We can modulate the detector at the same frequency as the excitation for homodyne detection - or at a slightly different frequency for heterodyne detection.
This causes the heterodyne beat intensity to oscillate at the corresponding Dopplershifted frequency.
In heterodyne SLDV, a scanned laser beam incident on the vibrating test surface undergoes a Doppler radial frequency shift proportional to the instantaneous velocity.
In the finished models of the theremin, volume levels were controlled by means of a comparable heterodyne effect triggered by the player's other hand.
The system achieves this by measuring the target velocity of the cylinder carrier from optical phase shift, using an optical heterodyne interferometer to exploit the temporal, rather than spatial, coherence of the laser.
Due to spatial frequency heterodyning , upper and lower side band information falls in the pass band of the imager.
When the two frequencies were mixed, or heterodyned , the difference between them resulted in a third frequency; it was this so-called ‘difference tone’ that was amplified and channeled to a loudspeaker.
This mixer heterodynes the IF against the VFO to produce a signal at 455 kc.
This intermodulation creates an effect called heterodyning , where additive and subtractive tones, known as beat frequencies, are created.
When blue and green colored light are mixed, a cyan colored light can be produced by heterodyning .