Synchronised control method of a plurality of formatting equipment and stream formating equipment
View Patent ↗The present invention relates to the domain of control methods of a plurality of formatting equipment (FE 1 , FE 2 ) of streams (TS) used as backup. The items of equipment receive the streams (TS) and send, to a modulator (MOD 1 ), formatted streams (TS_SFN 1 , TS_SFN 2 ) comprising a succession of blocks of packets called “megaframe” and megaframe initialization packets (MIP) used by the modulator (MOD 1 ) to identify in time a megaframe (MF n ) relatively to a time base (TB). According to the invention, the method comprises steps consisting in: defining a reference date (DREF) that corresponds to the transmission date of a megaframe (MF 1 ), determining a current date (DCOUR) common to the equipment (FE 1 , FE 2 ), determining a temporal position (POS) of a megaframe (MF n ) after the date (DCOUR) in relation to the time base (TB) from a temporal position of the megaframe (MF n ) determined in relation to the date (DREF), determining a megaframe initialization packets (MIP) content from the temporal position (POS), inserting the packet (MIP) in the formatted streams (TS_SFN 1 , TS_SFN 2 ).
1. Synchronised control method of a plurality of formatting equipment (FE 1 , FE 2 ) of streams (TS), said items of equipment (FE 1 , FE 2 ) receiving the stream (TS) and transmitting to at least one modulator (MOD 1 , MOD 2 ) a formatted stream (TS_SFN 1 , TS_SFN 2 ) each comprising a succession of blocks of packets called “megaframes” (MF 1 , MF 2 , . . . , MFn) and megaframe initialisation packets (MIP) comprising a pointer to a subsequent megaframe, said packets (MIP) being used by the modulator (MOD 1 , MOD 2 ) to temporally identify a temporal position of a megaframe (MFn) relatively to pulses supplied by a time base (BT), said pulses being received by the items of equipment (FE 1 , FE 2 ) and the modulator (MOD 1 , MOD 2 ), the method comprising:
defining a reference date (DREF) that corresponds, by convention, to the transmission date of a megaframe (MF 1 ) by the equipment (FE 1 , FE 2 ), said date (DREF) is expressed in a time system (TAB) and is common to the plurality of equipment (FE 1 , FE 2 ), and at each transmission of a megaframe (MFn):
determining a current date (DCOUR) from a clock (HA) common to the plurality of equipment (FE 1 , FE 2 ), said date (DCOUR) is expressed in the time system (TAB),
determining a temporal position (POS) of a megaframe (MFn+1) relatively to the time base (TB) from a temporal position of the megaframe (MFn+1) determined relatively to the reference date (DREF),
determining a megaframe initialisation packet (MIP) content from the temporal position (POS),
inserting the megaframe initialisation packet (MIP) in the formatted stream (TS_SFN 1 , TS_SFN 2 ).
2. Method according to claim 1 , the time base (TB) delivering the main pulses having a period TB, wherein the determination step of the current date (DCOUR) has a better accuracy than TB/2.
3. Method according to claim 2 , the time base (TB) further delivering secondary pulses having a period TA, where TA is less than TB, wherein the temporal position (POS) is expressed in a number of periods TA.
4. Method according to claim 1 , wherein the definition step of the date (DREF) consists in a reading of a date value (DREF) stored in a storage means of the equipment (FE 1 , FE 2 ).
5. Method according to claim 1 , wherein the formatted streams (TS_SFN 1 , TS_SFN 2 ) comply with the DVB standard.
6. Method according to claim 1 , wherein the formatted streams (TS_SFN 1 , TS_SFN 2 ) comply with the ISDB-T standard.
7. Method according to claim 1 , wherein the formatted streams (TS_SFN 1 , TS_SFN 2 ) comply with the ATSC standard.
8. Method according to claim 1 , wherein the formatted streams (TS_SFN 1 , TS_SFN 2 ) comply with the CMMB standard.
9. System for driving a plurality of equipment (FE 1 , FE 2 ) for formatting streams (TS), said system comprising said equipments (EF 1 , EF 2 ), at least one modulator (MOD 1 , MOD 2 ) and a time base (BT), said equipment (FE 1 , FE 2 ) delivering a formatted flow (TS_SFN 1 , TS_SFN 2 ) to the modulator (MOD 1 , MOD 2 ), the flow (TS_SFN 1 , TS_SFN 2 ) comprising a succession of blocks of packets called “megaframe” (MF 1 , MF 2 , . . . , MFn) and megaframe initialisation packets (MIP) comprising a pointer to a subsequent megaframe, said packets (MIP) being used by the modulator (MOD 1 , MOD 2 ) to identify temporal positions of subsequent megaframes (MFn) relatively to pulses supplied by a time base, said pulses being received by the item of equipment (FE 1 , FE 2 ) and the modulator (MOD 1 , MOD 2 ), the system comprising:
a memory configured to store a reference date (DREF) that corresponds, by convention, to the date at which a megaframe (MF 1 ) is transmitted by the equipment (FE 1 , FE 2 ), said date (DREF) is expressed in a time system (TAB) and is common to all the equipment (FE 1 , FE 2 ),
a timing module (TIM) configured to determine a current date (DCOUR) supplied by a clock (HA) in the time system (TAB),
a position module (DPO) configured to determine a temporal position (POS) of megaframe MFn relatively to said pulses from a megaframe temporal position determined relatively to the date (DREF),
an insertion module (INS) configured to insert, into the formatted stream (TS_SFN 1 , TS_SFN 2 ), synchronisation packets (MIP) comprising a content determined from said temporal positions (POS).
10. System according to claim 9 , wherein the time system (TAB) is a system of absolute time.
11. System according to claim 9 , wherein the clock (HA) is a clock supplied by a GPS receiver.
12. System according to claim 9 , wherein the clock (HA) operates according to the Network Time Protocol.