Control and filtering¶

lock¶

A simple lock which computes and applies the feedback to a given parameter using an error signal.

Syntax:

lock name error_signal feedback gain accuracy disabled=false offset=0

Required:

name: Name of newly created lock.

error_signal: An error signal parameter or an object capable of producing a real-type error signal. This is typically a demodulated PowerDetector instance (or the name of the instance).

feedback: A parameter of the model to apply the locks’ feedback signal to.

gain: Control loop gain.

accuracy: Threshold to decide whether the loop is locked.

disabled: If true this lock will not run when the RunLocks() action is used. Explicitly specifying the name of the lock will override this setting, e.g. RunLocks(name).

offset: An offset that is applied to the error signal before it is used.

degree_of_freedom¶ dof

Syntax:

dof name *node_amplitude_pairs DC=0

amplifier¶

Syntax:

amplifier name gain=1

filter_zpk¶ zpk

A zero-pole-gain filter element that is used for shaping signals in simulations. It is a two port element. p1 is the input port and p2 is the output port. Each one has a single node: p1.i and p2.o.

Syntax:

zpk name z p k=none fQ=false gain=1

Required:

name: Name of element in the model

z: A 1D-array of zeros. Use [] if none are required. By default these are provided in units of radians, not Hz.

p: A 1D-array of poles. Use [] if none are required. By default these are provided in units of radians, not Hz.

gain: Overall gain for the filter. Differs from k as this is a Parameter so can be easily switched on/off or varied during a simulation.

Optional:

k: Gain factor for the zeros and poles. If None then its value is automatically set to generate a unity gain at DC.

fQ: When True the zeros and poles can be specified in a tuple of (frequency, quality factor) for each pole and zero. This automatically adds the complex conjugate pair.

filter_butter¶ butter

Syntax:

butter name order btype frequency gain=1 analog=true

filter_cheby1¶ cheby1

Syntax:

cheby1 name order rp btype frequency gain=1 analog=true