Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
joeqsmith:
Wasn't sure how good your port match is.
points2:
Hi,
This post is from a noob that thought he understood some part of what the device can do... but when joey/ntcnico etc :-+ start posting... I lost again :palm:
A few questions at noob level, concerning the use of this "special" device, just to try to get a clearer picture about what it can do :
1. given its limiation due to the way it works => it is a big bargain vs any all-in-one DSO on the market ? correct ?
2. it is a device that works on repetitive signal (linked to the way it works). What kind of repetitive signal this device loves to trigger ?
2.1. Ethernet signal : my SDS2504++ (500M BW DSO) can trigger an ethernet signal (100Mb is easier to probe the 125MHz than the bi-directional 1Gb) ? but regarding signal between IC & SFP 1Gb (signal @ 1.25GHz), this device can do it ? (given that I have 1GHz active probes, PMK Tetris)
2.2. oscillators analysis ? to check freq stability, a TinyPFA is more precise by 1e3 min order of magnitude... Correct ?
2.3. regarding any "fast" digital signal, to analyse in the time-domain, this scope is more "precise" than any DSO (like my SDS2504X+) thanks to its much lower rise. Correct ?
I'm interested in the jitter (eye-diagram, or pseudo-eye-D) of some basic digital signal :
- USB 2.0 is based on 480MHz signal (SA snifing) => this device can help to get a +/- clear picture of the signal ?
- HDMI 1.4 is based on 650MHz (wrong figure but close, I can't remember the right one) signal (SA snifing) => this device can help to get a +/- clear picture of the signal ?
3. Channel 1 is labeled "trigger". This feature blurs me...
3.1. Why ? a "noob-level" reply is requested, please :palm: ;D
3.2. This "scope" doesn't work like a DSO, but you can plug any probe and you got the pattern on the screen... yes/no ?
3.3 Channel 1 is labeled "trigger" => does it mean that the scope is not able to find by itself that the main pattern is at 125MHz for instance, and then lock to it, do the sampling => and presents the signal on the screen ?
4. what's the trigger jitter of this scope ?
Thanks to anyone to answer these low-level questions... :palm:
Maybe I'm wrong but I see this device as a dead "cheap" alternative to upgrade (to be an add-on, restricted to some signals) a hobbyist-level DSO like a SDS2504X+ (sticker on the scope is 2104X+ of course.. a gem this DSO...)
Thanks for feedback
PS : if I'm wrong here & there => be rude & correct => I just want to learn :-+
SJL-Instruments:
--- Quote ---Wasn't sure how good your port match is.
--- End quote ---
Not the best, to be honest: -17 dB @ 3 GHz (although we don't characterize this on a per-unit basis).
We have a design with better matching (-30 dB) at the cost of 2x noise floor. We opted for the lower-noise design, since you can get essentially the same results with a 6 dB attenuator (but not the other way around).
Thanks points2 for your detailed questions. We'll try to keep our answers succinct but clear.
--- Quote ---1. given its limiation due to the way it works => it is a big bargain vs any all-in-one DSO on the market ? correct ?
--- End quote ---
Yes, if your signal is repetitive (i.e. you can trigger many times - no one-shot signals), and you can pre-trigger or delay your signal.
This is explained in more depth in Section 2.1 of the manual.
If you need to do serial decoding, you need a real-time DSO (or a logic analyzer).
If you're (for example) doing something weird with nanosecond laser pulses, where usually you have high rep rates, the GigaWave will likely do the job.
--- Quote ---2.1. Ethernet signal : my SDS2504++ (500M BW DSO) can trigger an ethernet signal (100Mb is easier to probe the 125MHz than the bi-directional 1Gb) ? but regarding signal between IC & SFP 1Gb (signal @ 1.25GHz), this device can do it ? (given that I have 1GHz active probes, PMK Tetris)
--- End quote ---
Yes, you can trigger on this signal. You can't decode the data (use a logic analyzer), but you can check signal integrity (pseudo-eye-diagram, real eye diagram if you have CDR).
