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Siglent SDS800X HD Review & Demonstration Thread

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Martin72:
Mostly the 800, except this one:
https://www.eevblog.com/forum/testgear/sds800x-hd-review-demonstration-thread/msg5494624/#msg5494624

eTobey:
Is there a way, to create a math formula, so one could easily see, what the duty cycle (yellow) roughly is?

ebastler:

--- Quote from: eTobey on May 12, 2024, 05:29:05 am ---Is there a way, to create a math formula, so one could easily see, what the duty cycle (yellow) roughly is?

--- End quote ---

A "Measurement Track" (section 18.5 of the manual) should do what you want: Calculates time-dependent measurements within one capture and plots them like a trace. 

Performa01:

--- Quote from: joeqsmith on May 11, 2024, 06:23:49 pm ---
--- Quote from: Performa01 on May 08, 2024, 05:58:39 pm ---...
The commonly agreed industry standard for the maximum acceptable input VSWR is 1.5:1, which is equivalent to 14 dB return loss.
...

--- End quote ---

I've never heard of such a standard.  Could you provide a reference?  If you are making measurements, 1.5 seems really high. 

Looking at the manual for my LeCroy 7200, they spec the VSWR at 1.2, BW is 4GHz with a 125pSec transition for 50mV and up.  Isolation is 60dB min at 1GHz.

--- End quote ---

I have no reference to such a standard – my statement is based solely on the impression left by various RF literature, experience and common sense. Sorry if it has been misleading.

At least one example, showing that I’m not the only one who thinks 1.5:1 is the limit of acceptable (some might call it ideal) VSWR, can be found here:

https://www.ahsystems.com/notes/VSWR-return-loss-sheet.php


--- Quote --- A VSWR of less than 1.5:1 is ideal, a VSWR of 2:1 is considered to be marginally acceptable in low power applications where power loss is more critical …
--- End quote ---

Very few oscilloscopes have the input return loss / VSWR specified; one of the few exceptions was the now discontinued 2 GHz R&S RTE. From the data sheet Version 16.01:


--- Quote ---Input VSWR : input frequency ≤ 500 MHz 1.25 (meas.); input frequency > 500 MHz 1.4 (meas.)

--- End quote ---

I take from this, that a company, that is renowned to be an RF-specialist since 1933, has no problems specifying a VSWR of 1.4:1 for frequencies >500 MHz on an instrument that isn’t exactly a cheap low-end product. There exists no VSWR-specification for its successor, the MXO5, anymore…

Finally, the common-sense part: A VSWR of 1.5:1 means 4 % reflected power, i.e. 4 % power loss at the receiver end (scope input). That’s 0.17 dB = ~2% voltage error. It is less than the DC-accuracy specification of most oscilloscopes.


As can be seen from my measurements, the 500 (actually 570) MHz SDS2000X HD provides a VSWR of <1.25:1 up to ~750 MHz. That should be in line with your expectations based on the LeCroy 7200.

joeqsmith:
Thanks for the response.  It could very well be my lack of any common sense and experience causing my confusion.

If I were considering the acceptable VSWR of my antenna system, I could see some general guidelines.   If I were trying to measure the output power of my amplifier, I would have a different criteria for the load match of my power meter (mine is 1.05 for example).   There is a reason you will find many application notes about using precision attenuators to improve port matching when making measurements.    Consider some parts may have a very good isolation between their input and output and the measurement uncertainty would be much less. 

My vintage LeCroy 8500A specs 50+/-2%.  20log10(50*0.02/50*2.02) = 40dB return loss, but that's at DC.   An 8-bit system like this is going to mask a lot of the errors which may be why manufactures didn't provide the details.   

I imagine as manufactures improve their products and users find more applications for them, spec's like return loss will become more important.   


--- Quote from: Performa01 on May 12, 2024, 06:45:31 am ---
--- Quote from: joeqsmith on May 11, 2024, 06:23:49 pm ---
--- Quote from: Performa01 on May 08, 2024, 05:58:39 pm ---...
The commonly agreed industry standard for the maximum acceptable input VSWR is 1.5:1, which is equivalent to 14 dB return loss.
...

--- End quote ---

I've never heard of such a standard.  Could you provide a reference?  If you are making measurements, 1.5 seems really high. 

Looking at the manual for my LeCroy 7200, they spec the VSWR at 1.2, BW is 4GHz with a 125pSec transition for 50mV and up.  Isolation is 60dB min at 1GHz.

--- End quote ---

I have no reference to such a standard – my statement is based solely on the impression left by various RF literature, experience and common sense. Sorry if it has been misleading.

At least one example, showing that I’m not the only one who thinks 1.5:1 is the limit of acceptable (some might call it ideal) VSWR, can be found here:

https://www.ahsystems.com/notes/VSWR-return-loss-sheet.php


--- Quote --- A VSWR of less than 1.5:1 is ideal, a VSWR of 2:1 is considered to be marginally acceptable in low power applications where power loss is more critical …
--- End quote ---

Very few oscilloscopes have the input return loss / VSWR specified; one of the few exceptions was the now discontinued 2 GHz R&S RTE. From the data sheet Version 16.01:


--- Quote ---Input VSWR : input frequency ≤ 500 MHz 1.25 (meas.); input frequency > 500 MHz 1.4 (meas.)

--- End quote ---

I take from this, that a company, that is renowned to be an RF-specialist since 1933, has no problems specifying a VSWR of 1.4:1 for frequencies >500 MHz on an instrument that isn’t exactly a cheap low-end product. There exists no VSWR-specification for its successor, the MXO5, anymore…

Finally, the common-sense part: A VSWR of 1.5:1 means 4 % reflected power, i.e. 4 % power loss at the receiver end (scope input). That’s 0.17 dB = ~2% voltage error. It is less than the DC-accuracy specification of most oscilloscopes.


As can be seen from my measurements, the 500 (actually 570) MHz SDS2000X HD provides a VSWR of <1.25:1 up to ~750 MHz. That should be in line with your expectations based on the LeCroy 7200.

--- End quote ---

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