Today, we ran a little test of the SAFARI demux/fee-scripts. It's the second time this week, and I'm quite happy how it all turns out.
We're finding some issues, but it's developing into a base from which we build a complete system. First we tested the menu for the testpulse generator.
This is an important part, because the testpulse generator can simulate a detector (with a pulse, it's like a particle hit the bolometer). It's fed into the feedback. Besides pulses, we can also generate a square wave. This allows the user to inject high frequencies into the system, which is apparently used to assess its robustness. For now, I'm just taking note of that.
When that appeared to work, we continued with the pixel menu. This is a part of the script that allows you to put a carrier wave routed to a certain pixel. You can change characteristics such as amplitude and frequency. We found some bugs there, but nothing serious.
We then turned on pixel 1, and routed the testpulse generator to that pixel, configured to generate pulses.
The plot option has a number of options. The above plot is a "normal" plot (in the time domain). If you would zoom in, you'd see a sinus. The plot shows 400,000 samples or so, thus we'd just see a dense area plotted. The first part of the plot is pre-trigger data. Then the test signal generator pulses, and the amplitude drops. The logic behind that, is that our sensor behaves like a resistor. Upon particle impact, the resistance raises, thus the amplitude of our biasing signal is lowered. And that's why you see the "trough" in the plot above.
It's also possible to get a spectrum (i.e. plot in the frequency domain). We played with that too, and found some issues there.
Finally, we used the Demux Test menu choice, and configured it to grab data from ADC 1, which measures the error signal. This is the difference between the feedback and the input of the SQUID. The error signal is the cause of overdriving the SQUID. Because it's so sensitive to this, we want to eliminate the error signal as much as possible -- thus it's important that users can measure and plot this signal.
All in all, a nice result to head into the weekend.