Initializing method and data transmitter

• US 20040042542A1
• Filed: 04/04/2003
• Published: 03/04/2004
• Est. Priority Date: 10/05/2000
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yasui, Nobuhiko, Takahira, Yutaka, Katta, Noburo, Mizuguchi, Yuji, Sakai, Takahisa, Kawada, Hirotsugu, Kurosaki, Toshihiko
• Granted Patent: US 7,012,936 B2
• Time in Patent Office: Days
• US Class Current: 375/220
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only
• CPC Class Codes: H04L 25/066 Multilevel decisions, not including self-organising maps
• CPC Class Codes: H04L 25/085 Arrangements for reducing interference in line transmission systems, e.g. by differential transmission
• CPC Class Codes: H04L 25/4919 using balanced multilevel codes H04L25/4927 takes precedence
• CPC Class Codes: H04L 7/046 using a dotting sequence
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

A first initialization pattern signal is a signal in which a maximum signal level and a minimum signal level appear alternately, and a second initialization pattern signal is a signal in which all signal levels appear in a predetermined arrangement. In a ring-shaped network including plural stages of data transmission apparatuses (100), a transmission unit (110) of each data transmission apparatus outputs the first initialization pattern signal successively to a next-stage data transmission apparatus at turn-on of power or immediately after reset, and a reception unit (120) establishes clock synchronization on the basis of the first initialization pattern signal received. When synchronization is established in all of the data transmission apparatuses, the transmission unit (110) outputs the second initialization pattern signal successively to the next-stage data transmission apparatus, and the reception unit (120) sets evaluation levels for the respective signal levels on the basis of the received second initialization pattern signal, and transmission/reception of data is started when evaluation levels are set in all of the data transmission apparatuses.

Claims

1. An initialization method to be used in a network in which plural stages of data transmission apparatuses, each performing data transmission while assigning one or more bits of data as one data symbol to a signal level, are connected in a ring shape, wherein

one of the data transmission apparatuses is a master data transmission apparatus, while the other data transmission apparatuses are slave data transmission apparatuses;

at turn-on of power or immediately after reset, the master data transmission apparatus outputs a first initialization pattern signal to a slave data transmission apparatus in the next stage;

the next-stage slave data transmission apparatus establishes clock synchronization on receipt of the first initialization pattern signal;

when clock synchronization is established, the next-stage slave data transmission apparatus outputs the first initialization pattern signal to a slave data transmission apparatus in the next stage;

when synchronization is established in all of the slave data transmission apparatuses and the master data transmission apparatus which are connected in the network, the master data transmission apparatus outputs a second initialization pattern signal to the next-stage slave data transmission apparatus;

the next-stage slave data transmission apparatus receives the second initialization pattern signal, sets an evaluation level for each signal level, and outputs the second initialization pattern to a data transmission apparatus in the next stage; and

transmission/reception of data is started after evaluation levels of data are set in all of the slave data transmission apparatuses and the master data transmission apparatus which are connected in the network.

2. An initialization method as defined in claim 1, wherein

the first initialization pattern signal is a signal in which a maximum signal level and a minimum signal level appear alternately;

and

the second initialization pattern signal is a signal in which all signal levels appear in a predetermined arrangement.

3. An initialization method as defined in claim 2, wherein

the first initialization pattern signal is a signal in which a signal for discriminating between the first initialization pattern signal and the second initialization pattern signal appears at the end.

4. An initialization method as defined in claim 2, wherein

the second initialization pattern signal is a signal in which a signal for discriminating between the first initialization pattern signal and the second initialization pattern signal appears at the beginning.

5. A data transmission apparatus which is connected in a ring-shaped network, and performs data transmission while assigning one or more bits of data as one data symbol to a signal level, said apparatus comprising:

a first initialization pattern output unit for outputting a first initialization pattern signal for establishing clock synchronization to a data transmission apparatus connected in the next stage;

a second initialization pattern output unit for outputting a second initialization pattern signal for setting an evaluation level by which the signal level is subjected to threshold evaluation, to the data transmission apparatus connected in the next stage; and

a synchronization establishment unit for receiving the first initialization pattern signal transmitted from a data transmission apparatus connected in the previous stage, and performing clock reproduction to establish synchronization;

wherein transmission/reception of data is started after synchronization is established on receipt of the first initialization pattern signal, and evaluation levels of data are set on receipt of the second initialization pattern signal.

6. A data transmission apparatus as defined in claim 5 being a master data transmission apparatus in which the first initialization pattern output unit outputs the first initialization pattern signal at turn-on of power or immediately after reset, and the second initialization pattern output unit outputs the second initialization pattern signal when synchronization is established in all of the data transmission apparatuses.

7. A data transmission apparatus as defined in claim 5 being a slave data transmission apparatus in which the first initialization pattern output unit outputs the first initialization pattern signal when synchronization is established, and the second initialization pattern output unit outputs the second initialization pattern signal when the beginning of the second initialization pattern signal is received.