Arrangement for generating a decoder clock signal
View Patent ↗The invention relates to an arrangement for generating a decoder clock signal for decoding a data signal which is available together with a clock signal and a data word signal signalizing data words, both of which signals may each have different frequencies. The arrangement comprises a phase control circuit ( 1 ) which receives the clock signal and supplies the decoder clock signal from its output, and which comprises at least one adjustable divider ( 14 ) which is preferably arranged at the input of the phase control circuit ( 1 ) and whose division ratio is adjustable.
1. An arrangement for generating a decoder clock signal for decoding a data signal which is available together with a clock signal and a data word signal signalizing data words, both of which signals may each have different frequencies, the arrangement comprising: a phase control circuit which receives the clock signal and supplies the decoder clock signal from its output, and which comprises at least one adjustable divider which is preferably arranged at the input of the phase control circuit and whose division ratio is adjustable, and a detector which determines at least the ratio between the frequency of the clock signal and the frequency of the data word signal and adjusts, in dependence upon this frequency ratio, the division ratio in the adjustable divider in such a way that the frequency of the decoder clock signal has a fixed, predetermined frequency ratio with respect to the frequency of the data word signal in the case of all possibly occurring frequency ratios between the clock signal and the data word signal.
2. An arrangement as claimed in claim 1 , characterized in that the arrangement comprises three dividers, one of which is arranged at the input and at the output of the phase control circuit and one is arranged in the feedback loop of the phase control circuit between its controlled oscillator and its phase comparator, and at least one of which, preferably the divider arranged at the input of the phase control circuit, has an adjustable division ratio.
3. An arrangement as claimed in claim 1 , characterized in that a table is provided from which a suitable value of the division ratio for the adjustable divider or dividers is obtainable for every possibly occurring frequency ratio between the frequency of the clock signal and the frequency of the data word signal.
4. An arrangement as claimed in claim 1 , characterized in that the data signal is a digital sound signal and the data word signal has a frequency corresponding to the sampling frequency of the digital sound signal.
5. An arrangement as claimed in claim 4 , characterized in that a second mode of operation is provided in which the phase control circuit in the arrangement receives a quartz oscillator signal instead of the clock signal and in which the division ratios of the variable dividers are adjusted at predetermined values which are chosen to be such that the frequency of the output signal of the phase control circuit has a predetermined value.
6. An arrangement as claimed in claim 1 , characterized in that a third mode of operation is provided which is chosen when the occurring frequency ratio between the frequency of the clock signal and the frequency of the data word signal does not have any of a plurality of predetermined nominal values.