Products > Test Equipment

Upcoming Rigol DSG815/830

<< < (6/18) > >>

TurboTom:
I'ld rather think that Rigol simply didn't finish the I/Q add-on board at the time they first released the DSG800 series and had to create some cash flow to compensate for the design expenses of the project. The option to install an add-on I/Q board is clearly present on the early models and shown in Dave's DSG815 teardown, and hardware-wise, there's no indication that it wouldn't be operational.

Moreover, there's just a single firmware available for the whole range of instruments. I'ld rather say that after Rigol produced the initial batch of instruments, they quickly realized that the hardware is capable of more than initially anticipated, so they upped the bandwidth to 2.1GHz vs. 3.6GHz (of the 1.5G and 3G models, respectively) and finished the I/Q module and the accompanying firmware extensions. Shame that they don't offer the add-on as a separate option so users of the basic version can later on decide to upgrade to I/Q functionality.

tv84:

--- Quote from: TurboTom on July 10, 2020, 07:29:31 am ---Shame that they don't offer the add-on as a separate option so users of the basic version can later on decide to upgrade to I/Q functionality.

--- End quote ---

Yes but that is  also a factor behind my theory.

TurboTom:
We can only know for sure after someone posts a detailed set of photos of a DSG800A teardown.

With the help of Rigol's spec sheet of the DSG800(A) I've been able to complete my flow scheme of the DSA815 of Dave's teardown (sorry for the "ill" choice of colours, some lables have to be magnified to be deciphered -- maybe I'll draw a block diagram to simplify understanding the signal flow). I added signal frequencies as far as possible.

Considering Rigol's preference of Hittite / Analog components, my best bet for the I/Q modulator they used on the add-on board would be the HMC1097. Unfortunately, Hittite's evaluation board for this chip isn't as complete to permit a direct use in the DSG since it requires differential I and Q signals. In order to achieve a good carrier suppression over the whole frequency range, it may also be necessary to adjust the I and Q bias levels depending on the LO frequency. So there probably is an additional look-up table stored soemwhere on Rigol's IQ add-on board. Likely just too much hassle for a DIY solution.

But there may be a real chance for a frequency upgrade... Seems like hardware-wise, evereything's already there.

tv84:

--- Quote from: TurboTom on July 10, 2020, 01:21:00 pm ---But there may be a real chance for a frequency upgrade... Seems like hardware-wise, evereything's already there.

--- End quote ---

Nice work!  :-+

noreply:
OK noticed some other interesting parameters ....

001A - PLL              PLL         :SERVice:SET:BANDwidth:MODE:PLL
001B - DETect           DET         :SERVice:SET:BANDwidth:MODE:DETect
001C - MODulation       MOD         :SERVice:SET:BANDwidth:MODE:MODulation
001D - ALC              ALC         :SERVice:SET:BANDwidth:MODE:ALC

These are ONLY SET commands - so critical

BUT you can set the PLL BANDWITH - really stupid if Rigol has defined model independent of BW setting - possibly can set the 3.6GHz BW here??

Problem is there is no equivalent READ command - so we can see what the current setting is set at??

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod