We are currently building an experiments about lock-in amplifiers with Moku:Go and have following problems when use the device.
- The value of input signal (show with the figure 1)
A calibrated R&S RF signal source is used to produce a CW signal with 1 MHz and a series amplitude from 0.06 V to 0.4 V.
Input these signals into the input port 1 of Moku:Go box.
Then we use the desktop app of Moku, run the Lock-in amplifier function, set the “A” probe on the “In 1” point.
Switch on the RF signal source out, the waveform and the amplitude could be observed.
The values displayed on two devices have a quite large difference, show as follow:
Signal Source Value (V): 0.06 0.07 0.08 0.09 0.10 0.20 0.30 0.40 Moku device app value (V): 0.17 0.20 0.23 0.26 0.29 0.67 1.01 1.34 Ratio (Moku / Signal): 2.83 2.86 2.88 2.89 2.90 3.35 3.36 3.35
The change of the difference is not linear either.
Thus we guess if there is an amplifier at the input of Moku device?
How could we fix this difference?
- The noise at input port (show with the figure 2)
Continue with the above setting, when the RF signal source output are switched off,
there is still a 2.44 mV exist at “In 1”.
We’re not sure if this is normal?
Is there any way to reduce this value?
- Self defined data acquisition
We also use Python to read the data from Moku device and we notice there is a similar topic:
We need API that the frame length could be self defined (2^n or arbitrary number).
It mentioned that related features are under development and testing.
What is the situation now and any progress?
Thank you for your attention and looking forward to your replies.