installed on the scope that could adversely affect the performance?

I've only seen a WR 6000A once, but from what I know it does reach the specified waveform rate.

[Wuerstchenhund]

For the 1ns results for instance, at 200MS/s there would be a sample every 5 nsecs which would mean that there would only be 2 or 3 actual sample points on the screen. I assume therefore that it does a lot of interpolation (sinc x I guess) which presumably is processor intensive and accounts for the slow update rate.

The rate is perhaps much higher in RIS mode because it is not doing such interpolation (the points themselves provide the interpolation) so it triggers much more frequently but because it is building up to 10GS/s from its natural maximum rate of 200MS/s it is grabbing 50 triggers worth for each screen that is shown and perhaps just doing linear interpolation or no interpolation.

I'm sorry but that is incorrect. RIS (time-equivalent sampling) is NOT interpolation. All data points in RIS mode are true data points, not interpolated data points. And of course interpolation can be used even in RIS mode.

In addition, on LeCroy scopes like the Waverunner series, interpolation is off by default, and both linear and sin(x)/x interpolation can be enabled independent of the sampling mode (real time or RIS). The scope also does not switch off interpolation when RIS is enabled.

This aside, enabled interpolation does barely affect the waveform rate of my WR LT 224, and on the 6000A Series (which is a  first gen X-Stream scope, running Windows XP Pro and using a much more powerful CPU) it shouldn't be much different.

Edit: of course the WR6000A is a 1st gen X-Stream scope, not second gen, and runs XP Pro and not Embedded. Corrected.

[jpb]

For the 1ns results for instance, at 200MS/s there would be a sample every 5 nsecs which would mean that there would only be 2 or 3 actual sample points on the screen. I assume therefore that it does a lot of interpolation (sinc x I guess) which presumably is processor intensive and accounts for the slow update rate.

The rate is perhaps much higher in RIS mode because it is not doing such interpolation (the points themselves provide the interpolation) so it triggers much more frequently but because it is building up to 10GS/s from its natural maximum rate of 200MS/s it is grabbing 50 triggers worth for each screen that is shown and perhaps just doing linear interpolation or no interpolation.

I'm sorry but that is incorrect. RIS (time-equivalent sampling) is NOT interpolation. All data points in RIS mode are true data points, not interpolated data points. And of course interpolation can be used even in RIS mode.

In addition, on LeCroy scopes like the Waverunner series, interpolation is off by default, and both linear and sin(x)/x interpolation can be enabled independent of the sampling mode (real time or RIS). The scope also does not switch off interpolation when RIS is enabled.

This aside, enabled interpolation does barely affect the waveform rate of my WR LT 224, and on the 6000A Series (which is a second gen X-Stream scope, running Windows XP Embedded and using a much more powerful CPU) it shouldn't be much different.

I wasn't saying that RIS was interpolation - I know that it isn't as I have a WaveJet which has it. What I was saying was RIS increases the number of points, thus removing the need for interpolation or decreases the size of the gaps requiring, fewer interpolated points. But you report that interpolation doesn't slow the scope down - something I find surprising even if it has a powerful processor but is perhaps a feature of the intrinsically slow update rate (the overhead would be much more significant when there is only a microsecond between waveforms).

The trigger rate will go up with RIS in that it triggers multiple times for each screen (presumably 50 times if going from 200MS/s to 10GS/s). In the 6000 manual I notice it says that it can trigger on up to 40k times per second in RIS mode which is much less than the 125k wf/s maximum quoted by elecBlu but nearer to the 25k that elecBlu measures in RIS mode.

[elecBlu]

I own the 500Mhz 2channel model- hat a good offer, slightly over DS2072, but way better specs, only the lower memory depth (and maybe really poor update rate? i didn`t expect that)
Aux out is set to trigger out, yes. There are no special things activated, no software active. I get the higher "trigger out" rate when I enable RIS, so it seems to be the correct way of measure the trigger rate.
The scope is running various settings, timebase, number of channels, external or internal trigger signal, memory depth... none of that change the frequency at "trigger out" excessively. When trig out frequency goes down to ~20Hz, you can "see" it on the screen, it's refreshing much slower. That LeCroy seems to be really "slow" in that thing.
I will try to verify the waveform update rate with an real measurement, some sort of waveform which is modified every 100 or 1000 waveforms.