set_demodulation

Configures the demodulation source and optionally its frequency and phase

Demodulation source descriptions

Internal

The Internal option allows the use of the local oscillator that is generated internally. This oscillator utilizes the same timebase as the clock reference. Note: Moku devices with an external clock reference port can be synchronized with an externally connected device. Read more about configuring the external reference clock.

External

The External option allows the second input channel to be used as the reference oscillator. This also allows non-sinusoidal references to be used as the demodulation source, and can be used to measure correlation or recover specific components of complex input signals. As the external signal can be an arbitrary shape, it cannot be used to perform dual-phase demodulation, it can only interrogate one quadrature, X.

External PLL

The External (PLL) option allows the second input channel to be used as the reference oscillator for dual-phase demodulation. The option uses a digitally implemented phase-locked loop (PLL) to track the phase of the external reference with a user-selectable bandwidth. The PLL allows the instrument to generate synchronized in-phase and quadrature sinusoids at the same frequency, with adjustable phase and frequency multipliers. This mode enables the Lock-in Amplifier to recover both quadrature signals without sharing the same timebase as the external signal.

None

The None option can be used to bypass the mixing operation, passing the signal directly to the lowpass filter. This is useful if the necessary signal extraction is done on an external system or another instrument in Multi-Instrument Mode, and enables modulation-free locking techniques such as DC locking, side-of-fringe locking, and tilt locking.

Parameters

mode string required

The demodulation source

allowed values:Internal, External, ExternalPLL, None

frequency number

Frequency of internally-generated demod source

default: 1000000

allowed values:

units: Hz

phase number

Phase of internally-generated demod source

default: 0

allowed values:

units: degrees

strict boolean

Disable all implicit conversions and coercions.

default: true

Examples

Sample response

{
    "frequency": 1000000.0,
    "mode": "Internal",
    "phase": 0.0
}