Products > Test Equipment
SainSmart DDS120 & DDS140 USB Oscilloscope
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doctormord:
Confirmed.

Regards,

doc
sandos:
I was looking at DDS120 before buying the Hantek6022, but it seems the community around the sainsmart is even more lively than that around the Hantek!

I assume you people have already seen https://github.com/rpm2003rpm/HT6022_Driver which is a libusb based driver for the 6022. You guys seem to have an even better grasp of things, so this might not change anything. I am curious though what the exact differences are between the DDS120 and the 6022? I am planning on writing an android app to talk to the Hantek, by simply translating the libusb code to androids native usb host API. Was planning on doing it in java to start with, even though performance is likely to suffer. I was also planning on using the 1Khz square wave to try ascertain any "dead periods", but I will have to see how that works out.
doctormord:
The 6022 got no AC-coupling.
doctormord:

--- Quote from: psynapse on November 01, 2014, 05:21:33 pm ---I would suggest that (for DDS120 users) channel interleaving might be really useful, doubling the maximum acquisition rate, but wouldn't that need a small hardware modification? There are several ways of tackling that problem,  which one are you thinking of?
--- End quote ---

Sure, we need to double the ADC-frequency at first, i.e.:

http://www.maximintegrated.com/en/app-notes/index.mvp/id/3327

and then attach a phase-splitter (0/180) to feed both channels seperately. The AFE might some compensation due to lower the (now) lowered input impedance.

Alternatively, the clock needs to be shifted by 1/2 clock-cycle to feed into ENCA/ENCB. (Without frequency doubling)
Should work with "data aligning enabled" - or the delay needs to be corrected in the host-app.
psynapse:
All,

Sorry I have gone quiet a couple of days, I have been improving my Qt skills (which did not exist).  Except for the all important trace display, I now have Donut6 code running under Qt,  which is probably easy for all you young guys out there , but has proved very difficult for me. When I have graphics up and running, I shall go back to the firmware.

Doctormord,

Obviously phase inverting the clock to one ADC is the easiest solution conceptually, but I rather guess it demands taking the ADC off the board in order to cut the trace beneath the chip itself.  That is something you are capable of,  but it is way too difficult for me! Perhaps lift a leg (but a pretty poor engineering solution).

Also, not sure whether you have seen this information from the ADC datasheet

"The other option allows the user to skew the B channel output
data by 1/2 of a clock cycle. In other words, if two clocks are fed
to the AD9288 and are 180° out of phase, enabling the data
align allows Channel B output data to be available at the rising
edge of Clock A. If the same Encode clock is provided to both
channels and the data align pin is enabled, then output data
from Channel B is 180° out of phase with respect to Channel A.
If the same Encode clock is provided to both channels and the
data align pin is disabled, both outputs are delivered on the
same rising edge of the clock.
Table 4. User-Selectable Options
S1        S2     Option
0           0       Standby Both Channels A and B.
0           1       Standby Channel B Only.
1           0       Normal Operation (Data Align Disabled).
1          1        Data Align Enabled (data from both channels avail-
                       able on rising edge of Clock A. Channel B data is
                       delayed a 1/2 clock cycle).

Badly expressed, but seems to suggest that programming the S1 S2 pins might get us what we want
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