Author Topic: [UPDATE]Strange behavior of HW counter of RIGOL DS1074Z  (Read 5997 times)

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Offline whowe

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[UPDATE]Strange behavior of HW counter of RIGOL DS1074Z
« on: February 06, 2014, 09:50:07 am »
I just got my new RIGOL DS1074Z and replaced my old DS1072U.
When I was playing with it, I found something strange with the hardware counter.

If the DS1074Z is just powered up and I use CH1 to probe the built-in 1KHz calibration signal, the hardware counter reads normal (999.253 Hz, not bad). (See Pic 1).

But if I press "AUTO" button for a quick auto-setting, the hardware counter reads with big error (984.928 Hz). No matter how I adjust the vertical or horizontal or even some other settings, it never come back to normal.  (See Pic 2).

To summarize, before I press "AUTO" button, the counter works; after "AUTO" adjustment, the counter is broken and I have to reboot the DS1072U to make it back to normal.

It happens to every channel.

Is it normal, is there anything I missed? Please help. I really bothers me and confuses me.
« Last Edit: February 18, 2014, 11:37:08 am by whowe »
 

Offline peter.mitchell

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #1 on: February 06, 2014, 10:04:42 am »
Have you tried it with a different signal source?
Just incase the counter still works fine, but it's the built in cal signal that changes?
 

Offline whowe

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #2 on: February 06, 2014, 10:10:30 am »
Have you tried it with a different signal source?
Just incase the counter still works fine, but it's the built in cal signal that changes?

Hi Peter, thank you for your quick reply.
I tried different source, different trigger level and some other settings. Those didn't work.
I also used my Fluke 189 multimeter to measure the frequency of the calibration signal, it was always a perfect 1.0000 kHz.
 

Offline WVL_KsZeN

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #3 on: February 06, 2014, 11:04:37 am »
What happens when you change the # of samples? I noticed something similar on D2072. Your screenshots don't seem to work, so I can't read the # of samples that are taken.
 

Offline whowe

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #4 on: February 06, 2014, 11:39:33 am »
What happens when you change the # of samples? I noticed something similar on D2072. Your screenshots don't seem to work, so I can't read the # of samples that are taken.

In both screenshots (good one and bad one), are 1GSa/s, 6.0Mpts.  I changed it to some different numbers and didn't help.
 

Offline electronics man

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #5 on: February 06, 2014, 11:50:13 am »
That's strange the software counter seems to work
follow me on twitter @get_your_byte
 

Offline fed0r

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #6 on: February 06, 2014, 09:38:18 pm »
Here's a video on the software freq counter drawbacks, and apparently HW counter reads steady 1KHz, even after pressing the auto button. Sooo, your scope may be a bit defective, i guess?
http://youtu.be/bc49tgS3JpA?t=2m55s
« Last Edit: February 06, 2014, 09:41:00 pm by fed0r »
 

Offline whowe

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #7 on: February 07, 2014, 03:17:54 pm »
Here's a video on the software freq counter drawbacks, and apparently HW counter reads steady 1KHz, even after pressing the auto button. Sooo, your scope may be a bit defective, i guess?
http://youtu.be/bc49tgS3JpA?t=2m55s

What's the title of the video? I can't directly access YouTube.

I guess I have to wait until the Rigol guys get back from new year holidays.
 

Offline cybermaus

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #8 on: February 07, 2014, 06:23:53 pm »
Did you notice the +Width also changes? To 505.0uS
Is there a software measurement for the -Width also? Maybe its 511uS?
 

Offline Dave Turner

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #9 on: February 10, 2014, 11:54:10 am »
I checked this out on my DS1074Z-S and got the same result.
 

Offline cybermaus

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #10 on: February 10, 2014, 02:12:10 pm »
Tested, and mine too. Whats more, I had my DMM connected, and it stayed at 1kHz, so its not the calibration signal that is wrong, but the counter itsself.

I also set my -S signal gen to a 1kHz. Same results.

Even more weird: if you change the signal source from the hardware counter to CH4 (nothing connected to CH4) it keeps reading the same 984Hz. But if you disconnect CH1 the readout for CH4 also jumps to infinite. 

