**Goal**:
To estimate the transfer function and the noise in the FC that is a part of the FOL-PID loop.
**Measurements Taken**:
The setup used for the measurements is described in my previous elogs.
The input modulation signal and the FC output were recorded simultaneously for a certain period of time and the phase and gain are estimated from the data.
**Analysis**(Data and code attached):
The recordings must contain equal number of data points(around 6000 data points in my measurements) for analysis.
The steps I followed to generate these plots are:
- Took the FFT of both FC out data(from FC) and Modulation input(from SRS via ADC).
- Estimated the phase angles at the particular modulation frequencies from the FFT data(in Matlab using angle(x) for phase at the frequency f(x);x: is the frequency bin)
- Then for the phase of the system at a particular modulation frequency,
Phase(system) =Phase(FC Signal) - Phase(Input Signal)
- Plotted the acquired phase vs the modulation frequency on a Semi-log graph.
**Results:**
From the plots its can be inferred that :the delay of the FC is almost 0 until the modulation of 0.1 Hz. Then there are phase shifts of +/- 180 degrees showing that the system has multiple poles and zeroes(will be estimated after I have phase plots at few more carrier frequencies).
**To Do Next**:
Phase plots for varying carrier frequencies and different sampling times.
Installation of FC inside the 40m. |