--- Quote ---2.2. oscillators analysis ? to check freq stability, a TinyPFA is more precise by 1e3 min order of magnitude... Correct ?
--- End quote ---
Yes, oscillator stability/jitter/etc is better-suited for frequency-domain tools. The exception is rise/fall time - the GigaWave is great for that.
--- Quote ---USB 2.0 is based on 480MHz signal (SA snifing) => this device can help to get a +/- clear picture of the signal ?
- HDMI 1.4 is based on 650MHz (wrong figure but close, I can't remember the right one) signal (SA snifing) => this device can help to get a +/- clear picture of the signal ?
--- End quote ---
Yes, the GigaWave can generate an eye diagram for these protocols (see caveat on CDR above).
Jitter analysis/mask testing is planned but not yet implemented. We understand if you want to wait for this feature before purchasing.
--- Quote ---3. Channel 1 is labeled "trigger". This feature blurs me...
3.1. Why ? a "noob-level" reply is requested, please :palm: ;D
--- End quote ---
To offer this bandwidth at this price, only Channel 1 has trigger hardware. It is a real channel (i.e. you can plug in a sine wave to CH1 and look at it). You will need to swap around cables to trigger on a different channel.
--- Quote ---3.2. This "scope" doesn't work like a DSO, but you can plug any probe and you got the pattern on the screen... yes/no ?
--- End quote ---
Yes, with the caveats that you can only trigger on CH1, and the signal must be repetitive. (i.e. think about which channel will be the trigger before you set up the cables.)
You can (for example) feed in a clock signal directly to CH1. It will show up, and you can measure its risetime and jitter.
If nothing's plugged into to CH1, nothing will happen.
--- Quote ---3.3 Channel 1 is labeled "trigger" => does it mean that the scope is not able to find by itself that the main pattern is at 125MHz for instance, and then lock to it, do the sampling => and presents the signal on the screen ?
--- End quote ---
If you plug in a 125 MHz square wave into CH1, you'll see a 125 MHz square wave.
If you plug in a 125 MHz data signal, you'll get something resembling an eye diagram (not a "true" eye diagram, though).
If you want to see a repetitive pattern, you'll need some auxiliary clock signal that repeats once per period of the pattern. Then plug the pattern into CH2 and the auxiliary clock into CH1.
--- Quote ---4. what's the trigger jitter of this scope ?
--- End quote ---
Typically 4 ps RMS. This is calibrated per-device, and is listed on the accompanying calibration sheet.
Do note that the effective jitter increases with the timebase delay (i.e. for best jitter, keep the signal before 100 ns on the timebase). The exact formula is in Section 2.3.
In summary:
- This device does not replace a DSO. If you need to look at rare events, or single-shot info, you should buy a realtime DSO.
- If you don't need the bandwidth, buy a realtime DSO or a random sampling scope. The price decreases exponentially with bandwidth.
- But, if your application allows for repetitive triggers, and you're looking at the overall behavior (not single-shot), the GigaWave might work. Things like rise/fall times of clocks, eye diagrams for signal integrity, and any experimental/oddball application requiring picosecond timing are all great applications for the GigaWave.
Thanks for the detailed questions - hope this cleared things up a bit!
points2:
Hi SLS,
many thanks for your reply, that can help others : Cool !
Sorry again vs the "very jittery" way I exposed "simple" stuff.. so far away from the maestros (joey & many others :-+)
KRgds
SJL-Instruments:
--- Quote ---It, meaning your products serial interface.
--- End quote ---
We received a few other requests, so we bumped up the priority of the serial interface guide.
It is now available in Section 4 of the User Manual. (Refresh if it's not updating for you.)
https://www.sjl-instruments.com/user-manual.pdf
Let us know if anything is unclear.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version