Method of phase-synchronizing a transit exchange in a digital telecommunication network

Claim 2

Method of synchronizing the phase of clocks from links from different stations in a transit exchange in a digital telecommunication network, including a signal-controlled oscillator, the output of which is dependent on collectively weighted phase differences between a local exchange clock and the clocks of the other stations, characterized in that for avoiding a phase jump the following steps are carried out: a signal corresponding to the phase difference is sampled for each of the incoming links, producing sampled values; the sampled values are differentiated, producing differentiated values; the differentiated values are compared with a limiting value for indicating a phase jump when said limiting value is exceeded; when this limiting value is exceeded, a compensation signal having a control signal's highest value but with opposite sign is added to the differentiated value to form a compensated differentiated value; after possible weighting, the compensated differentiated value is added to the compensated differentiated values corresponding to other links, producing a sum value; and the sum value is integrated for obtaining the control signal.

Claim 3

Apparatus for synchronizing the phase of clocks from links from different stations in a transit exchange in a digital telecommunication network, including a signal-controlled oscillator (K1) the output of which is dependent on collectively weighted phase differences between a local exchange clock and the clocks of the other stations as claimed in claim 1, characterized in that the apparatus includes: phase detectors (2) for sensing the phase difference between the local exchange clock from the signal-controlled oscillator and the clocks of each of the incoming links for generating a signal proportional to the phase difference; differentiation circuits (3) for differentiating said phase difference-proportional signal, producing a differentiated signal; compensation means (6) for adding to the differentiated signal, in response to the differentiated signal exceeding a given value, a compensation signal with opposite sign and corresponding to the greatest value of a control signal to form a compensated differentiated signal; a summing circuit (10) for adding, after possible weighting, the compensated differentiated signal to the compensated differentiated signals from other links, forming a summing result; and integration means (1) for integrating the summing result to obtain the control signal.

Claim 4

Method of synchronizing the phase of clocks from a link from a different station in a transit exchange in a digital telecommunication network, including a signal-controlled oscillator, the output of which is dependent on phase differences between a local exchange clock and the clock of the other station, characterized in that for avoiding a phase jump the following steps are carried out: a signal corresponding to the phase difference is sampled for the incoming link, producing sampled values; the sampled values are differentiated, producing differentiated values; the differentiated values are compared with a limiting value for indicating a phase jump when said limiting value is exceeded; when this limiting value is exceeded, a compensation signal having a control signal's highest value but with opposite sign is added to the differentiated value to form a compensated differentiated value; the compensated differentiated value is processed for obtaining the control signal.

Claim 5

Method of synchronizing the phase of clocks from a link from a different station in a transit exchange in a digital telecommunication network, including a signal-controlled oscillator, the output of which is dependent on phase differences between a local exchange clock and the clock of the other station, characterized in that for avoiding a phase jump the following steps are carried out: a signal corresponding to the phase difference is sampled for the incoming link, producing sampled values; the sampled values are differentiated, producing differentiated values; the differentiated values are compared with a limiting value for indicating a phase jump when said limiting value is exceeded; when this limiting value is exceeded, a compensation signal having a control signal's highest value but with opposite sign is added to the differentiated value to form a compensated differentiated value; the compensated differentiated value is processed for obtaining the control signal.

Claim 6

The method of claim 3 wherein said processing is an integration step.