Could this be a crosstalk issue? Or a firmware issue (anything can be a firmware issue)

Maybe I should do this again with 50Ohm terminators connected to the other channels.

Edit: with 50 Ohm terminators, the CH4 nicely shows <15Hz. But then when I removed the 50 Ohms, it kept doing so and I could not recreate that issue that CH4 shows the CH1 frequency. The 984Hz issue however was consistently present. After pressing auto, the hardware counter is wrong.

My firmware version is 00.02.00.SP1 DS1074Z-S
« Last Edit: February 11, 2014, 07:33:08 am by cybermaus »
 

Offline cidcorp

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #11 on: February 10, 2014, 06:51:25 pm »
Well I can confirm this does the same thing on the DS1074Z-S I have here on my bench.  After first starting up I get a solid 999.256 Hz on the HW Counter, but
as soon as I hit The AUTO button, the hardware couter shows 984.930.  Software counter seem to work fine no changes.

Yes I also confirmed that if you turn the scope on, place CH1 probe on probe calibration terminal, turn on HW counter - shows 999.256 Hz...change Counter to CH2, CH3 or CH4
and it shows the same value 999.256 (even with no probles on those channels).  Hitting AUTO, drops the value down to 984.930 Hz  :o, and again it stays on the screen whether
you select CH1, CH2, CH3 or CH4 as the counter source.

Seems there is a little firmware issue there.  It's getting the signal from somewhere... haven't tried the terminator but I'd expect the same results.

The terminator part worries me because that makes me think it is not firmware but more of a signal immunity thing. ???

-EDIT: Oh and before I forget, I did check the full range of the Trigger level just to see if that change would affect the counter, but no differences...
« Last Edit: February 10, 2014, 06:53:15 pm by cidcorp »
 

Offline cybermaus

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #12 on: February 10, 2014, 08:04:25 pm »
I did some more testing, and found a pattern, but also an exception to the pattern

So 1000 Hz (1kHz) gives 984.926 Hz?

Well, after pressing Auto:

100Hz      ->  84.2106 Hz
1kHz      ->  984.926 Hz
10kHz    ->  9985.00 Hz
100kHz  ->  99985.0 Hz
1MHz   -> 999.985 kHz (but alternating between 1000000 and 999985)
10MHz-> 10000.0 kHz (so spot on, but due to rounding?)


So it seems like he is always missing to count about 15 pulses per second
Or maybe exactly one pulse, but the refresh rate of the counter is 15/s? That would match the fact the lower limit for the counter seems to be 15Hz (the <15Hz message you get with no signal)

The 10 MHz may only be correct because the last digits is dropped and rounded.


Interestingly, before pressing Auto (so directly after reboot):

100Hz      -> 100.000 Hz
1kHz      -> 1000.00 Hz
10kHz    -> 10000.0 Hz
100kHz  -> 100000  Hz
1MHz   -> 999.985 kHz (still alternating between 1000000 and 999985 ?!
10MHz-> 10000.0 kHz

« Last Edit: February 11, 2014, 07:03:17 am by cybermaus »
 

Offline matkar

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #13 on: February 11, 2014, 12:43:36 am »
I have 00.02.01.SP1 software version and I have this issue too. I've tested on channel 1 on different frequencies. It happens if the signal is square or triangle but it doesn't happen with sine wave. The frequency measurement from the menu on the left side seems unaffected. But on the other hand it's less accurate than the counter.
 

Offline whowe

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #14 on: February 11, 2014, 02:11:42 pm »

Hi, everyone here.
RIGOL just game me a call. They conformed this issue and promised a patch or update.
 

Offline whowe

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Re: Strange behavior of HW counter of RIGOL DS1074Z
« Reply #15 on: February 18, 2014, 11:48:07 am »

Hi, everyone here.
RIGOL just game me a call. They conformed this issue and promised a patch or update.


RIGOL just told me that they have released a new official version and will soon send it to me.
Does anyone know a way to rollback if I dislike the new version?

If anyone is interested, I will post the new firmware after I receive it.
« Last Edit: February 18, 2014, 02:04:45 pm by whowe »
 


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