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Siglent SDS1104X-E In-Depth Review

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Performa01:

--- Quote from: tautech on March 11, 2018, 04:45:47 am ---500 frequency steps, low res mode ?

--- End quote ---

I’m not sure if I quite understand your remark/question…

Anyway, it might do no harm to give some additional information on the frequency resolution topic.

The Bode plotter in the SDS1004X-E has three different resolution modes, that provide a total number of frequency steps as shown below:

Low          20
Medium   100
High        500

The number of measurements, hence data points, is the number of frequency steps plus one.

The above scheme has been chosen in order to get a full resolution sweep (high), where each horizontal screen pixel corresponds to a measurement or a fast sweep (low) for a quick overview and also wideband structures that don’t require high frequency resolution. The medium resolution is just a compromise between the two and might be universal for pretty much everything that does not contain any high-Q resonant structures.

Still the 501 data points in high-res mode might not be enough for the following two scenarios:

1.   Detecting narrow resonance peaks in a wideband scan.
2.   Gaining additional detail when zooming into a Bode plot after the measurement has been made.

The first scenario is not very common and would be pretty similar to using peak detect in Y-t mode at a slow timebase in order to capture narrow spikes. While this is a realistic use case for a DSO, it isn’t very common for the frequency response of a circuit. It is only possible if the circuit includes high-Q resonant structures, which should not happen by accident, at least not in the frequency range up to 120MHz. For high-Q resonant structures, we are usually only interested in the frequency span around the resonance frequency, just as for the IF-filter in my previous example and then the frequency resolution is perfectly adequate.

Getting additional detail by zooming into a Bode plot after the measurement on the other hand was just not a design goal for the bode plotter in the SDS1004X-E. We rather have to repeat the measurement (or even take more than one measurement) with a narrow span. This is also a question of measurement speed. If Siglent engineers manage to significantly improve the sweep speed and come anywhere close to the FRA4PicoScope in this regard, then we could always add a “Super High” resolution mode or just increase the number of frequency steps for the existing ones.

Performa01:

--- Quote from: rf-loop on March 11, 2018, 09:50:24 am ---First thank this SFRA test and compare with these PC scopes and what  have very highly limited frequency range.
Unclear (for me) is: when they say some amount of points for decade... is it really what I think...
SFRA from 999000 Hz to 999500 Hz how many steps...  or  just normal IF channel filter and SFRA example from 21.375000 MHz to 21.425000 MHz (oops, there was some PC scope limited to 1MHz "audio" so that only somehow usable for 455kHz IF filters).  So how these points per decade things...

For IF filters tests of course this is very very limited due to very low dynamic  so we do not know "anything" about good filters stop band characteristics. But this is not designed for these. Still many things can do - up to 120MHz depending generator in use.

Only roughly this price class stand alone scopes what have SFRA is Keysight and some chinese GoodWill.
It looks like Kysight have nothing but just feature listed in advertisements (least data sheet what I have seen tell that 10 points/decade)

--- End quote ---

Your thinking is absolutely correct. The FRA4PicoScope can handle up to 1000 steps per decade, which may sound like a lot in wideband applications, but makes it unusable for extreme narrowband analysis. For your frequency span examples, it would be just one step (and/or an error message).

I should have pointed this out more clearly in my comparison and I’ve edited my posting in the meantime to include some additional information on the FRA4PicoScope.

Just now it occurred to me that the internal AWGs in the Picoscopes are not only limited to 1MHz and 2Vpp, but have 600 ohms output impedance on top of that, which also explains the high noise floor and poor dynamic of the measurements. We’d need a booster amplifier for proper usage in a 50 ohm system – and then the dynamic would most likely approach 90dB (and up to 100dB if the booster could deliver 10Vpp into 50 ohms).

When talking about just 10 steps/decade, this is clearly a joke and would not even remotely cover my test scenario. Here’s the same 455kHz IF filter plotted with the FRA4PicoScope using only 10 steps/decade:


10 points per decade

Performa01:

--- Quote from: rf-loop on March 11, 2018, 09:50:24 am ---
--- Quote from: Performa01 on March 11, 2018, 12:59:09 am ---
Top left is the interface box SLA1016 that connects to the SDS1004X-E through the Sbus cable at one end. The other end has a 2x34 connector for the ~80cm long high density flat ribbon cable, which in turn connects to the SPL1016 probe head. It is connected in the picture above, but can easily be detached.


--- End quote ---

This SPL1016 looks like exactly same SPL1016 what is used with SDS1002X+ models.
Only what I can not see enough clear in images is SLA1016 connector. (ribbon cable between SPL1016 head and SLA1016)
SPL1016 head include electronics, all comparators etc. After this head, in ribbon cable, signal is buffered.
I have used it with SDS1102X+

Now, because this kind of cables wear and damage quite easy in use it is nice if parts can buy separately and not need buy whole set including SLA1016 and SPL1016 together.
 
But question is: Is this SPL1016 head really same and cable with connectors also exactly same what is used in SDS1002X+ MSO.
If so, only new part is this SLA1016 control and converter box.

--- End quote ---

I've never had a SDS1000X+, so I cannot comment on it. However I happen to have a picture of the SLA1016 connectors:


SLA1016_Interface

tautech:

--- Quote from: Performa01 on March 11, 2018, 10:14:20 pm ---
--- Quote from: rf-loop on March 11, 2018, 09:50:24 am ---
--- Quote from: Performa01 on March 11, 2018, 12:59:09 am ---
Top left is the interface box SLA1016 that connects to the SDS1004X-E through the Sbus cable at one end. The other end has a 2x34 connector for the ~80cm long high density flat ribbon cable, which in turn connects to the SPL1016 probe head. It is connected in the picture above, but can easily be detached.


--- End quote ---

This SPL1016 looks like exactly same SPL1016 what is used with SDS1002X+ models.
Only what I can not see enough clear in images is SLA1016 connector. (ribbon cable between SPL1016 head and SLA1016)
SPL1016 head include electronics, all comparators etc. After this head, in ribbon cable, signal is buffered.
I have used it with SDS1102X+

Now, because this kind of cables wear and damage quite easy in use it is nice if parts can buy separately and not need buy whole set including SLA1016 and SPL1016 together.
 
But question is: Is this SPL1016 head really same and cable with connectors also exactly same what is used in SDS1002X+ MSO.
If so, only new part is this SLA1016 control and converter box.

--- End quote ---

I've never had a SDS1000X+, so I cannot comment on it. However I happen to have a picture of the SLA1016 connectors:


SLA1016_Interface

--- End quote ---
Do you happen to have a SCSI drive cable and can maybe check if it's the same 68 pin/plug format ?

A cable such as this could then offer a better solution to the gawd awful ribbon cable:
https://www.ebay.com/itm/SCSI-3-Ultra-Cable-68-pin-HD68-Male-to-68-pin-HD68-Male-HP-166298-038-AF-0-60m/391907302964?hash=item5b3f7ede34:g:6GkAAOSwNsRZ41iJ

rf-loop:

--- Quote from: Performa01 on March 11, 2018, 10:14:20 pm ---
I've never had a SDS1000X+, so I cannot comment on it. However I happen to have a picture of the SLA1016 connectors:


--- End quote ---

Physically connector looks same as SPL1016 used with SDS1102X+. At this point I´m quite sure SPL1016 including cables is same. Interface with scope is of course different, outside of scope SLA1016 with Sbus. SPL1016 price alone without license and SLA1016 interface box is around 189 Eur (VAT0). This is what need buy if you have full MSO set and later want new probe if it is damaged or want more than just one probe.

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