Multirate generator and multirate generating method

A multirate generator for generating a rate signal and a multirate signal having a subrate period and a subrate number which are set for each period of the rate signal, the multirate generator comprising:

• a first counter which takes the rate signal as a mode selection input, and in a load mode, counts down rate data to specify a period with which the rate signal is to be generated on the basis of a timing of an inputted clock, and outputs an obtained first count value;
• a first detection circuit which outputs a rate signal which comes to be at a specified level each time the first count value becomes a specified value;
• a second counter which takes the multirate signal as a mode selection input, and in a load mode, counts down multirate data to specify a subrate period with which the multirate signal is to be generated on the basis of a timing of the inputted clock, and outputs an obtained second count value;
• a second detection circuit which detects that the second count value becomes a specified value and outputs it as a detection signal;
• an OR gate which makes and outputs an OR signal of the detection signal and the rate signal;
• an AND gate which makes an AND of the OR signal and a mask signal and outputs it as the multirate signal;
• a third counter which takes the rate signal as a mode selection input, and in a load mode, counts down multirate data to specify a subrate number of the multirate signal to be generated on the basis of a timing of the multirate signal, and outputs an obtained third count value;
• and
• a third detection circuit which detects that the third count value becomes a predetermined value and outputs it as the mask signal.

A multirate generating method for generating a rate signal and a multirate signal having a subrate period and a subrate number which are set for each period of the rate signal, the multirate generating method comprising the steps of:

• taking the rate signal as a mode selection input, and in a load mode, counting down rate data to specify a period with which the rate signal is to be generated on the basis of a timing of an inputted clock, and generating a rate signal which comes to be at a predetermined level each time an obtained first count value becomes a predetermined value;
• taking the rate signal as a mode selection input, and in a load mode, counting down multirate number data to specify a subrate number of the multirate signal to be generated on the basis of a timing of the multirate signal, detecting that an obtained third count value becomes a predetermined value, and outputting it as a mask signal;
• and
• taking the multirate signal as a mode selection input, and in a load mode, counting down multirate data to specify a subrate period with which the multirate signal is to be generated on the basis of a timing of the inputted clock, outputting a detection signal by detecting that an obtained second count value becomes a predetermined value, making an OR signal of the detection signal and the rate signal, making an AND of the OR signal and the mask signal, and generating it as the multirate signal.

A multirate generating method for generating a rate signal and a multirate signal having a subrate period and a subrate number which are set for each period of the rate signal, the multirate generating method comprising the steps of:

• taking the rate signal as a mode selection input, and in a load mode, counting down rate data to specify a period with which the rate signal is to be generated on the basis of a timing of an inputted clock, and outputting an obtained first count value;
• outputting a rate signal which comes to be at a predetermined level each time the first count value becomes a predetermined value;
• taking the rate signal as a mode selection input, and in a load mode, counting down multirate number data to specify a subrate number of the multirate signal to be generated on the basis of a timing of the multirate signal, and outputting an obtained third count value;
• detecting that the third count value becomes a predetermined value and outputting it as a mask signal;
• taking the multirate signal as a mode selection input, and in a load mode, counting down multirate data to specify a subrate period with which the multirate signal is to be generated on the basis of a timing of the inputted clock, and outputting an obtained second count value;
• detecting that the second count value becomes a predetermined value and outputting the detection signal;
• generating and outputting an OR signal of the detection signal and the rate signal;
• and
• making the OR of an AND signal and the mask signal and outputting it as the multirate signal.