Method for synchronization adaptation of asynchronous digital data streams

• US 7,035,215 B1
• Filed: 06/30/2000
• Issued: 04/25/2006
• Est. Priority Date: 01/02/1998
• Status: Expired due to Fees

• Current Assignee: Nokia Networks (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Engdahl, Tomi
• Primary Examiner(s): LEE, CHI HO A
• Application Number:
  US09/608,667
• Time in Patent Office: 2,125 Days
• Field of Search: 370/235, 370/412, 370/465
• US Class Current: 370/235
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04L 2012/5616 Terminal equipment, e.g. codecs, synch.
• CPC Class Codes: H04L 2012/5671 Support of voice
• CPC Class Codes: H04L 2012/5674 Synchronisation, timing recovery or alignment
• CPC Class Codes: H04L 2012/5681 Buffer or queue management
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

The present invention proposes a method for synchronization adaptation of asynchronous digital data streams comprising the steps of providing a first digital data stream (PCM_IN) at a first sample rate (CLK_—1); inputting said first digital data stream (PCM_IN) to a sample rate conversion means (SRC); supplying data output from said sample rate conversion means (SRC) to a processing element (BUFFER); storing said supplied data into said processing element (BUFFER); and outputting said data stored in said processing element as a second digital data stream (PCM_OUT) at a second sample rate (CLK_—2), with said first and said second sample rates (CLK_—1, CLK_—2) being different from each other; and is characterized by the further steps of detecting a state (BUFFER_STATUS) of said processing element (BUFFER); and controlling said sample rate conversion means (SRC) dependent on the detected state of said processing element. The present invention also proposes a device for synchronization adaptation of asynchronous digital data streams, operating according to such a method.

Claims

1. A method for synchronization adaptation of asynchronous digital data streams comprising the steps of:

providing a first digital data stream at a first sample rate;

inputting said first digital data stream to a sample rate conversion means;

supplying data output from said sample rate conversion means to a processing element;

storing said supplied data into said processing element; and

outputting said data stored in said processing element as a second digital data stream at a second sample rate, with said first and said second sample rates being different from each other;

detecting a state of said processing element;

controlling said sample rate conversion means dependent on the detected state of said processing element; and

reducing and/or increasing a number of data samples contained in the data output by said sample rate conversion means and supplied to said processing means is randomized in time within the data stream, such that a position within a group where a sample is to be removed and/or to be added is randomly selected.

2. A method for synchronization adaptation of asynchronous digital data streams according to claim 1, wherein

said state of said processing element represents the amount of data currently stored in said processing element.

3. A method for synchronization adaptation of asynchronous digital data streams comprising the steps of:

providing a first digital data stream at a first sample rate;

inputting said first digital data stream to a sample rate conversion means;

supplying data output from said sample rate conversion means to a processing element;

storing said supplied data into said processing element;

outputting said data stored in said processing element as a second digital data stream at a second sample rate, with said first and said second sample rates being different from each other;

detecting a state of said processing element said state of said processing element represents the amount of data currently stored in said processing element;

controlling said sample rate conversion means dependent on the detected state of said processing element;

comparing a current amount of data stored in said processing element with a lower limit and an upper limit of respective admissible data amounts stored in said processing element; and

setting said state of said process element to a first value in case the detected actual amount of stored data exceeds the upper limit, to a second value in case the detected actual amount of stored data is below the lower limit, and to a third value in case the detected actual amount of stored data is found to be between the lower limit and the upper limit.

4. A method for synchronization adaptation of asynchronous digital data streams according to claim 3, wherein said controlling step controls said sample rate conversion means to be enabled if said detected state has said first value or said second value, and to be disabled if said detected state has said third value.

5. A method for synchronization adaptation of asynchronous digital data streams according to claim 3, wherein said controlling step comprises the steps of:

reducing the number of data samples contained in the data output by said sample rate conversion means and supplied to said processing means if said state has said first value,

increasing the number of data samples contained in the data output by said sample rate conversion means and supplied to said processing means if said state has said second value, and

leaving the number of data samples contained in the data output by said sample rate conversion means and supplied to said processing means unchanged if said state has said third value.

6. A device for synchronization adaptation of asynchronous digital data stream, comprising:

a sample rate conversion means to which is input a first digital data stream at a first sample rate;

a processing element for storing data output from said sample rate conversion means, and for outputting said data stored in said processing element as a second digital data stream at a second sample rate, with said first and said second sample rates being different from each other;

a detection means for detecting a state of said processing element;

a control means for controlling said sample rate conversion means dependent on the detected state of said processing element; and

means for reducing and/or increasing a number of data samples contained in the data output by said sample rate conversion means and supplied to said processing means is randomized in time within the data stream, such that a position within a group where a sample is to be removed and/or to be added is randomly selected.