Issue with impedance voltage for WG using the MI mode

Moku model: Moku Pro
Operating system: iPad
Software version: mokuv2.60b619

Bug or support request description:


I have been trying to set the output impedance voltage on the Waveform Generator (WG) to it’s maximum (10Vpp) in the Multi-Instrument (MI) mode (I want to have a TTL signal that feeds into the Lock-in-Amplifier), but I haven’t been able to do that on the MI mode, only if I use the WG by itself. It keeps saying that the maximum output voltage is ±1V… Is that possible to do or this not available in the MI mode? Can I do this in the API with Python?


Hey Sarah, the reason for this is because in MiM the WG does not know whether it’s output is being routed to another instrument slot (2 Vpp max) or to the outputs (max voltage based on gain, 0dB = 2Vpp and +14dB = 10Vpp). So in the app it is limited to 2 Vpp but the gain applied at the output still allows 10 Vpp maximum. More information can be found on our knowledge base here.

Yes, it is possible to do this in the python API, you will just have to make sure you set the appropriate gain for the output that you have routed that WG signal to just like in the app.

For your application specifically, you are wanting to pass a 5V TTL signal into the LIA via MiM. Since the inter-instrument buses are limited to 2 Vpp, this would mean that you would have to route the signal to one of the Moku:Pro outputs to generate the 10 Vpp signal, then loop it back to one of the inputs and have that as your input to the LIA. I know it is a bit of a workaround, but the reason the inter-instrument buses are limited to 2 Vpp is due to FPGA limitations which we are not able to alter. I hope this helps!

1 Like