Abstract: The characteristic test device 1 supplies the output from the photo detector of the optical pickup 2, as signals A to F, directly to the sample hold circuits 8a-8f. The sample hold circuits 8a-8f, the multiplexer 9, and the second analog/digital converting circuit 10 convert the signals A to F into digital data with the sampling frequency of 50 KHz or more. In the computer 12, the processing division 12d reads out the indicated program from the data storage division 12b, where the program P for measuring the level of RF signal, is stored. The processing division 12d performs the operation of the indicated measurement items, based on the digital data stored in the second memory 11, then measures the characteristic of the optical pickup 2.

Abstract: A jitter measurement device for reproducing a signal from an optical disc, which has simple circuit configuration and can effectively measure the jitter component. A matrix circuit 4 supplies the RF signals to the analog/digital converting circuit 6. Second, the computer 8 computes the slice level from the digitized data of the RF signals. Computer 8 computes the time point at which the RF signals become the indicated slice level, by interpolating, based on the digital data at the sampling point in the neighborhood of the said slice level, and the sampling frequency of the analog/digital converting circuit 6. A computer 8 computes each time breadth between the time points at which the RF signals become the slice level, then computes the jitter component of the reproduced signal, based on the each time breadth.