Products > Test Equipment
SSA 3021X 500 Hz off calibration
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KE4CDR:
Ok, my initial estimate was incorrect.  It is not off by 500 Hz but 43 Hz repeatedly.  Sorry for the error, but, it is there.  Maybe it's the firmware. I'm looking into that.  I have a siglent 1032 function generator that I'm monitoring with a Siglent 1102 CML+ Oscilloscope.  The scope shows the frequency of the sig gen at only a few hundredths of Hz off and steady.  When the SA is showing the peak 43 Hz off, the scope Hz reading has not changed and is constant at 50.75KHz.  So, it's apparent that something is going on in the SA.  I use the same wiring harness for the SA as I use to monitor the FG with the Oscope.  I've looked for problems in the wiring and the issue stays with the SA.  I talked to Siglent this morning and they are "looking into it."  Haven't heard back yet.  When I do, I'll post their response.  Thanks for all the comments.  73
Performa01:

--- Quote from: KE4CDR on July 12, 2022, 03:34:22 pm ---I have a siglent 1032 function generator that I'm monitoring with a Siglent 1102 CML+ Oscilloscope.  The scope shows the frequency of the sig gen at only a few hundredths of Hz off and steady.

--- End quote ---
Yes, if it was a constant error of less than two Hz, it could be the AWG. Not a huge error like this, that depends on the SA span randomly.


--- Quote from: KE4CDR on July 12, 2022, 03:34:22 pm ---I talked to Siglent this morning and they are "looking into it."

--- End quote ---
Since none of the SSA3000X owners in this thread has been able to reproduce your problem, I very much doubt that Siglent will. You should have told them that it appears to be a specific problem with your unit only.
Zenith:
According to the data sheet, the frequency reference in the SSA3021X 10MHz <1ppm. My frequency counter says the GPSDO is 1Hz over 10MHz and the 10MHz output from the SA is about 1Hz under 10MHz. The SA says the GPSDO is at 1Hz over 10MHz. I trust the GPSDO, which has been left on for months. I don't see any change on the SA, apart from maybe 1Hz, when I change the span.

I have a Siglent SDS1102 CML+. It doesn't have an output for its frequency reference. The datasheet doesn't talk about the quality of the frequency reference, but says the timebase is accurate to +/- 50ppm. The frequency counter is stated as good for 6 digits. Feeding it an accurate signal at around 10MHz, depending on how they do things, it could be anywhere +/- 100Hz of 10MHz and it would say 10MHz on the nose. That's about 10ppm and about what you'd expect for a pretty good plain crystal.  The frequency readout is very convenient for those times when a fairly good measurement of frequency is good enough and you don't want to drag out a proper frequency counter and give it half an hour to warm up.

I don't have a SDG1032x. The datasheet doesn't say much about the frequency reference but talks about an initial accuracy of +/-25ppm.

43Hz in 50.75MHz is <1ppm. The random changes seem odd.

You may have a hardware problem. You may have come across a firmware problem. If you haven't already done so already it makes sense to update to the latest firmware, as it's quick and easy. However, I suspect that you are judging the SA by assuming two pieces of kit with lesser frequency standards are totally accurate.

egonotto:
Hello,


KE4CDR: "50.75MHz at 1VPP (checked with my siglent oscilloscope (SDS1102cml) and function generator (SDG1032x) freq is right on) I'm getting a 50.83MHz on my SSA"

This is 80 kHz off not 500 Hz

KE4CDR: "Update:  At span 10KHz the peak is right on 50.75KHz"

KE4CDR: "For example at span 50KHz it will flip from 500Khz added to the actual frequency to the correct frequency reading several times going from 50KHz to 51Khz"

KE4CDR: "The SSA reading of the peak at 50.75KHz goes from the correct freq reading to a reading with 500Hz added throughout the span settings."

What ist the true problem?

Best regards
egonotto

mankan:
Your scope and function gen agrees on frequency and your SA does not show the same value for some cases.
How do you conclude that the SA is off frequency and not the scope and func gen?

I do not think there is anything wrong with your SA, just your perception on how the SA is supposed to work. Apologies for being blunt.

ps. I have an SSA 3021X and I get different results depending on span settings and if the SA uses external GPSDO reference or not.
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