Program unit, particularly for digital, data-compressed video distribution signals

• US 6,205,144 B1
• Filed: 12/31/1997
• Issued: 03/20/2001
• Est. Priority Date: 07/18/1995
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Mohrmann, Karl Heinz
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): BOAKYE, ALEXANDER O
• Application Number:
  US08/981,748
• Time in Patent Office: 1,175 Days
• Field of Search: 370/395, 370/503, 370/521, 370/529, 370/465, 370/486, 370/487, 370/428, 348/7, 348/12, 359/158, 359/137
• US Class Current: 370/395.64
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 2012/5616 Terminal equipment, e.g. codecs, synch.
• CPC Class Codes: H04L 2012/5674 Synchronisation, timing recovery or alignment
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

For the transmission of ATM digital signals of a program unit, particularly of digital, data-compressed video distribution signals, from a remote digital signal source, particularly a video server, via a head station of a light waveguide and/or coaxial line tree network respectively shared by a plurality of subscriber-side network termination units to at least one of the subscriber-side network termination units, whereby an intermediate storing of such ATM digital signals transmitted with elevated data rate occurs in the head station, the program unit is transmitted from the digital signal source to the intermediate memory of the head station with a data rate that is slightly elevated compared to the data rate nominally required for the program unit and that is retained for the entire duration of the transmission, the data stream being further-transmitted therefrom to the respective subscriber with the signal clock nominally required for the program unit that is offered by a reference clock source; the reference clock(s) is (are) thereby separately transmitted at any rate from the head station to all network termination units connected to the light waveguide and/or coaxial line tree network, whereat the digital signal acquired from the received ATM cells is thus time-regenerated.

Claims

1. A method for transmission of ATM digital signals of a program unit comprising digital data-compressed video distribution signals from a remote digital signal source comprising a video server via a head station of a light waveguide or coaxial line tree network to at least one of a plurality of subscriber-side network termination units being fed by the network, comprising the steps of:

temporarily intermediately storing ATM digital signals in a buffer memory of the head station, the program unit being transmitted in a data stream from the digital signal source to the buffer memory of the head station with a data rate which is elevated compared to a data rate nominally required for the program unit and which is retained for an entire duration of the transmission;

further transmitting the program unit in a data stream from the buffer memory to the respective subscriber termination unit with a reference clock provided by a reference clock source and at said nominally required data rate employed for the program unit; and

separately transmitting the reference clock from the head station to the respective network termination unit connected to the light waveguide or coaxial line tree network so that the digital signals acquired from received ATM cells is time-regenerated.

2. The method according to claim 1 including the step of transmitting the reference clock in the form of pilot signals from the head station via the light waveguide or coaxial line tree network to all network termination units connected thereto.

3. The method according to claim 2 including the step of directly deriving a frequency of the reference clock from a pilot frequency transmitted to the subscriber-side termination units via the light waveguide or the coaxial tree network in a region that is not spectrally used in some other way.

4. The method according to claim 3 including the step of operating the pilot frequencies with the required reference clock frequencies in the form of whole-numbered parts or multiples.

5. The method according to claim 2 including the step of determining pilot frequencies which are not numerically linked with reference clock frequencies and modulating carriers of the pilot frequencies which are not numerically linked with the reference clock frequencies.

6. The method according to claim 1 wherein the network connecting to the head station comprises a light waveguide network or coaxial line tree network.

7. A method for transmission of ATM digital signals of a program unit comprising digital data-compressed video distribution signals from a remote digital signal source via a head station of a tree network to at least one of a plurality of subscriber-side network termination units being fed by the network, comprising the steps of:

temporarily intermediately storing ATM digital signals in a buffer memory of the head station, the program unit being transmitted in a data stream from the digital signal source to the buffer memory of the head station with a data rate which is elevated compared to a data rate nominally required for the program unit;

further transmitting the program unit in a data stream from the buffer memory to the respective subscriber termination unit with a reference clock provided by a reference clock source and at said nominally required data rate employed for the program unit; and

transmitting the reference clock from the head station to the respective network termination unit connected to the tree network so that the digital signals acquired from received ATM cells is time-regenerated.