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Sniffing the Rigol's internal I2C bus

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ted572:

--- Quote from: nazar404 on December 05, 2013, 03:08:37 am ---Mr Ted572, Thank you for your great great fix ...  And Thanks to all the people who worked on this project.
I am sure it took many hard hours of work!!! :-+

--- End quote ---
Good job, and congratulations.  All that I did was put together the information I found here.  That is all.  We are all grateful to the people that did all the hard work developing the these upgrades.

bandgap:

--- Quote from: ted572 on December 04, 2013, 08:26:34 pm ---Well that is great news, congratulations.  I will be going ahead also of course, but I have to wait a few days due to a family medical issue.  In the meantime it would be nice to see your before/after spreadsheet data.  It is encouraging to hear that you were able to successfully complete the process.  Thank you for describing your method and offering to share your data with us.

--- End quote ---

Ted,

As promised, here's a plot of my pre-cal / post-cal (for Channel 1, Channel 2 is similar) after I hacked my DG4102 to a DG4202. As you can see, it looks DANG good after the cal.

Here's a little more description of the steps I did (I didn't do things in the cleanest way, but it gave good results, so...)

1) Set cal item to AC amplitude (all measurements here are at 1kHz if I recall correctly.)
2) Go through and record each voltage value (RMS) using DM3068 and DS2202 ("DS2302"). I set each value in the DG using the DM3068 measurement.
3) Fit a line through DS2302 vs DM3068 measurements (needed to do this so that I could correct my scope measurements since it had a small offset)
4) Save and set cal item to LF flat.
5) Set each point value to the measured value on the DM3068.
6) Save and set cal item to HF flat. (DG will automatically set output to 50-ohm for this cal item.)
7) Connect a 50-ohm through terminator to the scope.
8) Use the corrected RMS value from the DS2302 (using the relationship in step 3) and calculate dBm. dBm=10*LOG10(Vrms^2/(50*0.001))  Record this value into the DG for each point.
9) Save and enjoy flat response from DG.

The only problem I have is that I have quite a bit of drop off when I get to low frequencies, say at 1Hz and below. (Is this normal? - Probably not. I'm redoing my channel 2 to see if this problem exists on channel 2.)

EDIT: Added channel 2 plot. Again, below 10 Hz, I'm seeing rapid fall-off (maybe something wrong with my cal method.)  At 1 Hz, I've got around -4 dB (the plots start at 10 Hz, so this isn't shown.) :-//  10 Hz and above is very flat, though.  :-+

Thanks,
Clayton



Pinkus:
Maybe I missed this information in this huge thread:
At a DS2072 (not DS2072A), improved to 200/300 Mhz: can the CAN protocoll analyzer be enabled in any way or not?

Marc M.:

--- Quote from: Teneyes on December 04, 2013, 05:50:41 pm ---...see the values that an Owner with a DG4162 can help as a base line values...
--- End quote ---
I took the time to record the cal values in my DG4162 for the community effort and stuck them in an Excel 97 xls file.  I recorded the values for CH1 first then started to do CH2 and realized they were all identical.  I then did some spot checking of random values and couldn't find any differences between the 2 channels so I didn't spend the time to finish going thru all of CH2. 

I also had a problem reading all the values for LOAD except the first (1-1).  I kept getting a dialog box stating that I needed to remove the 50ohm load.  Both channels were set internally to HI-Z and there were no loads connected to the generator.  I was unable to select any other item under load apart from 1-1. 

I also encountered odd behavior under HFLAT.  When I initially started recording values, the units were in dBm.  At some point I accidentally exited the cal procedure.  When I re-entered it I got a warning dialog that the units were in mVrms :o.  I power cycled the generator and re-entered the HFLAT cal table and it was back to dBm.  I finished recording the dBm values, I jumped out and back in to trigger the mVrms values to record those.  It turns out that they are identical to the dBm values :wtf:  ?? ?? ??

I hope this helps.  If there is anything else I can do to help, feel free to ask.

Marc -

ted572:

--- Quote from: bandgap on December 05, 2013, 04:29:30 am ---
--- Quote from: ted572 on December 04, 2013, 08:26:34 pm ---Well that is great news, congratulations.  I will be going ahead also of course, but I have to wait a few days due to a family medical issue.  In the meantime it would be nice to see your before/after spreadsheet data.  It is encouraging to hear that you were able to successfully complete the process.  Thank you for describing your method and offering to share your data with us.

--- End quote ---

Ted,

As promised, here's a plot of my pre-cal / post-cal (for Channel 1, Channel 2 is similar) after I hacked my DG4102 to a DG4202. As you can see, it looks DANG good after the cal.

Here's a little more description of the steps I did (I didn't do things in the cleanest way, but it gave good results, so...)

1) Set cal item to AC amplitude (all measurements here are at 1kHz if I recall correctly.)
2) Go through and record each voltage value (RMS) using DM3068 and DS2202 ("DS2302"). I set each value in the DG using the DM3068 measurement.
3) Fit a line through DS2302 vs DM3068 measurements (needed to do this so that I could correct my scope measurements since it had a small offset)
4) Save and set cal item to LF flat.
5) Set each point value to the measured value on the DM3068.
6) Save and set cal item to HF flat. (DG will automatically set output to 50-ohm for this cal item.)
7) Connect a 50-ohm through terminator to the scope.
8) Use the corrected RMS value from the DS2302 (using the relationship in step 3) and calculate dBm. dBm=10*LOG10(Vrms^2/(50*0.001))  Record this value into the DG for each point.
9) Save and enjoy flat response from DG.

The only problem I have is that I have quite a bit of drop off when I get to low frequencies, say at 1Hz and below. (Is this normal? - Probably not. I'm redoing my channel 2 to see if this problem exists on channel 2.)

EDIT: Added channel 2 plot. Again, below 10 Hz, I'm seeing rapid fall-off (maybe something wrong with my cal method.)  At 1 Hz, I've got around -4 dB (the plots start at 10 Hz, so this isn't shown.) :-//  10 Hz and above is very flat, though.  :-+

Thanks,
Clayton

--- End quote ---

Thank you very much Clayton.  This is great.

Was it necessary to go through Menu 1 (AC) and 2( LFLAT)? Could you have avoided some of the LF issues (10 Hz and below) by leaving these as they were?

I was assuming before that it may be possible to skip these and just deal with Menu item 3 (HFLAT) (?).

   Thanks for all the info and your help, Ted

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