Lecroy 4054HD vs Siglent SDS6204A eval - Page 1
Forum section: electronics / testgear

author: jayk
author_rank: Regular Contributor
timestamp: May 17, 2024, 06:14:55 pm
content: I've got a pair of scopes to try out for a week: Siglent SDS6204A and Lecroy 4054HD (unfortunately the 4104HD wasn't available for eval). Both have all options and latest FW. I've got a bunch of things I want to test, but if anyone has any particular comparisons they'd like to see let me know and I'll see what I can do.Just to start here are some pics and noise comparisons, with full BW and with 200MHz BW limiting.

author: rf-loop
author_rank: Super Contributor
timestamp: May 17, 2024, 06:40:24 pm
content: You use RMS in the measurement, which also include DC component (for example, the DC offset of the channel, which is usually not completely zero)When measuring the amount of noise, you should use AC RMS measurement.On a Siglent oscilloscope it is Stdev in the measure select menu. (which is mathematically just RMS without the DC component, also called AC RMS)

author: jayk
author_rank: Regular Contributor
timestamp: May 17, 2024, 07:22:06 pm
content: Thanks... missed that... will retest later.

author: jayk
author_rank: Regular Contributor
timestamp: May 17, 2024, 07:31:23 pm
content: Here are some pulse captures (not super-fast... 2ns rise/fall time). Nice improvement from the hi-res mode.The web control on the Siglent is awesome... works great. Unfortunately nothing like that on the Lecroy - just a basic web page you can use to capture the current screen image. I thinkg there's some software you can buy, but it's not part of my demo.I do like being able to drag a square around a region on the Lecroy and having a zoomed version of that open. That doesn't seem to work on the Siglent.

author: jayk
author_rank: Regular Contributor
timestamp: May 22, 2024, 07:16:25 pm
content: I've found lots of little bugs in the Siglent UI. After capturing a sequence of I2C transactions I can scroll through them on the History List popup but the index number and time displayed at the bottom are incorrect. I've had the I2C SDA threshold change to 13.0V a couple of times while not in the Trigger menu at all. Also there are some incorrect messages (like misidentifying a differential probe as a current probe). This stuff is pretty minor but a little disappointing for a product released in 2021 that's had 7 firmware updates (my demo unit has the latest version).The Lecroy UI just overall looks nicer and is functionally better with respect to serial decoding.I've had the Siglent lock up a couple of times and require a reboot - happened when I was trying to do a sequence capture, but I haven't been able to reproduce it.The Siglent feels slightly more responsive in terms of menus opening and closing. I find the Siglent UI somewhat more efficient by having most of the menus pop up in a strip on the right side of the screen. The Lecroy opens a strip at the bottom that requires more hand motion to make changes.The big 1280x800 screen on both scopes is great. Would be hard to go back to a smaller screen.The Lecroy can get it's date and time from the internet... the Siglent cannot.I don't have a siggen suitable for measuring bandwidth, but I have one of the Bodnar pulsers and made some measurements with that:Rise time BW BW(ps) (BW*RT=0.35) (BW*RT=0.45)MHz MHz222.0 1576 2027 SDS6204A + SAP2500D, probing unused output of driver on Bodnar pulser253.0 1383 1778 SDS6204A, pulser plugged into scope, normal acq369.0 948 1219 SDS6204A, pulser plugged into scope, hi-res +1bit mode430.0 814 1046 4054HD, pulser plugged into scope668.0 524 673 SDS6204A, pulser plugged into scope, hi-res +2bit modeMy pulser is an SMA output so I have a couple of adapters to convert to BNC and that may be costing my a little bandwidth.This 4054HD is spec'd at 500MHz, but I wonder if there's actually any difference between it and the 4104HD (which is spec'd at 1GHz). Or maybe Lecroy just specs BW really conservatively and the 4104HD is actually more like 1.5-2GHz. With the 5Gsps converters, seems like Lecroy could offer something closer to 2GHz.

author: 2N3055
author_rank: Super Contributor
timestamp: May 22, 2024, 08:36:18 pm
content: Quote from: jayk on May 22, 2024, 07:16:25 pmLeCroy 4000HD is all same 1GHz hardware, license unlocks BW.

author: jayk
author_rank: Regular Contributor
timestamp: May 23, 2024, 04:49:25 am
content: I think I was doing my BW calc wrong... if you use 10-90% the 4054HD is 597ps, for a BW of 586MHz, which makes more sense.The Spectrum Analyzer option on the Lecroy is nice, but whenever you change the resolution bandwidth or even sometimes the frequency range the instrument freezes and just displays "Processing..." at the bottom for like 15-20s. It's super frustrating, and makes you not even want to use it.

author: jayk
author_rank: Regular Contributor
timestamp: May 23, 2024, 06:00:37 am
content: Here's something fun. This is a spread-spectrum clock signal. I wanted to look at the frequency change over time and the spectrum. Lecroy lets you configure a math trace as a trend of a measurement. Siglent can display what they call a 'track' of a measurement in a small window. The Siglent spectrum looks nicer because their FFT function also supports averaging. The Lecroy FFT doesn't appear to support averaging (at least not that I can find - I emailed support asking if this is possible).Note the Siglent has four math functions while the Lecroy only two.

