Radio terminal station apparatus for SDH network and method of selecting operation clock thereof

A method of selecting an operation clock in a radio terminal station apparatus for an SDH network including plural sets of up-link and down-link transmission systems in each of which a degree of priority is given to its input port part in advance, comprising:

• a clock selection step of selecting a clock of the best quality as the clock in the apparatus from an external clock, an internal clock, and a line clock from each up-link and down-link transmission system connected to the apparatus on the basis of quality information indicating their qualities;
• and
• a multiplexing step of comparing the insertion direction and insertion system to multiplex and insert said quality information with the input direction and system providing the clock in the apparatus, respectively, and, in the case of the insertion system not being the system providing the clock in the apparatus and the insertion direction being opposite to the input direction of the clock in the apparatus and when the priority degree information of the system having an input direction opposite to the insertion direction is a special value defined in advance, multiplexing and sending out the same quality information as said clock in the apparatus,
• wherein the special value defined in advance is not a value that is a priority degree to which other priority degrees can be compared to provide a relative priority.

A recording medium on which a program is recorded for controlling a method of selecting an operation clock in a radio terminal station apparatus for an SDH network including plural sets of up-link and down-link transmission systems in each of which a degree of priority is given to its input port part in advance, said program comprising:

• a clock selection step of selecting a clock of the best quality as the clock in the apparatus from an external clock, an internal clock, and a line clock from each up-link and down-link transmission system connected to the apparatus on the basis of quality information indicating their qualities;
• and
• a multiplexing step of comparing the insertion direction and insertion system to multiplex and insert said quality information with the input direction and system providing the clock in the apparatus, respectively, and, in the case of the insertion system not being the system providing the clock in the apparatus and the insertion direction being opposite to the input direction of the clock in the apparatus and when the priority degree information of the system having an input direction opposite to the insertion direction is a special value defined in advance, multiplexing and sending out the same quality information as said clock in the apparatus,
• wherein the special value defined in advance is not a value that is a priority degree to which other priority degrees can be compared to provide a relative priority.