ENGINEERING REPORTS Digital Audio Modulation in the PALand NTSCOptical Video Disk Coding Formats*

An extension of the current optical video disk format that includes a digital audio signal is presented. The feasibility of a combined digital audio signal according to the Compact Disc digital audio format and the current analog audio signals in the NTSC video format is described, which permits the realization of a compatible system. For the PAL and SECAM video formats the feasibility of digital audio is shown, but it cannot be combined with the analog audio carriers. 0 INTRODUCTION an important role in the overall design. A low modulation index of the digital audio signal results in a poor In the current optical video disk coding formats signal-to-noise ratio, giving rise to a high bit error (NTSC, PAL, and SECAM) the analog audio stereo rate. Many experiments have been done to arrive at a channels are frequency-modulated and added by means compromise on these conflicting parameters

Sensor device with alternating excitation fields

The invention relates to a magnetic sensor device comprising excitation wires (11, 13) for generating a magnetic excitation field and a magnetic sensor element, particularly a GMR sensor (12), for sensing magnetic fields generated by labeling particles in reaction to the excitation field. The magnetic excitation fields are generated with non-sinusoidal forms, particularly as square-waves, such that their spectral range comprises a plurality of frequency components. Magnetic particles with different magnetic response characteristics can then be differentiated according to their reactions to the different frequency components of the excitation fields. The magnetic excitation field and the sensing current driving the GMR sensor (12) are preferably generated with the help of ring modulators (22, 24). Moreover, ring modulators (27, 29) may be used for the demodulation of the sensor signal