author: nctnico
author_rank: Super Contributor
timestamp: May 23, 2024, 08:16:48 am
content: On the Lecroy you may be able to use an extra math trace to get averaging.

author: jayk
author_rank: Regular Contributor
timestamp: May 23, 2024, 03:52:50 pm
content: Yes I just figured out that you can use the second math trace to average. Unfortunately at that point you've used both of the available math traces.The Spectrum Analyzer option supports averaging, but on my demo unit the UI freezes for between 10-20s whenever I change the SA frequency settings (or even when I disable the SA completely!). I've asked Lecroy if this is just a bug that will be fixed, but for now it's pretty unpleasant to use.Definitely nice having four math channels on the Siglent (plus FFT averaging is built into the Siglent FFT function - doesn't take another math channel).Does anyone know if these two scope share the same processing platform? They look very similar from the outside, but I'm not going to take my demo loaners apart. I know the Lecroy runs Windows CE (which hasn't had a major update in 10 years and is now officially out of support) and I think the Siglent runs Linux. So I'm worried about updates to the Lecroy going forward. Also I can't tell how many updates these 4000HD's have ever had, since Lecroy's website only shows the latest version (whereas on Siglent you can see and download all seven software releases).

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 23, 2024, 04:00:32 pm
content: Siglent is generally Linux. That model also has 4 math traces. I'm a little jelly of that.

author: jayk
author_rank: Regular Contributor
timestamp: May 23, 2024, 06:05:10 pm
content: The Spectrum Analyzer problem seems to be intermittent... I did a Default Setup recall and now the SA seems to work fine. Some weird software bug I guess.Saw on another thread people trying to use Lecroy probes with Siglent. Too bad Lecroy doesn't make an adapter to use Siglent probes with their scopes. Both use a 6-pin connector, but it's different between Siglent and Lecroy. The Siglent active probes are a fraction of the cost of comparable probes from Lecroy. I wonder what the margins are like on the active probes from Keysight/Tek/Lecroy.

author: nctnico
author_rank: Super Contributor
timestamp: May 23, 2024, 06:30:43 pm
content: Quote from: jayk on May 23, 2024, 03:52:50 pmI wouldn't be worried about that. CE is a very limited OS out of the box so Lecroy had to bolt on many pieces of software they can control themselves. Although I'd get a Lecroy scope running on a PC platform as this has more processing power and thus the full set of features can be implemented.

author: Martin72
author_rank: Super Contributor
timestamp: May 23, 2024, 07:31:27 pm
content: Hi,We had an HDO4000A on loan before we decided on an HDO6000A because it has more horsepower(Intel i5 CPU).QuoteNo, like the other larger models, the HDO4000 has Windows 10 as its operating system:QuoteWindows CE is used with the WS3000Z only.The HDO4000 is a PC-based system, the Siglent is underneath it, with Linux as OS as mentioned.

author: jayk
author_rank: Regular Contributor
timestamp: May 24, 2024, 05:57:52 am
content: My demo unit came with a pair of SAP2500D active differential probes. These are mechanically very nice, seem to get me pretty close to the the full 2GHz BW of the scope, and cost a fraction of comparable probes from the big names. I measured a fast edge (just an LVDS driver, but still pretty fast) with both probes on the same points and found about 50ps difference in delay between them. I've never tried to align scope channels this carefully, and I guess the delta could be inside the scope itself. The SDS6204A lets you adjust the delay on each channel in increments of 10ps. Here's the original (unadjusted) capture and again after adjusting Ch2 by 50ps. 50ps is about 1cm in RG58.

author: jayk
author_rank: Regular Contributor
timestamp: May 24, 2024, 06:01:44 am
content: Quote from: Martin72 on May 23, 2024, 07:31:27 pmI'm looking at the Wavesurfer 4000HD family... the HDO4000A is a different (higher-end) series. The naming is confusing.

author: Martin72
author_rank: Super Contributor
timestamp: May 24, 2024, 11:42:56 am
content: Oh, I was completely on the wrong track.Yes, then it's Win CE, because lecroy really want their MAUI on the rather "small" Scopes.A performance challenge for SoC scopes, with the WS3000 without Z that went down the drain back then....

author: jayk
author_rank: Regular Contributor
timestamp: May 29, 2024, 04:28:15 am
content: I tried to come up with a 'busy' configuration to see how bogged down the Siglent could get. I ended up showing two FFTs and some zoom and math functions. The UI was still pretty responsive.

author: jayk
author_rank: Regular Contributor
timestamp: May 29, 2024, 05:28:40 am
content: Here's something similar on the Lecroy. Only two math channels available.

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 29, 2024, 03:02:14 pm
content: You posted the Siglent screenshot again.

author: jayk
author_rank: Regular Contributor
timestamp: May 29, 2024, 05:48:36 pm
content: Oops... here's the correct one.