Abstract: Following a loss of track, the laser beam in a compact disc audio player is returned to the position at track loss by a "go-to" control signal signifying the number of tracks between the end position after track loss and the position at track loss. Preferably, an incremental position is added to the track loss position so that the beam is returned to the position it would have reached had no track loss occurred.

Abstract: Receiver for a search tuning circuit which in a wave range effects a presearch operation to determine a receiving condition criterion and effects thereafter in that waverange a search operation to find a transmitter satisfying the receiving condition criterion, the receiver comprising a circuit (124) whereby the presearch operation is limited to a frequency range less than one fifth of the wave range and the subsequent search operation starts at a frequency which is removed by at least the receiver bandwidth from the transmitter last received when no receivable transmitter is detected during the presearch operation.

Abstract: Signal comparison arrangement for comparing a first and a second analog signal with each other. For each of these signals the number of zero-crossings occurring within each measuring interval of a sequence of N consecutive measuring intervals T(1), T(2), . . . T(N) is counted. The N numbers x(1), x(2), . . . x(N) which represent the numbers of zero-crossings of the first analog signal in the consecutive measuring intervals T(1), T(2), . . . T(N) and the N numbers y(1), y(2), . . . y(N) which represent these numbers of zero-crossings of the second analog signal in the said measuring intervals, are applied to a programmable computer which determines the value of a statistical quantity by means of these 2N numbers and compares this value with a threshold value. This statistical quantity may be formed by the directional coefficient of a straight line which is closest to either the N numbers x(n), or the N numbers y(n), but may alternatively be formed by the correlation coefficient.