Modem apparatus, communication apparatus and communication control method
View Patent ↗The present invention calculates a product of the present sampling data by the sampling data one data unit ahead through a multiplier, adds up product values calculated for every sampling by adding product values calculated from previous samples occurring one data unit in advance through an adder and detects a reference timing with regard to a CP (cycle prefix) signal using the addition value.
1. A modem apparatus comprising:
a sampling section that samples a reception signal;
a multiplier that calculates a product of the present sampling data by the sampling data one data unit ahead;
an adder that adds up product values calculated for every sampling by adding product values calculated from previous samples occurring one data unit in advance; and
a detector that detects a reference timing with regard to a cyclic prefix signal using an addition value calculated by said adder.
2. The modem apparatus according to claim 1 , wherein said detector detects a minimum value from a time series data of said addition value and recognizes a sampling timing corresponding to the detected minimum value as said reference timing.
3. The modem apparatus according to claim 1 , wherein said detector detects a sampling timing at which a sum of products of each sampling data item corresponding to a final symbol of a REVERB signal sent in an initializing signal by each sampling data item corresponding to a first symbol of a SEGUE signal sent following said REVERB signal is output as said reference timing.
4. The modem apparatus according to claim 2 , wherein a position nine symbols ahead of the sampling timing corresponding to said minimum value is recognized as a beginning of the cyclic prefix signal.
5. An ADSL terminal side apparatus equipped with the modem apparatus according to claim 1 .
6. An ADSL station side apparatus equipped with the modem apparatus according to claim 1 .
7. A communication apparatus equipped with the modem apparatus according to claim 1 .
8. A communication control method comprising:
sampling a reception signal;
calculating a product of the present sampling data by the sampling data one data unit ahead;
adding product values calculated for every sampling by adding product values calculated from previous samples occurring one data unit in advance; and
detecting a reference timing with regard to a cyclic prefix signal using an addition value.
9. The communication control method according to claim 8 , wherein a minimum value is detected from a time series data of said addition value and a sampling timing corresponding to the detected minimum value is recognized as said reference timing.
10. The communication control method according to claim 8 , wherein a sampling timing at which a sum of products of each sampling data item corresponding to a final symbol of a REVERB signal sent in an initializing signal by each sampling data item corresponding to a first symbol of a SEGUE signal sent following said REVERB signal is output as said reference timing.
11. A modem apparatus, receiving, in a initialization sequence, symbols of a signal to which a cylic prefix signal is added, after receiving a predetermined number of symbols of a SEGUE signal, the modem apparatus comprising:
a sampler configured to sample a received signal by each predetermined symbol;
a multiplier configured to multiply sampling data of a present symbol by sampling data of one symbol unit in advance;
an adder configured to cumulatively add an output value of the multiplier, the output value having a polarity;
a detector configured to detect a minimum value output by the adder;
a judger configured to judge a starting position of the cyclic prefix signal, based on the minimum value, the minimum value indicating a boundary between a first symbol of the SEGUE signal and a second symbol of the SEGUE signal, the starting position of the cylic prefix signal coming after the predetermined numbers of symbols of the SEGUE signal.
12. The modem apparatus according to claim 11 , wherein the predetermined numbers of symbols of the SEGUE signal comprises ten symbols of the SEGUE signal.
13. The modem apparatus according to claim 12 , wherein the judger judges that the starting position of the cyclic prefix signal comes after the ninth symbol of the SEGUE signal from the detection of the minimum value.
14. An ADSL terminal side apparatus equipped with the modem apparatus according to claim 11 .
15. An ADSL station side apparatus equipped with the modem apparatus according to claim 11 .
16. A communication apparatus equipped with the modem apparatus according to claim 11 .
17. A communication control method, symbols of a signal to which a cylic prefix signal is added, being received after a predetermined number of symbols of a SEGUE signal being received in a initialization sequence, the communication control method comprising:
sampling a received signal by each predetermined symbol;
multiplying sampling data of a present symbol by sampling data of one symbol in advance;
cumulatively adding an output value of the multiplier, the output value having a polarity;
detecting a minimum value output by the adder;
judging a starting position of the cyclic prefix signal, based on the minimum value, the minimum value indicating a boundary between a first symbol of the SEGUE signal and a second symbol of the SEGUE signal, the starting position of the cylic prefix signal coming after the predetermined numbers of symbols of the SEGUE signal.